Browsing by Subject "Broiler"

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DIE BEDEUTUNG DER LAUFAKTIVITÄT UND DER GEWICHTSENTWICKLUNG BEI DER ENTSTEHUNG VON BEINSCHÄDEN BEIM MASTGEFLÜGEL
(2006) Djukic, Mirjana; Bessei, Werner
Within the last 50 years, an intensive selection took place in broilers on high growth and therefore there exists a clear reduction of the age at slaughter. Side effects of the selection of faster and higher growth are leg disorders. RUTTEN et al. (2002) tried to reveal the causal relations between weight load, activity and leg disorders by reducing the weight load on legs of fast growing broilers (FB) by a special device. The weight reduced FB showed higher locomotor activity and better bone quality. However, the harness used for the reduction of weight load on the legs impaired the growth rate. In the present study, the experiment of RUTTEN et al (2002) was repeated with an improved device for reduction of weight load of FB. In addition, slow growing broilers (SB) were used, and were brought to the same weight load as weight reduced FB by additional load. In total three experiment were carried out. The first experiment was split in two parts (1a and 1b) so as to incrase the number of replicates. For each experiment, 24 male broilers were used: 12 FG (ROSS 308) and 12 SB (ISA S 257). Load reduced birds weared a harness which was connected to the load reducing device. The load increase of SB weared the same harness with small pieces of led. The chicks of the groups were treated as follows: one with harness and suspension (HS), one with a harness and without suspension ? control bird 1 (C1) and a control bird with no harness and no suspension ? control bird 2 (C2). The load of FB was reduced to the average weight of SB-C2 and FB C2. The load of the SB was increased to the same average value. The following parameters were recorded: body weight, food consumption, weight of breast muscle, thigh, tibiotarsus, femur; length of tibiotarsus and femur; angular deformity of distal femur, distal and proximal tibiotarsus; torsional deformity of femur and tibiotarsus, total area, total density, Corticalis area, Corticalis density, SSI, walking, sitting, standing, eating and ?other behavior?. The weight load reduction in FB led to a significant increase of the locomotor activity. Both the torsional and angular deformities of the Tibiotarsus were clearly reduced, while total area, total density, Corticalis area and SSI were increased. It can be assumed that this was caused by the higher locomotor activity of load reduced FB. The increase of load in the SB diminished the locomotor activity but bone characteristics were not deteriorated. The improvement in the bone conditions of the FB was obviously caused by the increase in activity. In order to determine the influence of decreased load in FB and of increased load in SB the opportunity to move was restricted by reduction of the length of the compartments from 2 to .45 meters. All other experimental conditions remained the same as in experiment 1. Despite the restricted space there was a significant increase in locomotor activity of the load reduced FB. The torsion and angular deformity of the proximal and distal angular deformities of the Tibiotarsus were reduced. There was no significant effect of the increase and decrease of load on the CT-criteria. As in experiment 1, the weight load in the SB diminished the locomotor activity, but the bone characteristics were not influenced significantly. In the third experiment the gait of the load increased SB and load decreased FB was analyzed by a foot print program. For this purpose the length and width of the steps were measured at 4, 5 and 6 weeks of age. The same breeds and the same technique of the modification of the load were used. The load treated birds were kept individually and could use the full length of the test pens. In contrast to the previous experiments the control birds were kept in pens of 1 m² floor space (1 x 1 m). Only the birds without harness (C2) were kept as control. The results of the morphometric and CT- criteria confirmed the results. The FB control birds showed higher step length and greater step width than SB controls. The step length of FB was increased through the load reduction, and decreased through load increase in SB. The treatment had no influence on the step width. SB broilers showed problems to keep their balance under increased weight load. As indicated in the low width of the foot prints the load increased SB broilers tried to place their feet, as usual, under the point of gravity of their body. This seems to impair the stability of gait under increased weight load. FB in contrast, move their centre of gravity above the supporting leg which allows a stable gait under high load. FB did not change the width of their foot prints when the load was decreased, and only the length of the steps increased. The results underline the importance of locomotor activity on the leg conditions of FB. They clearly show that low activity of FB is not caused by lack of motivation but by the high weight load.
Bestimmung des Verknöcherungsverlaufs des Brustbeins von schnell und langsam wachsenden Masthühnern
(2007) Schmid, Britta Ariane; Grashorn, Michael
According to EU marketing regulations for poultry chicken carcasses have to be marketed either as ?young chicken with a flexible breastbone processus? or as ?chickens with a rigid breastbone processus? due to their age at slaughter. Market prices of meat form young chickens are manifold higher than for old ones. Meanwhile, extensive (especially organic) broiler meat production has increased. As in these production systems age at slaughter has to be at least 81 days the question arises whether the breastbone processus is yet not ossified. Up to now the knowledge on the development of the breast bone in chicken is limited. More extended information is only available for bones of extremities. The objective of the present study was, therefore, to investigate the ossification process of breastbones in fast and slow growing broiler strains between first weeks of life and sexual maturity. Visual assessment and assistant characteristics (metric measurements, computerized tomography, chemical composition) of the breastbone and the Os coracoideum, should be applied to analyze the course of ossification. In total, 1000 fast growing broilers of the breed Ross 308 and 1000 slow growing broilers of the breed Isa S 457 were reared for this experiment under standard conditions in a temperature controlled poultry house. Finally, 480 chickens of each breed were used for determination of the breastbone characteristics. Starting with week 4, 12 cocks and 12 hens of each breed were slaughtered weekly until week 23 of life. Life weight and weight of breast meat were recorded besides breastbone characteristics. The breastbone was completely removed and its weight, as well as numerous measures of the breastbone were recorded: Breastbone weight (BBG), Breastbone length (L), Width between the Proc. craniolaterali (BPC), Width between the Trab. intermediae (BTI), Width between the Trab. lateralis (BTL), Length of the Trab. intermedia (LTI), Length of the Trab. lateralis (LTL), Length and width of the Inc. medialis (LIM and BIM), Length and width of the Inc. lateralis (LIL and BIL), Height at Rostrum (HR), Heigth of breastbone keel at 50% of total length (HK), Cartilage length of the Trab. mediana (LC), Relationship between LC and L, Weight of cartilage of the Trab. mediana (GK) and Relationship between GK and BBG. Furthermore, the Os coracoides were removed as bones of reference. Computerized tomography (pQCT) scans were taken at special reference points from 10 randomly sampled breastbones and their Os coracoids of each genotype and gender. The reference points of the breastbone were located at 33% and 66% of total length, whereas, the reference points of the Os coracoides were located at 50% of total length. Total area, Total density, Cortical area, Cortical density as well as SSI were measured by pQCT. Furthermore, photos were taken of characteristic breastbones from each gender and breed and 6 breastbones of each breed and gender were analyzed for contents of dry matter, ash, calcium and phosphorus. Fast growing broilers reached higher life weights and breast muscle weights than slow growing broilers. While weight differences between cocks and hens of the fast growing strain diminished at the end of the experiment, slow growing broilers still showed distinct weight differences between genders in week 23. The breastbone dimensions reached their final values at different times. Determination of breastbone characteristics by metric measurements of dimensions, by computerized tomography and by chemical analyses showed clearly that the ossification process of breastbones of hens is faster than for cocks. This was also reflected by the relations Cartilage length of the Trab. mediana (LC) / breastbone length (L) and Weight of cartilage of the Trab. mediana (GK)/ breastbone weight (BBG). Both indices were higher in males than in females. Breastbones of Ross 308 hens are ossified faster than of Isa S 457 hens. In general, most breastbone parameters differed between breeds. The development of the dry matter content of the breastbone was not finished till the end of week 23. The storage of inorganic material (ash, calcium and phosphorus) showed breed specific differences at the beginning of the experiment, but during the experiment the increase of inorganic material in breastbones was higher for hens than for cocks. The breastbone of a newly hatched chicken consists completely of cartilage and ossification started immediately after hatch from a central ossification centre to caudal and to cranial. Further ossification centres existed at the lateral Trabeculae. The ossification of the lateral Trabeculae progressed independently of the ossification of the breastbone processus. In the present investigation the direction of ossification to the caudal end of the breastbone processus was of special interest. The central ossification centre showed up in the front keel range of the breastbone. With the sprouting of blood vessels and increased metabolic activity the colour of the centre turned to deep red and spread to cranial and caudal. During the proceeding ossification process due to pneumatisation the deeply red coloured areas turned to bright and finally transparent, especially in the front of the breastbone. The results from computerized tomography of breastbones confirmed the visual observations of the ossification of the breastbone processus. Obviously, the ossification process of the breastbone needs a large time frame and ossification seems to be a multilayered process. The increase in breastbone dimensions is paralleled by an increased storage of inorganic material. The weight of the breastbones was decreasing with increasing age due to the reduction of the water content during the process of pneumatisation. The breastbone processus was not completely ossified in fast and slow growing broilers up to the end of the experiment (week 23 of life). The results on the ossification process in fast and slow growing broiler breeds clearly revealed that a prolongation of the fattening process does not affect marketing of broiler meat from extensive production. The breastbone processus is not fully ossified at the normal slaughter age of 81 to 84 days. But, the results also indicated that a more clear definition of the term ?ossified breastbone processus? is necessary as the breastbone is still not fully ossified on start of laying in hens.
Bone ash data in the context of phosphorus and phytase evaluation in poultry
(2021) Künzel, Susanne; Rodehutscord, Markus
Phosphorus (P) is an essential element that is crucial for various metabolic processes in the body of animals and humans. To keep the animals healthy and to obtain food products rich in nutrients, an adequate P supply is indispensable. Plant feedstuffs, the main components of poultry diets, contain P in a form that is only partially available to poultry. For this reason, poultry diets are often supplemented with mineral P. However, global rock phosphate reserves, where mineral P is mined from, are limited. Additionally, excessive P supply should also be avoided because of the environmental impact of P accumulation in the soil. Consequently, P supply not exceeding the requirements of poultry is essential to ensure animal wellbeing and to protect the environment. In order to feed diets with adequate concentrations of P, it is necessary to have suitable approaches for the determination of available P in the animal. The availability of P varies widely between feed components and it is also influenced by feed supplements and other factors. Bone ash analysis is an often-used tool to evaluate the relative bioavailability of P since a high amount of P is stored in the bones. A standard assay for bone ash analyses has never been agreed on. Therefore, many different approaches are described in the literature with an unknown impact on the results of P bioavailability studies. The main objective of the present thesis was to examine the suitability of bone ash data for the evaluation of available P in poultry with emphasis on methodological aspects. Therefore, different studies with broiler chickens and Japanese quail were conducted. The experiments comprised various aspects related to P availability in poultry. The effect of feed supplements in the form of phytase products, myo-inositol and a coccidiostat were evaluated. Furthermore, quantitative genetic analyses were performed. All experiments had in common that tibiotarsus (tibia) or foot ash data or both were used for the examination of the relative bioavailability of P. Based on the data that accrued during the studies described in the four manuscripts of this thesis, comprehensive methodological analyses were performed. The tibia and foot were compared regarding their appropriateness as a trait for the evaluation of the relative bioavailability of P by using bone ash data. The relationship between the two traits was investigated, as well as the relationship between foot or tibia ash and quantitative P measurements. Additionally, P concentration in the ash of both bone fractions was analysed and compared. Results indicated only minor differences between tibia and foot ash data. No clear preference for one of them could be deduced from the data. The left and right feet of broiler chickens were compared in terms of both ash concentration and total ash amount. Significant differences between the two feet of the same animal were detected for both traits. Consequently, not only the choice of the bone fraction but also of the body side should be considered when sampling for bone ash data. Ash data are mostly expressed as a concentration of the dry matter content of the bone. Also possible is the use of the absolute ash amount. The relationship of both ways of expression with traits of quantitative P measurements was analysed by using correlation coefficients and regression analyses. Results showed that the absolute ash amount was at least as suitable as ash concentration but has the advantage that it is easier to determine. Possible selection procedures for animals for bone ash analyses were simulated with data from two of the experiments. Often it is not possible to use all animals involved in an experiment for bone ash analyses. Therefore, the influence of sampling frequency and selection method on the outcome of P availability studies was evaluated. Results indicated that the number and selection method of animals for bone ash data might influence the results. However, it was not possible to recommend a specific selection method based on the obtained results. Estimates of heritability and genetic correlations showed the suitability of bone ash data as a proxy trait for P efficiency breeding of poultry. The absolute amount of bone ash data appeared to be most promising for this purpose. Bone ash data are a very useful and easy to determine trait to estimate the relative bioavailability of P. However, investigations performed in this thesis showed the importance of a careful selection of methods. A standardised assay would be helpful to obtain meaningful and more comparable estimates of relative P bioavailability.
Comparison of effects of Echinacea purpurea juices and Nigella sativa seeds on performance, some blood parameters, carcass and meat quality of broilers
(2009) Nasir, Zahid; Grashorn, Michael
Use of phytogenic substances in animal production is increasing due to their beneficial effects on feed digestion, promotion of production performance and improving product quality. They contain a number of pharmacologically active substances which have shown their activities in different body systems and, therefore, they are considered as one viable alternative to in-feed antibiotics. Presence of a variety of active ingredients indicates that phytogenic substances may have affects on different metabolic pathways, activity of different enzyme systems, immunity and performance parameters. Especially, improvement of immunity may help birds to cope in a better way with stress situations during fattening and by this may enhance well-being as well as quality of products of animal origin. Echinacea purpurea (EP) and Nigella sativa (NS) belong to the group of phytogenic substances that have been reported to stimulate immune system in laboratory trials as well as in human studies. Positive effects of EP and NS have been observed in a number of in vitro and in vivo experiments, which show that their application in poultry can be beneficial for maintaining health, improving immunity and performance parameters. However, no study was conducted to evaluate the comparative as well as synergistic effects of EP juices and NS seeds on broiler health, performance and activities of different enzymes related to heart and liver functions. The objectives of this thesis were set to investigate the effects of EP juices and grounded NS seeds on performance, metabolism (serum protein, blood picture and some liver and heart associated enzymes in blood), carcass and meat quality in broilers (Ross 308). For this purpose five preliminary trials were performed to investigate the effects on bird?s metabolism. Fattening trial was carried out to study the comparative and synergistic effects of EP juice and NS seeds on performance, carcass and meat quality. Three preliminary experiments were performed using two different preparations of EP juices; EP-F (EP fermented juice) and EP-A (EP juice on alcohol basis). Initially, effects of EP-F and EP-A were compared along with testing different dose levels. EP juices were orally supplemented intermittently for a 3 days (1-3, 13-15 and 25-27), followed by 9 days without EP application. Comparing the effects of EP-F and EP-A, better performance and improved health was observed by application of EP-F juices. Application of 0.25 ml/kg BW0.75 EP-F juice has shown more positive effects as compared to other treatment levels. EP-F treated birds showed significantly better average daily weight gain and significant improvement of serum globulins, indicating beneficial treatment effect on broiler performance as well as immunity. Levels of serum CK were significantly reduced in EP-F treated birds as compared to control, which shows that EP-F posses the potential to reduce incidence of mortality related to dysfunction of the cardio-vascular system in broilers. Two preliminary experiments were performed using grounded NS seeds. In first experiment different levels (0, 0.5, 1.0, 1.5, 2.0, and 2.5 %) of NS seeds were supplemented in basal broiler diets. 1 % NS was found to be most suitable, which was used in second experiment against a negative control. Numerically better FCR during starter phase was obtained by application of 1 % NS seeds, but these effects were decreased during grower phase. Less number of mortalities was observed in NS treated birds as compared to control. In the fattening trial, four treatment combinations were tested as: control (without any feed or water additive), E (drinking water intermittently supplemented with EP-F), N (feed supplemented with NS seeds) and EN (drinking water intermittently supplemented with EP-F and feed supplemented with NS). The results showed that application of EP-F as well as NS has no negative effect on broiler performance, carcass and meat quality. Birds performed to their maximum potential and supplementation of EP-F and NS helped birds to perform better. Combined application of EP and NS resulted in reduced mortality and numerical improvement in weight gain and feed consumption, significantly (P<0.05) higher meat CP as compared to E and N treatments. In general, a synergistic positive effect of simultaneous application of EP and NS was observed on performance, carcass and meat quality in broilers. Based on these results, it can be concluded that intermittent application of EP-F and continuous application of NS seeds has no negative effect on broiler performance, carcass and meat quality. Beneficial effects of Echinacea supplementation on broiler performance, health and immunity can be obtained by intermittent application of EP-F through drinking water. Combined application of EP-F and NS seeds has shown a trend of improved broiler performance and meat quality, which indicate synergistic effects of active ingredients of both phytogenic compounds.
Dose Titration, Tolerance and Compatibility of some Feed Additives in Broiler
(2005) Islam, Khan Md. Shaiful; Drochner, Winfried
In two dose titration studies on chicken for fattening growth promoting efficacy and some aspects of safety of fumaric acid (FA), an approved preservative, and humic acid (HA), approved as veterinary drug, were examined. In a third experiment on chicken for fattening the compatibility of the ionophore coccidiostat semduramicin (AVIAX®), also approved at EU level, with the veterinary antibiotic tiamulin should be investigated. In experiment 1 six diets with increasing FA contents were fed for 26 days to 96 newly hatched male chicks per treatment. Final body weight (feed efficiency) amounted to 1,506 (756), 1,597 (767), 1,532 (754), 1,485 (759), 1,342 (738), and 1,378 g (747 g gain kg-1 feed) for the groups with 0, 1.25, 2.50, 3.75, 5.0, and 7.5 % FA, respectively. The 1.25 % FA group showed significantly (p<0.05) better weight gain than all other groups and better feed efficiency than the groups with 5.0 and 7.5 % FA. Body weight of the 5.0 and 7.5 % FA groups was significantly lower than that of the other groups. The relative organ weight was not affected by the treatment. In experiment 2 six diets containing 0, 0.3, 0.6, 1.2, 2.4, and 4.8 g Huminfeed® (74 % humic acid in DM) kg-1, respectively, were fed for 35 days to 80 newly hatched male chicks per treatment. Initially HA depressed weight gain, but recovery started in the third week, so that at the end no significant differences could be observed. But body weight gain was negatively correlated with the HA content of the diets (y (weight gain) = 2327.98 ? 0.0181x (Huminfeed content), r = -.280*). Feed intake was not affected by the treatment. The relative organ weights did not differ among the groups. Experiment 3 (35 days) with a total of 320 female broilers chicks was conducted to study the effect of 25 mg semduramicin kg-1 feed and the potential interference between semduramicin and tiamulin on zootechnical parameters (10 replicates with 8 chicks each), haematology, blood routine biochemistry and health status (1 chick per replicate). Tiamulin medication (250 mg L-1 water) from day 15 to 19 reduced significantly water intake, especially when concurrently given to birds fed semduramicin. Also feed intake was depressed in that period. Body weight gain of the semduramicin/tiamulin group in the third week was affected too. After 35 days, body weight (feed efficiency) was 2,062 (665), 2,067 (669), 2,084 (678), and 2,008 g (679 g gain kg-1 feed) for the control, the tiamulin, the semduramicin and the semduramicin/tiamulin group, respectively. All data obtained form haematology, blood biochemnistry ad pathology did not give evidence for any adverse influence of the coadministration of tiamulin and semduramicin. After a withdrawal period 20 broilers from the control and the semduramicin group were slaughtered and examined for product quality. No treatment effects (P>0.05) on hot carcass weight, viscera, dressing percentage, edible portions (breast muscles, haunch), fat and skin portions were seen. Also the sensory characteristics (juiciness, tenderness, unpleasant pungent aroma, general impression) except the aroma/flavour were not influenced by the treatment.
Effect of sodium and potassium chloride supplementation in drinking water on performance of laying hens and broilers under high ambient temperature
(2008) Nguyen Van, Dai; Bessei, Werner
It is well known that water intake and maintenance of electrolyte balance play a vital role in the resistance of chicken to high temperature. It was hypothesis that voluntary water intake in response to heat stress may not be sufficient to prevent the reduction of performance in laying hens and broilers, and that stimulation of water intake through supplementation of electrolytes in drinking water may assist the birds to maintain high productivity under heat stress. The present study includes three experiments. Two experiments were carried out with laying hens in controlled ambient temperature conditions to study the effects of sodium chloride (NaCl) and potassium chloride (KCl) supplementation in the drinking water on water intake, feed intake, egg quality, body temperature, body weight and productivity of laying hens under high temperature. The third experiment with broilers was conducted in tropical summer conditions of Viet Nam to find out whether supply NaCl and KCl in drinking water would improve productivity and carcass quality of broilers under tropical summer conditions and which concentration of both minerals should be used. The first experiment was conducted for three weeks (from 26 March to 16 April 2007) at the research station of Hohenheim University, Germany. A total of 48 Hisex hens (76 weeks old) were kept in individual laying cages in climatic chambers and were randomly allocated to three experimental groups of 16 hens each. These groups were given 0; 0.2 and 0.4 % KCl in the drinking water for seven consecutive days of heat stress. Before and after heat stress, birds were given normal drinking water. Water and feed were provided ad libitum. The birds were fed a layer diet containing 11.45 MJ/kg Metabolizable Energy, 16.97 % Crude Protein, 3.73% calcium, 0.62% phosphorus, 0.22% sodium and 0.33% chloride. The room temperature was constant at 21±1°C for 7 days, afterwards, it was cycled from 21±1°C to 34±1°C (from 9 to 22 o?clock) for 7 days, and then constant at 21±1°C for 7 days. Humidity was not controlled. 14-hours lighting schedule was maintained during the experiment. Water and feed intake, water: feed ratio, body weight, body temperature, egg production, egg weight, egg shell thickness, egg deformation, egg shell strength, yolk colour and Haugh Unit (HU) were recorded. In the second experiment, effect of NaCl supplementation (0.2 and 0.4%) in drinking water on laying hens was tested under the same temperature program as in the first experiment. A total of 48 Hisex hens (80 weeks old) were used. The third experiment was carried out on the commercial chicken farm from 26 June to 14 August 2007 (49 days). A total of 240 21-day-old broiler chicks (Lohmann meat) were randomly allocated to 5 treatment groups in a randomized block design. Each treatment consisted of three replicates of 16 chickens each. Both, NaCl and KCl, were supplemented from the beginning of the 4th to 7th weeks of age at 0.2% and 0.4% to drinking town water, and unsupplemented water was used as control. The birds were kept in an open sided poultry house on the rice hull litter. Temperature and humidity of the house were not controlled. Water and feed intake were measured weekly. Body temperature of 15 birds per treatment was measured at 23, 33 and 40 day of age. All birds was individually weighed on day of hatching and afterwards at weekly intervals up to 7 weeks of age. At 49 days of age, one male and one female bird from each replicate (a total of 30 birds) were slaughtered to determine carcass characteristics. The results showed that in laying hens, heat stress increased water intake, water to feed ratio, body temperature and eggshell defects. Feed intake, egg production and egg weight decreased tendentiously during heat stress. Body weight, eggshell thickness, eggshell strength, egg deformation, yolk color and HU were not significantly affected by heat stress. Supplementation of KCl or NaCl in drinking water increased water intake and water: feed ratio. Only KCl supplementation maintained body weight, egg weight and egg production, and decreased eggshell defects. Feed intake, eggshell deformation, yolk color and HU were not significantly affected by either KCl or NaCl supplementation. The results showed that KCl supplementation through drinking water may be a means to maintain egg production and egg quality which are usually deteriorated when the temperature in the layer house increases while NaCl was less effective under these conditions. Supplementation of KCl or NaCl in drinking water enhanced water intake and water: feed ratio of broilers under tropical summer conditions. 0.4% NaCl supplementation in drinking water reduced body temperature, increased body weight, improved feed conversion ratio (FCR) and decreased abdominal fat while feed intake was not affected by both NaCl and KCl supplementation. Therefore, 0.4% NaCl added in drinking water may be a means to improve productivity of broiler under high temperature. 0.4% KCl supplementation increased thigh meat, and improved FCR. However, carcass percentage was reduced by KCl supplementation. Therefore, in the tropical summer conditions, higher levels of KCl concentration and economic aspect should be further studied. It was not clear whether the beneficial effects of KCl and NaCl supplementation in drinking water was caused by the cooling effect of the increased water intake and/or the maintenance of electrolytes balance.
Effects of strain, lifespan and dietary myo-inositol sources on poultry metabolism
(2020) Gonzalez Uarquin, Duvan Fernando; Huber, Korinna
Poultry production has shown a significant increase during the last decade. Meat and egg industry rapid growth implicates accelerating metabolic rate and general performance of birds. To maintain a high level of production, several strategies to achieve optimal raising and feeding have been implemented. Previous studies demonstrated the importance of MI metabolism on animal physiology; however, at present there is a substantial lack of information about the roles of MI and its metabolism in poultry. For instance, no information is available about MI concentration in organs of poultry. Moreover, it remains no elucidated, which are the effects of dietary sources of MI such as dietary phytase or pure MI supplementation. This thesis focused on gaining a comprehensive understanding of the potential roles of strain, productive period, and dietary sources of MI on poultry metabolism. To obtain the state of the art research on MI metabolism and its dietary sources in poultry, a comprehensive review of dietary MI was written (manuscript 1, chapter 3). This review revised information about MI in poultry such as feed sources, transport and cell metabolism, physiological meaning, and the influence of dietary MI in poultry. The revision indicated that MI appears to play critical roles in several different metabolic pathways so that understanding them could be an essential approach for future research in poultry. The second study was performed to study the effects of phytase and pure MI supplementation on the metabolite profile of broilers (manuscript 2, chapter 3). It was observed that phytase supplementation affected differently the metabolite profile than the supplementation of pure MI. Metabolites affected by phytase comprised several groups of metabolites such as acylcarnitines, phosphatidylcholines, sphingomyelins, lysophosphatidylcholines, and biogenic amines, whereas pure MI supplementation increased plasma concentrations of dopamine and serotonin. The third study was performed to get preliminary information about the effects caused by dietary phytase on systemic MI on the gastrointestinal tract, blood, and organs MI of broiler chickens (manuscript 3, chapter 3). Supplementation of 1500 FTU phytase/kg feed increased plasma and kidney MI concentrations. Plasma MI correlated negatively with InsP6 and positively with intestinal MI concentrations. A fourth study gave a general description of MI concentrations and general metabolite profile during the productive life of Lohmann Classic Brown and Lohmann LSL Classic laying hens. It was found that productive period affected MI and MI key enzymes expression. Moreover, the analyses showed differences in metabolite profiles being the onset of egg production, a determinant point. Differences were attributed to different groups of metabolites such as amino acids, biogenic amines, phosphatidylcholines, lysophosphatidylcholines, and sphingomyelins. The above mentioned, indicated each strain could express different MI concentrations and metabolite profiles during distinct productive periods what should be considered to future interventions. To conclude, findings from these investigations suggested intrinsic traits such as breed and stage of production and diet could affect MI and MI key enzymes expression as well as metabolite profiles. Future studies are needed to establish the roles of MI on poultry metabolism.
Entwicklung und ernährungsphysiologische Bewertung mikrobieller Hybrid-Phytasen
(2023) Metten, Alexander; Rodehutscord, Markus
To degrade the organic phosphate storage in the best possible way, it is necessary to increase phytase efficiency in vivo. Both a better understanding of the influencing factors limiting phytate degradation in vivo and a continuous improvement of the biochemical properties of phytases to be best adapted to the conditions in the digestive tract of non-ruminants will help to achieve this. Therefore, the main objective of this work was the generation of a large number of sequentially unique hybrid phytases by directed recombination of known phytase genes with the goal to achieve improved biochemical properties compared to the wild-type phytases used. The focus of this work was the biochemical and nutritional evaluation of the newly generated hybrid phytases with respect to their suitability as feed supplements. All hybrid phytases examined showed more efficient InsP6 degradation at pH 3.0 than at pH 5.5, although the phytase activity supplemented was the same at both pH values. While InsP6 was dephosphorylated to InsP1-2 in many cases at pH 3.0, accumulation of the Ins(1,2,5,6)P4 isomer occurred at pH 5.5. In an in vitro model simulating the digestive tract of broilers, hybrid phytases with high sequential homology to the E. coli and C. braakii phytase showed high accumulation of InsP4 isomers. Interestingly, these phytases preferentially formed the Ins(1,2,5,6)P4 isomer. In contrast, other hybrid phytases were able to degrade all InsP4 isomers and in some cases high InsP2 concentrations were observed. Another in vitro experiment with a complex feed matrix consisting of soybean meal, rapeseed meal, and wheat with a high mineral content, illustrated the negative influence of certain feed-related factors on phytase efficiency. InsP6 present in the feed was significantly less degraded by all phytases used compared to a corn and soy-based feed matrix with a low mineral content. While a hybrid phytase was able to completely dephosphorylate the InsP6 of the corn and soy-based feed matrix down to the InsP3 isomer resulting in high InsP2 concentrations, the InsP6 were still detectable in the in vitro model with the more complex feed matrix and high mineral content, despite identical reaction conditions. In a final feeding trial with broilers, one of the hybrid phytases was supplemented at two doses each (500 and 1500 FTU/kg) to evaluate its suitability as a feed supplement. Also, a commercial phytase was included in the study design at the same doses setting the benchmark for phytase efficiency. A low phosphorus experimental feed based on corn and soybean meal was used. The supplementation of the used hybrid phytase resulted in a dose-dependent increase in broiler performance data such as daily weight gain, feed intake and significantly improved feed efficiency compared to the basal ration without enzyme supplementation. In addition, foot ash content was increased by 21.6% at a dose of 1500 FTU/kg phytase, indicating significantly improved bone mineralization due to the released InsP6 phosphate. By analyzing InsP6 concentration and its degradation products in different segments of the digestive tract, efficient InsP6 degradation was observed. In contrast to the in vitro experiments, no accumulation of InsP3-4 isomers could be detected in crop, gizzard or small intestine. In addition to a high exogenous phytase activity, this result also suggests a high endogenous phytase as well as phosphatase activity in the digestive tract of broilers. It can be assumed that the absence of monocalcium phosphate in the experimental rations may have induced the expression of endogenous phytases and phosphatases. This assumption is confirmed by the high precaecal InsP6 degradation, which was 63.5% in the basal ration without phytase supplementation. Nevertheless, the used hybrid phytase significantly increased the precaecal InsP6 degradation to 76.3%. The high phytase efficiency was also reflected in the measured precaecal phosphorus digestibility, which was increased by 6.8% compared to the basal ration. The commercial phytase used showed comparable improvement in broiler performance data to the non optimized hybrid phytase. This project demonstrated the development of a variety of sequentially unique hybrid phytases by recombination of known phytase genes, which exceeded the biochemical properties of the wild-type phytases in some relevant aspects. Some of the phytases showed very efficient phytate degradation when simulating the digestive tract of broilers in vitro. Also, the suitability of the tested hybrid phytase as feed additives was demonstrated by the increased performance data of broilers. The higher performance data of the broilers could be attributed to efficient phytate degradation. To achieve maximum InsP6 degradation in vivo, the feed-related and animal-related factors on phytase efficiency need to be better understood.
Evaluation of the availability of different mineral phosphorus sources in broilers
(2012) Shastak, Yauheni; Rodehutscord, Markus
Inorganic feed phosphates are an indispensable supplement for compounding poultry feed. The requirement of available P in broiler chicks cannot be covered only with plant ingredients as P in plant feedstuff is largely presented in form of phytate which is only partially available in avian species. Due to the increase in prices for feed phosphates and environmental concerns associated with excessive excretion of P by livestock, the knowledge about the availability of P from mineral sources has gained in importance during the last decade. However, there is still no standardized method available for assessing the P availability of inorganic feed phosphates. Without knowledge of the exact quantitative values of the P availability for different P sources, it is not possible to formulate adequate diets without the risk of deficiency or excess supplementation. There are various approaches which are used by different laboratories for the determination of P availability. The main problem is, however, that it is not clear how the differences between approaches affect the results. The development of a standardized method of P evaluation, which allows obtaining quantitative values for P availability, is the basis for optimizing the dietary P concentration in broiler diets. The major objective of this thesis was to compare various methodological approaches that are used internationally to determine P availability in terms of their suitability. Therefore, firstly the P availability of two mineral phosphates was determined in 3- and 5-wk-old broilers based on data for P retention and prececal digestibility. The P availability of both mineral sources was calculated for both ages of birds by regression analyses for comparison of both response criteria. Secondly, the tibia bone ash and other bone criteria were determined. A comparison of these bone response criteria was then carried out by relating these data to measurements made on P retention. Thirdly, the suitability of tibia P retention for the estimation of the whole body P retention was investigated at both ages of birds. Variation in P retention of birds in these studies was additionally caused by the level and the source of P in the diet. In a fourth study, the effect of the basal diet composition on the availability of a feed phosphate was investigated based on quantitative P retention. A phytin-containing corn-SBM-based as well as a purified basal diet was used. Moreover, the impact of the inorganic phosphate level on the IP6 hydrolysis of the corn-SBM-based diet was assessed on the basis of excreta collection. In the first study, a corn-SBM-based basal diet was used (0.35% P on dry matter basis). MSPa or DCPa was supplemented to increment the P concentration by 0.08%, 0.16%, and 0.24%. Two balance trials (n=8 birds per diet) and two digestibility trials (n=8 pens with 10 birds per diet) were conducted (8 treatments per diet). In 3-wk-old broilers, P retention for MSPa was 70% and significantly higher (P < 0.001) than for DCPa (29%), as calculated by linear regression analysis. Values determined for P pc digestibility at the same age were very similar (67% for MSPa and 30% for DCPa; P < 0.001). In 5-wk-old broilers, P retention was 63% (MSPa) and 29% (DCPa) (P < 0.001), and pc digestibility was 54% (MSPa) and 25% (DCPa) (P = 0.002). In conclusion, in 3-wk-old broilers results obtained with both approaches were the same. In 5-wk-old broilers, the ranking of the two P sources was the same for both approaches. Values differed not greatly between the two age periods. The second study was linked to the first one, and the experimental design was the same. The study comprised two periods with birds of different ages, but from the same hatch. The response criteria evaluated were tibia, tarsometatarsus, toe ash, and P, as well as the Quantitative Computed Tomography measurements of tibiae, blood Pi concentration, and body weight gain. Responses were evaluated and compared based on linear regression analysis. In general, MSPa had a greater slope than DCPa for all criteria studied. For the different bones, the ratio of slopes was very similar based on the amount of ash in both periods. Foot ash was proved to be as sensitive as tibia ash in both periods. Blood serum Pi and body weight gain were not sufficiently sensitive criteria for P evaluation. We concluded that the ranking of both mineral P sources based on bone criteria differed from the ranking that was based on P retention or pc digestibility. The third study was also linked to the first one. Thus, the experimental design was the same. On days 21 and 35, two chicks per treatment were randomly chosen. Contents of P and Ca were determined in tibiae-free bodies and tibiae. The whole body P to tibia P ratio was 21.3±1.3 at d 21 and 19.8±1.1 at d 35 of age. The slope of linear regressions between the tibia P and the whole body P for both ages was identical (17.7). Results indicated that changes in tibia P may be suitable to predict changes in whole body P retention. In the last experiment, a phytin-containing as well as a purified basal diet, both containing 1.8 g available P per kg feed dry matter, was supplemented with MSPa to increment the P concentration by 0.05%, 0.1%, and 0.15%. A retention trial with excreta collection from d 20-24 was conducted (n=7 birds per diet). The level of P did not significantly affect the total P retention either of the corn-SBM-based or of the purified basal diet (P > 0.05). However, increasing the P level significantly reduced (P = 0.015) the IP6 hydrolysis for the corn-SBM-based diets. Percentage P retention for MSPa was calculated by linear regression analysis. P retention for MSPa was 50% for the corn-SBM-based diet and 51% for the purified diet. We concluded that there was no difference in P retention from MSPa between corn-SBM-based and purified diets. It can be concluded from the results of the present thesis that both retention and pc digestibility can be used for evaluating mineral P sources in broilers based on a regression approach. The ranking of mineral P sources based on bone criteria differed from the ranking that was based on P retention or pc digestibility. There was no difference in P retention from MSPa between corn-SBM-based and purified based diets, but a significant effect of the P-level on the IP6 hydrolysis in corn-SBM-based basal diets was found.
Factors influencing the response of broiler chicken to glycine supplements in low crude protein diets
(2016) Siegert, Wolfgang; Rodehutscord, Markus
The increasing demand for meat and other animal products along with the global limitation of arable land for crop production is expected to result in a shortage of protein-rich feedstuff. Furthermore, the excretion of nitrogenous compounds has negative effects on the environment because of the risk of nitrogen (N) leakage into the groundwater. Ammonia emissions from livestock enterprises have been associated with environmentally damaging effects. The biggest determinant of ammonia emissions associated with livestock farming is excretion of N. Excretion of N in part is inevitable but N excretion can be reduced by avoiding excessive intake of feed protein. At present, there is a substantial lack of knowledge about the requirement of nitrogenous nutrients except for essential amino acids (AA) and the influence of these nutrients on animal physiology. As reported in the literature, this has often led to undesirable effects of low crude protein (CP) diets on growth. This partly is due to a deficient glycine (Gly) and serine (Ser) supply in low CP diets. This thesis focused on factors influencing the response to Gly and Ser in low CP broiler feed because growth response to these AA was inconsistent in the literature. In the first study, a meta-analysis was conducted to investigate the response of broilers to dietary levels of Gly equivalents (Glyequi) of Gly and Ser in existing literature. A curvilinear relationship between Glyequi and daily gain (ADG), daily feed intake (ADFI) and feed efficiency (G:F) was found. The impact of dietary Glyequi on ADFI was low, but G:F and ADG varied markedly at different levels of Glyequi. The effect of dietary Glyequi depended on the supply of both methionine (Met) and cysteine (Cys). The G:F and ADG response to dietary Glyequi was different for different Met:(Met+Cys) ratios and Cys concentrations. This was explained by a decreased necessity of conversion of Met to Cys, for which Ser is needed. Adequate concentrations of both Met and Cys probably reduced the necessity of the conversion of Met to Cys. The second study investigated the effect of threonine (Thr) and choline, which are endogenous precursors of Gly, on the response to dietary Glyequi. An increase in Thr concentration reduced the Glyequi concentration required to achieve certain response levels of G:F and ADG. Choline also exerted a considerable effect, but the Glyequi replacing effect of choline was less pronounced than Thr. The observed replacement values of dietary Thr and choline for dietary Glyequi exceeded the possible replacement values calculated by considering endogenous conversion. This likely originated from an excess supply of other essential AA than Thr. If Thr and, to a lower extent, choline limited growth, then excessive intake of other AA had to be catabolized, resulting in an increased need for Glyequi for uric acid formation. It was concluded that further studies should take Glyequi, choline, and Thr together into consideration when determining the requirements for these nutrients. The third study aimed to investigate whether the growth performance and N utilization of broilers are influenced by different proportions of free and peptide-bound AA in diets, and if his influences Glyequi requirements. The hypothesis was that an increased oxidation of free AA leads to an increased ammonia production, which must be detoxified to uric acid in a Gly-dissipating process. 2×2 factorial arrangements were used where one factor was AA from soy protein isolate or from a free AA mix. The other factor was a low and high level of Glyequi. Replacing AA from the soy protein isolate with free AA reduced ADG and G:F, mainly due to reduced ADFI. Reasons for that cannot be identified clearly. The N efficiency on day 21 was not different between the AA sources, possibly due to the lower AA digestibility of the soy protein isolate and higher urinary excretion of nitrogenous substances in the treatments with the AA mix. Thus, availability of AA for protein synthesis after ingestion probably did not limit broiler growth. The ADG of the treatments with the high Glyequi concentration was higher for both AA sources. This increase was due to higher ADFI by broilers in the treatments with soy protein isolate and due to the increased G:F in the treatments with the AA mix. Contrary to the hypothesis, these responses did not give an indication of different utilization of Glyequi for uric acid synthesis. In conclusion, the response of broiler chicken to dietary Glyequi depends on other dietary characteristics, like the concentrations of Cys, Thr, and choline. The information described in this thesis contribute to enable further optimization of the dietary Glyequi concentration as well as the other dietary characteristics influencing the response to Glyequi. This enables reducing the CP concentration in diets without adverse effects on growth and, therefore, diminishing the negative effects of broiler production on the environment.
High-throughput sequencing techniques to analyze microbial communities in the gastrointestinal tract of broiler chickens
(2018) Borda Molina, Daniel Enrique; Camarinha-Silva, Amélia
Broiler chicken represents an excellent case-study to elucidate the inter-communication between the host and its microbial communities. The general aim of this thesis was to describe the changes in bacterial community structure that occurred in chickens, in response to different experimental diets. An update of the state of the art of the chicken gastrointestinal microbiota was done in chapter 2. The composition and functionality are described through the most recent technologies that provide taxonomic information at DNA level using 16S rRNA genes. Gene catalogs and their abundance are deciphered through shotgun metagenome sequencing, which is still at its infancy and only eight publications have been published so far. At the protein level, only two studies were found that contribute metaproteomic information. Thanks to these technologies many studies were able to focus on answering how feed supplementations altered the microbes in GIT sections. The second part presented in chapter 3 comprises an extensive investigation of the broiler chicken microbiota composition in digesta and mucosa of individual samples under varying supplementation of calcium, phosphorus, and phytase. The dietary impact on the distribution of the microbial communities was studied in the crop, ileum, and caecum through illumina sequencing of the 16S rRNA gene. One important outcome was the high variability in the microbial composition between individual samples. Significant differences were observed between the digesta and mucosa samples, supporting the hypothesis that being close to the host, mucosa-associated communities show a different composition. A calcium effect on the performance was observed, where values for body weight gain and feed conversion were lower in comparison to the other treatments. Microbial communities in the crop mucosa revealed a dietary effect, while in the digesta samples no significant changes were seen. Regarding the ileum mucosa, there was an effect of P addition on the microbial distribution. As expected, caeca-derived samples showed an increase in the diversity indexes when compared to the ileum and crop and butyrate producers were detected in higher abundance. A lower microbial diversity in the crop was linked to lower growth performance regarding the supplementation of Ca. Hence, each dietary treatment affected the microbial communities; nevertheless, none of the dietary treatments displayed a consistent effect across the studied gut sections. Additionally, the effects of supplementing different proteases and one phytase on the microbial community of the ileum of broiler chickens was assessed. Thus, the specific aim of chapter 4 was to determine how enzyme supplementation affects the microbiota composition in the ileum of broilers and whether these effects were related to differences in pre-caecal AA digestibility. Three different protease sources at a low and high level were included. The microbial taxonomy was assessed through 16S rRNA gene Illumina amplicon sequencing. Performance results revealed a significant increase in growth and feed efficiency in broilers fed with phytase only and the high dosage of protease C, in comparison to the control. Most of the AA showed a significant difference between the control diet and protease C at high dosage and phytase diets. Effects on microbiota composition were observed at the genus level for some protease and phytase supplementations. The genera Streptococcus, Lactobacillus, and uncultured Clostridiaceae were responsible for these differences. This study demonstrates that effects of enzyme supplementation were evident in the terminal small intestine microbiota composition, and, to a lesser extent, in pc AA digestibility. However, the changes in microbiota composition and pc AA digestibility could not be correlated which may indicate the absence of a causal relationship. Finally, an outlook with metagenome sequencing is presented in chapter 5, to further characterize the result of feeding strategies. Metabolism information, essential to microbial activities registered 50% of abundant genes in the supplemented diets while being reduced to 40% in the control samples Phosphatases pathways and butyrate production increased in the supplemented diets while calcium signaling pathway was higher in the control. In conclusion, within this project a method of standardization to study the microbiota along the gastrointestinal tract of broiler chickens was successfully established. The obtained results revealed a significant impact of both, enzyme and mineral supplementation in the individual sections of the GIT. Also, it was proved that even if the GIT works as an interconnected system, its compartmentalization creates different environmental conditions which influence the microbiota. This study provides insights into the responses of the bacteria and their functionality which were stimulated by the feed supplementations.
In vivo and in vitro studies of degradation of inositol phosphates in the digestive tract of broiler chickens
(2017) Sommerfeld, Vera; Rodehutscord, Markus
Phosphorus (P) is an important element in poultry nutrition, which must be adequately supplied in the diet. However, for non-ruminant animals, it is only partially available from plant seeds—the major components of poultry diets—where P is predominantly bound as phytic acid (myo-inositol 1,2,3,4,5,6-hexakis (dihydrogen phosphate); InsP6) and its salts, called phytate. InsP6-P can be utilized after the stepwise cleavage of the P from the phytate molecule by phytases and other phosphatases. After the theoretical complete dephosphorylation of InsP6, six phosphate groups and myo-inositol (MI) are potentially available for absorption. Recent studies assume an effect of MI on growth performance when it is added in its free form to the diet or released as a result of InsP6 breakdown. Because P is of specific economic and environmental relevance, the improvement of the digestibility of plant P in poultry is of great interest. The overarching aim of this thesis was therefore to gain a deeper insight into the degradation of InsPs in the digestive tract of broiler chickens, with a focus on the intermediate and end-products as influenced by the diet composition. An in vitro assay was established to study the disappearance of InsP6 and the formation of lower inositol phosphate (InsP) isomers in the poultry digestive tract. The assay simulates the conditions (pH, temperature, proteolytic enzymes, water content, and retention time) of the crop, stomach, and small intestine, using a poultry diet as matrix. The assay yielded highly reproducible results and was sensitive to the factors that varied in the three experiments. A diminishing effect on InsP degradation was found by the supplementation of P and Ca. The described assay is a suitable tool that can be used to screen feed enzymes and to investigate the effects of supplements in the absence of endogenous phytases. The first in vivo experiment aimed to distinguish between the single and interactive effects of P, calcium (Ca), and phytase. Effects on lower InsP esters and their isomers and MI in different segments of the digestive tract, and on the prececal digestibility of P, Ca, and amino acids (AAs) in broiler chickens were studied. Moreover, a complete picture was drawn of all dephosphorylation steps from InsP6 to MI in the digesta of the terminal ileum. The dietary treatments included diets without (P-) or with (P+) monosodium phosphate supplementation, without (Ca-) or with (Ca+) additional limestone supplementation, and without or with 1500 FTU phytase/kg feed. Up to the terminal ileum, InsP6 disappearance was found to decrease in P+Ca-, and even more so in P+Ca+, when no phytase was added. Adding phytase removed all effects of P and Ca. However, P+Ca+ increased the concentrations of lower InsP esters and reduced free MI in the ileum, even in the presence of phytase. Supplementation with phytase increased the concentration of MI in all segments of the digestive tract and in blood plasma, demonstrating the ability of broilers to fully degrade phytate and absorb the released MI. While the prececal AA digestibility was not affected by P and Ca or an interaction between P, Ca, and phytase, it increased with the addition of phytase. The objective of the second in vivo experiment was to investigate the effects of supplementation with free MI or graded levels of phytase on InsP degradation, concentrations of MI in the digestive tract and blood, bone mineralization, and prececal digestibility of AA. Birds were fed a control diet with adequate levels of all nutrients without or with MI supplementation, or one of three experimental diets that differed in phytase level, with reduced P and Ca levels. These outcomes indicate that MI might have been a relevant cause for the increase in gain:feed. Therefore, it is likely that the release of MI after complete dephosphorylation of phytate is one of the beneficial effects of phytase, along with the release of P and improvement in digestibility of other nutrients. It can be concluded that the established in vitro assay is a suitable tool to investigate effects on feed enzymes or differences between different feed enzymes in a feed matrix under standardized conditions without the interference of endogenous phytases, or depending on animal-specific variations. Based on the outcome of the in vitro and in vivo experiments of the present project, the combined supplementation of P and Ca—rather than supplementation of P or Ca solely—seems to be crucial for InsP degradation. There is now some evidence that MI can affect the growth and feed efficiency of broiler chickens without affecting the metabolism of InsPs or AAs. As the results regarding the effects of P and Ca on InsP6 degradation or phytase effects on AA digestibility are not consistent across studies, and studies investigating the effects of MI are scarce and not consistent, further systematic research is needed.
Investigations on factors influencing the response of broiler chickens to low crude protein diets with specific regard to nonessential amino acids
(2020) Hofmann, Philipp; Rodehutscord, Markus
Nitrogen (N) excretion caused by animal husbandry can have negative effects on the environment. Lowering dietary crude protein (CP) concentrations can reduce these negative impacts by lowering the N excretion of the animals. However, reduction of dietary CP concentrations for broiler chickens may be accompanied by reduced growth. This thesis focused on the effects of dietary CP reduction on growth of broiler chickens and influencing factors that need to be considered in low CP diets. The first study was carried out to investigate to what extent dietary CP concentrations can be reduced when dietary glycine equivalent (Glyequi) and essential amino acid (AA) concentrations are adequately supplied. Further, it was the aim to determine the response of broiler chickens to dietary Glyequi concentrations at varying CP levels. Ten male broiler chickens each were housed in 1 of 84 metabolism units. Diets with three CP levels of 16.3% (CP16.3), 14.7% (CP14.7), and 13.2% (CP13.2) each containing four Glyequi concentrations of 12, 15, 18, and 21 g/kg were used. Quantitative excreta collection was carried out from days 18–21. The reduction of dietary CP concentrations decreased average daily gain (ADG) and gain:feed ratio (G:F) from days 7–21 and increased the nitrogen-utilization efficiency (NUE). Supplementation of Glyequi increased ADG and G:F at CP13.2. The ADG at CP14.7 and G:F at CP14.7 and CP16.3 increased up to 15 g Glyequi/kg. These results indicated that the minimum to which dietary CP concentrations can be reduced in broiler chickens up to three weeks of age is between 16.3 and 14.7% when dietary Glyequi and essential AA are adequately supplied. Further, these findings showed that the growth-response of broiler chickens to dietary Glyequi is influenced by dietary CP concentrations. The second study was conducted to determine whether supplementation of single nonessential AA (neAA) can diminish or overcome the growth-decreasing effect of a diet with reduced dietary CP and neAA concentrations. Further, the effect of non-protein nitrogen supplementation in a diet with insufficient neAA concentrations was investigated. Nine male broiler chickens each were kept in 1 of 81 metabolism units. Two diets with different neAA concentrations, except Glyequi, and adequate essential AA concentrations were mixed resulting in CP levels of 17.8% (CP17.8), and 15.6% (CP15.6). The dietary Glyequi concentration was 15 g/kg in each diet. Other diets were mixed by supplementing either L-Alanine, L-Proline, L-Aspartic acid, a mix of L-Aspartic acid and L-Asparagine·H2O, L-Glutamic acid, or a mix of L-Glutamic acid and L-Glutamine to CP15.6 to achieve the respective neAA concentration of CP17.8. Ammonium chloride (NH4Cl) was added to CP15.6 to achieve the CP concentration of CP17.8. Excreta were collected quantitatively from days 18–21. Highest ADG and G:F from days 7–21 were found at CP17.8 and decreased at CP15.6. Supplementation of aspartic acid and asparagine (Asp+Asn), glutamic acid (Glu), and glutamic acid and glutamine (Glu+Gln) increased ADG and G:F to a similar extent, but not to the level of CP17.8. The NUE was highest at CP15.6, and CP15.6 supplemented with alanine, proline, and Glu. Lower NUE was observed at CP17.8 than at CP15.6 without and with neAA supplementation. Overall lowest ADG, G:F, and NUE were found upon NH4Cl supplementation. These findings showed that individual supplementation of Asp+Asn, Glu, and Glu+Gln could partly overcome the growth-reducing effect of very low CP diets. NH4Cl was found unsuitable to increase growth. The aim of the third study was to investigate interactive effects among dietary Glyequi, cysteine (Cys), and choline (Cho) on the growth of broiler chickens. Ten male broiler chickens each were housed in 105 metabolism units. Excretion of N was determined from days 18–21. Five levels each of dietary Glyequi, Cys, and Cho were tested in 15 dietary treatments. Another diet was provided to 15 birds each in another 5 metabolism units to measure prececal AA digestibility. The G:F from days 7–21 increased with digestible Glyequi intake. Differences between low- and high-digestible Cys intake were low. Hardly any effect of Cho intake on G:F was found compared to digestible intake of Glyequi and Cys. The NUE was very high with low variation among treatments. These results showed that the interactive effects among dietary Glyequi, Cys, and Cho on growth were slightly pronounced. This was likely an effect of high NUE and its low variation that caused the Glyequi requirement to be low. In conclusion, the lowest level to which dietary CP for broiler chickens up to three weeks of age can be reduced is between 16.3 and 14.7%. The growth-decreasing effect of a diet with reduced neAA concentrations can be slightly overcome upon supplementation of Asp+Asn, Glu, and Glu+Gln. Moreover, dietary CP concentrations and the related amounts of excreted N influenced the response of broiler chickens to dietary Glyequi.
Phytate degradation and phosphorus digestibility in turkeys and broiler chickens fed maize-based diets
(2023) Novotny, Moritz Sebastian Daniel; Rodehutscord, Markus
A growing global human population, stagnation in available land for farming, and an increased interest in sustainable and eco-friendly food production necessitates a highly efficient and environmentally friendly food production. This includes the already very feed-efficient poultry meat production. Currently, using non-renewable mineral phosphate as feed additive is industry standard in poultry nutrition. This can lead to unwanted eutrophication of waterbodies by high faecal concentrations of unutilised plant-based phosphate. Degrading phytate via enzymatic hydrolysation by phytases drastically improves digestibility of plant-based phosphate. With dietary phytase supplementation, a tool is available to reduce necessity of dietary phosphate supplementation. However, predictability of the extent to which phytase supplementation can replace phosphate supplementation is not accurate enough to forego phosphate supplementation entirely. Subject of this doctoral thesis was to study the factors that can influence phytate degradation in the digestive tract of poultry, in order to improve predictability of plant-based phosphate digestibility. The focus was put on maize-based diets, as they are very common worldwide and phytate degradation is challenging due to low intrinsic phytase activity of maize. A literature review on the current state of knowledge on phytate degradation and phosphorus digestibility of chicken fed maize-based diets was conducted. Part of this review was to compare findings for chickens to findings in other poultry species. There is a plethora of studies that investigated the subject in broilers but comparatively little information on turkeys. There were indications of fundamental differences between broilers and turkeys. Consequently, the intention was to identify reasons for these differences and to evaluate to which extent knowledge transfer from chickens to turkeys is possible. Two consecutive trials comparing broilers and turkeys were designed. Factors studied were: supplemented phytase, dietary phosphorus and calcium concentration, age, and endogenous mucosal phosphatase activity. Broilers and turkeys studied were kept simultaneously and under identical conditions, including experimental diets. A total of 480 broiler and 480 turkey hatchlings were obtained at the same day and raised at the experimental facility. Halve of the animals of each species underwent the experiment from day 14 to day 21, the other halve from day 35 to day 42. This set up was chosen to study the influence of physiological development, as species with different maturation rates were compared. In 3-week-old broilers and turkeys, precaecal InsP6 disappearance was the same when no phytase was supplemented and dietary calcium and phosphorus level was low. This coincided with no differences in jejunal mucosal phosphatase activity. Without phytase supplementation, 6-week-old turkeys showed higher precaecal InsP6 disappearance than 6-week-old broilers. This coincided with higher jejunal mucosal phosphatase activity in turkeys than broilers. When phytase was supplemented, precaecal InsP6 disappearance was markedly increased in both species. This increase was always higher in broilers compared to turkeys of the same age. Increased dietary calcium and phosphorus levels led to decreased precaecal InsP6 disappearance in both species. This led to the conclusion that previously reported differences in precaecal InsP6 disappearance between broilers and turkeys were primarily due to the higher dietary calcium and phosphorus concentrations used in turkey diets, and secondly due to more phytate degradation by supplemented phytase in the crop of broilers compared to turkeys. The latter was attributed to more favourable conditions for the supplemented phytase. Although turkeys appeared to have compensated much of that in the more posterior parts of the digestive tract. Jejunal mucosal phosphatase activity was higher in treatments with phytase supplementation than without. As this coincided with high concentrations of lower inositol phosphates in the digesta, these might have triggered increased expression of phosphatases on the brush border membrane. In contrast, an increase in dietary calcium and phosphorus level coincided with a decrease in jejunal mucosal phosphatase activity, numerically in 3-week-old birds, but significantly in 6-week-old birds. This might indicate a downregulation of mucosal phosphatase expression based on phosphate concentration in the small intestine. In conclusion, fundamental mechanisms affecting phytate degradation in the digestive tract of broilers and turkeys seem to be the same. However, there is one big difference in recommended dietary calcium and phosphorus levels and many small differences in important details affecting phytate degradation and phosphate digestibility between the two species. These require dedicated attention to further improve phosphorus efficiency in poultry production.
Phytate hydrolysis and formation of inositol phosphates in the digestive tract of broilers
(2015) Zeller, Ellen; Rodehutscord, Markus
Phytate (any salt of myo-inositol 1,2,3,4,5,6-hexakis (dihydrogen phosphate) or InsP6) represents the major binding form of phosphorus (P) in plant seeds. In the digestive tract, availability of P from plant seeds and feedstuffs obtained thereof largely depends on the enzymatic hydrolysis of InsP6 and less phosphorylated inositol phosphate isomers (InsPs). High prices of mineral P supplements and environmental burden linked with excessive P excretion of animals as well as exhaustion of the global rock phosphate stores demand for maximization of phytate-P utilization in animal feeding. The major objective of this thesis was to understand better InsP6 hydrolysis and formation of lower InsPs in different segments of the digestive tract of broilers and how they can be influenced by different dietary factors. In the first study (Manuscript 1), broilers (n=10 pens per dietary treatment) were fed low-P (5.2 g/kg DM) corn-soybean meal-based diets without (basal diet) or with one of three different phytase supplements (an Aspergillus and two E. coli derived phytases) from days 16 to 25 of age. InsP6 hydrolysis until the lower ileum (74%) of birds fed the basal diet indicated a high potential of broilers and their gut microbiota to hydrolyse InsP6 in low-P diets. Different InsP pattern in different gut segments suggested the involvement of phosphatases of mucosal or microbial origin. Supplemented phytases significantly increased InsP6 hydrolysis in the crop but not in the lower ileum. Measurements in the crop and proventriculus/gizzard confirmed published in vitro degradation pathways of 3- and 6-phytases for the first time in broilers. Presence of InsP4 and InsP5 isomers specifically formed by different supplemented phytases indicated activity of these enzymes still in the small intestine. InsP4 accumulation differed between the 6- and 3-phytases in the anterior segments of the gut. In the second study (Manuscript 2), effects of supplemental mineral P were studied using different basal diets. Semi-synthetic and corn-soybean meal-based basal diets (experiment 1), or corn-based and wheat-based basal diets were used (experiment 2). Anhydrous monosodium phosphate (MSPa) or monocalcium phosphate monohydrate (MCPh) was supplemented to increment the P concentration by 0.05, 0.10, and 0.15% or by 0.075 and 0.150% in experiment 1 and 2, respectively. In experiment 1, total excreta were collected from day 20 to 24 of age (7 replicated birds per diet). In experiment 2, digesta from the terminal ileum was collected when broilers were 22 days old (5 replicated pens per diet, 19 birds per pen). No differences were found in InsP6 hydrolysis between the maize- and wheat-based diets (experiment 2). Mineral P supplements significantly decreased InsP6 hydrolysis from the InsP-containing diets in both experiments. The choice of the basal diet did not affect the evaluation of the supplemented mineral P sources. This lead to the conclusion that calculated availability values for mineral P sources need to be adjusted for the decline in hydrolysis of InsP contained in the basal diet resulting from the P supplement. In the third study (Manuscript 3), broilers (20 birds per pen; n=8 pens per treatment) were fed two low-P corn-soybean meal-based diets without (BD-; 4.4 g P/kg DM) or with monocalcium phosphate (MCP) (BD+; 5.2 g P/kg DM) and without or with added phytase at 500 or 12,500 FTU/kg from days 15 to 24 of age. Digesta samples were taken from the duodenum/jejunum and lower ileum. Another 180 broilers (n=6 pens per treatment, 10 birds each) were fed the three BD+ diets from day 1 to 21 of age to assess the influence of supplemented phytase on tibia mineralization and strength. Interactions between MCP and phytase affected InsP6 hydrolysis and the concentrations of specific lower InsPs. Supplementation with 12,500 FTU/kg phytase resulted in 92% prececal InsP6 hydrolysis and strong degradation of InsP5. This resulted in higher P net absorption, affirmed by higher body weight gain, tibia strength, and mineralization compared to treatments without or with 500 FTU/kg of phytase. MCP supplementation reduced InsP6 hydrolysis and the degradation of specific lower InsPs in birds fed diets without phytase or with 500 FTU/kg of phytase, but did not reduce InsP6 hydrolysis or degradation of InsP5 at the high phytase dose. Hence effects of added MCP on phytase efficacy depend on the dose of supplemented phytase. In the fourth study (Manuscript 4), broilers (15 birds per pen, n=8 pens per treatment) were fed a wheat-soybean meal diet low in P (4.8 g/kg DM) and containing either microwave-treated (BDTW; 121 U/kg of phytase) or non-microwave treated (BDUTW; 623 U/kg of phytase) wheat meal from d 16 to 23 of age. Diets were used without or with supplementation of a phytase, alone or in combination with a xylanase. Interactions between microwave treatment and enzyme supplementation were found for InsP6 hydrolysis in the ileum and P net absorption in the duodenum/jejunum and ileum. In the ileum, P net absorption was similar, but InsP6 hydrolysis was significantly higher for BDTW (78%) than for BDUTW (69%) in the absence of supplemental phytase. Microwaving may have disrupted wheat aleurone structures in ways that increased the accessibility of the phytate and may have encouraged higher levels of activity among specific phytases of microbial or endogenous mucosal origin in the lower small intestine. In both segments, InsP6 hydrolysis and P net absorption were significantly increased by supplementation of phytase, but no further by additional supplementation of xylanase. In birds that were fed the phytase-supplemented diets, microwave treatment of wheat had no effect on InsP6 hydrolysis, but it significantly reduced P net absorption in both segments. The fifth study compromised two experiments (Manuscript 5) in which the influence of different dietary factors on InsP6 degradation in the crop was investigated. The experimental designs was as mentioned for Manuscript 3 (experiment 2) and 4 (experiment 1) since the samples were taken in the same trials. In experiment 1, InsP6 hydrolysis in the crop was significantly increased by supplementation of phytase, but not further by the additional supplementation of xylanase. Microwave treatment of wheat reduced InsP6 hydrolysis and degradation of InsP5, due to reduction in intrinsic enzyme activity. The effect of 500 FTU/kg of supplemental phytase on InsP6 hydrolysis was much higher in broilers fed the maize- compared to those fed the wheat-based diets (experiment 2 and 1). Thus, for supplemental phytase the accessibility of phytate in wheat seems to be lower than in maize, perhaps due to different storage sites. Supplementation of 12,500 FTU/kg of phytase caused high InsP6 hydrolysis (up to 80%) and stronger degradation of InsP3-5 than supplementation of 500 FTU/kg (experiment 2). In both experiments, degradation of Ins(1,2,5,6)P4 was a limiting step in the breakdown process of InsP6 by the supplemented phytase. However, upon phytase supplementation Ins(1,2,5,6)P4 accumulated in BDTW diets whereas InsP4 degradation proceeded in untreated wheat diets (experiment 1). Ins(1,2,5,6)P4 seemed to be degraded synergistically by intrinsic wheat phosphatases and the supplemented phytase. Taking all studies together, it can be concluded that broilers and their gut microbiota have a very high potential to hydrolyze InsP6 in the digestive tract when diets low in P and Ca are fed. Differences in the concentrations of lower InsPs showed that the initial step of InsP6 hydrolysis is not the only catabolic step influenced by different dietary factors. To optimize efficacy of phytases and achieve a maximal InsP degradation and minimal P excretions the separate and interactive effects of different dietary influencing factors on InsP hydrolysis need to be better understood and considered in future diet formulations.
Zinc supplementation effects on phytate degradation, mineral digestibility, and bone characteristics in broiler chickens
(2024) Philippi, Hanna; Rodehutscord, Markus
An adequate supply of phosphorus (P) is important in poultry nutrition, as P is essential for numerous metabolic processes. However, oversupply should be avoided to reduce the environmental impact of poultry production. The main source of P in plant feedstuffs commonly used in poultry nutrition is phytate, the salt form of phytic acid (InsP6). For P from InsP6 to be utilized by animals, it needs to be cleaved by phytases or other phosphatases. However, the capacity of endogenous phosphatases of non-ruminant animals does not suffice to release sufficient P to fulfill the animal’s P requirement. Therefore, commercial poultry diets usually are supplemented with P from mineral sources. By using exogenous phytases, the supplementation of mineral P can be reduced, and finite P reserves can be conserved. To feed poultry without mineral P in the future, phytase efficacy must be improved further. Thus, it is important to know and understand all factors influencing phytase efficacy. The results of in vitro studies have indicated that zinc (Zn) may be an influencing factor. The supplementation of Zn could inhibit phytase activity, with the degree of inhibition depending on the exogenous Zn source used. A literature review on the interactions of Zn with phytate and phytase (Manuscript A of this thesis) has identified a lack of in vivo studies investigating the effects of Zn supplementation on phytase with direct measurements, such as intestinal phytate degradation and prececal P digestibility. Therefore, three in vivo studies were conducted as part of this thesis with the main objective to investigate the effect of Zn supplementation and exogenous Zn source on intestinal phytate degradation in broiler chickens. It was hypothesized that due to the formation of insoluble complexes of Zn and phytate, the supplementation of Zn could reduce phytase efficacy with the extent of reduction depending on the exogenous Zn source. Further, other traits that are affected by Zn supply, such as bone mineralization and gene expression, were also investigated in these in vivo studies. The first experiment (Manuscript B) aimed to determine the effect of dietary Zn level and source on intestinal phytate breakdown, mineral digestibility, bone mineralization, and Zn status without and with exogenous phytase in the feed. Ross 308 broiler chickens were fed experimental diets from day 7 to 28. The basal diet contained 33 mg/kg dry matter native Zn and a high phytate-P concentration to challenge interactions in the digestive tract. The experimental diets differed in the level of exogenous phytase (0 or 750 FTU/kg) and in the Zn source (none, 30 mg/kg of Zn-sulfate, or 30 mg/kg of Zn-oxide). Additionally, two experimental diets with a high Zn supplementation level (90 mg/kg) in the form of Zn-sulfate or Zn-oxide, both containing exogenous phytase, were tested. Intestinal phytate breakdown, P digestibility, and bone mineralization were not affected by Zn source or Zn level but only by phytase supplementation. The concentration of ileal myo-inositol was influenced by phytase × Zn source interaction. Birds fed without phytase supplementation had similarly low myo-inositol concentrations whether they received Zn supplementation or not, whereas birds receiving phytase supplementation and Zn supplementation had significantly higher ileal myo-inositol concentrations than birds fed without Zn supplementation but with phytase supplementation. The missing effect of Zn level or Zn source on phytate degradation indicates that no interactions of Zn and phytate relevant for phytase efficacy occurred in the digestive tract of broilers when Zn was supplemented at levels up to 90 mg/kg in the form of Zn-sulfate or Zn-oxide. Based on the results of the first experiment, where Zn alone did not show relevant interactions with phytate, the second experiment (Manuscript C) aimed to investigate whether the combined supplementation of Zn, copper (Cu), and manganese (Mn) from different sources without and with exogenous phytase in the feed affects intestinal phytate breakdown, prececal mineral digestibility, bone mineralization, and mRNA expression of mineral transporters. Cobb 500 broiler chickens received experimental diets from day 0 to 28. Experimental diets differed in the level of phytase supplementation (0 or 750 FTU/kg) and in the trace mineral source (TMS: 100 mg/kg Zn, 100 mg/kg Mn, and 125 mg/kg Cu as sulfates, oxides, or chelates). Prececal InsP6 disappearance and P digestibility were significantly affected by phytase × TMS interaction. Whereas birds receiving exogenous phytase had similar InsP6 disappearance and P digestibility irrespective of TMS, birds fed without exogenous phytase and with chelated trace minerals had a higher InsP6 disappearance and P digestibility than birds receiving no exogenous phytase and oxides or sulfates. These results indicate that the combined supplementation of Zn, Mn, and Cu at high levels may challenge interactions with phytate in non-phytase-supplemented diets with the extent of interaction depending on the TMS. In phytase-supplemented diets however, the choice of TMS was irrelevant for phytate degradation under the conditions of this study. The third experiment (Manuscript D) aimed to determine the impact of Zn level and Zn source on prececal phytate degradation, mineral digestibility, bone mineralization, and mRNA expression of intestinal (trace) mineral transporters. In contrast to the first experiment, an inorganic Zn source and a chelated Zn source were tested. Cobb 500 broiler chickens received experimental diets from day 0 to 21. The experimental diets differed in Zn supplementation level (10, 30, 50 mg/kg Zn) and exogenous Zn source (Zn-oxide or Zn-glycinate). A cornsoybean meal-based diet without Zn supplementation containing 35 mg/kg native Zn was used as a control. All experimental diets were supplemented with 750 FTU/kg phytase. Prececal InsP6 disappearance, P digestibility, and tibia ash quantity and concentration, and Zn concentration in tibia ash were not affected by diet. Bone breaking strength and tibia width did not differ between treatments. Tibia thickness was lower in the treatments with 30 mg Zn as Zn-oxide and 50 mg Zn as Zn-glycinate than in the treatment with 10 mg Zn as Zn-oxide. The expression of intestinal (trace) mineral transporters was not affected by treatment. These results indicate that in phytase-supplemented diets the native Zn concentration of cornsoybean meal-based diets is satisfactory to achieve maximal Zn concentration in tibia ash during the first 3 weeks of age. The missing effect of Zn level or Zn source on phytate degradation confirms the results from Manuscript B, that Zn and phytate do not interact to a level relevant for phytate degradation by exogenous phytase. It is concluded that contrary to the hypothesis that Zn inhibits phytate degradation by complex formation with phytate, the Zn supplementation up to 100 mg/kg does not appear to influence exogenous phytase efficacy. Minor effects were found on the endogenous phytate degradation if Zn, Cu, and Mn were supplemented combined at high levels, where the extent of reduction in endogenous phytate degradation was dependent on the TMS. It remains unclear whether the inhibiting effect on endogenous phytate degradation occurs only due to the combined supplementation or whether an individual high supplementation of a single trace mineral caused the effect. Further experiments are needed to investigate the effect of Zn on endogenous phosphatases, where the activity of endogenous mucosal activity should be determined in broilers fed diets differing in the Zn supplementation level. Moreover, further experiments are needed to test what level of Zn supplementation is needed in phytase-supplemented diets to ensure the birds sufficient supply in all areas. Besides bone development and growth, effects on the immune system, microbiota composition, and the antioxidative system should be considered.