Browsing by Subject "Ruminants"

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    Adaptation of herd simulation models to predict the efficiency of the use of resources in tropical ruminant production systems
    (2020) Bateki Adjogo, Christian; Dickhöfer, Uta
    Agricultural systems in the (Sub-)Tropics are under increasing pressure to produce more food and satisfy the growing demand of a rapidly growing and more affluent human population for agricultural products. With growing rates of urbanization in these regions and the associated dietary changes, the demand for calories from animal-based foods like milk, meat, and eggs could increase by 74 to 114 % between 2010 and 2050. Ruminant livestock have the potential to contribute to satisfying the demand for animal-based foods in the (Sub-)Tropics, but also raise considerable environmental concerns, amongst others due to their emissions. The use of simulation models is a holistic approach to identify how to sustainably harness the potential of ruminants for animal-based food production in the (Sub-)Tropics. Although several ruminant herd models are relevant for studying tropical ruminant production systems, most of them were developed using data that quantify and characterize biological processes of ruminants in temperate regions. Therefore, the present thesis identified and adapted an existing ruminant livestock herd model to adequately predict resource use and the potential outputs from production systems in the (Sub-)Tropics. The present thesis showed that state-of-the-art ruminant livestock herd models used to simulate tropical production systems need further development to enable them to address the modelling needs identified. Instead of developing new models to address these modelling needs, existing simulation models could be adapted using the increasingly available data that quantify and characterize biological processes in ruminants in these regions. This approach will ensure that not only the direction of change for different management strategies will be identified for tropical ruminant production systems, but also the correct magnitude of resources use and productive and reproductive performance.
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    Effects of ensiling conditions on the nutritional quality of forage legumes and their impacts on rumen fermentation and nutrient utilization by cattle
    (2022) Aloba, Temitope Alex; Uta, Dickhöfer
    Silage produced from forage legumes can contribute to the limiting protein supply of ruminants diets in the tropics, and reduced dependence on imported and high-carbon footprint feeds. However, the successes recorded with temperate forage legume silage feeding in ruminants have not been achieved in the tropics. Thus, the effects of silage feeding on ruminants’ performance cannot be isolated from the processes that occur during ensiling. Since controllable and uncontrollable factors govern silage quality, it is imperative to understand the processes that occur during ensiling tropical forage legumes under different conditions to widen knowledge. Therefore, the aim was to determine the effect of ensiling conditions on forage legume nutritional quality, their ruminal and post-ruminal fate, and their potential impact on nutrient utilization by cattle in the tropics. A silage study was conducted to evaluate the effects of ensiling length and storage temperature on the nutritive value and fibre-bound protein of three tropical forage legumes ensiled alone or combined with sorghum. The three forage legumes included soybean (Glycine max), lablab (Lablab purpureus) and jack bean (Cannavalia ensiformis). Silages from each legume were made individually or combined with sorghum (Sorghum bicolor) and stored outdoors or indoors for 30, 75, and 180 days. The results showed that the proportion of soluble nutrients preserved in most silage until 75 d of ensiling declined considerably, thereby increasing dry matter (DM) and crude protein (CP) losses, fibre concentration and reducing digestibility afterwards. Besides, storage temperature affected the fermentation and fibre-bound protein characteristics with higher variation in legume silages’ fibre-bound protein than the sorghum-legume silages. Silages of sorghum and soybean were selected from the first study to compose low and high CP diets with additional ingredients, and the effects of ensiling length, storage temperature, and its interaction with CP levels on in vitro rumen fermentation and post-ruminal digestibility were assessed. Dietary treatments were incubated in duplicate for 8 and 24 h in three runs using the ANKOM RF technique to study rumen fermentation. Post-ruminal digestibility was determined using the pepsin and pancreatic solubility procedure. The results showed that gas production (GP) and ammonia-nitrogen in the rumen inoculum increased quadratically with the ensiling length, with the highest GP and ammonia-nitrogen at 75 d of ensiling, irrespective of incubation times. The GP was higher in diets with low than high CP concentrations, while it was the opposite for ammonia-nitrogen. An interaction between ensiling length and storage temperature effect was found for the apparent CP intestinal digestibility. Overall, ensiling beyond 75 d reduces CP digestibility to the extent that it cannot be recovered by supplying additional CP. In the third study, the effects of CP levels on nutrient intake, digestibility, nitrogen metabolism and performance of growing steers fed corn or corn-soybean silage were investigated. Sixteen growing steers were fed with rations based on corn or corn-soybean silage at high or low CP levels in a 4 × 3 incomplete Latin square design comprising 17 d periods, each with 12 d of adaptation to dietary treatments and 5 d of sampling. While the effect of silages and CP levels were not found for nutrient intake, the apparent total tract digestibility of nutrients was reduced for low than high CP in both silages, with greater differences between the CP levels in corn than corn-soybean silage. The average daily gain and feed efficiency were greater in low than high CP of corn silage, but no differences between CP levels were found in corn-soybean silage. In general, corn silage with low CP concentration but with a high metabolizable energy supply supposedly improved nitrogen use efficiency with a higher yield of microbial protein and average daily gain than other diets. Conclusively, the results of the current thesis showed that ensiling forage legumes individually or in combination with cereal crops beyond 75 d at high temperatures of the tropics leads to a decline in the nutritional quality of legume silage and CP intestinal digestibility even with additional CP sources. Furthermore, prolonged ensiling of combined legume and cereal crops reduces nutrient availability for cattle performance.
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    Investigations on nutritional characteristics of microalgae with emphasis on ruminants
    (2019) Wild, Katharina Judith; Rodehutscord, Markus
    The main objective of the present thesis was to systematically determine nutritional characteristics of microalgae and evaluate the suitability of microalgae as feedstuffs, particularly for ruminants. The experiments comprised a comprehensive characterisation of microalgae nutrient profiles with chemical-analytical methods and the determination of extent and dynamics of nutrient utilization using in vitro methods. In order to generate a comprehensive database on nutrient composition of microalgae, 16 commercial microalgae biomasses of four genera (Arthrospira, Chlorella, Nannochloropsis, and Phaeodactylum) were analysed utilizing established methods for food and feed evaluation (Manuscript 1). These investigations included determination of the in vitro crude protein (CP) digestibility for pigs. Nutrient analyses showed a considerable variation particularly in concentrations of proximate nutrients, minerals, and fatty acids, both among and within genera. This variation presumably resulted from varying cultivation conditions and it was concluded that general mean values are not appropriate to characterize microalgae in terms nutrient composition. Manuscript 2 aimed to determine characteristics of the nutritional value of microalgae for ruminants utilizing different in vitro methods. The commercial biomasses included in Manuscript 1 were investigated using the Hohenheim Gas Test method. The investigations comprised the determination of several ruminal fermentation characteristics, of the energy value, and of the protein value. A three-step enzymatic in vitro system was used to estimate intestinal digestibility of ruminally undegraded CP (IDP). Ruminal fermentation of the investigated microalgae biomasses was overall low, which was indicated by an overall low level of production of gas and volatile fatty acids, and a low ruminal CP degradation. As a result of low ruminal fermentation, microalgae biomasses were characterized by high concentrations of ruminally undegradable CP (RUP; 386, 399, 315, and 263 g RUP/kg DM at passage rate of 8 %/h for Arthrospira, Chlorella, Nannochloropsis, and Phaeodactylum, respectively). Thus, microalgae appear to be potential alternative protein sources for high performing animals. However, this was contradicted by low IDP, which was determined for microalgae in the present thesis for the first time (mean values for Arthrospira, Chlorella, Nannochloropsis, and Phaeodactylum were 27, 43, 43, and 40 % of RUP respectively). The variation observed in nutrient profiles was reflected in several nutritional characteristics. A common objective of Manuscript 1 and Manuscript 2 was to investigate whether cell disruption affects nutritional characteristics of microalgae. In Manuscript 1, effects of cell disruption on in vitro CP digestibility for pigs were investigated and in Manuscript 2 several in vitro methods were utilized to investigate effects of cell disruption on the nutritional value of microalgae for ruminants. Mechanical cell disruption with a ball mill enhanced in vitro CP digestibility and ruminal fermentation in most of the samples, presumably by the destruction of cells and hence an increase in nutrient accessibility. Nevertheless, concerning the protein value of microalgae in ruminants, application of mechanical cell disruption cannot not be recommended because it decreased RUP but did not increase IDP so that intestinal digestible RUP was overall decreased by cell disruption. The aim of the third manuscript was to investigate the effects of variable cultivation conditions on nutrient composition and nutritional characteristics for ruminants of the microalgae Chlorella vulgaris. Chlorella vulgaris was cultivated under varying conditions (saturation, nitrogen and CO2 depletion, outdoor cultivation). The obtained biomasses were analysed for their nutrient composition and their nutritional value for ruminants using different in vitro methods. Both, nutrient composition and characteristics of the nutritional value for ruminants were affected by the cultivation process. Nutrient deficient conditions had rather adverse effects in terms of digestibility, protein value, and nutrient productivity. It can be concluded that microalgae have potential as alternative protein source for ruminants. Nevertheless, this potential is contradicted by low IDP, but the findings obtained herein have to be verified in future studies. Furthermore, the results of the present thesis show that nutrient composition and ruminal fermentation characteristics of microalgae vary considerably between and in many cases even within microalgae genera. Thus, to the extent possible, it should be strived for a standardisation of cultivation conditions, in order allow better predictions of nutritional characteristics of microalgae.
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    Investigations on phytate degradation of rapeseed meal and soybean meal in ruminants
    (2023) Chi, Yung-Ping; Rodehutscord, Markus
    Oilseed meals are widely used protein feeds in ruminant nutrition. However, aside from the high crude protein (CP) content, oilseed meals also contain high amounts of phosphorus (P), which is predominantly present in organic form as different salts of myo-inositol 1,2,3,4,5,6 hexakis dihydrogen phosphate (InsP6). To become available for intestinal absorption and further utilisation by animals, P must be cleaved from the InsP6 molecule by a specific group of phosphatases, which is known as phytase. Over the decades, ruminants were considered to be capable of utilising nearly all P bound in InsP6 because of the substantial phytase activity exhibited by rumen microbiota. Nevertheless, recent studies have reported variable extents of ruminal InsP6 degradation which seems to be influenced by different factors. In case of an incomplete ruminal InsP6 degradation, post-ruminal InsP6 degradation may be of higher relevance. However, post-ruminal InsP6 degradation has been rarely studied to date. The aim of this thesis was to systematically investigate InsP6 degradation of rapeseed meal (RSM) and soybean meal (SBM) in ruminants, including the possible influencing factors and their combinations. Different study methods (in vivo, in situ, and in vitro) were applied to evaluate the effects of RSM and SBM. The first study (Manuscript 1) was conducted to investigate ruminal and post-ruminal InsP6 degradation in wethers fed a diet containing RSM or SBM, and to link the ruminal disappearance determined in slaughtered wethers with in situ calculated rumen effective degradation of InsP6 (InsP6ED) from cows. Firstly, RSM and SBM was incubated according to a standard in situ procedure in three lactating Jersey cows for 2, 4, 6, 8, 16, 24, 48, and 72 h to obtain InsP6ED for the oilseed meals at rumen passage rates of 0.02 (InsP6ED2) and 0.05 h-1 (InsP6ED5). Secondly, eight wethers were randomly assigned to two treatment groups that were fed a diet containing equal amount of RSM (Diet RSM) or SBM (Diet SBM) for 8 weeks of adaptation. Then, digesta from the reticulo-rumen, omasum, abomasum, jejunum, colon, and rectum were sampled. In consistence with in situ calculated InsP6ED2 (83 and 93% for RSM and SBM, respectively), ruminal InsP6 disappearance was lower in wethers fed Diet RSM (76%) compared to those fed Diet SBM (89%). Post-ruminal InsP6 disappearance did not differ between dietary treatments (6% for Diet RSM vs. 4% for Diet SBM). A higher amount of ruminally degraded InsP6 was observed upon feeding RSM (4.5 g/d for Diet RSM and 3.4 g/d for Diet SBM). Due to the low rumen passage rate in this study, it was suggested that P from InsP6 being available to ruminants is almost entirely from InsP6 degradation in the rumen. As InsP6 is located in a protein-rich structure in seeds and InsP6 degradation has been recently reported to vary in a pattern similar to CP degradation for RSM, the second study (Manuscript 2) was carried out to investigate the variation of in situ ruminal InsP6 degradation of SBM and its relation to CP degradation. In this study, nine commercial solvent-extracted SBM from Europe and South America were incubated in three rumen-fistulated lactating Jersey cows with the same procedure performed in the first study. Rumen effective degradation of CP and InsP6 were calculated for a rumen passage rate of 0.06 h-1 (CPED6 and InsP6ED6). Chemical protein fractions of SBM variants were determined according to Cornell Net Carbohydrate and Protein System (CNCPS). The SBM variants exhibited a considerable variation in CP and InsP6 degradation. Significant correlations were found between InsP6ED6 and CPED6 and between InsP6ED6 and all CNCPS protein fractions, which confirmed the close relationship between CP and InsP6 degradation for SBM. The results suggested that using a general value of InsP6 degradation for diet formulation may not be precise enough, and InsP6ED may be predicted based on CPED or CNCPS protein fractions by using linear regression equations. The third study (Chapter 4.3) aimed to achieve a better understanding of how in vitro InsP6 degradation of RSM and SBM is influenced by different amounts of InsP6 in feed. The same batches of RSM and SBM as used in Manuscript 1 were incubated in a modified rumen simulation technique (RUSITEC) system with different amounts for 3, 6, 12, 24, and 48 h. Degradation of InsP6 from bag residues was calculated and expressed as amount and in percentage using the same equation as applied for in situ calculations. In vitro degradation of InsP6 in response to InsP6 amount differed between RSM and SBM, which may be attributed to the different internal structure and nutrient composition of the oilseed meals. Only when expressing in amounts, the calculated InsP6ED was observed to increase linearly with increasing InsP6 amount in feed. Accordingly, it was recommended to compare InsP6 degradation based on InsP6 amount in the feed and to express degradation as amount instead of using relative value which might not reflect the real degradation kinetics. In conclusion, the results of this thesis showed that the extent of ruminal InsP6 degradation differs when the diet contains either RSM or SBM, while post-ruminal InsP6 degradation is negligibly low given a long rumen retention time. By using linear regression equations, ruminal InsP6 degradation may be predicted from CP degradation due to the close relationship therebetween. Effects of InsP6 amount on InsP6 degradation is dependent on InsP6 source. Based on the high similarity among ruminal InsP6 degradation determined by different methods in this thesis, ruminal InsP6 degradation of oilseed meals measured by in situ or in vitro study may be applicable for in vivo conditions.
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    RumiWatch - Development and assessment of a sensor-based behavior monitoring system for ruminants
    (2018) Zehner, Nils; Schick, Matthias
    Sustainable and competitive milk production is highly dependent on securing the performance potential, health and fertility of dairy cows. Therefore, farmers can benefit from sensor data of animal monitoring systems to improve health management and work processes in dairy farming. The research during this PhD thesis aimed to contribute to the development and evaluation of a scientifically validated, sensor-based animal monitoring system that comprises a device for measurement of ingestive behavior and a device for measurement of movement behavior in cattle that interact as a system with system-specific software. Further aim of this thesis was to evaluate application potentials for this animal monitoring system by means of calving prediction in dairy cows and measurement of chewing activity in horses. The underlying experimental work was structured into four separate studies. The aim of the first study was to develop and validate a novel scientific monitoring device for automated measurement of rumination and eating behavior in dairy cows. Research works for this study aimed to provide a complete and detailed technical specification of the functionality of this device and to perform a validation under field conditions in stable-fed cows. The objective of the second study was to develop and validate a novel algorithm to monitor lying, standing, and walking behavior based on the output of a triaxial accelerometer collected from loose-housed dairy cows. The third study aimed to use automated measurements of ingestive behavior obtained from the developed sensor device to develop and validate a predictive model for calving in dairy cows. The aim of the fourth study was to investigate the suitability and validity of the developed sensor system for automated measurement of chewing activity in horses. In conclusion, the RumiWatch noseband sensor and pedometer that were developed and validated in the current project represent a suitable measuring instrument for automated recording of ingestive and locomotor behavior in dairy cows. The system-specific software is suitable for research purposes and shows a high performance for classification of extended parameters of rumination, eating, lying, standing, and walking behavior. The achieved validation results indicate that the measuring performance satisfies scientific requirements. Further application potentials were demonstrated by means of automated calving prediction in dairy cows and automated measurement of chewing activity in horses. The development and validation of a predictive model for calving time using measurements of the RumiWatch noseband sensor revealed a high amount of false positive alerts that was prohibitive for application of the model in farming practice. However, the analyses showed that particularly parameters of ruminating behavior have predictive value and should be taken into consideration for future research on calving prediction models. Furthermore, it was successfully demonstrated that it is feasible to apply the RumiWatch noseband sensor to horses. The results of direct observation compared with the automatic measurement showed a very high overall agreement of the observed and automatically measured data and, after minor refinements, this measuring device has the potential to become a valuable and easy-to-use tool for equine research and management.