Browsing by Subject "Feeding"

Now showing 1 - 4 of 4
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    Intrinsic and extrinsic factors affecting the color of fresh beef meat - comprehensive review
    (2023) Poveda-Arteaga, Alejandro; Krell, Johannes; Gibis, Monika; Heinz, Volker; Terjung, Nino; Tomasevic, Igor
    Meat color research from the last two decades suggests that a combination of different intrinsic (ultimate pH, age of the animals, muscle position, breed, slaughter weight, and sex) and extrinsic factors (production systems and feeding, pre-mortem stress, slaughter season, and chilling rates) might have a deep impact in the color of beef muscle and influence consumers’ acceptance of fresh meat. Ultimate pH and muscle position were perceived as the most determinant intrinsic factors, whereas production systems, feeding, and ante-mortem stress were the extrinsic factors that more strongly influenced beef color attributes. From an industrial perspective, the extrinsic factors can be improved through the technological process at a higher ratio than the intrinsic ones. This review aims to evaluate the effect of each of those factors on myoglobin oxidation and beef color traits from a comprehensive standpoint. All the information discussed in this manuscript focuses on an industrial environment and offers possible solutions and recommendations for the global meat industry.
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    Langfristige Beurteilung der Energieversorgung von Milchkühen bei unterschiedlichem Kraftfuttereinsatz
    (2020) Gerster, Elisabeth Katharina; Rodehutscord, Markus
    The first objective of the present study was to compile the current knowledge concerning the effect of the amount of CON on dry matter (DM) intake and milk yield of dairy cows, by regression analysis. For this purpose, a dataset was compiled containing 46 studies with feeding trials and graded inclusion levels of CON. When offering the roughage ad libitum, a quadratic relation was found between CON intake and roughage intake. Taking into account the substitution of roughage, the observed increase of milk yield was less than expected. The second objective was to verify the response of Simmental dairy cows to a long-term reduction of the CON input, in terms of dry matter intake, milk yield, and energy supply. During a feeding trial conducted over a two-year period at the experimental station LAZBW in Aulendorf (cooperative research project „optiKuh“) each 24 Simmental dairy cow was fed either 250 (group 250) or 150 (group 150) g CON per kg energy-corrected milk yield (ECM) throughout lactation. Grass and maize silage as well as straw and hay were combined in the total mixed rations to ensure an energy concentration of 6.6 MJ NEL per kg DM of the roughage in both groups throughout lactation. The CON contained a mixture produced on-site (winter wheat, winter barley, faba bean) and rapeseed meal. At 165 days in milk, each cow in both groups was switched individually to a ration containing less CON. Data were gathered also during the dry period. Feed was offered for ad libitum consumption. Statistical analyses were done separately for the lactation and dry period. As fixed effects the calendar week, the group, the parity, and the interaction group*parity entered the model, respectively. Additionally, the days in milk were included as a covariate during lactation. During lactation the mean daily DM intake did not differ significantly between group 250 (21.6 kg DM) and group 150 (21.0 kg DM). The calculated substitution of roughage amounted to 0.75 kg DM per kg CON DM during the mentioned trial period. As lactation progressed, more roughage was substituted. The group 250 had a higher milk yield during the first half of lactation, but a lower milk yield during the second half. The mean milk yield was equal in both groups (28.7 kg ECM per day). The examined blood characteristics (8, 28, 100 days p. p., at drying off, 14 days a. p.) and the milk fatty acids analysis by gas chromatography (5, 28, 100, 200 days p. p.) reflected the different progressions of the energy balance of the two groups. On average the group 250 reached a positive energy balance already at 37 days in milk. Probably owing to a better glucose supply after calving, the serum insulin concentration increased faster and supported the replenishing of body reserves at the expense of milk yield. On the contrary, the group 150 achieved a positive energy balance only after 72 days in milk on average. Indicating the mobilization of body reserves, the blood of group 150 showed a significantly higher D-ß-hydroxybutyrate concentration, and the milk fat a significantly higher concentration of long-chain fatty acids 28 days p.p.. However, the values were within the physiological range. The reduction of CON did not increase the likelihood of illness. During the dry period, despite equal feeding of both groups in this period, the group 150 had an increased DM intake of 0.9 kg DM per day (p=0,026). Thus, they restored body energy reserves. Over time both groups succeeded in balancing the energy deficit of the beginning of lactation. The proposal of SUSENBETH (2018) for the calculation of the energy requirement of dairy cows improved the plausibility of the calculated energy balances compared with the factors according to GfE (2001). The third objective was to develop a model for the estimation of energy balance in the first third of lactation based on characteristics of production with focus on concentration of milk fatty acids. For this purpose, the milk fatty acids analyses 5, 28 and 100 days p. p. of the feeding trial were used (n=200). The model was derived from the regularized linear regression method „elastic net“. The variables milk yield on sampling day, milk fat content, concentrations of the milk fatty acid C12:0 and the milk fatty acid C18:0, as well as the relations n-6/n-3, C15/C17 and oleic acid/C15 were selected. An estimation error of 13.1 MJ NEL per day was determined by leave-one-out cross-validation. Potentially, the model seems to be applicable for the detection of a severe negative energy balance at the beginning of lactation. But first a validation with an independent dataset is required.
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    Seasonal variation in growth, quantitative and qualitative food consumption of milkfish, Chanos chanos (Forsskål 1775), and Nile tilapia, Oreochromis niloticus (L. 1758), in Laguna de Bay, Philippines
    (2002) Richter, Hartmut; Becker, Klaus
    Laguna de Bay, the largest lake in the Philippines, lies directly southeast of the capital Manila. The lake has a mean depth of only 2.8m and a muddy bottom which is stirred during windy weather, causing turbid conditions (Secchi depth <30cm). In the dry season, the water level drops below that of the nearby sea, leading to a backflow of saline water which clears the water until the return of the monsoon winds (Secchi depth >100cm) and leads to algal blooms. Since the beginning of the 1970s, the lake has been used for culturing milkfish, Chanos chanos (Forsskål), in large netpens (max. 2000ha) and Nile tilapia, Oreochromis niloticus (L.), in smaller cages (max. 200m2). Initially, it was possible during the algal blooms to grow fish from fingerling (ca. 10g) to marketable size (ca. 200g) in three months, making two harvests a year possible. Aquaculture quickly spread until in the middle of the eighties, over a third of the lake was covered with cages. At the same time the growth of the fish declined, which was attributed to the excessive use of primary production. Since then, despite a reduction in aquaculture coverage to the generally recommended level of 10% of the lake, fish growth has never reached the levels of the early days of culture. In the present work, seasonal variation in growth, feeding spectrum and daily ration of these two species was to be investigated in relation to water quality in order to find out more about the interaction between aquaculture and the lake. Between May 1995 and August 1997, milkfish and tilapia were sampled on several occasions at commercial operations over the 24-hour cycle. Since milkfish, unlike tilapia, do not receive supplemental feed, the proportion of their growth derived only from natural food could be determined from the cultured fish. Tilapia were kept in cages without feed specially for this purpose and measured and weighed twice a month between March and November 1997. At the same time, selective water quality parameters (particulate organic and inorganic matter, Chlorophyll-a, zooplankton) were analysed weekly. The growth of unfed fish was significantly faster between saltwater intrusion (mid-May) and the return of the monsoons (late July) than at other times of the year. On the other hand, food consumption was only slightly higher in tilapia when the water was clear than at other times and in milkfish hardly differed over the year. Both species mainly fed on amorphous organic detritus; significant levels of phytoplankton were only found in the stomachs at times of algal bloom. In supplemented tilapia, the daily ration still consisted of 35-75% natural food, suggesting that pelleted feed was used inefficiently. The main factor limiting fish growth therefore seemed to be food quality since detritus has often been shown to be poor quality food. The weekly water samples collected in 1997 demonstrated that the total level of phytoplankton was not necessarily higher at times of rapid fish growth. The main difference was related to algal size, since at times of turbid water, small diatoms dominated but these were replaced by larger blue-green algae after saltwater intrusion. In conjunction with the feeding method of these fish, the strongly seasonal growth of the fish could now be explained. Phytoplanktivorous fish such as milkfish and tilapia can only select their food on the basis of size. Since the organic detritus in the lake consisted of particles smaller than 15µm, it was possible for the fish to selectively filter larger blue-green algae but not smaller diatoms. This could also explain why fish growth rates did not recover after a reduction in aquaculture in the mid-eighties, since the relationship between the level of algae and that of detritus seems to be more important than total algal biomass. In order to increase production to those levels found in the early seventies, the level of detritus in the lake would have to be reduced, for which its origin would have to be investigated first.
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    Untersuchungen zu den Beziehungen von Federpicken, Exploration und Nahrungsaufnahme bei Legehennen
    (2008) Benda, Isabel; Bessei, Werner
    First documented in 1873 by Oettel (1873), the problem of feather pecking and feather eating remains a major issue in modern laying hen husbandry. Various motivational models developed in the past years interpret feather pecking as redirected foraging behaviour, pecking while sand bathing or as misdirected exploratory behaviour. The laying hens, however, only show exploratory curiosity in these diverse materials for a short time. It has been shown that diet-related deficiencies elicit increased exploratory behaviour and feather pecking. In the first section of this experiment, we attempted to redirect the exploratory pecking activity of the laying hens to an alternative object (pecking block) for a sustained period of time through offering the animals food and calcium separately. Less feather pecking behaviour was expected to result. Investigations carried out in recent years indicate an association between feather pecking and feather eating. Although almost indigestible, both wood shavings (cellulose) and feathers are eaten by laying hens. Hence, the influence of feathers and cellulose in food on the behaviour of laying hens was tested in the second section of this experiment. The inclusion of feathers or cellulose in food was expected to reduce feather pecking behaviour, since the animals? requirement for these substrates was adequately covered in the food. The goal of the third section of the experiment was to determine if the ingestion of feathers or wood shavings has an underlying physiological background, which consequently initiates a need for these substrates. The effect of substrate ingestion was tested in two different lines. The first experiment comprised three feeding treatments. Group 1 received a calcium-poor ration (0.67% Ca) whereas groups 2 and 3 received a calcium-balanced ration (3.45% Ca). An additional pecking block containing molasses and bran was available to birds in groups 1 and 2. The pecking block available to birds in group 1 had a calcium content of 31%. Each of the 3 treatments was repeated 10 times with 8 laying hens per treatment. Half of the animals were brown, the other half white laying hybrids. The three groups did not differ in their propensity to feather peck. However, animals in group 1 showed a better feather condition than those in groups 2 and 3. Breed origin had a significant effect on pecking activity, whereby brown laying hybrids displayed aggressive and vigorous feather pecking more frequently than their white counterparts. The second section of the investigation likewise comprised three feeding treatments. The first group received pellets with 10% feather grit, the second group pellets with 10% cellulose and the third group received additive-free pellets. Each treatment was repeated 4 times on 15 hens (white laying hybrid). Feed preference with respect to the different pellet variations available was examined and feather eating behaviour was tested after the test rations were discontinued. Birds in both the feather grit and cellulose groups showed less feather pecking behaviour than control animals throughout the entire experiment. Likewise, birds in the feather grit group had a significantly better plumage condition than those in the control group. Animals in the feather grit group also ate more pellets and ingested significantly more feathers than those in both the control and cellulose groups. The third section of the experiment was conducted with animal selected on high (HFP) and low (LFP) feather pecking activity (KJAER et al., 2001); three different feeding treatments were tested. Birds in the first group were offered 70 feathers per week (HF and LF), birds in the second group had access to wood shavings ad libitum (HSp and LSp), and birds in the third group were not offered any additional substrates (H0 and L0). The intestinal passage rate of each group was investigated, whereby animals receiving additional substrates were selected for comparison when the amount of substrate (feathers or wood shavings) ingested was comparable. Animals in the HF group showed the fastest intestinal passage rate, followed by LF and H0 birds. The L0 animals had the slowest marker excretion. Although feather intake in HF and LF groups was similar, only the HF birds had a significantly faster passage rate. HFP birds which had access to wood shavings showed faster marker excretion as LFP birds in comparison. This experiment demonstrates that misdirected exploratory behaviour does not seem to be the primary cause of feather pecking. Rather the ingestion of feathers or wood shavings / cellulose plays a meaningful role in this behaviour. The results of this study show that feather pecking can be classified as feeding behaviour. This is in accordance with previous literature in which feather pecking is identified as feather eating. Furthermore, genetic discrepancies between HFP and LFP animals seem to exist, since the ingestion of a similar amount of feathers or wood shavings had different effects on the intestinal tracts of the animals in the two lines. Further research is necessary to validate the results of this study.