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In genetic evaluations, the definition of unknown parent groups (UPG) is usually based on time periods, selection path and flows of foreign founders. The definition of UPG may be more complex for populations presenting genetic heterogeneity due to both, large national expansion and coexistence of artificial insemination (AI) and natural service (NS). A UPG definition method accounting for beef bull flows was proposed and applied to the French Charolais cattle population. It assumed that, at a given time period, unknown parents belonged to the same UPG when their progeny were bred in herds that used bulls with similar origins (birth region and reproduction way). Thus, the birth period, region and AI rate of a herd were pointed out to be the three criteria reflecting genetic disparities at the national level in a beef cattle population. To deal with regional genetic disparities, 14 regions were identified using a factorial approach combining principal component analysis and Ward clustering. The selection nucleus of the French cattle population was dispersed over three main breeding areas. Flows of NS bulls were mainly carried out within each breeding area. On the contrary, the use and the selection of AI bulls were based on a national pool of candidates. Within a time period, herds of different regions were clustered together when they used bulls coming from the same origin and with an estimated difference of genetic level lower than 20% of genetic standard deviation (σg) for calf muscle and skeleton scores (SS) at weaning. This led to the definition of 16 UPG of sires, which were validated as robust and relevant in a sire model, meaning numerically stable and corresponding to distinct genetic subpopulations. The UPG genetic levels were estimated for muscle and SS under sire and animal models. Whatever the trait, differences between bull UPG estimates within a time period could reach 0.5 σg across regions. For a given time period, bull UPG estimates for muscle and SS were generally larger by 0.30 to 0.75 σg than those of cows. Including genetic groups in the evaluation model increased the estimated genetic trends by 20% to 30%. It also provoked re-ranking in favor of bulls and cows without pedigree.
A study was undertaken to compare the longevity and lifetime lamb output of purebred Scottish Blackface (BF) ewes with a range of crossbred genotypes from Scottish BF dams. For up to five successive breeding seasons, 1143 Scottish BF, Swaledale × BF (SW × BF), North Country Cheviot × BF (CH × BF), Lleyn × BF (LL × BF) and Texel × BF (T × BF) ewes were mated to a range of sire breeds on six hill farms across Northern Ireland. Dentition and lamb output were recorded annually until completion of the study or until the ewe was removed due to death or culling. Timing of mortality and the main reason for culling were also recorded. When survival analysis was undertaken, SW × BF and CH × BF ewes had better longevity (P < 0.05) than BF ewes due to their lower culling rate (P < 0.01) and lower mortality rate (P = 0.06), respectively. The relative proportion of LL × BF and T × BF culled due to infertility was lower (P < 0.05) than SW × BF and CH × BF, while a higher (P < 0.05) proportion of LL × BF and T × BF ewes were culled for prolapses compared with the other breed crosses. SW × BF ewes had consistently higher bite scores (P < 0.001) compared with BF, LL × BF and T × BF, indicating a greater prevalence and degree of overshoot. In ewes aged 5.5 years old, SW × BF also had a higher incidence of tooth loss (P < 0.01) compared with the other breeds. However, the proportion of SW × BF culled due to poor teeth condition was lower (P < 0.05) than BF. Across all breeds, the chances of surviving to their next mating were influenced by ewe breed (P < 0.05), age at mating (P < 0.001), body condition score at weaning (P < 0.001), number of missing teeth (P < 0.001) and average daily live weight gain per litter (P < 0.05). The cumulative number and weight of lambs weaned per ewe over five successive matings was higher (P < 0.05) for crossbred compared with pure BF ewes; however there were no differences in lifetime output between the different crossbred ewes studied. This study demonstrates that the higher lamb output of crossbred hill ewes does not compromise their longevity compared with pure Blackface, resulting in greater total lifetime production. When the crossbred ewes are sired by a second hill breed, longevity may be improved.
Conflicting hypotheses exist about the contribution of individual pigs to the development of a tail-biting outbreak, but there is limited quantitative information to support or dismiss them. This study aims to quantify the development of tail-biting behaviour at pen and individual piglet level, before and after the first visible tail damage. Video recordings of 14 pens with tail-biting outbreaks and individually marked weaned piglets were used to observe tail-biting incidents (TBIs; piglet biting a penmate’s tail). When visible tail damage was first observed in a pen (i.e. day of tail biting outbreak; D0), the video recordings of the previous 6 (till D−6) and the following 6 days (till D6) were analysed every other day for TBIs and the identities of the biter and bitten piglet were recorded. The average TBIs per individual piglet (within each pen) per observation day were analysed to quantify the development of tail-biting behaviour and to identify pronounced biters and/or bitten piglets. The (absence of) coherence for TBIs in a pen was used to test whether biters preferred a specific penmate. There was an exponential increase in the intensity (linear on log scale) of the TBIs from an average of 0.7 bites/h at D−6 to 2.3 bites/h at D6. An additional negative quadratic component suggests that a plateau for tail-biting behaviour was reached by the end of the observation period. Before any visible tail damage was observed (i.e. before D0), 82% of the piglets performed and 96% of them received tail bites. After D0, the figures were 99% and 100%, respectively. One or a few pronounced biters could be identified in almost all pens. These biters already showed more tail biting at D−6 than their penmates. Furthermore, these biters showed a greater increase in tail-biting behaviour during the observation period than the average scores of their penmates. In contrast, there was no apparent increase in the receipt of bites among the piglets that had already been bitten more than their penmates at D−6. Finally, there was no significant coherence between biters and bitten piglets, indicating that biters showed no preference for biting particular penmates, even when some of them had a damaged tail. These results show that, by using observations of TBIs, possible biters or bitten piglets can already be identified 6 days before tail damage is first apparent in a pen.
Increasing the polyunsaturated fatty acid (PUFA) composition of milk is acknowledged to be of benefit to consumer health. Despite the high PUFA content of forages, milk fat contains only about 3% of PUFA and only about 0.5% of n-3 fatty acids. This is mainly due to intensive lipid metabolism in the rumen (lipolysis and biohydrogenation) and during conservation (lipolysis and oxidation) such as drying (hay) and ensiling (silage). In red clover, polyphenol oxidase (PPO) has been suggested to protect lipids against degradation, both in the silage as well as in the rumen, leading to a higher output of PUFA in ruminant products (meat and milk). PPO mediates the oxidation of phenols and diphenols to quinones, which will readily react with nucleophilic binding sites. Such binding sites can be found on proteins, resulting in the formation of protein-bound phenols. This review summarizes the different methods that have been used to assess PPO activity in red clover, and an overview on the current understanding of PPO activity and activation in red clover. Knowledge on these aspects is of major importance to fully harness PPO’s lipid-protecting role. Furthermore, we review the studies that evidence PPO-mediated lipid protection and discuss its possible importance in lab-scale silages and further in an in vitro rumen system. It is demonstrated that high (induction of) PPO activity can lead to lower lipolysis in the silage and lower biohydrogenation in the rumen. There are three hypotheses on its working mechanism: (i) protein-bound phenols could directly bind to enzymes (e.g. lipases) as such inhibiting them; (ii) binding of quinones in and between proteins embedded in a lipid membrane (e.g. in the chloroplast) could lead to encapsulation of the lipids; (iii) direct binding of quinones to nucleophilic sites in polar lipids also could lead to protection. There is no exclusive evidence on which mechanism is most important, although there are strong indications that only lipid encapsulation in protein–phenol complexes would lead to an effective protection of lipids against ruminal biohydrogenation. From several studies it has also become apparent that the degree of PPO activation could influence the mode and degree of protection. In conclusion, this review demonstrates that protein-bound phenols and encapsulation in protein–phenol complexes, induced by PPO-mediated diphenol oxidation, could be of interest when aiming to protect lipids against pre-ruminal and ruminal degradation.
Skeletal muscle development in vertebrates – also termed myogenesis – is a highly integrated process. Evidence to date indicates that the processes are very similar across mammals, poultry and fish, although the timings of the various steps differ considerably. Myogenesis is regulated by the myogenic regulatory factors and consists of two to three distinct phases when different fibre populations appear. The critical times when myogenesis is prone to hormonal or environmental influences depend largely on the developmental stage. One of the main mechanisms for both genetic and environmental effects on muscle fibre development is via the direct action of the growth hormone–insulin-like growth factor (GH–IGF) axis. In mammals and poultry, postnatal growth and function of muscles relate mainly to the hypertrophy of the fibres formed during myogenesis and to their fibre-type composition in terms of metabolic and contractile properties, whereas in fish hyperplasia still plays a major role. Candidate genes that are important in skeletal muscle development, for instance, encode for IGFs and IGF-binding proteins, myosin heavy chain isoforms, troponin T, myosin light chain and others have been identified. In mammals, nutritional supply in utero affects myogenesis and the GH–IGF axis may have an indirect action through the partitioning of nutrients towards the gravid uterus. Impaired myogenesis resulting in low skeletal myofibre numbers is considered one of the main reasons for negative long-term consequences of intrauterine growth retardation. Severe undernutrition in utero due to natural variation in litter or twin-bearing species or insufficient maternal nutrient supply may impair myogenesis and adversely affect carcass quality later in terms of reduced lean and increased fat deposition in the progeny. On the other hand, increases in maternal feed intake above standard requirement seem to have no beneficial effects on the growth of the progeny with myogenesis not or only slightly affected. Initial studies on low and high maternal protein feeding are published. Although there are only a few studies, first results also reveal an influence of nutrition on skeletal muscle development in fish and poultry. Finally, environmental temperature has been identified as a critical factor for growth and development of skeletal muscle in both fish and poultry.
This study was conducted to investigate the effects of incorporation into pig diets of 20% of different co-products from the biofuel industries, which are rich in fibre, on animal growth performance, on nitrogen (N) and carbon (C) excretions, and on the subsequent ammonia volatilisation and methane production during the storage of slurry. Five experimental diets mainly based on wheat and soyabean meal were formulated: two control diets, a control high-protein (CHP) diet with 17.5% of crude protein (CP) and a control low-protein (CLP) diet with 14.0% of CP and three experimental diets with 20% of (i) dried distiller’s grain with solubles (DDGS), (ii) sugar beet pulp (SBP) or (iii) fatty rapeseed meal (FRM). The animals used (20 castrated males) were housed individually in metabolism cages and fed one of the five diets (i.e. four pigs per diet). Urine and faeces were collected separately from each pig in order to measure nutrient digestibility and the excretory patterns of N and C. For each diet, ammonia volatilisation was measured from samples of slurry subsequently produced, over a 16-day storage period in a laboratory pilot scale system. The ultimate methane potential (B0, expressed in litres CH4/kg organic matter (OM)) was measured from the same slurry, for each diet, in anaerobic storage conditions over 100 days. The addition of sources of fibres to the diet decreased (P < 0.05) the animal growth performance by 13% and increased (P < 0.05) the amount of faeces excreted by 100%, whereas the amount of urine was not affected. For the high-fibre diets, there was a shift of N partitioning from urine to faeces, resulting in a much higher faecal N excretion (10 v. 5 g N/pig per day). Concurrently, the fibre enrichment in diets significantly increased (P < 0.05) the C content of the faeces by 68%. Ammonia emission from slurry was significantly reduced (P < 0.05) by 19% to 33% for the high-fibre diets, compared to the CHP diet. Ammonia emission was also reduced (P < 0.05) by 33% for the CLP compared to the CHP diet. B0 values ranged from 428 to 484 l CH4/kg OM. When these are expressed per pig and per day, the B0 from slurry was, on average, 70 l for the two control diets, and 121, 91 and 130 l for the slurry originating from the DDGS, SBP and FRM diets, respectively.
Wheat grain (WG) is unique in possessing extensive starch and nitrogen fermentation (i.e. >85% in ground and steam-processed WG), low cation–anion difference and high-intake properties, making it a potentially useful prepartal dietary choice. The objective was to determine the effects of WG provision to pre-partum first-calf heifers on metabolic, health and productive criteria during the transition period. WG replaced barley grain that was commonly used earlier. Fifteen Holstein heifers at 31 ± 6 days pre partum were blocked based on expected calving date and assigned to three treatments or feeding totally mixed rations containing either (i) barley grain (13.8%) and wheat bran (6.1%), (ii) 10% WG (WG10) or (iii) 18% WG (WG18; dry matter (DM) basis) from 31 days pre partum until calving. In replacing WG for barley grains, some changes in WG use and slight changes in soybean and cottonseed meals use were made to properly formulate balanced rations for net energy for lactation, CP, calcium and P. Prepartal diets contained no supplemental anionic salts. Cows were monitored until 21-day post partum and received the same early lactation diet. The prepartal provision of WG and related dietary changes reduced urine pH at 7-day pre partum, and elevated blood calcium and glucose at 7-day pre partum and at 3-day post partum. Milk fat and protein yields were increased during the 21 days post partum by prepartal WG provision and related diet changes. Blood albumin, globulins, total proteins and urea concentrations were similar among treatments. Feeding diets with WG did not affect body condition score, calving difficulty, calf weight, placenta weight and the time interval from calving to placenta expulsion. It is suggested that prepartal provision of WG with necessary dietary changes led to simultaneous improvements in energy and calcium status of the heifers experiencing their first periparturient phase without compromising parturition status.
Intensive livestock grazing can largely deplete the natural fodder resources in semi-arid, subtropical highlands and together with the low nutritional quality of the pasture vegetation limit the growth and production of grazing animals. To evaluate the contribution of homestead feeding of grazing goats to rangeland conservation and animal nutrition, two researcher-managed on-farm trials were conducted in a mountain oasis of Northern Oman. Goats’ feed intake on pasture in response to four rations containing different levels of locally available green fodder and concentrate feeds was determined in six male goats each (35 ± 10.2 kg body weight (BW)). Total feed intake was estimated using titanium dioxide as external fecal marker as well as the diet organic matter (OM) digestibility derived from fecal crude protein concentration. The nutritional quality of selected fodder plants on pasture was analyzed to determine the animals’ nutrient and energy intake during grazing. The pasture vegetation accounted for 0.46 to 0.65 of the goats’ total OM intake (87 to 107 g/kg0.75 BW), underlining the importance of this fodder resource for the husbandry system. However, metabolizable energy (7.2 MJ/kg OM) and phosphorus concentrations (1.4 g/kg OM) in the consumed pasture plants were low. Homestead feeding of nutrient and energy-rich by-products of the national fishery and date palm cultivation to grazing goats increased their daily OM intake (R2 = 0.36; P = 0.005) and covered their requirements for growth and production. While the OM intake on pasture was highest in animals fed a concentrate-based diet (P = 0.003), the daily intake of 21 g OM/kg0.75 BW of cultivated green fodder reduced the animals’ feed intake on pasture (R2 = 0.44; P = 0.001). Adjusting homestead supplementation with locally available feedstuffs to the requirements of individual goats and to the nutritional quality of the pasture vegetation improves animal performance and eases the grazing pressure exerted on the natural vegetation. This management strategy therefore appears to be a valuable alternative to intensive livestock feeding in zero-grazing systems and may contribute to sustainable livestock production in ecologically fragile, semi-arid mountain regions.
Despite their major contribution to the energy supply of ruminants, the production of volatile fatty acids (VFA) in the rumen is still poorly predicted by rumen models. We have developed an empirical approach, based on the interpretation of large bibliographic databases gathering published in vivo measurements of ruminal VFA production rate (PR), rates of duodenal and faecal digestion and molar percentages of VFA in the rumen. These databases, covering a wide range of intake levels and dietary composition, were studied by meta-analysis using within-experiment models. We established models to quantify response laws of total VFA-PR and individual VFA molar percentages in the rumen to variations in intake level and dietary composition. The rumen fermentable organic matter (RfOM) intake, estimated from detailed knowledge of the chemical composition of diets according to INRA Feed Tables, appears as an accurate explanatory variable of measured total VFA-PR, with an average increment of 8.03 ± 0.64 mol total VFA/kg RfOM intake. Similar results were obtained when total VFA-PR was estimated from measured apparent RfOM (total VFA-PR/RfOM averaging 8.3 ± 1.2 mol/kg). The VFA molar percentages were related to dry matter intake and measured digestible organic matter (OM), digestible NDF and rumen starch digestibility, with root mean square error of 1.23, 1.45, 0.88 and 0.41 mol/100 mol total VFA for acetate, propionate, butyrate and minor VFA, respectively, with no effect of pH on the residuals. Stoichiometry coefficients were calculated from the slopes of the relationships between individual VFA production (estimated from measured apparent RfOM and individual VFA molar percentages) and measured fermented fractions. Coefficients averaged, respectively, 66, 17, 14 and 3 mol/100 mol for NDF; 41, 44, 12 and 4 mol/100 mol for starch; and 46, 35, 13 and 6 mol/100 mol for crude protein. Their use to predict VFA molar percentages appear relevant for most dietary conditions, that is, when the digested NDF/digested OM ratio exceeded 0.12. This study provides a quantitative review on VFA yield in the rumen. It contributes to the development of feed evaluation systems based on nutrient fluxes.
The effects of continuing spatial restraint were examined in domestic pigs. For this purpose, the animals (German Landrace barrows) were housed individually in metabolic cages (12 animals) and, as controls, in single pens (six animals). In six replications with two experimental animals and one control animal, we collected saliva each morning (0730 h) for the cortisol analysis, recorded the behaviour and the heart beat for 3 h/day (0800 to 0900 h, 1100 to 1200 h, 1400 to 1500 h). Each replication consisted of 5 days of habituation to single housing and 8 experimental days during which the experimental animals lived continuously in the metabolic cages. Weight gain, cortisol, heart rate and heart rate variability were not significantly affected by experimental narrow confinement that only had a significant influence on the behaviours, locomotion and sitting. In conclusion, the experimental animals adapted very fast and did not show physiological indications of chronic stress. However, the absence of apparent stress does not exclude other, subtler, welfare impairments.
The delivery of certain living microorganisms in food has long been suggested as having positive health effects in humans. This practice has extended into food animal production, with a variety of microorganisms being used; lactic acid bacteria, various Bacillus species and the yeast Saccharomyces cerevisiae have been particularly used in the pig industry. The increased interest in probiotics is essentially due to the problem of microbial resistance to antibiotics and following the ban of the use of antibiotics in animal production, probiotics being considered an alternative means to reduce pathogen infection and improve animal health especially around the time of weaning. However, there is still a need to clarify the probiotic effectiveness in pigs, and the underlying mechanisms. When assessing the efficacy of probiotics one must consider the particular strain of organism being used and the production stage of the pigs being treated. The reproducible delivery of probiotics in industrial pig production is problematic as maintenance of viability is key to their beneficial activity, but difficult to achieve with commonly used feed processing technologies. One specific context where probiotics organisms may be reliably delivered is in systems utilising fermented liquid feeds. Liquid feed may be fermented by the activity of wild lactic acid bacteria or may be stimulated using specific isolates as ‘starters’; the latter system has advantages in terms of reproducibility and speed of fermentation. The farm context in which the organism is used is likely to be critical; the use of probiotics is more likely to result in measurable economic gains in animals living in sub-optimal conditions rather than in those reared in the highest welfare and husbandry conditions. The establishment of a beneficial lactic acid bacteria population at birth may lead to healthier animals, this may be most effectively achieved by treating sows, which provide an amplification step and flood the neonatal pigs’ environment with desirable bacterial strains. In contrast, it may be sufficient to provide a supportive, protective microbiota around the time of weaning as this is a time of major crisis with instability and loss of certain bacterial populations.
Ruminant husbandry constitutes the most important source of anthropogenic methane (CH4). In addition to enteric (animal-derived) CH4, excreta are another source of CH4, especially when stored anaerobically. Increasing the proportion of dietary concentrate is often considered as the primary CH4 mitigation option. However, it is unclear whether this is still valid when diets to be compared are energy-balanced. In addition, non-structural carbohydrates and side effects on nitrogen (N) emissions may be important. In this experiment, diet types representing either forage-only or mixed diets were examined for their effects on CH4 and N emissions from animals and their slurries in 18 lactating cows. Apart from a hay-only diet, treatments included two mixed diets consisting of maize stover, pelleted whole maize plants and gluten or barley straw and grain and soy bean meal. The diets were balanced in crude protein and net energy for lactation. After adaptation, data and samples were collected for 8 days including a 2-day CH4 measurement in respiratory chambers. Faeces and urine, combined proportionately according to excretion, were used to determine slurry-derived CH4 and N emissions. Slurry was stored for 15 weeks at either 14°C or 27°C, and temperatures were classified as ‘cool’ and ‘warm’, respectively. The low-starch hay-only diet had high organic matter and fibre digestibility and proved to be equally effective on the cows’ performance as mixed diets. The enteric CH4 formation remained unaffected by the diet except when related to digested fibre. In this case emission was lowest with the hay-only diet (61 v. 88 to 101 g CH4/kg digested NDF). Feeding the hay diet resulted in the highest slurry-CH4 production after 7 weeks of storage at 14°C and 27°C, and after 15 weeks at 14°C. CH4 emissions were, in general, about 10-fold higher at 27°C compared with 14°C but only after 15 weeks of storage. Urinary N losses were highest with the barley diet and lowest with the maize diet. There was a trend towards similar differences in N losses from the slurry of these cows (significant at 14°C). However, contrary to CH4, slurry-N emissions seemed to be temperature-independent. In conclusion, energetically balanced diets proved to be widely equivalent in their emission potential when combining animal and their slurry, this even at a clearly differing forage : concentrate ratio. The variation in CH4 emission from slurry stored shortly or at cold temperature for 15 weeks was of low importance as such conditions did not support methanogenesis in slurry anyway.
Weaning of livestock mammals is often associated with digestive problems related to profound changes in the physiology of the gastrointestinal tract. This study was undertaken to study the developmental changes in the gastrointestinal tract of mink kits during the period of 34 to 59 days of age. Twenty-four mink kits from eight litters were included in the experiment. The dams and their litters were kept under standard farm conditions. The dams and the kits were fed a diet consisting of 48.1% protein, 40.7% fat and 11.1% carbohydrate of metabolizable energy. The mink kits were weaned at 42 days of age. At 34, 47 and 59 days of age, one male mink kit from each litter was euthanized. The activity of amylase, trypsin, chymotrypsin and lipase in the pancreatic tissue increased during the experimental period, whereas the activity of carboxyl ester hydrolase remained constant. The vitamin E concentration in plasma was stable from 34 to 59 days of age, whereas the concentration decreased in the liver. The stereochemical composition of α-tocopherol showed a steep decrease in the concentration of the biologically most active natural isomer in both plasma and liver through the whole weaning period, whereas the biologically less active 2S isomers showed a clear increase. The concentration of bile salts did not change during the experimental period. The villous height increased in the proximal part of the small intestine and decreased in the distal part, whereas the crypt depth was doubled in both the proximal and distal part of the small intestine. The mucin-staining area on the villi was markedly reduced during the experimental period but no change in the mucin-staining area in the crypts was observed.
The first limiting nutrients in typical laying hen diets are the sulphur-containing amino acids and, in particular, methionine. To fulfil the birds’ recommended requirement, conventional diets are supplemented with synthetic methionine. As this is not allowed in organic production it becomes very important to have access to alternative high-quality protein feed ingredients. An experiment was performed to evaluate the possibility to compose a diet with 100% organically approved feed ingredients using mussel meal as a major source of methionine. The experiment included 678 Lohman Selected Leghorn (LSL) and 678 Hyline White, W-98, layers during 20 to 72 weeks of age. There were 12 aviary pens with 113 birds in each. The birds were fed one of the two experimental diets containing either 3.5% or 7% dried mussel meat meal or a commercial organic diet from a Swedish feed manufacturer for comparison. Production and mortality were recorded daily per group, and egg weight was recorded once weekly. At 33, 55 and 70 weeks, 10 eggs from each treatment group were collected and analysed for internal egg quality. Diets had no significant effect on laying percentage, egg mass, feed intake, feed conversion ratio, mortality, bird live weight or proportion misplaced, cracked or dirty eggs. Egg quality, that is, shell deformation, shell breaking strength, albumen height, shell percentage and proportion of blood and meat spots were also unaffected. There was a significant difference in egg yolk pigmentation, that is, the egg yolk was more coloured when feeding 7% mussel meal compared with the other diets. Hyline hens had lower feed intake and laying percentage, and higher egg weight, but lower egg mass production than LSL birds. The age of the birds influenced all egg quality traits except for meat and blood spots. The dry matter of the excreta was significantly lower for both genotypes fed the 7% mussel meal diet. These results indicate that mussels may be a high-quality protein source and may replace fishmeal in organic diets for layers.
Cattle breeds indigenous to Africa (Sanga) compare favourably to Bos indicus breeds with regard to adaptation to harsh environments. This study compared the meat quality of three Sanga breeds (Nguni, Tuli and Drakensberger), a Sanga-related breed (Bonsmara) and a B. indicus breed (Brahman) and supported these results with biochemical and histological measurements on the M. longissimus lumborum. Twelve young grain-fed steers of each breed were slaughtered and carcasses were electrically stimulated. All Sanga (and related) breeds, with the exception of the Tuli, had lower Warner–Bratzler shear force (SF) values at 2 and 21 days post mortem compared with the BR (P < 0.05). Measurements related to the calcium-dependent protease system and myofibrillar fragmentation explained the bulk of the variation among breeds, whereas variation in fibre type, sarcomere length and connective tissue properties gave less convincing support. With the exception of the Tuli, Sanga and Sanga-related breeds produced more tender (according to SF) meat than BR, mainly due to favourable calpain-to-calpastatin ratios. Small differences in colour, drip loss and cooking properties were found among breeds (P < 0.05).
Theory that successfully explains the magnitude and range of estimates of protein retention (PR) efficiency from the cost of turnover of existing protein indicates that conventional curves for growth description are inappropriate for protein growth. A solution to this problem is found in the consideration that the rate-limiting steps for protein synthesis (PS) and breakdown are likely to be associated with the diffusion of metabolites in and between cells. The algebraic scaling of nuclear and cellular diffusion capacity with tissue or total body protein leads to a parameterization of the primal differential equation for PR (kg/day) based on two terms representing PS and breakdown, viz.where c is an arbitrary constant, Q is the proportion of nuclei active in cell growth or division in a tissue or the whole body, α is the limit mass for protein (P, kg) in a tissue or the whole body, the power X+Z represents the rate-limiting steps in protein breakdown and Y is the power of the relationship between cell volume and the amount of tissue protein. For the whole body, the contribution of the different tissues should be weighted in proportion to their PS rates with, on average, Y = 1/2. The constant 4/9 arises from the scaling of the specific diffusion rate of DNA activator precursors from nuclear dimensions and from the relationship between nuclear and cell volume. Experimental evidence on protein breakdown rate as well as protein and body mass points of inflection indicates that the range of theoretically possible numerical values of the rate-limiting powers X+Z = (i+ 3)/9 for i = 1, 2, … ,12 seems adequate for the description of the range of observed whole body protein and body mass growth patterns for mammals. Q = 1 represents maximal protein retention, and for 0 < Q < 1, experimental evidence exists in support of a theoretical relationship between Q and food ingestion. The conclusion follows that some knowledge of the protein limit mass (α) and of the point of inflection (related to X + Z) is the main requirement for the application of the theory for description and prediction in animal nutrition and breeding.
We developed a method for studying the synchrony of behaviour based on calculations of overdispersion of a binomial process. The lying behaviour of cows was investigated under two different housing units inside the same barn. The first unit housed 30 cows undergoing conventional milking and the second unit housed 27 cows undergoing automatic milking. The lying behaviour of the cows was observed over 3 weeks in 12 periods of 6 h each. Every 5 min, we counted the number of cows lying down in the cubicles. As external cues, like feeding and conventional milking, can promote synchrony in dairy cows, we expected that cows conventionally milked would show more behavioural synchrony than automatically milked cows. Cows lied down synchronously in both units (overdispersion 1.67, P < 0.01). Lying synchrony tended to be slightly bigger in automatically than in conventionally milked cows (overdispersion 1.76 v. 1.58, P = 0.09), although the proportion of cows lying down was on average greater in conventionally than in automatically milked cows (60.7% v. 45.6%). This suggests that synchronized lying behaviour in cows is a constant phenomenon that depends on social facilitation rather than on external cues. The overdispersion index appears to be a useful tool for studying the synchrony of animal behaviour when observations are made at the group level.
A 2 × 2 factorial experiment was conducted to investigate the effects of cereal type (barley v. oat) and exogenous enzyme supplementation (with or without) on intestinal fermentation, and on indole and skatole levels in the intestinal content and the adipose tissue in finisher boars. The experimental treatments were as follows: (i) barley-based diet, (ii) barley-based diet with enzyme supplement, (iii) oat-based diet and (iv) oat-based diet with enzyme supplement. The enzyme supplement contained endo-1,3(4)-β-glucanase (EC 3.2.1.6) and endo-1,4-β-xylanase (EC 3.2.1.8). The animals were fed ad libitum for 45 days from 76.0 to 113.6 kg live weight. Feeding barley-based diets led to higher (P < 0.05) total volatile fatty acids concentrations in the large intestine. Proportions of propionic- and butyric-acids were higher and that of acetic acid lower in digesta from barley-based in comparison to oat-based diets (P < 0.001). Consequently, pH in the large intestine was higher after feeding oat-based in comparison to barley-based diets. Animals fed unsupplemented oat-based diet had higher (P < 0.01) indole concentrations in the digesta from the proximal colon than those fed barley-based diets. Feeding oat-based diets led to lower (P < 0.01) skatole and higher (P < 0.001) indole concentrations in the digesta from the terminal colon than barley-based diets. skatole concentrations in the adipose tissue did not differ (P > 0.05) between the experimental treatments. Pigs offered the barley-based diets had lower (P < 0.001) indole concentrations in the adipose tissue compared with those fed the oat-based diet. In conclusion, barley-based diets were more efficient than oat-based diets in limiting concentrations of indole in the adipose tissue.