Eighty-two Scottish Blackface castrated male sheep were used to test whether, from weaning to near maturity, the gigot grew exactly proportionally to the half carcass and whether the tissue in the gigot grew at the same rate as the respective tissue of the half carcass.

While slight deviations from exact proportionality of growth occurred, none could be adjudged significant or important. If the gigot does not grow directly proportionally to the half carcass the data suggested that the gigot tended to grow slightly more slowly than the total half carcass over this period. If gigot muscle does not grow proportional to the total muscle the data suggested that gigot muscle might grow slightly more slowly. If growth of bone tissue is not directly proportional between the gigot and the half carcass the tendency was for the gigot bone to grow slightly faster than total bone while the fatty tissue of the gigot showed a slight tendency to grow more slowly than the half carcass fatty tissue.

An experiment was performed to examine the effects of feeding four concentrations of crude protein in the diet to lactating rabbits. Diets A, B, C and D contained 173, 181, 224 and 243 g crude protein per kg dry matter respectively. Each diet was offered at one of two feeding levels: H (330 g/day) or L (280 g/day) with three replicates in each of the eight treatment groups. Milk production and nitrogen balance were measured over a 28-day lactation.

Although dry-matter intakes on feeding level H were significantly higher than those on feeding level L the difference diminished as the crude protein concentration decreased. The effect of crude protein intake on doe milk production was estimated therefore by regression analysis with digestible energy intake as a covariate. Both crude protein intake and digestible energy intake alone had significant effects (P < 0·001) on daily milk production and there was also a significant effect (P < 0·05) of crude protein intake after fitting digestible energy intake. Overall the equation was:

Milk production (g/day) =

17·61 + 0·985 crude protein intake (g/day) + 30·3 digestible energy intake (MJ/day).

(±0·448) (±14·8)

The relationship between digested nitrogen and nitrogen output as milk was also examined by regression analysis with digestible energy intake as a covariate. This equation was:

Nitrogen output in milk (g/day) =

0·438 + 0·164 digested nitrogen (g/day) + 0·572 digestible energy intake (MJ/day).

(±0·068) (±0·294)

The practical implications of feeding high levels of crude protein in the diet to increase milk production and pup weaning weight are discussed.

Colonization of the gastrointestinal tract of cattle by Shiga toxin-producing Escherichia coli increases the risk of contamination of food products at slaughter. Our study aimed to shed more light on the mechanisms used by E. coli O157:H7 to thrive and compete with other bacteria in the gastrointestinal tract of cattle. We evaluated, in vitro, bovine intestinal mucus and its constituents in terms of their capacity to support growth of E. coli O157:H7 in presence or absence of fecal inoculum, with and without various enzymes. Growth of E. coli O157:H7 and total anaerobic bacteria were proportionate to the amount of mucus added as substrate. Growth of E. coli O157:H7 was similar for small and large intestinal mucus as substrate, and was partially inhibited with addition of fecal inoculum to cultures, presumably due to competition from other organisms. Whole mucus stimulated growth to the greatest degree compared with other compounds evaluated, but the pathogen was capable of utilizing all substrates to some extent. Addition of enzymes to cultures failed to impact growth of E. coli O157:H7 except for neuraminidase, which resulted in greater growth of E. coli O157 when combined with sialic acid as substrate. In conclusion, E. coli O157 has capacity to utilize small or large intestinal mucus, and growth is greatest with whole mucus compared with individual mucus components. There are two possible explanations for these findings (i) multiple substrates are needed to optimize growth, or alternatively, (ii) a component of mucus not evaluated in this experiment is a key ingredient for optimal growth of E. coli O157:H7.

Milk replacers in which skim milk protein (SMP) was replaced in various proportions by undried or dried fish protein hydrolysate (FPH) were offered twice daily to British Friesian male calves. Various proportions of fish protein and milk protein in the diets were obtained by mixing replacer made from SMP with replacers made from undried and dried FPH respectively. The ratios were: 100 FPH, 0 SMP; 67 FPH, 33 SMP; 33 FPH, 67 SMP; and 0 FPH, 100 SMP. Calves were offered the milk replacers only to a maximum of 5 1 per day until 28 days when concentrates and hay were offered ad libitum. The calves were weaned after 42 days. Feed intake and live-weight gain were recorded for 84 days.

There was a marked decrease in performance to weaning when the milk replacer contained two-thirds or more of the FPH. The FPH-fed calves had lower hay intakes than those fed milk only. Treatment differences in post-weaning live-weight gain reflected mainly differences in concentrate intake. There was no significant difference in live-weight gain nor food efficiency for calves fed either undried or dried FPH in any period to 84 days. The number of treatments for scour was similar for the two groups. However, the calves fed dried FPH had a lower dry-matter intake in the post-weaning period.

Two experiments are described in which growing lambs were offered ad libitum two concentrate pelleted diets containing 60 (diet C) or 230 (diet D) g/kg barley straw.

In the first experiment, eight male and eight female lambs were used to determine the outflow rate from the rumen of chromium-mordanted fish meal and soya-bean meal, estimated from faecal marker excretion. Diet D promoted a higher rumen outflow rate (0·0769 per h) than diet C (0·0486 per h); no differences were found either between sexes or between Cr-mordanted protein supplements.

In the second experiment, the rumen degradation of fish meal, soya-bean meal, sunflower meal, pea seeds and sweet lupin seeds was studied by incubating the supplements in polyester bags in the rumens of four lambs, following a change-over design. Increasing the proportion of straw to 230 g/kg increased the rate of nitrogen disappearance from all vegetable supplements, the differences being significant only for pea seeds.

When degradation kinetics and outflow rates were considered together, effective nitrogen degradability of protein supplements was reduced by the increased proportion of dietary straw, indicating a greater influence of rumen outflow rate than of the increased rate of microbial degradation.

Maize silage-based diets with three dietary crude protein (CP) supplements were offered to 96 finishing cattle of contrasting breed (Holstein Friesian (HF) v. Simmental × HF (SHF)) and gender (bull v. steer) housed in two types of feeding system (group fed v. individually fed). The three protein supplements differed either in CP or protein degradability (degradable (LUDP) v. rumen undegradable (HUDP)) and provided CP concentrations of 142 (Con), 175 (LUDP) and 179 (HUDP) g/kg dry matter (DM) respectively, with ratios of degradable to undegradable of 3.0, 1.4 and 0.9:1 for diets Con, LUDP and HUDP, respectively. DM intakes were marginally higher (P = 0.102) for LUDP when compared with Con and HUDP. Rates of daily live-weight gain (DLWG) were higher (P = 0.005) in LUDP and HUDP when compared with Con. HF had higher DM intakes than SHF although this did not result in any improvement in HF DLWG. Bulls had significantly better DM intakes, DLWG and feed conversion efficiency than steers. Conformation scores were better in SHF than HF (P < 0.001) and fat scores lower in bulls than steers (P < 0.001). There was a number of first order interactions established between dietary treatment, breed, gender and housing system with respect to rates of gain and carcass fat scores.

Groups of individually-fed pigs, each of three gilts and three castrates of mean live weights 18, 31, 46, 58, 72 and 80 kg, were given for 20 days feed allowances based on the ARC estimates of energy required for maintenance, assuming an efficiency of utilization of digestible energy (DE) of 77% for maintenance. As the actual diet used had a higher DE value than that calculated before the start of the experiment, DE intakes (260·3 W056) were about 4·0% above the ARC values.

There was no statistically significant change in live weight over the period of study. This supports the validity of the ARC estimates, if maintenance is defined as a lack of change in body weight.

The metabolizable energy (ME) intakes (248·3 W0·56) which maintained weight were also close to other estimates of ME requirements.

Early-cut, precision-chopped (EP) and late-cut, flail-harvested (LF) silages were offered ad libitum to breeding ewes during mid and late pregnancy in two experiments. Silages offered in late pregnancy were factorially arranged with silages offered in mid pregnancy giving four silage treatments. Voluntary drymatter intake, ewe weight change, lamb birth weight and blood levels of 3-hydroxybutyrate (3-OHB) and non-esterifiable free fatty acids (NEFA) were measured. The intake of LF silage was proportionately 0·61 and 0·72 of that of EP silage in mid and late pregnancy respectively. While type of silage given in mid pregnancy did not affect the mean silage intake in weeks 15 to 20 of pregnancy, the rate of decline in intake was higher and the intake during week 20 of pregnancy was lower following the feeding of EP silage in mid pregnancy. Despite a considerably lower level of body reserves associated with LF silage given in mid pregnancy, there was little effect on levels of 3-OHB or NEFA in late pregnancy or on lamb birth weight.

A total of 64 Border Leicester × Greyface ewes were offered eight diets comprising four levels of digestible crude protein and two levels of metabolizable energy (ME) intake during gestation. After parturition the ewes on each gestation treatment were offered a high or low level of ME intake at a constant level of crude protein intake. Nitrogen balances were carried out on all ewes during weeks three and four of lactation.

Digestibility coefficients and output of nitrogen in the milk measured during the lactation balance periods were not significantly affected by the gestation treatments. Body nitrogen balance during lactation was significantly affected by the level of protein offered during gestation.

Empirical equations relating digestible crude protein intake and ME intake to milk nitrogen production and body nitrogen balance indicated that a digestible crude protein intake of 7·9 g/kg W0·75 per day and a ME intake of 220 kcals/kg W0·75 per day resulted in the production of 0·70 g milk nitrogen per kg W0·75 or approximately 100 g of milk per kg W0·75. The corresponding level of body nitrogen retention was 0·162 g/kg W0·75 per day and showed no consistent trend due to level of protein intake during gestation.

Reducing the CP level of the diet allows for a reduction in N excretion without limiting performance as long as the amino acid (AA) requirements are covered. The availability of crystalline AA has permitted for a considerable reduction in the CP level of diets, practically used in pig nutrition. The adoption of low CP diets and the extent to which the CP content can be reduced further depends on the knowledge of the minimum levels of indispensable AA that maximize growth. The standardized ileal digestible (SID) Phe : Lys and Tyr : Lys requirements and the possibility to substitute Tyr by Phe have never been studied in piglets. The objectives of this study were to estimate these requirements in 10 to 20 kg pig as well as to determine the extent to which Phe can be used to cover the Tyr requirement. In three dose–response studies, six pigs within each of 14 blocks were assigned to six low CP diets (14.5% CP) sub-limiting in Lys at 1.00% SID. In experiment 1, the SID Phe : Lys requirement estimate was assessed by supplementing a Phe-deficient diet with different levels of l-Phe to attain 33%, 39%, 46%, 52%, 58%, and 65% SID Phe : Lys. Because Phe can be used for Tyr synthesis, the diets provided a sufficient Tyr supply. A similar approach was used in experiment 2 with six levels of l-Tyr supplementation to attain 21%, 27%, 33%, 39%, 45% and 52% SID Tyr : Lys. Phenylalanine was supplied at a level sufficient to sustain maximum growth (estimated in experiment 1). The SID Phe : Lys and SID Tyr : Lys requirements for maximizing daily gain were 54% and 40% using a curvilinear-plateau model, respectively. A 10% deficiency in Phe and Tyr reduced daily gain by 3.0% and 0.7%, respectively. In experiment 3, the effect of the equimolar substitution of dietary SID Tyr by Phe to obtain 50%, 57%, and 64% SID Phe : (Phe+Tyr) was studied at two limiting levels of Phe+Tyr. From 57% to 64% SID Phe : (Phe+Tyr), performance was slightly reduced. In conclusion, it is recommended not to use a Phe+Tyr requirement in the ideal AA profile but rather use a SID Phe : Lys of 54% and a SID Tyr : Lys of 40% to support maximal growth.

Feed conversion ratio (FCR) in grow-finishing pigs is one of the most important determinants of pig farm profitability and production efficiency. In its simplest form, FCR represents the amount of feed used per unit weight gain of the pig. Yet, this approach entails various limitations hampering its practical applicability such as availability of accurate data and large variation in ways to adapt FCR values for different starting and end weight as well as mortality rates. Various stakeholders are using their own formulas to determine FCR creating a ‘definition nonconformity’ when comparing FCRs among farms. This study aimed to optimize the calculation of FCR through the use of participatory qualitative research. A multidisciplinary research group of 9 persons (animal scientists, veterinarians and agricultural economists) and a consulting group of 31 stakeholders (representing the Flemish primary sector, feed industry, pharma, genetic companies, large retailers, academia and policy institutions) were involved. The decision problem analysis started with a literature review, followed by 25 in-depth interviews and their analyses (NVivo 11™). This led to an additional literature review and the formation of focus (expert) groups that helped to formulate preliminary FCR formulas. Revision rounds between the research team and the stakeholders further fine-tuned the formulas with the final result being two distinct complimentary formulas that are fit for purpose. Both refer to carcass gain per kg feed intake (plain (CGF) and standardized (CGFstandardized)). The first formula (CGF), namely ${{{\it{number \, delivered \, pigs}} \times {\it{average \, warm \, carcass \, weight}} - {\it{number \, stocked \, piglets}} \times {\it{average \, piglet \, weight}} \times {\it{piglet \, carcass \, yield}}} \over {{\it{feed \, consumption}}}}$ is an objective representation of the animals’ performance. The second formula (CGFstandardized) was developed for farm benchmarking, incorporating a seven-step standardization process that corrects for mortality and ‘standardizes’ for a fixed (yet fictive) live weight trajectory of 25 to 115 kg. This second formula allows to compare farms (or batches of fattening pigs) with different weight trajectories and different mortality rates. A webtool was designed to ease this standardization process (https://varkensloket.be/tools/CGF).

In two experiments a high dry-matter silage (36·8% DM) was offered ad libitum, together with a supplement of a conventional concentrate or cobs of dried grass, to young British Friesian castrated male (steer) calves. The silage was readily acceptable to the calves and was preferred to the dried grass. Intakes of silage DM were significantly higher (P<0·001) when supplemented with dried grass than when supplemented with concentrates, but daily gains were significantly (P<0·001) lower by 0·15 kg. The lower daily gains supported by the silage/dried grass diet were related to lower intakes of digestible organic matter (DOM); efficiency of utilization of silage/dried grass DOM was similar to that of concentrate/silage DOM. The results are discussed in relation to recommended levels of production for calves in a semi-intensive beef system.

The body dimensions and live weight of 126 Mule (Bluefaced Leicester × Scottish Blackface) and Scottish Blackface ewes were measured during the 1986/87 housing season. Body dimensions included: head and neck length, body length, diagonal body length, height to withers, height to rump, girth at widest point, heart girth, width at widest point and width at shoulders. It was found that most body dimensions varied greatly with body weight. However, some body dimensions such as head length were found to be independent of weight within the weight range studied. Prediction equations are presented for each body dimensions for unshorn sheep.

These predictions can be used as a basis for the design of sheep housing, for example, trough space allowances, design of feeders or as a biological basis for space allowance.

The aim of this study was to investigate chromosomal regions affecting gestation length in sows. An experimental F2 cross between Iberian and Meishan pig breeds was used for this purpose and we genotyped 119 markers covering the 18 porcine autosomal chromosomes. Within this context, we have developed a new empirical Bayes factor (BF) approach to compare between nested models, with and without the quantitative trait loci (QTL) effect, and after including the location of the QTL as an unknown parameter in the model. This empirical BF can be easily calculated from the output of a Markov chain Monte Carlo sampling by averaging conditional densities at the null QTL effects. Linkage analyses were performed in each chromosome using an animal model to account for infinitesimal genetic effects. Initially, three QTL were detected at chromosomes 6, 8 and 11 although, after correcting for multiple testing, only the additive QTL located in cM 110 of chromosome 8 remained. For this QTL, the allelic effect of substitution of the Iberian allele increased gestation length in 0.521 days, with a highest posterior density region at 95% ranged between 0.121 and 0.972 days. Although future studies are necessary to confirm if detected QTL is relevant and segregating in commercial pig populations, a hot-spot on the genetic regulation of gestation length in pigs seems to be located in chromosome 8.

Two castrated male pigs from each of 620 litters were fed ad libitum to 90 kg market weight at three stations. The pigs represented 20 three-breed crosses produced by mating Yorkshire, Landrace, Lacombe, Hampshire and Duroc sires to Landrace-Yorkshire, Hampshire-Landrace, Large Black-Lacombe, Large Black-Landrace, Duroc-Lacombe and Duroc-Yorkshire dams. The data on feed conversion, average daily gain, age at slaughter, backfat thickness and area of loin eye muscle were analysed by least-squares.

Within breed cross of dam, pigs sired by Hampshire were consistently superior in feed conversion, carcass quality and in 3 crosses out of 5 had the fastest growth rate during the fattening period. They were, however, the oldest at 90 kg live weight. Pigs sired by Duroc ranked second in carcass quality and growth rate, whereas those sired by Landrace had the slowest growth rate. The pigs produced by Hampshire-Landrace sows were superior in carcass quality but inferior in feed conversion and growth to those from sows of the other five crosses.

In descending order, the four highest ranking crosses based on an index combining average daily gain, backfat thickness and feed efficiency were Hampshire × (Landrace-Yorkshire), Hampshire × (Duroc-Lacombe), Duroc × (Landrace-Yorkshire) and Hampshire × (Large Black-Landrace).

Two experiments were conducted to elucidate the effects of intra-muscular injection of oestradiol within 1 min of birth (experiment 1) or within 4h of birth (experiment 2) on piglet activity, growth and pre-weaning survival rate. In experiment 1, 248 piglets (25 litters) were alternately injected within litter at birth with either 1 ml peanut oil/saline solution or 0·1 mg oestradiol benzoate in this carrier solution. The subsequent behaviour, growth and survival of these piglets were recorded. Experiment 2 used 38 litters (385 piglets), these being treated by litter with either of the same two treatments as soon after birth as they were found (approx. range 0 to 4 h). Piglet survival data were collected from this field trial. Oestradiol treatment significantly reduced the intervals from birth to reaching the udder (596 v. 740 s, P < 0·05) and from birth to first sucking (1060 v. 1497 s, P < 0·01) relative to control piglets in experiment 1. Treatment had no significant effect on pre-weaning growth rate (experiment 1), but did tend to reduce early postnatal mortality rate in both experiment 1 (7·2 v. 2·4% for control and oestradiol-treated piglets respectively) and experiment 2 (13·0 v. 10·2% for control and oestradiol-treated piglets respectively). It is concluded that oestradiol treatment at, or soon after, birth induces short-term hyperactivity in piglets. This may subsequently be reflected in an improvement in pre-weaning survival rate of piglets, although further data are required to confirm this conclusion.

1. The area of eye muscle cross-section of beef carcasses may be accurately measured by tracing the boundary and measuring the tracing with a planimeter. Taking a single area measurement from each of duplicate tracings increases the accuracy by some 30%. If a planimeter is not available, the area may be estimated by superimposing a grid on the tracing and counting squares; although this method is some 25% less accurate than the planimeter method it is sufficiently repeatable for experimental use.

2. Area estimated by combinations of linear measurements is highly repeatable, but predicts true area with insufficient accuracy for experimental use. The standard error of prediction is about 7% of the mean area. Regression equations relating planimeter area and combinations of measurements for various cuts and animals are given.

This study aimed to determine the consequences of altering the fatty acid profile of sow diets during mid-to-late gestation; oils of different fatty acid composition were chosen as energy supplements to provide diets with different fatty acid profiles. Forty-eight multiparous sows were used to evaluate the effects of fat supplementation from day 60 of gestation until parturition. Sows were allocated to either 3 kg/day of commercial sow pellets (control; C) or an experimental diet consisting of 3 kg/day of commercial sow pellets supplemented with 10% extra energy in the form of excess pellets (E), palm oil (P), olive oil (O), sunflower oil (S) or fish oil (F). From days 0 to 60 of gestation, all sows were given 3 kg/day of sow pellets as for the C group. The E diet resulted in the heaviest piglets at birth whereas the offspring of O and S sows were the lightest at birth. The offspring of S sows remained lighter throughout the pre-weaning period, and were also the leanest by 14 days of age. In contrast, pigs born to S sows possessed more fat by the time they reached commercial end point (≈140 days of age). In conclusion, altering the fatty acid profile of the sow diet during the second half of gestation has long-term consequences for the development of their offspring.

Data were obtained from 27 pure Shorthorn, 22 Angus × Shorthorn, 31 Charolais × Shorthorn and 27 Hereford × Shorthorn cows, during 10 years. Angus × Shorthorn cows required the least number of services per conception (1·17), had the shortest average gestation lengths (280·6 days), and had a calving percentage of 88·2% and birth weight of calf of 29·8 kg. The respective figures for Charolais × Shorthorn were 1·21 services, 281·6 days, 88·3% (the highest) and 32·9 kg (the heaviest), for Hereford × Shorthorn 1·23 services, 283·6 days, 84·4% and 31·6 kg, and for pure Shorthorn 1·20 services, 282·2 days, 82·7% and 29·6 kg. Average calf weight at birth increased with the advance in age of cow up to 5 years, then showed little change. Seventy-two per cent of the crossbred cows calved for the first time at 2 years old compared with 65% of the Shorthorns. On the other hand, Shorthorn cows had the highest twinning percentage (2·9%) and the lowest single calf mortality at birth (1·4%). The maximum body weights of Angus, Charolais, and Hereford crossbreds and Shorthorn cows were 576·8, 655·8, 6254 and 553·8 kg respectively at 7–8 years of age.

The effects of breed and feeding on the prediction of carcass fat and carcass muscle using rump ‘P8’ subcutaneous fat thickness were investigated in heavy-weight beef carcasses (277 to 512 kg). Hot side weight, eye muscle area and their combination added to fat thickness were evaluated as additional predictors. The predictions of carcass composition from grass-fed steers were validated on data from grain-fed steer carcasses. There were differences between breeds and feeding regimes in the level of tissue proportions at a given fat thickness, but no differences in regression slopes. Fat thickness alone was, therefore, not an accurate indicator of the proportions of side fat or side muscle in heavy-weight carcasses. In the grain-fed steers, the correlations between P8 and tissue proportions were relatively strong, and the addition of hot side weight and eye muscle area, alone or in combination, did not significantly improve the predictions. Conversely, in grass-fed steers where the relationships between carcass composition and fat thickness were weaker, the addition of hot side weight and eye muscle area made a significant contribution to prediction. In the predictions of tissue weights, hot side weight and eye muscle area when added to fat thickness, significantly contributed to the prediction of side muscle weight for both feeding systems. These three variables did not account for the observed differences between breeds or feeding regimes in the proportion or weight of fat, nor in the proportion of muscle; but they effectively eliminated these groups' differences in the estimation of muscle weight.