Previous studies have demonstrated that even though the polyunsaturated fatty acids (PUFA) in linseed (principally α-linolenic acid, C18:3n-3) were largely biohydrogenated in the rumen significant improvements in the PUFA content of the resultant beef were observed (Choi et al., 1997, Scollan et al., 1997). Treating whole linseed with formaldehyde should help to reduce the degree of biohydrogenation of C18:3n-3, resulting in higher responses at the muscle level. Genetic variation may also play a role in regulating the PUFA content of beef. The objectives of this study were to assess the effect of different sources of dietary PUFA, including formaldehyde treated whole linseed on muscle fatty acids and to determine whether breeds differ in their ability to incorporate n-3 PUFA into muscle lipids.

Continental bulls of high genetic potential for lean tissue growth (½ Blonde d’Aquitaine ⅜ Charolais genotype) have exhibited high rates of liveweight and carcass gain when grass silage based diets were offered with a moderate proportion of concentrates, i.e. concentrates comprising 0.40 of total dry matter intake (Patterson et al., 1994). It was the objective of the present experiment to examine the effect of forage to concentrate ratio in the diet on growth rate and carcass composition.

The experiment was a five treatment continuous design randomised block arrangement with five concentrate ratios in the total diet (DM basis) namely: 0.25, 0.40, 0.55, 0.68 and 0.75 and grass silage (D value 730 g/kg) as the sole forage. The diets were fed ad libitum. A total of 45 continental bulls (½ Blonde d’Aquitaine ⅜ Charolais) were used with mean initial and final live weights of 467 and 651 kg respectively.

Ultrasound imaging has proved a very useful tool for the modern animal breeder wishing to improve carcass composition. However, more accurate imaging technologies, such as X-ray Computer Tomography (CT), could accelerate genetic improvement of carcass composition, and widen the range of traits assessed (e.g. by considering deeper tissues). Carcass quality is assuming more importance for breeders but quality traits are difficult to assess objectively and accurately in live sheep. The present study was designed to identify a few CT scan positions from which accurate prediction of dissected tissue weights could be made in meat sheep.

One hundred Suffolk lambs (50 of each sex) were CT scanned and slaughtered at 14, 18, 22 or 26 weeks of age (59±16kg LW, range 20-96kg). Each animal was scanned at seven sites; three in the gigot (ISC, caudal ischium; FEM, mid-shaft of femur; HIP, hip joint), two in the loin (LV5 and LV2, 5th and 2nd lumbar vertebrae) and two in the chest/ shoulder (TV8 and TV6, 8th and 6th thoracic vertebrae).

The heritable components of many traits in which livestock producers strive for improvement comprise a number of genetic loci. Many workers have now reported the identification of such quantitative trait loci (QTL) using model crosses between divergent breeds or lines in combination with whole genome scans using mapped DNA markers. Such methods rely on two or three generation pedigrees in order to be able to trace the inheritance of markers and the QTL. However, it is not yet clear if such QTL have application in commercial pig populations. The AFLP™ technology is a very efficient method for identifying markers segregating in any population. We have previously reported the successful use of the AFLP™technology and bulk segregant analysis (BSA) for the detection of markers associated with pig coat colour, a monogenic trait (Plastow et al 1998). We set out to determine whether these methods could be used for the detection of loci associated with quantitative traits directly in commercial populations.

The use of genetic markers to identify regions of the genome associated with variation in quantitative traits (QTL) is now widespread. Several studies have attempted to find QTLs for growth and fatness in pigs. Since the first published study (Andersson et al., 1994) many groups have found effects on chromosome 4, albeit with different breeds. In theory, joint analysis offers considerable potential to extract additional information from the data. This study aims to investigate the benefits and drawbacks of joint analysis.

Data on birth weight (BWT), growth rate to end of test or slaughter (GRE) and average backfat depth (BF) were supplied from seven different pig populations in six countries. The data from Scotland, France, USA, Netherlands and half of the data from Germany were Meishan (MS) x commercial F2 populations. Data from Sweden and the remaining German data were from wild boar (WB) x commercial F2 populations. A total of 31 different markers were used, all on chromosome 4.

Early in the 1980s a selection index was designed at SAC to improve the rate of lean growth in terminal sire sheep which combined ultrasound measurements of fat and muscle depth, and live weight at 150 days of age (Simm and Dingwall, 1989). Beginning in 1985, this index was applied in the SAC Suffolk flock in a performance test. In 1994, rams from a line selected on this index weighed on average 12% more (8 kg) and had 12% lower fat depth (– 0.9 mm) and 10% higher muscle depth (2.9 mm) than rams from an unselected Control line. Comparison of Selection and Control line animals has thus far been based on live predictors of carcass composition at weights substantially heavier than typical market lamb weights. The aims of this study were to test whether selection decisions based on the lean growth index produced an improvement in actual carcass composition in purebred terminal sire sheep and whether these changes persisted at live weights different from those under which selection was carried out.

Net feed efficiency refers to variation in feed consumption between animals net of requirements for maintenance and production, and may be measured as residual feed intake (RFI). Because RFI is independent of liveweight (LW) and growth rate, selection for improved net feed efficiency is likely to reduce feed intake with little change in growth. The purpose of this study was to establish whether there exists genetic variation in RFI in young British Hereford bulls, and to determine the phenotypic and genetic correlations of RFI with key production traits.

The data consisted of performance measurements on 540 bull progeny of 154 British Hereford sires, collected over ten 200-day postweaning performance tests conducted between 1979 and 1988. The traits analysed were food intake (FI), 200 to 400-day daily gain (ADG), 400-day weight (W400), predicted carcass lean content (LEAN), lean growth rate (LGR), food conversion ratio (FI/ADG) and lean FCR (LFCR; FI/(ADG x LEAN), described by Bishop (1992).

Genetic evaluations for Somatic Cell Counts (SCC) and Lifespan (LS) have recently been introduced in the UK. LS is a measure of longevity and predicts the ability of a cow to withstand involuntary culling while SCC is used as an indirect measure of mastitis, which is a major reason for involuntary culling. Optimum use of both sources of information require incorporation of both traits in an index. In addition, the usefulness of including some Type traits with SCC to improve the accuracy of indirectly measuring mastitis has been demonstrated. Knowledge of the genetic relationships between SCC, LS and Conformation is crucial to the construction of such indices. This study investigates the relationship between SCC and LS and Conformation in some UK dairy breeds.

There is evidence from UK field data to suggest that selection for milk yield has led to a deterioration in the fertility of lactating dairy cows (Pryce et al., 1997). As cow fertility may be affected by metabolic load and lactation effects, it is important to investigate the fertility of non-lactating heifers. Since 1973 selection line (S) cows at the Langhill Dairy Cattle Research Centre have been bred to bulls with the highest predicted transmitting abilities for weights of fat plus protein (PTA F+P) available in the UK, while the control line (C) are of about UK average genetic merit for PTA F+P. Results using data from lactating Langhill cows show that S cows have calving intervals that are, on average, 12 days longer than C cows, which is a combination of poorer conception rates and a delay in first observed oestrus (Pryce et al., 1999). The objective of this study was to investigate the effect of selection for PTA F+P on the fertility of maiden heifers at Langhill.

Urea is non-toxic, not foreign to the body and it shows an even and rapid distribution throughout the total body water without any physiological effect or toxic manifestation. For these reasons and for its easy and accurate measurement, urea is an ideal tracer to estimate body composition in vivo. Total body water volume (urea space) can be estimated by dividing the total amount of urea infused by the increase in plasma urea concentration between prior to infusion and 12, 18 or 24 min after mean infusion time (Preston and Kock, 1973). In this experiment the urea infusion technique was evaluated to estimate body composition of Belgian Blue double-muscled bulls.

Several studies have investigated once-bred heifers as a means of improving the efficiency of beef production. In these studies, when compared with unbred heifers, the observed carcass effects were usually associated with simultaneous changes in several factors namely: diet composition, plane of nutrition, carcass weight and age at slaughter. The present study aimed to examine the effects of reproductive state on carcass weight and carcass composition, with bred and unbred heifers grown at equal rates of carcass gain on diets of equal composition.

The objective was to examine the effects of parity of cows at slaughter on the growth and development of the carcass, and changes in carcass composition in continental suckler cows in a lowland beef system.

The experiment had a factorial design based on the factors : parity and level of finish. The parity treatments were parities: 0 (maiden), 1, 3 and 5. The levels of finish were medium (fat class 3) and high (fat class 4 L). A group of three Blonde d’Aquitaine AI sires was common to parities 1, 3 and 5. Mean lactation length was 163 days which was spent at pasture. Animals for the medium level of finish were slaughtered at the point of service (maiden heifers) or at weaning (parities 1, 3 and 5), while high finish animals all had an additional finishing period on a grass silage/concentrate diet. A total of 77 animals of ¾ Charolais genotype were slaughtered within the experimental design with approximately equal numbers of animals slaughtered within each treatment.

There is increasing public concern about the welfare of farm animals and one of the issues recently raised has been the use of totally slatted floors for rearing and finishing beef cattle. The objective of this experiment was to examine the effects of using different types of floors in accommodation for beef cattle on the performance, physiology and behaviour of beef cattle.

Sixty Continental-cross steers (mean initial live weight 450 (s.e.m. 2.5) kg) were blocked according to live weight and randomly assigned to one of three floor types, namely fully slatted floors, fully slatted floors covered with perforated rubber mats or solid floors bedded with straw. There were four pens of five animals in each treatment. Daily food intakes and live-weight and carcass weight gains were determined for a mean duration of 139 days. Each individual animal was observed directly, once per week.

Wheat requires processing for feeding to cattle otherwise large amount remain undigested. Processing methods can be mechanical or chemical (sodium hydroxide or aqueous ammonia) but these require specialised equipment and/or the use of contractors. The objective of this trial was to evaluate moist wheat fed whole, but treated with urea at harvest as a means of generating ammonia in situ, in diets for intensively finished cattle.

Eighty tonnes of wheat (variety Riband) was harvested on 21-22 August 1997 at a dry matter (DM) of 750 g/kg and treated immediately with 53 l/tonne of a urea solution (430 g urea/litre) to supply 30 g urea/kg wheat DM. Treatment was achieved by applying the urea to the wheat as it was augered into the storage silo, which was then sealed with polythene.

By contrast to bulls, fattening cull cows deposite large amounts of fat in the carcass. Furthermore, the live weight gain are low. Methionine (M) is a limiting amino acid for muscle growth in Belgian blue cattle (Hornick et al., 1997). Supplementation with M in fattening diets for cattle could therefore improve weight gain or feed conversion ratio. An experiment was thus conducted in Belgian Blue cull cows in order to assess the effects of M in fattening diet on characteristics of tissue deposition.

Twenty four Belgian Blue females from double muscled type -8 heifers (H), 8 cows with 2 calving (C2) and 8 cows with 4 calving (C4)- were used. In each group, 4 animals received a control fattening diet (M0) based on maize silage complemented with cereals, sugar beet pulp and protein from vegetable origin (10.3 MJ ME and 160 g/ kg CP per kg DM), while 4 other received similar diet but with 3.5 g of rumen protected methionine (M1).

Intensive cereal based rations for beef cattle are typically formulated to contain 175 g/kg DM crude protein. Many different sources of protein have been successfully used to supplement cereals. In this study, the performance of bulls fed three different protein supplements were compared, namely rapeseed meal (R), urea (U) and a combination of urea and soya (S). The study also examined the performance of beef cattle fed a yeast culture (Diamond V ‘XP’ Yeast - Rumenco).

A total of 48 Limousin x (Hereford x Friesian) suckled bull calves at approximately 8 months old were allocated to one of three treatments with four replicates per treatment. Two replicates from each treatment were fed 40 g/head/day of yeast culture. Each diet was fed ad libitum with free access to barley straw and water. The feed ingredient inclusions in the rations were: R, 0.775 barley, 0.15 rape, 0.05 molasses, 0.025 minerals; U, 0.85 barley, 0.10 mineralised urea concentrate (Promol™ Rumenco), 0.05 molasses; S, 0.80 barley, 0.10 mineralised urea concentrate, 0.05 soya and 0.05 molasses. The R diet was used as the control. The bulls were slaughtered at fat class 4L. Statistical analysis was by ANOVA unless otherwise indicated.

The aim of future beef production is healthier, tastier products which consumers will find attractive. Combinations of breed and feeding system are required to fulfil these aims. In this project we compared the Holstein- Friesian (HF) breed, an allegedly inferior beef producer, with Welsh Black (WB), a traditional beef breed. Of particular interest was the role of polyunsaturated fatty acids (PUFA) in flavour development.

Thirty six steers, 18 HF and 18 WB, were reared on grass silage plus one of three concentrates. The concentrates contained different fat sources at 0.03 of intake: 1. megalac (control, C16:0); 2. formaldehyde-protected whole linseed (Lin, C18:3 n-3); and 3. an equal mix on a fat basis of protected linseed and fish oil (Lin/fish, C20:5 and C22:6 n-3). The animals were slaughtered after 90 days consumption of the diets. Fortyeight hours after slaughter, three forequarter muscles (M. supraspinatus, M. infraspinatus and M. triceps brachii caput longum) were trimmed of fat, minced and displayed in modified atmosphere packs (0.8 02:0.2 CO2, 4°C in 1000 Lux) for 3 or 10 days.

Assessment of the quality characteristics of meat is time consuming and, due to the heterogeneity of muscle tissue, is subject to considerable variability. A cheap, fast, accurate and non-destructive method of assessment of meat with the potential to predict subsequent quality, would be useful to the meat industry. Near infra red spectroscopy (NIRS) offers this potential for rapid quality assessment and has been shown to be a valuble tool in the evaluation of a variety of meats (Cozzolino et al 1996)

Twenty beef bulls were selected from a commercial herd. Ten bulls (group US) were fed a standard barley-based ration consisting of (g kg–1 DM) barley, 900; GFS Beef 34 protein pellets, 100. Ten bulls (group S) were fed an identical ration supplemented with α-tocopherol acetate (ATA). The average daily intake of these diets was 10 kg DM head-1 d-1 over 100 days prior to slaughter.

In suckler cows follicular development resumes early in the postpartum period, but failure of successive dominant follicles to ovulate results in a prolonged interval from calving to first ovulation (postpartum interval, PPI). Calf isolation and restricted suckling induce ovulation of either the current or subsequent dominant follicle (DF), probably due to changes in LH pulsatility, but this ovulation is generally silent and followed by an 8-10 day cycle due to lack of progesterone priming. The aim of this study was threefold: 1) to examine the acute effects of calf isolation and restricted suckling on LH pulse frequency and PPI, 2) to determine if progesterone priming would eliminate silent heats and short cycles, and 3) to determine if oestradiol treatment would cause atresia of the current dominant follicle and induce new wave emergence providing a “fresh” dominant follicle at progesterone withdrawal.

Supplements of dietary fat are highly effective in boosting energy intake at critical phases during the reproductive cycle. When fed to ruminants in the form of calcium salts of fatty acids, they have been shown to increase plasma cholesterol and progesterone levels (Spicer et al, 1993) which, in turn, could have beneficial effects on ovulation rate and embryo quality. In sheep, a likely reproductive state for a physiological response to a lipid supplement is during the superovulation of young animals in which the post-ovulatory steroidogenic capacity of the corpora lutea may be sub-optimal. The present study examined the effects of donor age and dietary fat on plasma progesterone concentration, and the yield and quality of embryos in superovulated Cheviot sheep.