Search

In this study, sows were fed 200 (LD), 800 (ND) and 3200 (HD) IU of vitamin D3/kg basal diet during pregnancy (from 41 d to birth), respectively. All their offspring pigs were fed the same vitamin D3 replete die. At 150 days of age, a total of 18 offspring pigs (six offspring pigs per maternal diet group, sex balance) were weighed and slaughtered to investigate effects of maternal vitamin D3 during pregnancy on fatty acids synthase (FASN) and hormone-sensitive lipase (LIPE) expression in offspring pigs. The results showed that LD offspring pigs had higher FASN mRNA expression and the ratio of FASN/LIPE mRNA expression in subcutaneous adipose tissue, as well as higher LIPE mRNA expression of longissimus dorsal muscle, whereas, had lower the ratio of FASN/LIPE mRNA expression in longissimus dorsal muscle compared with ND or HD offspring pigs, respectively. Meanwhile, LD offspring pigs had higher carcass fat, average backfat thickness (ABFT), serum insulin and leptin levels, lower intramuscular fat (IMF), serum free fatty acid and triglycerol levels compared with ND or HD offspring pigs. In addition, the ratio of FASN/LIPE mRNA expression was negatively correlated with IMF content, and positively correlated to carcass fat content and ABFT in offspring pigs. Meanwhile, FASN mRNA expression was positively correlated with carcass fat content, while negatively correlated with ABFT in offspring pigs. These results suggested that maternal vitamin D3 affected fat accumulation and meat quality by regulating FASN and LIPE mRNA expression in offspring pigs.

SummaryChamaritolamb was recognized as a quality brand in Spain in April 2010 and this meat is highly appreciated in the local market, but little is known about how a short fattening period may affect final product quality. Twenty lambs, ten from the Ternasco category and ten from the suckling lamb category, were slaughtered and their carcass characteristics compared. All animals were weighed at birth, weaning and before slaughter, and average daily gain was calculated. Cold carcasses were weighed and bruising score, carcass conformation and carcass fatness were noted. The left back of each carcass was separated for dissection. The meat pH, cooking and thawing losses, texture, colour and fatty acid composition were measured on M.longissimussamples. Production traits and meat quality variables were analysed fitting a one-way model with the fixed effect of mean lamb age at harvest. The conformation and degree of fatness of Ternasco-type lambs was not significantly different from suckling lambs but the pH values 24.00 hours post-mortem in muscle (pHult) of the former was slightly higher. The fatty acid profile of suckling lambs was more suitable for a healthy human diet.

The aim of this study was to rank diverse beef cattle genotypes for meat quality characteristics and to determine whether that ranking changed depending on the environment in which the animals were finished. Breed groups, ranging from 100% Bos indicus to 100% Bos taurus content, were derived from Indian zebu (Brahman), African zebu (Boran), British breeds (Hereford-Shorthorn), continental breeds (Charolais and Simmental) and Sanga (Tuli and Belmont Red). Heavy steers (>600 kg) were raised in a tropical environment and finished either on pasture or in a feedlot. For striploins (longissimus) from feedlot finished steers, cooking loss was greatest for zebu (Z) steaks, least for British (B) steaks (P < 0·001), and intermediate for the other breeds. For striploins from pasture finished steers and eye rounds (semitendinosus) from both pasture finished and feedlot finished steers, there were no breed differences in cooking loss. For both feedlot finished and pasture finished steers, striploin steaks from B steers were most tender, and Sanga (S) and zebu × continental cross (ZC) steaks were more tender than Z steaks. Warner-Bratzler initial yields suggested that the lower toughness of these breeds was due to lower myofibrillar toughness. Peak force minus initial yield suggested a smaller, opposite effect of increasing connective tissue toughness associated with increasing Bos taurus content. This breed effect on connective tissue toughness was more prominent in the eye round samples. In the feedlot finished steers, Z eye round was as tender as B eye round. In pasture finished steers, Z eye round had a peak force 1·3 kg lower than B in contrast to the results for striploin where Z was 1·2 kg higher than B. Sanga eye round followed the same trend as B relative to Z but to a lesser extent. From the feedlot, S eye round was more tender than Z eye round and from pasture, S eye round was the same as Z eye round. There was no evidence of heterosis f or any meat quality attribute. These results are best explained in terms of a model incorporating differential effects of breed on the myofibrillar and connective tissue components of toughness. The implications of this study are that the tenderness of grilling and roasting cuts of meat from the predominantly Brahman-based beef herd of northern Australia can be improved through crossbreeding with any of the taurine breeds studied.

A study was carried out involving 721 pigs, comprising boars and gilts, with either 0, 0.25 , or 0.50 Duroc inclusion level, which were produced by mating Large White boars with Large White × British Landrace sows, Large White boars with Duroc × (Large White × British Landrace) sows, or Duroc boars with Large White × British Landrace sows, respectively. Animals were reared on one of seven different feeding regimens from 30 to 90 kg live weight. Tissue growth rates were determined using a triple sampling procedure based on a combination of full-side and ham joint dissection on subsamples of pigs (127 and 366 pigs, respectively) and P2 backfat thickness on the remainder. Initial body composition was determined at 30 kg on subsamples of the three genotypes. Daily food intakes increased with increasing Duroc inclusion but live-weight gains were similar for the three genotypes. Lean and fat growth rates and food conversion ratios were greatest for the 0·50 Duroc group, although the genotype differences were small. Killing-out proportions and P2 fat depths were higher for the 0.25 and 0·50 Duroc groups. The proportion of lean in the carcass was lower (P < 0·01) for 0·50 Duroc pigs. Japanese colour scores and EEL reflectance indicated that the longissimus muscle was darker for the 0·25 and 0·50 Duroc genotypes. Subcutaneous fat firmness scores and penetrometer readings taken in the mid back indicated softer fat for the 0 Duroc group. Intramuscular fat levels increased (P < 0·01) with increasing Duroc inclusion (10.4, 11.2, and 18·2 g/kg for the 0, 0.25, and 0.50 groups respectively). Cooked longissimus from pigs with 0·50 Duroc had a lower shear force and was judged to have a stronger pork odour and to be more tender and acceptable than that from the 0 Duroc group. The 0.25 Duroc group showed a small improvement in tenderness but a weaker pork odour and similar overall acceptability compared with the 0 Duroc group. This study suggests that the use of the Duroc in crossing systems in the United Kingdom will have limited impact on growth performance but that 0·50 Duroc inclusion will result in fatter carcasses, higher intramuscular fat levels and improved eating quality.

The objective of the study was to investigate the influence of amino acid-deficient diets and high dietary leucine levels offered for intervals of either 21 or 35 days pre-slaughter on the intramuscular fat content of pig muscle. Twenty-four hybrid gilts were offered individually ad libitum one of four diets that comprised combinations of amino acid levels (supplemented or deficient: 5·6 v. 4·0 g lysine per kg) and low or high leucine levels (10·3 v. 30·3 g leucine per kg). Live weights at the start of the study were 74·5 and 87·0 kg for pigs on the 35- and 21-day feeding regimens, respectively. There were no significant effects of dietary amino acid level, leucine level, or feeding interval on food intake, daily live-weight gain or food efficiency. Pigs given the amino acid-deficient diets had lower killing-out proportions (736 v. 747 (s.e. 3·4) g/kg; P < 0·05) and longissimus dorsi muscle areas (32·6 v. 35·7 (s.e. 0·71) cm2, P < 0·01) than those given amino acid-supplemented diets. Subjective score for longissimus dorsi colour indicated that pigs on the high leucine diet had darker muscle than those on the low leucine diet. Intramuscular fat contents of the longissimus dors i muscle at the Wth/llth rib and the 3rd/4th lumbar vertebra and of the semimembranosu s muscle were increased by 19, 18 and 18 g/kg, respectively (P < 0·05), for pigs given amino acid-deficient compared with those given amino acid-supplemented diets. Dietary leucine level had no significant effect on intramuscular fat level. Pigs given the diets for 35, compared with 21, days had higher fat levels in the semimembranosu s muscle (52 v. 30 (s.e. 5·2) g/kg; P < 0·01) but not in the other two muscle locations studied. This study suggests that relatively short-term feeding of amino acid-deficient diets can produce substantial increases in intramuscular fat levels.

One hundred and twenty spring-born steers, comprising 40 Friesians (FR), 40 Meuse-Rhine-lssel (MRI) × Friesians (MR), and 40 Belgian Blue × Friesians (BB) were reared together from 3 weeks of age to the start of their second winter. During the second winter there was a 3 (FR, MR and BB breed types) × 2 (3 kg and 6 kg supplementary concentrates per head daily with grass silage ad libitum) × 2 (96- and 220-day finishing periods) factorial arrangement of treatments (10 animals per subgroup). Carcass weights and grades were recorded after slaughter at the end of the second winter, and one side from each of 96 carcasses (eight per subgroup) was dissected into bone, muscle, intermuscular fat and subcutaneous fat. A sample of m. longissimus from the 10th rib was chemically analysed. Slaughter weights and carcass weights per day from arrival to slaughter were 796, 813 and 828 (s.e.d. 11·7) g and 419, 440 and 457 (s.e.d. 7·1) g for FR, MR and BB, respectively. Corresponding carcass weights were 314, 329 and 342 (s.e.d. 4·5) kg. BB had better conformation than both FR and MR. BB also had a lower carcass fat score, lower proportions of bone, intermuscular fat and subcutaneous fat, a higher proportion of muscle and muscle with higher proportion of moisture and a lower proportion of lipid than FR and MR. The higher level of concentrates increased side iveight by 8 kg, but the overall effects on carcass composition were small. The longer finishing period increased side weight by 25 kg and was associated with significantly reduced proportions of bone and muscle and an increased proportion of fat. Allometric regression coefficients for carcass weight on slaughter weight, and for bone, muscle and fat weights on side weight were 1·19, 0·39, 0·80 and 2·16, respectively. It is concluded that despite the better carcass conformation of MR, there was little difference in carcass and muscle composition between FR and MR. BB, in addition to having a higher growth rate and better carcass conformation than FR, also had more muscle in the carcass, more of the total muscle in the higher value joints and a lower proportion of lipid in the muscle. It was calculated that FR, MR and BB would have similar proportions of separable fat in the carcass at approximate carcass weights of 300, 320 and 400 kg, respectively.

One hundred and twenty spring-born steers comprised of 40 Friesians (FR), 40 Canadian Hereford × Friesians (HF) and 40 Simmental × Friesians (SM) were reared together from shortly after birth to slaughter after a mean period of 740 days. During the finishing winter there was a 3 (breed types) × 2 (3 and 6 kg supplementary concentrates per head daily with grass silage ad libitum) × 2 (222- and 225-day finishing periods) factorial arrangement of treatments. One side from each of 96 carcasses (eight per treatment) was completely separated into bone, muscle, intermuscular fat and subcutaneous fat and a 10th rib sample of m. longissimus was chemically analysed.Carcass weights per day of age and carcass weights were 404, 433 and 449 (s.e. 4·6) g and 301, 320 and 330 (s.e. 3·4) kg for FR, HF and SM, respectively. Corresponding proportions of carcass muscle were 602, 577 and 628 (s.e. 4·8) g/kg. FR and HF had similar proportions of their total muscle in the hindquarter, whereas SM had more of their muscle in the hindquarter. M. longissimus lipid concentrations for FR, HF and SM were 36, 39 and 26 (s.e. 1·96) g/kg. Increasing supplementary concentrate level from 3 to 6 kg/day increased side weight by 7 kg, of which proportionately 0·48 was fat. Extending the finishing period from 121 to 225 days increased side weight by 22 kg of which proportionately 0·45 was fat. Both the higher concentrate level and the longer finishing period reduced carcass muscle and bone proportions, and increased carcass fat proportion. Allometric regression coefficients for side muscle, bone and fat weights on side weight were 0·75, 0·51 and 2·13, respectively. It was calculated that FR, HF and SM would have similar carcass fat proportions at approximate carcass weights of 320, 290 and 380 kg, respectively.

A total of 96 Large White weaner pigs, comprising equal numbers of entire males and females, and of controls and eighth generation index-selected genotypes, were fed ad libitum until 40 kg live weight. From 40 kg until slaughter at 85 kg live weight pigs within genotype and sex groups were fed either ad libitum or 2·2 times maintenance. The left sides of the carcasses were divided into shoulder, middle and ham portions and the middles further divided into eye, wedge and belly dorso-ventral portions. Tissue dissection was performed on all portions separately.Selected pigs yielded proportionately 0·15 less fat, 0·08 more muscle, a smaller muscle: bone ratio and 4·05 mm less P2 backfat depth than the controls. When the data were adjusted to the same mean P2 fat depth, the carcasses of selected pigs had 0·07 less fat and 0·03 more muscle. There were no appreciable differences between the genotypes in cranio-caudal tissue distribution. However, there were differences in dorso-ventral tissue distribution since the middles of selected pigs had proportionately and absolutely more of each tissue in the belly. There was no evidence that selection against fat at the P2 site had caused any increase in fat lateral to the m. longissimus.Food restriction increased carcass muscle by 0·10 and decreased fat by 0·17, but had no effect on muscle: bone ratio or cranio-caudal or dorso-ventral tissue distribution. At the same carcass side weight and P2 fat depth, restricted feeding decreased fat by 0·10 and increased muscle by 0·06 in the carcass side.It is concluded that carcasses of the selected pigs would be undervalued relative to the controls due to less fat and more muscle at the same weight and P2 fat depth. Also, restriction on food intake can cause carcasses to be undervalued relative to feeding ad libitum.

An experiment was carried out to compare sire breeds for carcass traits and to estimate heritabilities and phenotypic and genetic correlations. There were 1908 male cattle from 5 birth years. The sire breeds, each evaluated over three locations, were Blonde d'Aquitaine, Charolais, Chianina, Limousin, Maine Anjou, Simmental (four strains: Austrian, French (Pie Rouge), Swiss and West German) and South Devon (i.e. seven imported breeds) and Angus, Friesian, Hereford and Jersey (four local breeds), with a total of 161 sires represented. Each location contained Angus cows and additionally one location contained Hereford cows. Proportionally 0·72 of the cattle were slaughtered at about 20 months of age, whilst random samples from each of the first 4 years were retained for slaughter at about 31 months of age.Sire breeds ranked similarly for live weight at 13 months of age and for pre-slaughter weights at both 20 and 31 months of age. Relative to the Hereford-cross, the seven imported breeds were proportionally 0·054 to 0·072 heavier at slaughter (depending on slaughter age) and they had 0-065 to 0·077 heavier carcasses. Dressing proportions for the Blonde d'Aquitaine, Chianina and Limousin sire breeds were higher by at least 0007 units than for the Hereford-cross. The seven imported breeds were all leaner and had larger areas of m. longissimus than the Hereford-cross cattle. Friesian-crosses also had high live or carcass weights although they were intermediate for fat depth.The interaction of sire and dam breeds were only significant for fat depth (both slaughter ages) and for pre-slaughter and hot carcass weights (31-month slaughter age only). Interactions between sire breed and location were not important.Heritability estimates on data adjusted to a slaughter age of 595 days were: pre-slaughter weight 0·29, hot carcass weight 0·28, dressing proportion 0·14, fat depth 0·03 and m. longissimus area 0·30. Corresponding values on cattle whose records were adjusted to an age of 935 days were 0·56, 0·44, 0·39, 0·37 and 0·29. These values were from cattle grazed on pasture, and were generally lower than those from America (from cattle offered high energy rations). Phenotypic correlations among all pairs of traits were positive, whilst genetic correlations were positive for all pairs except those involving fat depth (where standard errors were large).

Increasing the ratio polyunsaturated:saturated fatty acids (P:S) in beef muscle by nutrition is hampered by the high levels of ruminal biohydrogenation of dietary polyunsaturated fatty acids (PUFA). Effective ruminal protection of dietary fatty acids, such as that provided by encapsulation of PUFA in formaldehyde-treated protein may ameliorate this situation. This study evaluated the effects of including in the diet a ruminally protected lipid supplement (PLS), containing linoleic (C18:2) and α -linolenic (C18:3) acids, on the fatty acid composition of the m. longissimus.

The calpain enzyme system plays an important role in the proteolytic events leading to the conversion of muscle to meat in livestock species. Increasing evidence suggests that calpastatin, the inhibitory component of the system, correlates negatively with tenderness in beef and pigs (Koohmaraieet al., 1995; Senskyet al., 1998). In this study, the immunoreactivity of calpastatin in three pig breeds with different meat quality traits have been measured.Thirty-six female pigs, comprising equal numbers of Duroc (D), Large White (LW) and Duroc x Large White (50:50 DxLW) breeds were reared under identical conditions at a commercial pig unit and slaughtered at a commercial slaughterhouse on the same day by electrical stunning and severance of the carotid arteries. Carcass weight, backfat thickness, pH45and pHuwere all monitored.

Two hundred and twenty-four pig carcasses were used to compare the Hennessy Grading Probe and the Fat-O-Meater in their accuracy for measuring fat and muscle thickness (m. longissimus). Accuracy was defined in terms of precision and bias. The precision (relationship between repeated measurements) of the two probes in measuring fat and muscle thickness varied with the probing locations. When differences were detected, the higher precision was found with the Fat-O-Meater. The mean bias in measuring fat thickness was negative for the Hennessy Grading Probe (P < 0·01); however, for the Fat-O-Meater, no mean bias was detected. Furthermore, the extent and the direction of the bias in measuring fat over the range of fat thickness studied varied with the probe and the probing location.

The Hennessy and Chong Fat Depth Indicator and the Ulster Probe automatic recording instruments developed for measuring fat thickness were tested against the optical probe for use in pig carcass classification and grading.Fat thickness measurements were taken using each probe 60 mm from the dorsal mid-line over the m. longissimus at the positions of the 3rd/4th lumbar vertebrae, 3rd/4th last ribs and last rib on a total of 110 hot carcasses covering the range of market weights in Great Britain. The standard deviation of carcass lean proportion at equal carcass weight was 35·4 g/kg.The instruments differed little in the precision of carcass lean proportion prediction: residual standard deviation (g/kg) for the multiple regression with carcass weight and the best individual fat measurement for each probe were: last rib optical probe, 22·1; last rib Ulster Probe, 22·7; and 3rd/4th last rib Fat Depth Indicator, 21/6. Residual standard deviation (g/kg) for carcass lean proportion prediction from carcass weight and all three fat measurements in multiple regression were 21·3 optical probe, 21·3 Ulster Probe and 201 Fat Depth Indicator.Similar mean fat measurements were obtained from the optical probe and Fat Depth Indicator, and for these instruments, but to a lesser extent for the Ulster Probe, the regression relationships with each other and with fat thickness measurements taken on the cut surface of the cold carcass were also similar.The differences recorded in precision are unlikely to be sufficiently important to influence the choice of one probe rather than another.

Evaluations of meat quality were made of 300 carcasses, of average weight 58 kg, falling into three fatness groups, 8, 12 and 16 mm for P2 fat thickness. There were equal numbers of entire males and gilts. An increase in fat thickness was associated with an increase in the firmness of loin and shoulder backfat, a reduced incidence of fat separation and changes in the composition of both muscle and backfat: the concentration of lipid increased and that of water decreased, more markedly in backfat. In addition, the concentration of collagen in backfat decreased. The loin joint was visually most attractive when P2 was 11 mm, attractiveness decreasing below and particularly above this value. Eating quality of grilled chops was assessed in a representative subsample of 96 pigs falling into the 8-mm and 16-mm P2 categories. The only statistically significant difference observed between these extremes of fat thickness was in juiciness which was lower in the leaner pigs; the correlation between juiciness score and m. longissimus lipid concentration (‘marbling fat’) was 0·31. Juiciness did not influence the assessment of overall eating quality which showed no association with fatness. Entire males of similar backfat thickness to gilts (12 mm P2) had a higher concentration of water and lower concentration of lipid in backfat and slightly softer backfat. There were no differences in eating quality, or in the presence of abnormal odours or flavours, between entire males and gilts. These results confirm those obtained in butcher and consumer panel tests in the same carcasses.

Two experiments, each involving 48 British Friesian cattle, were carried out to examine the performance and carcass quality of bulls and steers implanted with one of three oestrogenic growth promoters in a semi-intensive system of beef production in which the animals were slaughtered at 14 to 17 months of age. The treatments used in experiment 1 were: (1) control steers (no implant); (2) steers implanted with 45 mg oestradiol in silastic rubber at 4·5 months of age and with 300 mg trenbolone acetate at 10·5 and 13·5 months; (3) steers implanted with 20 mg oestradiol and 200 mg progesterone at 95-day intervals from 4·5 months and with 300 mg trenbolone acetate at 10·5 and 13·5 months of age; (4) bulls (no implant). For treatments 1 to 4 respectively dry-matter (DM) intakes were 6·74, 7·24, 7·50 and 7·16 (s.e. 0·092) kg/day; carcass weights were 260, 283, 298 and 290 (s.e. 5·4) kg; and fat depths over m. longissimus were 6·5, 5·3, 6·3 and 3·4 (s.e. 0·53) mm. The same treatments were used in experiment 2, except that 36 mg Zeranol® was used in treatment 3 instead of 20 mg oestradiol plus 200 mg progesterone, and the bulls in treatment 4 were implanted with 36 mg Zeranol at 7·5, 11 and 14·5 months. For treatments 1 to 4 respectively DM intakes were 7·37, 7·85, 7·76 and 7·42 (s.e. 0·092) kg/day; carcass weights were 262, 285, 284 and 296 (s.e. 7·1) kg and mean fat depths over m. longissimus were 7·1, 5·9, 7·0 and 5·2 (s.e. 0·54) mm. Implantation of steers increased food intake but also improved food conversion efficiency and did not consistently affect carcass fatness or conformation. Repeated implantation with 20 mg oestradiol plus 200 mg progesterone produced a greater response in performance than a single implantation with 45 mg oestradiol-17β in a controlled-release silastic-rubber implant, while repeated implantation with 36 mg Zeranol produced a similar response to the single silastic-rubber implant. Bulls produced leaner carcasses and converted food to carcass gain more efficiently than implanted steers.

An electronic meat-measuring equipment (EMME) determination (average of three consecutive readings) and backfat thickness (averaged over two sites) were taken on each of 107 live Yorkshire pigs weighing approximately 110 kg. After slaughter, 10 carcass traits: killing out, grade fat (fat thickness at maximum loin of split carcass), in. longissimus area, total and individual weights of the four untrimmed primal cuts (butt, picnic, loin and ham) and total weight of lean and subcutaneous fat in the four primal cuts, were measured and used to evaluate the EMME and ultrasound backfat probe, alone and in combination, in predicting carcass merit. Value of prediction was measured as significant improvement in correlation over a base model (A/?2). After adjustment for live weight and treatment (diet, sex and housing) differences, the EMME alone was significant in predicting grade fat (A/?2 = 007), weight of the four untrimmed primal cuts (A/?2 = 0·03) and weights of ham (A/?2 = 0·04), lean (A/?2 = 0·17) and subcutaneous fat (A/?2 = 0·08). Backfat thickness alone was significant in predicting grade fat (AR2 = 0·21) and the weights of loin (AR2 = 0·03), ham (AR2 = 0·02), lean (AR2 = 0·09) and subcutaneous fat (AR2 = 0·42). Their combined information was superior in predicting fat thickness (AR2 = 0·24), weight of lean (AR2 = 0·21) and weight of subcutaneous fat (AR2 = 0·44). Similar results were obtained when treatment effects were ignored. Correlations of the EMME number with fat thickness, weight of total lean and total subcutaneous fat were 0·31, 0·49 and -0·30, respectively. Correlations of backfat thickness with grade fat, weight of total lean and total subcutaneous fat were 0·53, -0·35 and 0·72, respectively.

SUMMARYCarcass data for 1053 steers from the Meat and Livestock Commission's beef breed evaluation programme were used to examine the relative precision of alternative fatness assessments for predicting carcass lean percentage. The data were from four trials and comprised both dairy-bred and suckler-bred cattle by a wide range of sire breeds.A visual assessment of carcass subcutaneous fat content to the nearest percentage unit (SFe) was the single most precise predictor both overall (residual S.d. = 2·28) and within breed (residual S.d. = 2·05). Precision was improved by the addition in multiple regression of the percentage perinephric and retroperitoneal fat (KKCF) in carcass, a visual score of the degree of marbling in the m. longissimus and selected fat thickness measurements taken by calipers on cut surfaces (residual S.d. = 2·11 (overall) and 1·90 (within breed)).When the best overall equation was applied to the breed means, there was substantial bias (predicted – actual carcass lean percentage). Biases ranged from +2·5 (purebred Canadian Holstein and Luing) to – 1·3 (Limousin crosses).Breeds differed significantly in carcass lean content when compared at equal levels of fatness measurements. The differences depended both on the precision with which the measurements predicted carcass lean content and the observed differences in carcass composition that existed before adjustments to equal fatness were made.The robustness of prediction equations was examined by applying them to independent sets of data (a total of 334 carcasses) from four other trials involving steers, heifers, cows and young bulls. Equations were stable for cattle of the same breed, sex and similar levels of fatness but important bias was found between more extreme types of cattle.

Scans of the m. longissimus and overlying fat at the 12th rib were taken, just prior to slaughter, on 254 lambs using the Scanogram and Danscanner ultrasonic machines. The lambs were from a ram breed trial and comprised six sire breed × five dam breed groups. Mean live weight at slaughter was 44·5 kg.The precision with which scan measurements predicted comparable carcass measurements and carcass lean content (g/kg lean) was examined within groups with variation in live weight eliminated.Residual s.d. for the prediction of carcass m. longissimus area from the corresponding scan measurement was 141 and 158 mm2 for the Scanogram and Danscanner respectively (s.d. of carcass m. longissimus area was 162mm2). Residual s.d. for the prediction of lean from the best combination of fat measurements was 32·0 for the Scanogram and 35·8 for the Danscanner (s.d. of lean was 38·5). M. longissimus did not increase the precision of lean prediction.In a comparable evaluation of the Scanogram, involving 147 lambs, the residual s.d. for the prediction of lean was 24·0 (s.d. = 28·9).The levels of precision obtained were low and it is debatable whether the ultrasonic techniques examined would be of value for carcass lean prediction in practical applications. They might be of use in selection programmes within nucleus flocks of the more important meat sire breeds or as an aid in experiments for differentiating between animals of widely differing composition.

A trial was carried out to examine some of the factors involved in the possible deterioration in pig meat quality associated with the trend towards leaner carcasses. Five batches of pigs, each one as far as possible from the same producer, were identified at each of 10 abattoirs. Three gilts and three entire males were selected from each batch to show a range of fatness. Overall mean fat thickness measurements over the m, longissimus at the last rib (P2, mm) for lean, average and fat carcasses were 8·8, 11·6, and 16·9 (gilts) and 8·4, 11·7 and 15·5 (entire males). The overall mean carcass weight was 58 kg. Loin and leg joints were assessed for cutting and presentational characteristics by a panel of 45 butchers. Loin chops and shoulder and leg joints were assessed for eating characteristics by consumer panels involving a total of 500 families. Butchers judged the fat of lean carcasses to be softer and the meat to be floppier and with more tissue separation. Entire males also had slight disadvantages in these respects. Consumers found the chops of lean carcasses to be less juicy on average (0·16 lean carcasses were judged to have dry chops compared with 0·09 for fat carcasses) with a tendency towards toughness and less flavour. There were no differences in overall acceptability. Meat from the two sexes did not differ in eating quality or overall acceptability to consumers. The butchers were more critical of overlean carcasses than were consumers. The trial indicates that the trend towards leaner carcasses is likely to create butchery problems but not consumer dissatisfaction.

Fat thickness and measurements of the m. longissimus (‘eye’ muscle) were taken at the last rib in 350 lambs' carcasses which were fully dissected. The lambs were from two ewe breeds, Clun and Colbred, and two ram breeds, Suffolk and Hampshire, and the carcass weight range was 15 to 21kg. Castrated males and females, and singles and twins, were evenly represented.Rib fat thickness (J) was a slightly more precise predictor of the weights of lean, subcutaneous fat and subcutaneous plus intermuscular fat, when used in a multiple regression equation along with carcass weight, than fat thickness directly above the greatest depth of the ‘eye’ muscle (C). Both of these were more precise predictors than ‘eye’ muscle width and depth. Accounting for breed, either by allowing for different intercepts or completely different regression lines, did increase the proportion of variation in tissue weights explained by carcass weight and J or C, but to a small and, it was considered, commercially unimportant extent. This was despite differences in conformation between the breeds, reflected in this work by smaller ‘eye’ muscles in the ewe than the ram breeds and also in maturity, which might have been expected to influence tissue, including fat, distribution.The results indicate that breed differences in partition and distribution within and between the carcass fat depots in sheep are smaller than those between the carcass and intra-abdominal fat depots.

To gain approval for use in the revised European Community (EC) Pig Grading Scheme to be introduced in 1989, methods of estimating carcass lean proportion must be shown to do so with a coefficient of determination greater than 0·64 and a residual s.d. of less than 25 g/kg. A trial was carried out to assess a number of methods for use in the EC Scheme as applied in Great Britain. Subcutaneous fat and m. longissimus depths at the head of the last rib and at the third/fourth from last rib were measured using the optical probe (OP), the Fat-O-Meater (FOM), the Hennessy Grading Probe II (HGP) and the Destron PG-100 Probe (DST) on a broad sample of 162 commercial carcasses representative of the ranges in fatness and weight found nationally. The left side of each carcass was separated into component tissues. Although the instruments all achieved similar levels of accuracy in predicting carcass lean proportion, some differences were found. The DST just failed to reach the required statistical criteria for approval in the EC Scheme. The results for the other three instruments were submitted to Brussels as evidence of suitability and they have been approved.Using the regression relationships found between carcass composition and fat thickness together with results from earlier studies, it was estimated that the carcass separable fat proportion of British slaughter pigs has fallen at the annual rate of 7 g/kg since 1975.

Sixty-four commercial hybrid male pigs given different levels of feeding between 27 and 87 kg live weight were used to determine whether quality differences between boars and castrates, when used for bacon production, are true castration effects or due to the greater leanness of boars. At the same carcass composition as castrates, boars had: a higher proportion of water inm. longissimus; a higher proportion of water and lower proportion of lipid in both layers of backfat at last rib; and slightly lower curing gain as the result of a greater loss of tissue water during curing. A separate study on the composition of backfat in lighter weight pigs also revealed a higher proportion of water and lower proportion of lipid in boar backfat compared with that of castrates or gilts, and in both studies a higher proportion of fat-free dry matter in boar backfat indicated greater synthesis of connective tissue protein. Subjective assessment of backfat firmness and whiteness revealed no important castration effects that were independent of carcass composition. The leanest group of boars (average 12 mm P2) had the lowest score for firmness. Fatty acid composition of outer and inner backfat layers was determined more by the rate of fat deposition than by castration.

AbastractMeasurements of live weight and of ultrasonic (Scanogram) fat depth and m. longissimus cross-sectional area at the 12th/13th rib were taken at 4— to 6-week intervals from 10 to 35 months of age (23 occasions) on 15 Hereford males (bulls), 15 castrate males (steers) and 15 females (heifers) managed under grazing conditions.Mean rates of live-weight change throughout the measurement period (0·51, 0·47 and 0·39 kg/day for bulls, steers and heifers, respectively) were significantly different. When compared at the same ages, fat depth was similar in the steers and heifers, beginning at about 3 mm and increasing to 11 mm. Fat depth changed little in the bulls, beginning at 1·7 mm and increasing to 3 mm. At the same age, bulls had larger m. longissimus cross-sectional areas than steers and steers had larger muscle cross-sectional areas than heifers.Absolute variation within sex groups increased throughout the experiment in live weight and fat depth, but not in m. longissimus crosssectional area. Simple correlation coefficients, pooled within sex groups, of relationships between the same measurements at various measuring occasions, indicated that measurements of fat depth and of muscle cross-sectional area at 10 to 12 months of age are poor indicators of these measurements at periods of 6 months or more later in life.When compared at the same live weights, heifers had the greatest and bulls had the smallest fat depth and, within animals, fat depth was closely related to live weight. At any live weight, m. longissimus cross-sectional area was less in heifers than in steers and bulls, which were not significantly different from each other in this trait. Equations relating fat depth and muscle area to live weight are presented and, under the conditions of this study, indicate that there is no basis for adjustment of fat depth for live weight in bulls subjected to contemporaneous selection.

Data for 15 487 pigs taken from the first 8 years (1973–81) of the Meat and Livestock Commission's Commercial Pig Evaluation were used to examine the effects of sex, feeding regimen, slaughter weight and day of slaughter on muscle quality characteristics in 20 populations (pigs from different commercial breeding companies and control populations). The characteristics examined included pH measurements both at 45 min post mortem (pH,) and after overnight cooling (pH2), in the m. longissimus and m. semimembranosus. Visual assessments of m. longissimus colour and condition were also made.The overall mean for pH, in the m. longissimus was 6·34; 0·12 of pH, values were less than 6·0. The proportion of carcasses visually assessed as either pale or wet was 0·116, and 0·027 were assessed as both pale and wet.The populations were compared separately within each of three time periods (covering the full 8 years) since significant population × time period interactions were recorded for several characteristics. Within each period the populations differed significantly for all characteristics examined (P < 0·05); but with the exception of two extreme populations, the differences were relatively unimportant.The effects of sex, feeding regimen and slaughter weight were negligible but the effect of day of slaughter was very important: the s.d. of pH1 was reduced by 0·15 when calculated within day but by only 0·01 when adjusted for all other factors.Muscle quality characteristics were poorly correlated with carcass characteristics: the highest correlation within day of slaughter was −0·23, recorded between pH, and ham conformation score.

SUMMARYResults are reported from four separate trials carried out to determine the precision of the Sonatest (simple A-mode ultrasonic machine) and the Scanogram (modified linear scanner) for predicting the body composition of live cattle. Cattle in the four trials differed in breed, sex and origin, and the data provided an opportunity to determine the consistency of results in different circumstances. A total of 210 cattle were involved.Fat thickness measurements (Sonatest and Scanogram) and fat and M. longissimus areas (Scanogram only) were taken at the 10th and 13th ribs and at the position of the 3rd lumbar vertebra. Their precision as predictors of carcass tissues percentages was examined when they were used in addition to live weight at evaluation.There was little consistency between trials in the positions and measurements which gave the most precise prediction. The lowest within-breed residual standard deviations of carcass lean percentage obtained with fat thickness measurements taken by Sonatest were in the range 2·5–2·7 and there was little advantage in using additional measurements in multiple regression.Fat areas taken by Scanogram were more precise predictors (within-breed residual standard deviations were close to 2·0). Precision was improved marginally to about 1·8 by using combinations of fat areas but M. longissimus areas were of little additional value.

Carcass evaluation data from two breed-comparison trials were used to examine the value of conformation as an indicator of carcass composition when used in addition to carcass weight and different measures of fatness. One trial involved 1478 crossbred lambs out of three ewe types by Border Leicester, Dorset Down, Ile-de-France, North Country Cheviot, Oxford Down, Southdown, Suffolk, Texel and Wensleydale sires. The other trial involved 920 crossbred lambs out of two dam types by Dorset Down, Ile-de-France, Oldenburg, Oxford Down, Suffolk and Texel sires. Each trial extended over 3 years.Conformation contributed little to the prediction of carcass lean percentage or proportion of lean in the higher-priced joints, although the additional precision was often significant at PConformation was slightly more valuable for the prediction of lean to bone ratio and m. longissimus depth. The addition of sire-breed effect to weight and fat class provided an important increase in the precision of prediction of percentage lean in carcass and lean to bone ratio. Texel progeny had higher lean to bone ratios and more lean in the carcass than progeny of other sire breeds, but they did not have sufficiently high conformation scores to clearly identify this advantage.

Two experiments have been carried out to examine the effects on the intake and performance of finishing beef cattle of supplementing grass silages (perennial ryegrass) of medium and high digestibility (MD and HD respectively) with either extracted soya-bean meal or fish meal. In each experiment, the two silages were supplemented with (1) barley (107 g crude protein (CP) per kg dry matter (DM)), (2) a mixture of barley and soya-bean meal (187 g CP per kg DM) and (3) a mixture of barley and fish meal (182 g CP per kg DM) in a 2 × 3 factorial design. The MD silages were supplemented with 4·5 kg concentrates per head daily in each experiment and the HD silages with 2·75 and 2·5 kg per head daily in experiments 1 and 2 respectively. In experiments 1 and 2 respectively the diets were offered to 72 and 60 castrated male cattle of late maturing breed type which were initially 455 (s.e. 3·6) and 484 (s.e. 3·2) kg live weight; the MD silages contained 642 and 652 g digestible organic matter (DOM) per kg DM, 119 and 114 g CP per kg DM, 72 and 68 g NH3N per kg total N, and the HD silages contained 698 and 724 g DOM per kg DM, 158 and 148 g CP per kg DM, 58 and 51 g NH3N per kg DM. In experiment 1 for the MD silages supplemented with concentrates 1, 2 and 3 and the HD silages supplemented with concentrates 1, 2 and 3 respectively silage DM intakes were 5·47, 5·29, 5·24, 6·86, 6·77 and 6·76 (s.e. 0·129) kg/day; carcass gains 0·76, 0·74, 0·72, 0·75, 0·75 and 0·79 (s.e. 0·011) kg/day; subcutaneous fat depths 6·8, 7·8, 8·0, 9·2, 7·2 and 7·1 (s.e. 0·59) mm and areas of m. longissimus 21·5, 21·7, 23·2, 21·5, 22·4 and 21·9 (s.e. 0·78) mm2/kg carcass weight. Corresponding values for experiment 2 were 6·12, 6·05, 6·18, 7·65, 7·53 and 7·36 (s.e. 0·235) kg/day; 0·82, 0·88, 0·83, 0·85, 0·89 and 0·83 (s.e. 0·042) kg/day; 8·1, 7·8, 7·5, 9·1, 8·3 and 7·4 (s.e. 0·77) mm; 22·8, 21·9, 21·9, 21·0, 21·9 and 21·7 (s.e. 0·79) mm2/kg carcass weight. It is concluded that supplementation of MD or HD grass silages with soya-bean or fish meals did not significantly affect the intake, performance or carcass fatness of finishing beef cattle although the carcasses of animals offered HD silage supplemented with barley tended to be fatter than those from the other treatments.

Two experiments have been carried out to compare silage-based and dried forage-based diets for finishing beef cattle, and to examine the effect of supplementing the silage-based diet with additional protein. The three diets used in experiment 1 consisted of (1) grass silage supplemented with a low-protein, cereal-based concentrate (98 g crude protein (CP) per kg dry matter (DM)) (2) grass silage supplemented with a high-protein, cereal/soya-bean meal concentrate (208 g CP per kg DM) and (3) grass hay supplemented with a cereal-based concentrate (130 g CP per kg DM). The two diets used in experiment 2 consisted of (1) grass silage supplemented with barley and (2) a mixture of grass hay and artificially dried grass supplemented with barley. All the diets contained approximately 700 g forage and 300 g concentrates per kg DM except diet 3 in experiment 1 which contained 240 g hay and 760 g concentrates per kg. The silages were of high digestibility (digestible organic matter in dry matter 0·72) and were well preserved (ammonia N 36 g/kg total N). The diets were offered to castrated male cattle which were initially 384 kg in experiment 1 and 515 kg in experiment 2. For diets 1 to 3 in experiment 1 and diets 1 and 2 in experiment 2 respectively metabolizable energy intakes were, 92, 94, 94, 124 and 120 MJ/day; live-weight gains were 1·21, 1·16 and 1·21 (s.e. 0·044) and 1·25 and 1·22 (s.e. 0·060) kg/day; carcass gains were 0·76, 0·76 and 0·75 (s.e. 0·034) and 0·80 and 0·74 (s.e. 0·036) kg/day; carcass fat classifications (five-point scale; 1 = leanest, 5 = fattest) were 2·4, 2·9 and 2·2 (s.e. 0·09) and 3·6 and 3·6 (s.e. 0·18); mean subcutaneous fat depths were 6·8, 8·1 and 6·6 (s.e. 0·74) and 7·8 and 7·4 (s.e. 0·48) mm; areas of m. longissimus dorsi at the 10th rib were 66·4, 69·4 and 71·3 (s.e. 3·16) and 77·6 and 72·3 (s.e. 1·52) cm2 and marbling scores (eight-point scale; 1 = leanest, 8 = fattest) for m. longissimus were 1·7, 2·5 and 2·2 (s.e. 0·24) and 3·2 and 2·8 (s.e. 0·16). It is concluded that performance, efficiency of energy utilization and carcass fatness were similar for silage-based and dried forage-based diets, and that protein supplementation of a silage-based diet did not affect performance but tended to increase carcass fatness.

Measurements of the m. longissimus and overlying fat at the last rib were taken on 39 live entire male pigs using three ultrasonic machines of differing complexity: Sonatest (simple A-mode machine), Scanogram (modified linear scanner) and Danscanner (‘real time’ scanner). Each machine had a different operator and interpreter. The pigs were from two lines of Large White, one selected for efficiency of lean-tissue gain (20 pigs) and the other a genetic control line (19 pigs). They were measured in the week prior to slaughter at approximately 90 kg live weight (91·4 (s.e. 4·4) kg).The analysis was pooled within line and the precision of carcass lean prediction at constant live weight examined for the three machines. Standard deviation of lean in carcass at equal live weight was 16·2 g/kg.A single fat thickness measurement taken by the Sonatest gave the most precise prediction (residual s.d. = 12·9 g/kg). Marginally poorer relationships were recorded for a similar measurement taken by the Scanogram (13·5 g/kg) and Danscanner (13·3 g/kg). Precision was not improved from the use of additional fat thickness measurements or, in the case of the scanning machines, from the addition of fat area over the m. longissimus or the area of the muscle itself. The results confirm that the Scanogram and Danscanner do not offer significant advantages over the simpler and cheaper Sonatest in the circumstances considered.

Curing data were obtained from the carcasses of 54 boars (B), 58 gilts (G) and 46 castrates (C) reared from birth to slaughter at 89 kg live weight. Middle bacon rashers were compared for colour and incidence of fat splitting. The uptake of curing salts was similar for each sex group but carcasses of B retained proportionately 0012 less of the cure compared with G and C which did not differ significantly. Bacon yields from B, G and C at a final live weight of 88·6 kg were 40·6, 42·4 and 42·2 kg respectively. Sex did not influence the degree of splitting of the backfat layers in bacon rashers and had little effect on the colour of their lean tissue, but B compared with G and C tended to have a higher incidence of separation of the inner fat layer from the m. longissimus in the bacon rasher.