The use of variation in metabolism to predict genetic merit for milk production was studied using 42 Friesian calves: 11 ♀♀, 10 ♂♂ were the offspring of four bulls with high (H), and 11 ♀♀, 10 ♂♂ of four with low (L) improved contemporary comparison (ICC) values (mean = + 402 kg and − 276 kg respectively). The animals were 14 or 15 weeks of age at the start of the study and treated similarly throughout.Blood samples were collected: I—in relation to feeding; II—at set intervals; III—during a 44-h fast; and IV—following the sudden introduction of an energy metabolite (sodium propionate), and then refeeding. Plasma concentrations of β-hydroxybutyrate, glucose, urea, free fatty acids, total proteins and albumin were measured in all samples.Blood characteristics apparently differed among animals, particularly protein and urea (repeatability 0·74 and 0·62 respectively).The progeny of high ICC bulls had lower levels of urea during fasting (H = 4·70, L = 5·62P< 0·05) but higher levels of free fatty acids (H = 578, L = 492 μ equivalents/l;P< 0·05). There was a small difference in total protein (H = 69·7, L = 66·8 g/l,P< 0·05) but the other metabolites showed no significant ICC group difference.In general, sex of the animal did not influence the metabolites.Results suggest that calves with different potentials for milk production vary in aspects of energy and nitrogen metabolism; the possibility of using these as criteria for genetic selection for milk production is discussed.

1982). An evaluation of two ultrasonic machines (Scanogram and Danscanner) for predicting the body composition of live sheep. ABSTRACT 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 x 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 mm 2 for the Scanogram and Danscanner respectively (s.d. of carcass m. longissimus area was 162mm 2 ). Residual s.d. for the prediction of lean from the best combination of fat measurements was 320 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 240 (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.

Understanding the relationships between food intake, milk output and body condition in high-yielding dairy cows is crucial in determining suitable management strategies. During two winter feeding periods 38 and 37 cows were individually fed, to appetite, complete diets which on average contained 11-7 MJ metabolizable energy per kg dry matter and comprised grass silage, concentrate meal and brewers' grains (draff). The groups' mean 305-day yield was 7 240 kg (s.d. 1 281) with 42 g (s.d. 4-3) fat per kg. Regression analysis was carried out to describe dry-matter intake both for 26 weeks post calving and for four successive 6-week periods from calving. The final equations, which had a residual s.d. of 0-07 to 0-10 of the observed intake, included milk yield, cow size and a measure of body-condition change. The cows were divided into three groups (high, medium and low) on two criteria: (1) mean milk yield (MJ/day) during the first 26 weeks of lactation and (2) post-calving backfat index determined ultrasonically. Differences were found between milk-yield groups from gross efficiency (milk yield (MJ)/ energy intake (MJ metabolizable energy)) (P < 0-001), mean metabolizable energy intake (MJ/day) (P < 0-01), dry-matter intake as a proportion of live weight (P < 0-05), and post calving live weight (kg) (P < 0-05). Differences were found between backfat-index groups for maximum backfat loss, and loss to day 42 (P < 0-001); also for mean live weight during the 26 weeks and post calving live weight (P < 0-001), dry-matter intake as a proportion of live weight (P < 0-05) and lactation number (P < 0-05). Interactions were found between the milk yield groups and backfat groups for milk yield (P < 0-01) and gross efficiency (F < 0-05) with the fattest group containing the highest and lowest yields and efficiencies.

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.

Measurements of the m. longissimus and overlying fat at the last rib were taken on the live pig u'ing ultrasonic machines of differing complexity: Sonatest (simple A-mode machine), Scanogram and His Observer (modified linear scanners), and Danscanner ('real time' scanner). These measurements were examined as predictors of the corresponding carcass measurements and percentage lean in the carcass. Sonatest and Scanogram were compared using 143 purebred and crossbred pigs of different types. The analysis was pooled within breed-type and sex. The standard deviation for percentage lean was 3-94. Residual standard deviations for predicting percentage lean from live weight and best fat thickness were 2-72 (Sonatest) and 2-56 (Scanogram). Addition of m. longissimus depth (Sonatest) and m. longissimus area (Scanogram) reduced these to 2-69 and 2-29 respectively. The use of two or more fat measurements provided no extra precision over a single fat measurement. Scanogram and His Observer were compared using a subset of 38 pigs. Scanogram was a better predictor of percentage lean using a single fat measurement but when a combination of measurements was used, there was little difference between the machines. Scanogram and Danscanner were compared using a subset of 27 pigs. The standard deviation of percentage lean was 3-57. Residual standard deviations for predicting percentage lean from live weight, best fat depth and m. longissimus area were 2-18 (Scanogram), and 2-03 (Danscanner). Fat areas had similar predictive precision to fat thickness measurements.