Conformation scores can account for more than 20% of cattle price variation at Australian livestock sales. However, there are limited available references which define genetic factors relating objective live developmental traits to carcass composition. Weaning and post-weaning weight, height, length, girth, muscle (ratio of stifle to hip width) and fat depth of 1202 progeny from mature Hereford cows (637) mated to seven sire breeds (Jersey, Wagyu, Angus, Hereford, South Devon, Limousin and Belgian Blue) were examined for growth and development across ages. Crossbred Wagyu and Jersey were both lighter in weight and smaller in size (height, length and girth) than purebred Hereford and crossbred Angus, South Devon, Limousin and Belgian Blue. Within the five larger crossbreds, there were significant changes in relative weight from weaning to 600 days. Sire breeds differed in fat depth, with Angus being the fattest (9% on average fatter than Hereford and Wagyu), and Jersey 5% less fat than Hereford, followed by South Devon and Limousin (19% lower than Hereford) and Belgian Blue (39% lower than Hereford). Direct heritability ranged from 19 to 42% and was higher than the proportion of total phenotypic variance accounted for by maternal effects (which ranged from 0 to 17%) for most body measurement traits except for weight (38 v. 18%) and girth (36 v. 9%) traits at weaning, an indication of maternal effect on some body conformation traits at early ages. Muscularity (19 to 44%) and fat depth (26 to 43%) were moderately to highly heritable across ages. There were large differences for growth and the objective measures of body development between crossbreds with a degree of overlap among the progeny of the seven sire breeds. The variation between genetic (positive) and environmental (negative) correlations for dry versus wet season average daily gains in weight and fat, suggested the potential use of live-animal conformation traits for within breed selection of genetically superior animal in these traits across seasons.

The confirmation of the segregation of experimentally populations is required before their commercial design of such confirmation experiments has the the pedigree while maintaining the power to detect chromosomes of a complex pedigree of 570 Charollais contained a moderately sized half-sib family which was wide level were detected in the half-sib analysis and analysis of the complex pedigree using identity-by-estimation of QTL effects was achieved by fitting all observed in the single QTL models. Both methods of different regions, and the variance components method demonstrates the viability of applying a variance inbreeding.

Seventy-four New Zealand ✕ Californian females were used to determine the influence of dietary energy source on the performance and perirenal fat thickness (PFT) change measured by ultrasound of primiparous rabbit does. Three highly concentrated diets were designed with different dietary energy sources: animal fat (diet F), vegetable oil (diet O) and cereal starch (diet S), and does were fertilized by artificial insemination after parturition (AP group) or around weaning (AW group), litters being weaned at 28 days of age. There were no significant differences in live weight and food intake of females throughout gestation, but does given diet S showed a higher increase in their PFT until 28th day than those given diets F and O (P < 0·01), although all females had a similar PFT at parturition. Rabbit does given diets S and O showed a significantly higher dietary energy intake than those given diet F (P < 0·01) during the first weeks of lactation, and similar thereafter until the second parturition. Milk yield and litter weight gain were significantly higher with fat-enriched diets (P < 0·05), and milk composition of rabbit does given diet F showed a higher total solids content (P = 0·01), fat (P < 0·001) and energy (P < 0·01) than milk of does receiving diets O or S. Although pups on fat diets showed a higher weaning weight (P < 0·05), dietary treatment during lactation did not have any effect on the performance of pups during the subsequent growing period. PFT always decreased during lactation for does given fat-enriched diets, while it increased for does given diet S and fertilized after parturition. Live weight of AP does was significantly higher at 21st day of lactation (P < 0·01) and at weaning (P < 0·001), and they showed a significantly lower food intake during the final week of lactation. The period from weaning to parturition was too short for AP does, which showed a decrease of their PFT, while AW does showed an increase of their PFT and a greater number of pups alive at birth (P < 0·05). Due to the lower milk yield of rabbit does fertilized AP, their pups showed a significantly higher solid food intake (P < 0·001), resulting in a similar value for the live weight of pups in both groups at weaning. The earlier promotion of solid food intake significantly affected the food intake of litters during the subsequent growing period, presenting higher values for pups coming from AP does. In conclusion, the addition of dietary fat, especially from animal origin, seems to improve the utilization of energy for milk production, while the use of a high level of starch could decrease the negative balance of primiparous rabbit does during lactation.

Commercial carcass grading measurements and sample joint dissection were evaluated as predictors of carcass lean concentration using a data set of 1320 pig carcasses from four breeding companies. Entire males, castrated males and gilts from White-type and Meat-type populations were reared on ad libitum or restricted feeding regimens and slaughtered to achieve a carcass weight of either 52·5 kg or 72·5 kg. A model was fitted which examined the accuracy and stability of regression equations for different populations, sexes and feeding regimens, and different values of P2 and carcass weight. The regression slope of lean concentration on P2 differed by sex and population. Lean concentration decreased faster with increases in P2 among gilts than among entire or castrated males. At the same level of P2 and carcass weight, pigs fed ad libitum contained 5 g/kg less lean in the carcass than pigs fed at a restricted level. Biases among populations, sexes and feeding regimens were also found when carcass lean concentration was predicted from additional measurements: muscle depth at P2, fat thickness and muscle depth at 3/4 last ribs, and eye-muscle area. The regression slope of lean concentration on sample joints showed little evidence of variation among populations (except for the hand joint), sexes or feeding regimens. There were important differences in the intercept for different populations. The ham was the most accurate (residual s.d. = 11 g/kg) and least biased joint.