Effects of breed, sex and diet and their interactions on carcass composition and tissue weight distribution of broiler chickens AbstractThe effects of breed (Hubbard and Anak), sex and diet (two levels of protein (high or low) with two levels of crude fiber (low or high) at each level of protein) on carcass composition and distribution of tissues over the carcass were studied. Carcass composition and ratios of muscle: bone, muscle: fat and meat: bone in the carcass did not differ significantly between breed groups. Male carcasses had more muscle, more bone, more fat-free carcass, higher ratios of muscle: bone, muscle: fat but less fat, less meat and lower meat: bone ratio than female carcasses. Carcasses of chicks fed high protein (with either low or high fiber) diet had more muscle than carcasses of chicks fed low protein (with either low or high fiber) diet. Carcasses of chicks fed high fiber (with either low or high protein) diet had more bone but less meat than carcasses of chicks fed low fiber (with either low or high protein) diet. Increasing both protein and fiber in the diet resulted in lowering carcass fat, consequently raising muscle: fat ratio. Breed and sex did not influence the distribution of muscle and meat throughout the carcass parts. Breed differences in fat weight distribution were not significant. Anak had significantly higher proportions of bone in wing and neck than Hubbard did. The proportion of total carcass muscle in breast, drumstick, wing were not significantly affected by diet. Carcasses of chicks fed high fiber (with either low or high protein) diet had higher proportion of total meat in thigh and neck than carcasses from chicks fed low fiber (with either low or high protein) diet. Diet had no significant effect on bone weight distribution. Increasing crude fiber in diets resulted in lowering proportion of total fat in breast, thigh but increasing proportion of total fat in drumstick and wing. Breed x sex, breed x diet and sex x diet interactions did not significantly influence most of carcass traits indicating that the factors under consideration act independently of each other's. Significant sex x diet interactions was found for carcass fat and boneless carcass relative to live body weight: the sexual dimorphism in low protein diet is more pronounced than in high protein diets.

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-Body measurements (body length, thigh circumference, shank length and chest width) of 311 rabbits representing three breeds, New Zealand White (NZW), Red Baladi (RB) and Black Baladi (BB) purebreds were subject to factor analysis. The objectives of this study were (a) to disclose the main sources of shared variability among body shape characters, (b) deduce the factors that describe these traits, (c) quantify the breed differences in size and shape and (d) predict live weight at marketing age from orthogonal body shape characters. Body conformation 'shape' appeared to be controlled by common and unique factors. The communalities ranged from 0.80 for chest width to 0.99 for thigh circumference and uniqueness (special factors) made the balance. Compared with local breeds (RB and BB), NZW had higher communality (proportion of variance for a variable that is shared in common by other variables) for chest width and lower communality for thigh circumference and body length. Our findings indicated that most of the common variability in NZW body dimensions could be accounted for by factors representing general size and chest width. Corresponding factors in RB were general size and shank length and those in BB were general size and thigh circumference. Independent body shape characters derived from factor analysis accounted for 83.4%, 87.9% and 90.8% of the variation in live body weight in New Zealand White, Red Baladi and Black Baladi, respectively.

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Abstract. Estimates of genetic and phenotypic parameters for body weight at birth, 3, 6, 9, and 12 months of age, and for preweaning and postweaning average daily gain were computed and used to construct 14 selection indexes to improve the 12-month weight in Egyptian buffaloes. The full index incorporating body weight at birth, 3, 6, 9 and 12 months of age had the highest correlation with aggregate breeding value (rTI=0.63). The correlation fell to 0.62 when body weight at birth and 3 months were omitted from the index. Selection for body weight at 12 months of age alone is expected to be 76.2 % as efficient as selection for the full index. The maximum expected genetic gain in 12-month body weight was 8.85 kg/generation when all five body weights were included in the index; this decreased to 8.09 kg/generation when body weights at birth, 3 and 6 months were excluded and further decreased to 6.94 kg/ generation when selection based on yearling weight only. From the practical standpoint, selection on I5 involving body weight at 9 month of age can be considered as the best for improving body weight at 12 month since its application is earlier, less expensive, higher accuracy than any index excluding body weight at 12 month and giving reasonable amount (+5.39 kg) improvement in yearling weight as compared to direct selection (+6.94 kg).