Effects of birth type and family on the variation of carcass and meat traits in Santa Ines sheep.

This study aimed to evaluate the effects of birth type and family on quantitative and qualitative meat traits in Santa Ines lambs and to do a descriptive study of variation inside of breed. A total of 50 carcass and meat traits were evaluated in up to 101 lambs slaughtered at 424 days of age. Random effect of family, the fixed effect of birth type (single or double) and year, and the covariates of dam's weight at weaning and age (in days) at slaughter were inserted in the model. This study shows that some carcass and meat traits in Santa Ines raised on pasture has large variability, specially for meat cut yields, several carcass non-components yields, and rib eye area, subcutaneous fat thickness, shear force, cooking losses, and b* color parameter. The birth type effect influenced (P < 0.05) rump width; reticulum, leg, heart and kidney yields; and the carcass pH at 24 h after slaughter. The family effect was significant (P < 0.05) for cold carcass weight; hot, cold and true carcass yields; external carcass and leg lengths; perimeter and width of the rump; kidney, liver and tail yields; and carcass pH at slaughter.

Performance of the Santa Ines breed raised on pasture in semiarid tropical regions and factors that explain trait variation.

This study aimed to evaluate sex, the number of lambs per birth, and the family effects on production traits in the Santa Ines breed of sheep by estimating the least square means and coefficient of variance for those traits. A total of 484 lambs were evaluated for the following traits: weight at birth, at weaning, and at 240 days of age; weight gain during the pre-weaning and post-weaning periods; height, width, and length of different body regions; and rib eye area and fat thickness between the 12th and 13th ribs. We observed coefficients of variation higher than 10 % for several traits. Generally, males were larger than females (P < 0.05), while lambs from single and double births were larger than lambs from triple births (P < 0.05). Family effect was significant (P < 0.05) for most traits and explained the highest percentage of residual variance. The results showed good development of Santa Ines sheep, especially during the pre-weaning period but no in post-weaning. Our study also showed that there is an effect of sex, birth type, and family, which must be included in any statistical model for the estimation of least square means and residual variance in ANOVA.