Postweaning growth of the non-carcass components of Texel crossbred lambs

Abstract

Twenty 11/16 Texel x 5/16 Ile de France crossbred lambs were slaughtered at different body weights to evaluate the growth of their non-carcass components. Animals were weaned at 42 days of age (15.9 ± 2.1 kg of body weight), housed in individual stalls, and fed ad libitum. After ten days of an experimental adaptation period, 5 lambs were slaughtered. The remaining lambs were randomly assigned to one of three following slaughter weights: 25, 30 or 35 kg of body weight at fast. At slaughter, all body components were individually weighed and expressed as percentage of the empty body weight. To determine allometric growth of individual components, the exponential equation Y = aXb was logarithmically transformed and used. Proportions of feet and head decreased, while wool proportion increased linearly as slaughter weight increased. Greater fat deposition in viscera (kidney and mesenteric fat) was observed for lambs slaughtered at more elevated body weights. Growth rate of small intestine was lower than that of the empty body (b = 0.39), and it decreased linearly as a proportion of empty body weight with advancing maturity. Growth rates of both liver and large intestine were isogonics (b = 0.90 and 1.08, respectively), i.e., similar to the empty body weight. On the other hand, rumen presented late growth (b = 1.37), and its proportion was lower only for the lambs slaughtered at weaning (1.58% of EBW). Once increased slaughter weights result in higher deposition of nutrients on body parts that are not intended to consumption, maximum slaughter weight of 11/16 Texel x 5/16 Ile de France crossbred lambs is recommended to be at 30 kg of body weight.