Loin tissue composition and carcass cuts in ram and castrated lambs, exposed to two photoperiods

Abstract

The objective of this study was to evaluate the effects of the photoperiod and castration upon the weights and percentages of cuts and tissue composition of the loin. Twenty one Polwarth crossbred lambs were divided into 4 treatments: 5 ram (R) and 6 castrated (C), during a short photoperiod (SP) of 12 light hours, and 5 castrated and 5 ram, during a long photoperiod (LP) of 18 light hours. The animals were allocated in individual pens, in two identical rooms, with light intensity of 300 lux. They were fed with an “ad libitum” balanced diet. The distribution for the treatments was at random, by a factor of 2 x 2 (R & C x SP and LP). The animals were slaughtered when reaching 37kg of body weight. There was no influence of the photoperiod in any of the variables analyzed. The castrated animals showed a bigger percentage and weight of the loin. For the other carcass sections, there was no effect of castration. In relation to the tissue composition, just the percentage of the muscles was higher in the ram lambs.