R. Bras. Zootec.06/Jun/2019;48:e20180206.
Residual intake and gain for the evaluation of performance, non-carcass components, and carcass characteristics of confined crossbred Texel lambs
We evaluated performance, non-carcass components, and carcass characteristics of crossbred Texel lambs in different categories of residual intake and gain (RIG). We assessed 77 crossbred (¼ Pantaneira and ¾ Texel) non-castrated animals in two study phases. The first phase included 47 lambs with an initial average weight of 29.9±5.5 kg, and the second phase included 30 lambs with initial average weight of 22.4±3.3 kg. Dry matter intake (DMI) and average daily gain (ADG) were evaluated for 70 days. Animals were divided into three groups in terms of efficiency: efficient (high RIG), intermediate (medium RIG), or inefficient (low RIG), based on the standard deviation of the mean for the RIG variable. We measured the yield of non-carcass components, carcass characteristics, and yield of meat cuts. Efficiency group had no association with DMI, nor with initial and final body weights of the animals. The ADG of efficient (0.310 kg day−1) and intermediate (0.290 kg day−1) animals was greater than observed in inefficient (0.260 kg day−1) animals. Lambs in the efficient and intermediate groups had significantly higher levels of all efficiency indicators evaluated. Efficient and intermediate animals yielded significantly more wool/skin in comparison with lambs in the inefficient group. Animals with high RIG also had lower relative weight of testicles/scrotal sac in comparison with inefficient animals. Fat deposition in the omentum and mesentery as well as total fat were decreased in efficient animals. No significant differences occurred among groups regarding carcass characteristics and yield of meat cuts. The RIG index allows for the identification of lambs with higher growth rates and greater wool/skin yield and lower proportion of visceral fat.