Uso de avaliações visuais como características auxiliares à seleção de ovinos de corte

Abstract

This study aimed to evaluate the use of visual evaluations of conformation, precocity and musculature in identifying animals for meat quality production, and to evaluate the efficiency of a commercial production system producing carcasses and standardized meat for the consumer market. In this study were evaluated in two lots of termination, morphometric traits and visual aspects were evaluated in 92 non-castrated crossbred male lambs, weaned between 70 and 90 days of age. Up to 84 days of confinement, the lambs of the first lot showed higher value in body weight gain, heart girth and body depth. However, in the final phase of confinement, between 84 and 98 days, the animals of the second lot showed better performance, surpassing the lambs of the first lot. The visual evaluations within the first 84 days of follow-up showed a homogeneous behavior for the two lots. However, after 98 days of confinement, it was observed higher scores of the first lot, with average scores of 3.0, 3.2 and 3.0, for conformation, precocity and musculature, respectively, different from the second lot, with average scores of 2.6, 2.6 and 2.7. In the traits measured before slaughter, positive correlations were observed between weight and the traits which they are commonly used to estimate the live weight of the animal like body length (0.65) and thoracic girth (0.78). The principal component analysis identified the characteristics weight, withers height, thoracic girth, body depth, body length, chest width, body condition score, conformation, precocity and musculature as important to characterize the growth development of the lambs. There were differences between the two lots for the traits slaughter weight (13.30 kg vs. 12.25 kg) and hot carcass yield (49.34% vs. 41.72%), weight (13.00 kg vs. 12.00 kg) and cold carcass yield (48.22% vs. 40.89%), biological yield (71.67% vs. 60.67%), loin eye area (76.2 vs. 64.2 cm) and fat thickness (1.49 mm vs. 1.10 mm). There was no difference between lots for the loss by cooling, or to the profile of fatty acids. In the sensorial analysis, by the affection test, 40,14 % of assessors demonstrated acceptance consumption for meat, with no differences between the two lots evaluated. The visual appraisal of conformation, precocity and musculature were correlated (P <0.05) with the loin eye area, yield of hot and cold carcass and biological yield. The results of this study indicated that the visual appraisal of conformation, precocity and musculature can be used as auxiliary traits in selecting animals for slaughter, such as selection criteria for identifying animals for more efficient meat production in commercial systems. However, this must be confirmed by posterior studies considering the genetics aspects of these relations. The uncontrolled use of different genetic groups contributed to the inefficiency of the production system for the provision of standardized carcasses to market.