Subcutaneous fat thickness at slaughter in castrated and non-castrated Santa Inês and Dorper lambs and its influence on meat and carcass quality

Abstract

The objective of this study was to evaluate the carcass characteristics and meat quality of castrated and non-castrated Santa Inês and Dorper lambs, finished in confinement and slaughtered with different subcutaneous fat thickness (SFT), which was evaluated using in vivo ultrasound. Sixty-nine male lambs from two genetic groups were used - 34 Santa Inês and 35 Dorper. Dorper lambs showed superior conformation and finishing, 22% and 15.73%, respectively, compared to that of the Santa Inês lambs. The lambs were classified and slaughtered according to the following criteria: intended subcutaneous fat thickness close to 0 mm, close to 3 mm and close to 6 mm. Measurements were taken of the longissimus lumborum muscle in the region between the 12th and 13th ribs on the left side of the animal. Dorper lambs deposited more fat than Santa Inês lambs, and when slaughtered with the intended thickness of subcutaneous fat of 6 mm, they presented 7.34 mm fat thickness made in the muscle, while 3.61 mm was observed in Santa Inês lambs with the same age and confinement period. The meat became darker, less reddish, and less yellow at subcutaneous fat thickness (SFT) between 0 and 6 mm. The measurement of SFT using the ultrasound showed a high positive correlation with the fat thickness measured in the muscle with a caliper (MFT), demonstrating the possibility of using this method in vivo for accurate prediction of MFT. Slaughter of lambs with 3 mm of subcutaneous fat is recommended and is enough to guarantee a quality standard for both carcass and meat.