Tissue deposition in Santa Inês, ½ Dorper-Santa Inês and ½ White Dorper-Santa Inês lambs assessed by ultrasonography

Abstract

Thirty six male lambs, not castrated, twelve of each genetic group: Santa Inês, ½ Dorper-Santa Inês and ½ White Dorper-Santa Inês, were used, and raised in feedlot. Weight measurements and assessments in the region of the loin, between the 12th and 13th ribs, by ultrasound, were conducted weekly, to obtain the subcutaneous fat thickness and the Longissimus lumborum muscle depth. To verify differences in the development of subcutaneous fat thickness and Longissimus lumborum muscle depth in function of the day in feedlot between the groups, a normal distribution was assumed in a Bayesian analysis. The equation obtained for weight gain in function of the day in feedlot showed higher b1 coefficient for ½ Dorper-Santa Inês (0.26) and lower for Santa Inês (0.22). The angular coefficient (b1) of subcutaneous fat thickness in function of days in feedlot was higher for ½ Dorper-Santa Inês (0.038) and ½ White Dorper-Santa Inês (0.039) than for Santa Inês (0.037), indicating the precocity of this characteristic in the crossbred lambs. The evaluation of the Longissimus lumborum muscle depth indicated higher rate (b1) of muscle deposition for Santa Inês (0.072) compared to ½ Dorper-Santa Inês (0.057) and ½ White Dorper-Santa Inês (0.057), however, the initial deposit of muscle was higher in the crossbred lambs. The crossbred lambs have an earlier development, and can be slaughtered with more muscle and more fat in less time.