Morphological characteristics in vivo and carcass of lambs finished in feedlot and their correlations

Abstract

Thirty-two male Ile de France lambs, non castrated, with a mean age of 6 months, were distributed to four treatments, consisting of diets with two types of roughages (corn silage and sugar cane) and two roughage:concentrate ratio, 60:40 or 40:60. The lambs were confined individually until they reached 32 kg of body weight, when they were slaughtered. It were realized morphological in vivo and carcass measurements, and ribeye area and fat thickness were measured for different methods. It were held some correlations between these measures. The roughage:concentrate ratio affected only the body condition, which was higher (3.85) in lambs that received 40% of roughafe in the diet, while the type of roughage affected conformation and carcass fat cover, higher in lambs fed with corn silage, by 3.65 and 3.50, respectively. The measurements of ribeye area and fat thickness obtained by different methods (ultrasound, caliper and planimeter) were not affected by the roughage:concentrate ratio and type of roughage. The highest correlation among the methods for RA determination was between ultrasound and planimeter (0.56). The use of ultrasound to measure the ribeye area and fat thickness of lamb carcass was efficient, with similar values to those obtained directly from the carcass. It is recommended to conduct further studies assessing higher slaughter weights as used in this research, since the slaughter at 32kg for Ile de France breed did not provide the minimum fat thickness recommended for lamb carcasses, of 0.30cm