This study was conducted with the aim to determine the optimal level of protein replacement of cottonseed meal protein by sunflower cake in diets for Santa Inês lambs, through the evaluation of consumption, weight gain, feed conversion and morphometric measurements. Thirty Santa Inês lambs, bulls, with age and weight at the beginning of the experiment of 80 days and 21.45±2.16kg, respectively, were confined for 60 days. A completely randomized experimental design was used, where the animals were divided into 5 treatments with 6 replicates per treatment. For the treatments, the protein from the cottonseed meal was replaced by the protein of the sunflower cake (0, 20, 40, 60 and 80% of substitutions). For morphometric determinations, the following measurements were taken: pre-slaughter body length, leg length, leg perimeter, height of the dorsum; hip height; chest girth, hip width and chest width. Final weight, dry matter intake and feed conversion were not affected by the experimental diets, although the average daily gain was lower for diets with higher content of sunflower cake. For consumption parameters, there was a difference only in the consumption of ether extract in relation to metabolic weight (g/kg PV 0, 75), where lambs receiving diets with higher levels of sunflower cake ingested larger amounts of ether extract. Regarding the morphometric measurements, there was a linear decrease of the height of the dorsum and hip width with the inclusion of sunflower cake in the diet. The replacement of cottonseed meal protein by sunflower cake protein negatively affected the weight gain of Santa Inês lambs. However, it affected little or nothing the parameters of consumption and in vivo morphometric measurements.
biodiesel; coproducts; feedlot; sheep