Utilização de Dietas com Grão de Milho Inteiro para Produção de Vitelos Modificados.

Abstract

This study aimed to assess the bioeconomic performance and the qualitative and quantitative characteristics, physical and chemical composition of the carcass and components not included in the carcass of veal calves fed in confinement exclusively with concentrated diet fed ad libitum or restrictively (2kg.100kg PV-1 ), and slaughtered at 8 or 10 months of age. We used twenty-eight uncastrated calves with initial age of 3 months and initial body weight of 71.56 kg . The experimental design was completely randomized with treatments in a 2x2 factorial arrangement (two slaughter ages and two diet levels), using seven replicates. There was no difference in ruminal pH according to feeding level with an average of 5.82. There was no interaction between the factors for feed conversion. Animals slaughtered at 8 months of age fed restrictively showed better feed conversion. Animals slaughtered at 10 months of age had higher final weight and average daily weight gain, as well as those fed ad libitum. The costs with corn grain, with calves 90 days of age, and with the same price paid per kg of carcass for the veal calves as for the fat steers, made the production of veal calves unfeasible in northern Tocantins. Calves slaughtered at 10 months of age had higher hot carcass yield (51.46 vs. 49.65 kg.100kg live weight-1 ) and cold carcass yield (50.04 vs. 48.52 kg.100kg live-weight-1 ) than those slaughtered at 8 months of age. Older calves had carcasses with higher subcutaneous fat thickness (2.17 vs. 0.78mm) and mm/100 kg of cold carcass weight (1.57 vs. 0.80), higher side cut (13.30 vs. 12.03 kg.100 kg-1 ) and lower pistol cut (46.62 vs. 48.92 kg.100kg-1 ) than calves slaughtered with younger age. The supply of food ad libitum and the slaughter of older animals increased the participation of adipose tissue in the carcass. The increase in slaughter age and the level of food supply in the diet promoted higher absolute weight of the small intestine and higher absolute weights of internal and mesentery fat. The absolute weights of the contents of the gastrointestinal tract, internal fat, total internal organs and empty body weight were influenced by the supply levels of the diet and slaughter age of modified veal calves. The use of ad libitum feeding and slaughtering of calves at 10 months of age improves the quantitative carcass traits of calves benefitting the producer and beef industry but the largest slaughter age worsens the primary attribute sought by the consumer for this product type, which is the tenderness of the meat.