Whole cottonseed and Vitamin E in diets for Nellore cattle finished in feedlot: Performance traits and Feed conversion

Abstract Text: This study aimed to evaluate the daily live weight gain, live weight evolution, feed efficiency (ratio live weight gain/dry matter intake), hot and cold carcass weight and carcass yield of bulls finished in feedlot feeding. A total of 54 bulls were confined, with approximately 350 kg initial weight, average age of 24 months, in a randomized blocks design with factorial arrangement of treatments (3 x 3), totaling 9 treatments with 6 animals in each treatment. The animals were fed three diets: 1) control without cottonseed (CTL), 2) containing cottonseed at 30% of DM (CAR) and 3) diet containing cottonseed at 30% of DM and 500 IU vitamin E/kg of DM (VITE). The diets used were composed of different concentrates, including dry corn grain, citrus pulp, sugarcane  bagasse raw and soybean meal with forage concentrate ratio of 86:14 and an average of 55% CP in the three diets The animals were kept in pens, three to three, and fed once a day, for 83, 104 and 111 days and slaughtered. For feed conversion and carcass weight, the  the fixed effects of treatment, slaughter period and the interaction between them, and the block random effect were included in the model. For repeated measured traits, the fixed effects of treatment, weighing period and the interaction between them, and the block random effect were included in the model. The  data were submitted to an analysis of variance using the proc mixed command (SAS statistical program) applying  a significance level of 5%.  The interaction between treatment x slaughter period was significant (P <0.05) for  feed conversion  where  animals fed the VITE and CAR diets and slaughtered at 111 days showed better feed conversion efficiency with averages of 4.68 kg DM and 4.94 kg DM respectively. The interaction treatment x slaughter period was also significant (P <0.05) for live weight evolution (P <0.01). The mean daily live weight gains were 4.10 kg, 3.74 kg and 0.6 kg for CAR, VITE and CTL respectively. There was  a significant effect of diets containing whole cottonseed (CAR and VITE) on hot and cold carcass weight  compared to the diet without whole cottonseed (P <0.01), while for carcass yield, animals slaughtered at 111 days showed higher (56,33%) than animals slaughtered before (P <0.05). The animals fed diets with cottonseed have better performance for live weight gain, feed conversion and carcass weight.

Keywords: Cottonseed, feed efficiency, daily live gain