Fibre Sources on Performance and Carcass and Meat Characteristics of Feedlot Nellore Young Bulls.

ABSTRACT We evaluated the replacement of neutral detergent fibre levels from forage (NDFfor) by cottonseed cake on the performance, and carcass and meat traits of Nellore young bulls finished in a feedlot. Individual data from 24 Nellore young bulls with 330 ± 4.54 kg of body weight (BW) and 18 ± 1 months old were used. The animals were randomly distributed in four nutritional treatments containing 9.5%; 5.5%; 2.5%; and 0.0% NDF from whole corn plant silage (forage source), replaced by cottonseed cake, in the total diet. Animal performance and carcass and meat characteristics were analysed by orthogonal polynomial regression. A positive quadratic effect was observed for DM, CP, EE, NDF, and physically effective NDF intake (peNDFI8 mm, and peNDFI1.18 mm). There was no NDFfor‐level effect for final weight, hot carcass weight, carcass yield, internal and external depth, carcass length, pH, subcutaneous fat thickness, and loin eye area. A positive quadratic effect was detected for average daily gain. Feed efficiency demonstrated a positive quadratic trend, reaching an optimum peak level when young bulls 4.01% of NDFfor. There was no NDFfor‐level effect for meat and fat colour variables. The NDFfor‐level with the highest DM intake (2.01% BW) was 5.15%, and the highest ADG (1.54 kg/day) was 4.91% of NDFfor. Thus, although NDFfor levels did not affect carcass characteristics, fat, and meat colour, levels between 4.50% and 5.15% NDF from forage replaced by cottonseed cake are recommended to enhance the productive performance of feedlot Nellore young bulls. Cottonseed cake as a source of fibre can partially or totally replace corn plant silage. [ABSTRACT FROM AUTHOR]