Intake, digestibility, performance, and nitrogen metabolism of feedlot-finished young bulls (Bos indicus) fed diets containing peanut cake1

Abstract

This aim of this study was to evaluate the use of peanut cake as a dietary substitute for soybean meal and to determine the effects on intake, apparent digestibility, performance, and N metabolism in feedlot-finished young bulls. Thirty-two young Nellore bulls with an average initial BW of 390 ± 43.5 kg were distributed in a completely randomized design and individually housed in stalls. The young bulls were fed Tifton 85 hay and 4 concentrate mixes containing 0, 33, 66, or 100% peanut cake replacing soybean meal. The diets were formulated to be isonitrogenous, containing 150 g/kg CP, and isocaloric (65% TDN), to have a 40:60 forage:concentrate ratio, and were provided as a total mixed ration. The experiment lasted 90 d and data were collected every 28 d. Blood and urine samples were taken during the last 6 d. Intakes of DM ( = 0.005), OM ( = 0.006), CP ( = 0.002), NDF ( = 0.022), nonfiber carbohydrates ( = 0.002), and TDN ( = 0.018) linearly decreased as the dietary inclusion of peanut cake in the diet was increased. Conversely, intake and ether extract digestibility linearly increased ( < 0.035). The average daily weight gain decreased ( = 0.015) as the peanut cake levels were increased. Plasma urea N decreased (linearly; = 0.005). Peanut cake may not be used to replace soybean meal in the diet of young feedlot-finished Nellore bulls.