Digestion characteristics, feed intake and live weight gain by cattle consuming forage supplemented with defatted rice bran or other feedstuffs

Abstract

Effects of supplementing cattle with defatted rice bran compared with full-fat rice bran, ground corn or wheat middlings on feed intake, digestibility and live weight gain (LWG) were determined. In Experiment 1, in situ (ruminal) dry matter disappearance in two steers consuming forage was 75, 45, 77 and 53% at 12 h (standard error (SE) 4.4), and 86, 95, 83 and 82% at 48 h (SE 0.6) for full-fat rice bran, corn, wheat middlings and defatted rice bran, respectively. In Experiment 2, six Holstein steer calves (193 ± 1.3 kg average trial body weight (BW); 6 × 6 Latin square) consumed a 1:1:1 mixture of alfalfa, orchardgrass and bermudagrass hay ad libitum without supplementation (Control), or with 0.80% of BW of full-fat rice bran (FR), 0.62% of BW of corn (C), 0.81% of BW of wheat middlings (W), 0.80% of BW of defatted rice bran (L-DR) or 1.10% of BW of defatted rice bran (H-DR). Total organic matter intake was lower ( P < 0.05) for FR than for C, W, L-DR and H-DR (5.65, 5.48, 5.96, 5.90, 6.03 and 5.86 kg per day; SE 0.127), digestibility of neutral detergent fiber was 53.3, 49.5, 53.7, 51.4, 50.9 and 49.8% (SE 1.13), and digestible organic matter intake was 2.96, 2.98, 3.35, 3.32, 3.17 and 3.11 kg per day (SE 0.088) for Control, FR, C, W, L-DR and H-DR, respectively (C and W greater than Control and FR; P < 0.05). In Experiment 3, six mature beef cows (564 ± 37 kg BW) with cannulae in the rumen and duodenum (6 × 6 Latin square) were fed the same hays with similar dietary proportions of supplement. True ruminal nitrogen disappearance was greatest ( P < 0.05) for W (62.5, 60.2, 63.0, 79.6, 68.1 and 65.7% for Control, FR, C, W, L-DR and H-DR, respectively; SE 3.24), microbial efficiency was similar among treatments ( P > 0.10), and acetate: propionate in ruminal fluid was decreased ( P < 0.05) by FR, L-DR and H-DR relative to Control (4.06, 3.69, 4.00, 4.09, 3.89 and 3.80 for Control, FR, C, W, L-DR, and H-DR, respectively; SE 0.053). In Experiment 4, crossbred beef calves (48 steers and 48 heifers; 232 ± 2.1 kg initial BW) grazed paddocks with fescue, clover and bermudagrass in the spring for 84 days and were supplemented as in Experiment 2. LWG was lower ( P < 0.05) for W, L-DR and H-DR than for FR and C (1.06, 1.18, 1.14, 0.99, 1.04 and 0.98 kg per day for Control, FR, C, W, L-DR and H-DR, respectively; SE 0.027).