DIGESTION CHARACTERISTICS, FEED-INTAKE AND LIVE WEIGHT-GAIN BY CATTLECONSUMING FORAGE SUPPLEMENTED WITH DEFATTED RICE BRAN OR OTHER FEEDSTUFFS

Effects of supplementing cattle with defatted rice bran compared with full-fat rice bran, ground com or wheat middlings on feed intake, dige stibility and live weight pin (LWG) were determined. In Experiment 1, in situ (ruminal) dry matter disappearance in two steers consuming for age 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, com, wheat mid dlings and defatted rice bran, respectively. In Experiment 2, six Hols tein steer calves (193 +/- 1.3 kg average trial body weight (BW); 6X6 Latin square) consumed a 1:1:1 mixture of alfalfa, orchard grass and b ermuda grass hay ad libitum without supplementation (Control), or with 0.80% of BW of full-fat rice bran (FR), 0.62% of BW of com (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 in take was lower (P<0.05) for FR than for C, W, L-DR and H-DR (5.65, 5.4 8, 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, 3.3 2, 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 X 6 Latin square) were fed the same hays wi th similar dietary proportions of supplement. True ruminal nitrogen di sappearance 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 acet ate: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 C ontrol, FR, C, W, L-DR, and H-DR, respectively; SE 0.053). In Experime nt 4, crossbred beef calves (48 steers and 48 heifers; 232 +/- 2.1 kg initial BW) grazed paddocks with fescue, clover and bermudagrass in th e 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-D R, respectively; SE 0.027).