Evaluation of annual ryegrass straw:corn juice silage with cattle and water buffalo: digestibility in cattle vs. buffalo, and growth performance and subsequent lactational performance of Holstein heifers

Abstract

Two experiments were undertaken to evaluate ryegrass straw:corn juice silage (35:65 wt. wt. ) as a basal feed for Holstein heifers and to determine digestibility of this silage in water buffaloes and Hereford cows. In experiment 1, (143 d) 48 pregnant heifers (16 animals; 3 pens per treatment) were fed (1) mixed cool season grass hay (GH), (2) straw:corn juice silage (S), and (3) S + 125 g fishmeal d −1 (SF). All animals were also fed 2.27 kg concentrate per day. Average daily gain (kg) was 1.00, 0.82 and 1.02 for GH, S and SF groups, respectively. ADG in the SF group was higher ( P < 0.05) than in the S group. Roughage DM intake was 7.77, 6.45 and 6.02 (kg d −1) for the GH, S and SF treatments, respectively. Roughage intakes were lower ( P < 0.05) for S and SF than for GH and lower ( P < 0.05) for SF than F. Feed efficiency was 12.91, 14.31 and 10.96 for H, S and SF, respectively. Feed efficiency was better in SF vs. S ( P < 0.05). Subsequent milk yields and composition data were obtained for 300 days post-partum after the completion of the feeding trial. Milk, milk fat and SNF yields (kg d −1) were 30.91, 1.13, 1.03; 31.5, 1.19, 1.05; and 32.06, 1.19 and 1.07 for H, S, and SF, respectively. None of the milk production parameters differed ( P > 0.05) among animals from the different pre-partum treatments. In experiment 2, six water buffaloes and six Hereford cows were fed the same silage as fed to experiment 1 animals. The silage was mixed with 0.39% chromic oxide and fed for 15 days. Fecal grab samples were obtained over several days. Digestibility (percent) of DM, CP, NDF and ADF was calculated by determination of the chromic oxide concentration in feed and feces. Respective apparent digestibility values for buffaloes and cows were: dry matter, 47 and 40%; crude protein, 47 and 34%; neutral detergent fiber, 47 and 41%; and acid detergent fiber, 43 and 35%. All digestibility parameters were significantly higher ( P < 0.05) in buffaloes than in cows. In conclusion, straw:corn juice silage was equivalent to grass hay in supporting weight gain and feed efficiency of Holstein heifers, and FM supplementation of the silage significantly improved performance. There was no effect of pre-partum feeding of grass straw:corn juice silage on subsequent lactational performance of Holstein heifers as compared to the control diet containing grass hay.