EFFECT OF ALTERING PHYSICAL FORM OF CORN SILAGE ON UTILIZATION BY DAIRY CATTLE

In a 70-day experiment, 12 lactating cows were fed either field chop or plant rechop (field chop passed through a rechopper) corn silage (37% dry matter) ad libitum, and concentrate at 1 kg : 3 kg milk. Fat-corrected milk yields averaged 20.0 kg/day and were not significantly different between rations for the total period, but differences were apparent at the end of the experiment. This was due to milk fat percentage, which declined from 3.5 to 3.0 during ten weeks on rechop silage. Dry matter voided as whole kernels was 480 and 90 g/day for field chop and rechop silages. In a succeeding 56-day experiment, 18 cows were randomized to receive one of the following silages: field chop, ear ground and mixed with field chop fodder, and plant rechop. The resulting silages (44% dry matter) contained on a dry basis 10.1, 1.4, and 0.3% whole kernels, respectively. Fat-corrected milk production was highest (P < .05) on field chop (28.0 versus 25.0 and 26.3 kg/day). Milk fat tests during the last two weeks were 86.0, 75.8, and 81.1% of the standardization period. For a digestion study, cows received soybean meal 1 kg : 8.5 kg fat-corrected milk. Digestibilities of dry matter and nitrogen-free extract were higher (P < .01) on the ear-ground and mixed with field chop fodder and on the plant rechop, whereas crude fiber was highest on the field chop. Dry matter excreted as whole kernels was 162, 21, and 1 g/day for the field chop, ear ground and mixed with field chop fodder, and plant rechop, respectively. Analysis of fecal kernels indicated loss of ash and protein. No difference in growth occurred when the silages were compared with dairy heifers. © 1969, American Dairy Science Association. All rights reserved.