In Vivo Evaluation of Brown-Midrib Corn Silage by Sheep and Lactating Dairy Cows

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Abstract
Brown-midrib (bm3) corn silage was compared with normal genetic corn silage after ensiling. Analytical contents for dry matter, crude protein, N-free extract, ether extract, crude fiber, acid detergent fiber and ash were similar, but acid detergent fiber and lignin was reduced in brown-midrib silage. Wethers fed brown-midrib silage consumed 1.36 kg dry matter/day compared to 1.15 when fed normal control silage. Apparent digestibility of dry matter (70.9 vs. 64.3%) and acid detergent fiber (61.8 vs. 46.8%) were greater for wethers fed brown-midrib silage. Apparent N digestibility was not different (59.7 vs. 60.6%); absorbed was greater when wethers were fed brown-midrib silage (15.0 vs. 13.4 g/day). In a single reversal lactation trial, 20 cows consumed more silage dry matter when offered brown-midrib silage ad lib than when control silage was fed (8.7 vs. 8.1 kg/day), but total dry matter intake was not different (17.6 vs. 17.1 kg/day). Milk production (actual or 4% fat-corrected) was not different. Body weight change (kg/day) was 0.19 during feeding of brown-midrib and 0.11 during feeding of normal silage. Even though brown-midrib silage was more palatable and digestible in sheep, there was no difference in milk production when it was fed to cows averaging 109 days postpartum in a switch-over trial of 100 days.