Corn silage hybrid effects on intake, digestion, and milk production by dairy cows

Three corn hybrids harvested as whole-plant silage were evaluated in three separate feeding trials with lactating dairy cows. In trial 1, 24 multiparo us Holstein cows were used in a replicated 4 x 4 Latin square with 28-d per iods. Treatments were conventional (Pioneer 3563) and leafy (Mycogen TMF 10 6) corn silage hybrids, each planted at low (59,000 plants/ha) and high (79 ,000 plants/ha) plant populations. There were no milk production difference s between treatments. Total-tract digestibility of dietary starch was highe r for leafy compared with conventional corn hybrids. In trial 2, 26 multipa rous Holstein cows were assigned randomly to diets containing either conven tional (48% forage diet) or brown-midrib (60% forage diet) corn silage in a crossover design with 8-wk periods. Milk yield was lower, but milk fat per centage and yield were higher, for the high-forage diet containing brown-mi drib corn silage. In trial 3, 24 multiparous Holstein cows were used in a r eplicated 4 x 4 Latin square with 28-d periods. Treatments were corn silage at two concentrations of neutral detergent fiber (Garst 8751, 39.2% NDF; C argill 3677, 32.8% NDF) each fed in normal- (53% of dry matter) and high- ( 61 to 67% of dry matter) forage diets. Milk production was not different be tween corn hybrids. Increased concentrate supplementation increased DMI and milk production. There were minimal benefits to the feeding of leafy or lo w-fiber corn silage hybrids. Feeding brown-midrib corn silage in a high-for age diet increased milk fat percentage and yield compared with conventional corn silage fed in a normal-forage diet.