Effect of Stage of Maturity on the Nutritive Value of Atlas Sorghum Silage for Lactating Dairy Cows

Abstract

Summary Atlas sorgo silages harvested at the milk, soft dough, hard dough, and mature stages have been compared as roughages for lactating cows. Two experiments were conducted, each using 12 cows in a switch-back design. With advancing maturity, consumption of dry matter increased and 4% fat-corrected-milk (FCM) per pound dry matter intake decreased; consumption of silage (as fed), milk fat percentage, and body weight change were not significantly affected by maturity at harvest. FCM production was slightly higher for the two more mature stages, but differences among maturities were significant only in the first experiment, in which the soft dough stage was inferior to the more mature stages. Since daily performance of the lactating cow was not appreciably influenced by the stage of maturity, it appears advantageous to harvest Atlas sorghum when acreage yields are near maximum, usually at the hard seed stage. At this station dry matter yields of Atlas sorghum increased 33% from the milk stage to the mature stage. Delaying harvest an additional ten days resulted in a 57% increase in dry matter yield, compared to that at the milk stage. The differences found in quality of the silage dry matter favoring early-cut silage appear insufficient to compensate for the usual yield advantage of harvesting Atlas after reaching maturity.