Effects of Two Harvesting Methods and Grinding on Growth, Intake, and Digestion of Corn Stover Silage Diets by Yearling Dairy Heifers

Abstract

Four total mixed diets were fed after ensiling for 45 days to four groups of seven yearling Holstein heifers for 168 days. Diet 1 (control) consisted of 84% whole corn plant and 16% dehydrated poultry excreta. Diets 2, 3, and 4 contained 60% whole corn plant, 25% corn stover, and 15% dehydrated poultry excreta. Source of stover for diet 2 was 2-yr-old baled stover and for diets 3 and 4 fresh stover harvested by rotary mower and forage harvester with a pickup head attachment immediately after removal of whole ear corn. Stover in diets 2 and 3 was also ground through a 6.35-cm tub grinder screen. Heifers were housed in a free stall shed with open side and fed individually via electronic feedgates. Average daily gains and intakes of dry matter were: .88, 8.60; .65, 7.37; .65, 9.70; and .58, 8.70 for the four diets. Four additional heifers were fed diets in a 4×4 Latin square digestion trial. Dry matter, acid detergent fiber, and crude protein digestion coefficients were: 62.5, 62.3, 47.2; 60.7, 56.3, 41.9; 61.0, 46.7, 45.9; and 63.1, 58.1, 51.0%. Grinding fresh stover prior to ensiling had no effect on intake or gain compared with the unground fresh stover. Heifers fed the 2-yr-old baled ground stover diet consumed less (2.3kg) feed per day but produced the same average daily gains as those fed the fresh ground stover diet.