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ARS Home » Midwest Area » Madison, Wisconsin » U.S. Dairy Forage Research Center » Research » Publications at this Location » Publication #118923
Title: EFFECT OF COARSE OR FINE GRINDING ON UTILIZATION OF DRY OR ENSILED CORN BY LACTATING DAIRY COWS

Author
item SAN EMETERIO, F - UNIVERSITY OF WISCONSIN
item REIS, R - UNIVERSITY OF WISCONSIN
item CAMPOS, W - UNIVERSITY OF WISCONSIN
item Satter, Larry

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/21/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary: The starch granules in corn grain have a protein wrapper that inhibits digestion of the starch by rumen microbes unless the wrapper is physically disrupted. If the starch is not digested, the corn grain is not fully utilized by the host ruminant. This is costly, and results in waste of feed energy. Grinding of corn grain can disrupt the protein wrapper, but the question is how fine does the grain need to be ground to assure digestion of the starch, and does it matter if the grain is dry or ensiled high moisture grain. This study evaluated the effect of coarse or fine grinding of three forms of corn. The corn treatments were dry shelled corn, high moisture ensiled ear corn, and high moisture ensiled shelled corn. Thirty-six lactating cows were used in the experiment. Milk production and milk composition, along with starch digestibility, were measured. Ammonia concentrations in the rumen were also measured to give an indirect indication of microbial protein production in the rumen. Feeding high moisture corn always resulted in lower ruminal ammonia concentrations, indicating that microbial growth was stimulated by the high moisture grain. There was a tendency for increased milk production with the finely ground high moisture corn treatments, and starch digestibility was always increased with fine grinding. Results indicated that high moisture ensiled corn as well as fine grinding improved protein and starch utilization. This research can be used by dairy producers to increase digestibility of corn supplements in their dairy diets. Fine grinding is an economical management practice that can be incorporated directly on the dairy farm.

Technical Abstract: This study evaluated the effect of course or fine grinding of three forms of corn on the performance of lactating cows. Six diets, fed as total mixed rations, were identical except for the corn portion of the diet. Corn treatments were dry shelled corn, high-moisture ensiled ear corn, and high-moisture ensiled shelled corn, either coarsely or finely ground. The experimental design was a 6x6 Latin square with 36 cows. Eighteen cows were assigned to the six different treatments and were fed once daily. Within this group of 18 cows, six had a ruminal cannula and were used to evaluate nutrient digestibilities and ruminal fermentation. The remaining 18 cows, six of which were ruminally cannulated, were similarly assigned, except they were fed twice daily. In the group fed once daily, milk production and composition were not affected by treatment. Starch digestibility was greater with the high-moisture and with the finely ground corn treatments. In addition, the high-moisture ensiled corn treatments had reduced ruminal ammonia concentrations. In the group that was fed twice daily, milk production and protein yield were greatest for the finely ground high-moisture ensiled shelled corn treatment. Starch utilization was improved by fine grinding. Lower ruminal ammonia concentrations were obtained with the high-moisture ensiled corn treatments, and there was a tendency for reduced ammonia concentration with fine grinding. Results indicate that high-moisture ensiled corn, as well as fine grinding, improved nitrogen and starch utilization.