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Corn silage maturity discussed at recent American Dairy Science Association meetings.

Dairy Pipeline: August 1996

by Charles C. Stallings
Extension Dairy Scientist, Nutrition
Virginia Tech

A joint study from Washington State University, University of Idaho, and Pioneer Hi-Bred demonstrated the value of harvesting corn for silage before physiological maturity or black line formation. They compared corn silage harvested at 1/2 milkline versus 3/4 or black line formation. Milkline is the light colored area of the grain progressing from the top to the tip. The less mature corn silage (1/2 milkline) resulted in 2.9 lbs. more actual milk and 1.1 lbs. more 3.5% fat corrected milk. Corn kernels and starch were greater in feces from cows fed the more mature silage indicating less digestible grain. Therefore, for higher levels of milk it is desirable to harvest corn for silage at or before 1/2 milkline. At denting, milkline is approximately 1/3 of the way from the top to the tip of the grain. Another study by the same group looked at processing of corn forage at ensiling when black line formation had already occurred. They processed kernels with an on-board processor mounted on a forage harvester. Silages were stored in bunker silos. Processing resulted in 2 lbs. more milk per cow per day, but fat corrected milk was not increased because milk fat content decreased (3.75 versus 3.58%). Amount of corn in feces was reduced by kernel processing. Therefore, processing can reverse some of the detrimental effects of harvesting mature corn for silage by making the starch more digestible. This, however, can result in reduced rumen pH and milk fat content. Harvesting at or before 1/2 milkline is desirable.

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