Formulating Dairy Rations with Neutral Detergent Fiber. 1. Effect of Silage Source

Abstract

Alfalfa and corn silages were evaluated as sources of forage fiber in diets for early lactation cows formulated to contain equal amounts of neutral detergent fiber. Diets were designed to contain 32% neutral detergent fiber and 17% crude protein. Twenty-four cows were assigned on the basis of parity and calving date to one of three experimental diets fed as complete mixed rations. Silage contents of the three complete mixed rations on a dry basis were 54.8% alfalfa silage, 67.4% corn silage, and 60.1% of a 1:1 combination of these two silages. The remainder of the experimental rations was composed of corn, soybean meal, minerals, and vitamins. Experimental rations were fed for a 9-wk period, which was preceded and followed by 3-wk periods when all cows were fed a standard diet. Using the average of pre- and postexperimental period means as a covariate, no significant differences were found among the experimental means for actual milk and fat-corrected milk yield or milk composition. Daily dry matter intake as a percent of body weight was lower for cows fed the corn silage-based diet. There were no differences in milk production between alfalfa silage and corn silage when diets contained similar concentrations of neutral detergent fiber. Rations containing 32% neutral detergent fiber were adequate for cows in early lactation producing approximately 30 kg of 4% fat-corrected milk/d. © 1986, American Dairy Science Association. All rights reserved.