Net Energy Value of a Corn and a Barley Ration for Lactation

Abstract

Two rations containing 39% corn silage, 12% protein-mineral supplement, and 49% of the dry matter from either corn or barley were each fed continuously to four Holstein cows during a 12 wk experiment. The amount of ration fed was restricted to minimize body tissue change and eliminate feed refusals. Two complete energy balance measurements were made on each cow during the experiment. Ration had no effect on digestibility of proximate and fiber components, but increasing intake from near maintenance to three times maintenance was associated with a depression in digestibility of organic matter and energy. Digestibility of cellulose and hemicellulose declined 8 percentage units and starch declined 3 percentage units for each increase in intake equivalent to one multiple of maintenance. Assuming net energy for maintenance of 73 kcal/wt.75 per day, the average net energy value for lactation of the corn ration adjusted to maintenance intake was 1.99 Mcal/kg dry matter compared to 1.83 for the barley ration. Net energy value decreased with increasing intake. © 1974, American Dairy Science Association. All rights reserved.