FEEDING VALUE FOR BEEF STEERS OF CORN SILAGE AS AFFECTED BY HARVEST DATES AND FROST

Abstract

An experiment was conducted in 3 consecutive yr with corn grown each year on a field from which silage was made of corn harvested at different dates before and after freezing. Yields of green and dry weight were recorded at each harvest. Individual whole plants and plant parts were evaluated for dry matter (DM), total nitrogen, total available carbohydrates and in vitro digestibility of DM. Animal gains, feed consumption and carcass grades were determined by feeding the silages to yearling Hereford steers and DM digestibility determined with sheep. The total yield and contribution of the ear increased from the first to the second harvesting date. The in vivo digestibility of DM of the silages declined between the second and final harvests in all years as did animal gain in years 1 and 3. The in vitro digestibility appeared to underestimate the effect of frost on the in vivo digestibility of silage made with corn. When the silages were fed to steers, they consumed more dry matter per day from that harvested on the intermediate date than from either the early or late date. Higher carcass grades occurred when the steers were fed corn harvested at the intermediate dates. The results of these experiments show clearly that corn which has been heavily frozen will loose dry matter and feeding value if left standing in the field for a period of time; however, corn harvested soon after freezing is not as seriously affected.