PERFORMANCE OF BEEF STEER CALVES DURING WINTER AND ON PASTURE AS AFFECTED BY FEEDING A WINTERING RATION AT DIFFERENT LEVELS WITH AND WITHOUT ADDED FAT

Abstract

Gains by Hereford and Angus steer calves overwintered at a total digestible nutrient (TDN) level of intake 14% above the U.S. National Research Council standard were still greater at the end of a 100-day grazing period than those by comparable calves wintered on approximately 2, 8, 14, or 22% lower levels of intake. There was little difference in gains at the end of the grazing period between the calves fed at the two lower feeding levels. The TDN:gain ratio for the calves fed at the lowest level of intake (1.13 kg TDN daily/100 kg body weight) was significantly (P < 0.01) greater than those for the calves on higher levels of intake.Mean gains by the calves fed added fat were greater during the winter and the subsequent grazing period than those by calves on corresponding rations without added fat. Calves fed added fat were significantly (P < 0.01) more efficient in feed utilization than those that did not receive added fat in their diets.Within the relatively narrow intake ranges studied, apparent digestibility of ration components other than crude fiber were not affected by level of intake. Fiber digestion coefficients by the calves fed at the higher levels of intake were greater (P < 0.05) than those by the calves on the lowest feeding level.Winter and summer gains were greater (P < 0.05 and P < 0.01, respectively) and efficiency of feed conversion was higher (P < 0.01) for Hereford than for Angus calves.