Effects of Diet and Climate on Growing Horses

Abstract

The effects of diet and climate were assessed in 42 light horse weanlings over 30 wk. Horses were fed diets varying in energy and phosphorus content. Diets were predominantly forage (73 to 77.5%) or concentrate (62 to 62.25%) and had 2.65 or 3.09 Meal DE/kg DM, respectively. Horses were weighed every 14 d. Group feed intakes and climatic variables were recorded daily. Dietary phosphorus content did not affect intake or gain. Horses fed forage diets ate 18% more (P < .001) DM than horses fed concentrate, but DE intakes did not differ. Average DE intakes, 21.5 Meal daily, were 33% more than those given in 1978 National Research Council (NRC) tables. Overall ADG by forage- and concentrate-fed horses were .83 and .89 kg, respectively. These values were 23 and 32% above mean ADG values given for horses at 6 and 12 mo in 1978 NRC tables. Average daily gain declined (P < .01) with age, although daily DE intake increased (P < .01). Total DM and DE intakes were determined largely by body weight, but age was the main determinant of weight-scaled DE intake. Weight- and age-scaled DE intakes were reduced (P < .001) by 6.1% at temperatures below −10°C compared with temperatures above −10°C. Temperatures below −20°C had no greater effect on DE intake than those between −10 to −20°C. Neither precipitation nor wind alone affected weight- and age-adjusted DE intake. In conclusion, weanling horses fed readily digested diets ad libitum gained weight at or above expected values even at severely cold ambient temperatures. Copyright © 1989. American Society of Animal Science . Copyright 1989 by American Society of Animal Science