EFFECT OF INTRODUCTION OF UREA ON FEEDING-BEHAVIOR OF HOLSTEIN HEIFERS

Effects of introduction of urea upon feeding behavior were studied in dairy heifers that never had been exposed to urea. Twelve dairy heifers (158 ± 40 kg) exhibited no significant aversion or preference in 20 two-choice preference tests with tap water versus tap water adulterated with urea (1 to 64 × 10-2M). Ammonia intoxication was avoided by limiting liquid volumes offered so that urea intake would not exceed .35 g/kg body weight during the 30-min test period. In single stimulus preference tests with five pairs of heifers (156 ± 24 kg), animals fed urea versus soy protein diet during the daily 6-h test period did not decrease consumption until day 3 of exposure. Heifers provided with urea diet spent as much time feeding, but eating rate was decreased. They remained averse to urea diet after we fed soy protein diet for 4 days. We postulate the decreased consumption of urea diets fed below toxic amounts is not due to taste and/or odor per se but probably results from association of the flavor of urea diets with a malaise produced by ammonia. © 1979, American Dairy Science Association. All rights reserved.