VOLUNTARY ROUGHAGE INTAKE BY NONPREGNANT AND PREGNANT OR LACTATING BEEF COWS

Abstract

Pregnant and nonpregnant Shorthorns were group-fed either hay or grass silage ad libitum from December until midsummer in 2 successive yr. Stage of gestation at the start of feeding each year averaged 120 days. In the 1st yr the cows were housed and in the 2nd they were confined to outside paved lots. Until the start of calving, the pregnant groups tended to consume less than their nonpregnant counterparts. During the 2 wk before the start of calving this difference in intake between pregnant and nonpregnant cows increased up to 12%. However, it was only for the silage-fed, pregnant cows wintered outside that intake was clearly insufficient for maintenance up to 48 h postcalving. Depsite a rapid increase in postcalving intake, all lactating groups lost weight. Results indicated that pregnancy in beef cattle may reduce intake below that expected from nonpregnant animals and may result in insufficient forage consumption for maintenance. During early lactation, beef cows were unable to consume enough stored forage to meet their full energy requirements.