EFFECTS OF HOUSING AND TYPE OF FORAGE ON THE RESPONSE OF PREGNANT BEEF COWS TO DIETARY ENERGY INTAKE IN WINTER

Pregnant hay-fed beef cows confined in an insulated, forced-air ventilated barn (In) and those in an open yard with access to a log barn (In–Out), gained weight from autumn to late winter (273 and 257 g/day for In and In–Out, respectively), compared with those out-of-doors with only a windbreak shelter (Out), which lost weight (−31 g/day) (P < 0.05), when all groups were adjusted by co-variance to the mean digestible energy (DE) intake for hay-fed cows. For grass silage-fed cows, the In groups gained 196 g/day, more (P < 0.05) than the In–Out (132 g/day), and In, and In–Out groups gained more (P < 0.05) than Out cows (−185 g/day) when all groups were adjusted to the mean DE intake for silage-fed groups. Estimated daily DE intake required for maternal maintenance and fetal growth for the period covered by this experiment (beginning 238–243 days, ending 59–75 days before parturition) was 3.10, 3.12, and 4.32 Mcal/100 kg initial weight (IW) for hay-fed cows In, In–Out, and Out, respectively, and 2.84, 3.00, and 3.91 Mcal/100 kg IW for silage-fed cows In, In–Out, and Out, respectively.