BODY-WEIGHT LOSS AND CESSATION OF LUTEAL OVARIAN CYCLIC ACTIVITY IN CROSSBRED MILK-COWS

The effect of nutrition on luteal cyclic ovarian activity (LCOA) was e valuated in 30 non-lactating, multiparous Holstein-Zebu crossbred cows , weighing 535,5 +/- 48,4 kg in average. Body conditions were good or very good (scores ranging from 4 to 5, in a scale of 1 to 5). Cows wer e randomly assigned to one of the two treatments: (1) ten cows were fe d at maintenance level; (2) twenty cows were underfed up to cease LCOA . The following measurements were made weekly: body weight changes, bo dy conditions (scores); blood progesteron levels (RIA); visual oestrus observations and gynecologic examinations. Cows underfed showed anest rus in 183,5 +/- 30,3 days, after loosing 35,7 +/- 3,8% of body weight . These cows were weighing 344,5 +/- 25,3 kg, and showed body score of 2,2 +/- .3, in average. Cows fed for maintenance continue showing est rus regularly, throughout the trial. It was concluded that cows scorin g 4 or 5 need to loose a lot of weight before ceasing LCOA.