Body weight loss and cessation of luteal ovarian cyclic activity in crossbred milk cows

Abstract

The effect of nutrition ou luteal cyclic ovarian activity (LCOA) was evaluated 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 were randomly assigned to one of the two treatments: (1) ten cows were fed at maintenance level; (2) twenty cows were underfed up to cease LCOA. The following measurements were made weekly: body weight changes, body conditions (scores); blood progesteron levels (RIA); visual oestrus observations and gynecologic examinations. Cows underfed showed anestrus 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 ± 0.3, in average. Cows fed for maintenance continue showing estrus regularly, throughout the trial. It was concluded that cows scoring 4 or 5 need to loose a lot of weight before ceasing LCOA.