SUMMARY This research was designed to test the effect of urea supplementation for periparturient beef cows in order to improve reproductive efficiency. At approximately 5 months of pregnancy the cows were divided in two groups, one receiving urea and the other remained as control. After parturition, the cows were submitted to rectal palpation to evaluate ovarian activity and, for estrus detection the cows were observed twice a day, using a teaser. To indirectiy evaluate the nutritional status, serum leveis of glucose and albumin were determined monthly and the cows were weighted in the same periods. There was no effect of urea on pós-partum ovarian activity. Only one cow in each group ovulated within the 120 days post-partum. There was no significant difference on weight means among groups (x = 305.2kg). There was a significant weight loss during the last 120 days pre-partum in both groups, however, the treated group showed a trend to stabilise the weight after parturition while the control group continued to lose weight, suggesting a slight beneficial effect of urea. With regard to albumine (x = 4.1 g/dl), the treated group showed a lesservariation on serum concentration, without presenting a negative slope around parturition as the control group. The serum glicose concentration were not different among groups (x = 50.5mg/dl) and no changes were observed over time. It can be concluded that urea supplementation without sufficient availability of roughage is ineffective to improve reproductive efficiency of post-partum beef cows.
reproduction; post-partum beef cattle; urea
