The relationship between energy balance after calving and reproductive functions in Holstein dairy cows treated by the OVSYNCH system

Abstract

The objective of this research was to evaluate the relationship between the course and the depth of negative energy balance (NEB) rated by changes of the body condition after calving and subsequent recovery of reproductive abilities of Holstein dairy cows treated by OVSYNCH. The body condition was evaluated by the BCS system one week before calving and subsequently at 30-day intervals for the period of 6 months of lactation. Recovery of ovarian functions was evaluated by the results of ultrasound examination of all the dairy cows’ ovaries in two controls after calving. The first one was performed on an average of 67 days after calving, and the second at a 60-day interval. The occurrence of individual findings - the presence of corpus luteum, ovarian cysts or ovaries without findings was evaluated as an effect of NEB on the recovery of the ovarian cycle of dairy cows and their subsequent possibility of conception. The suitable cows were treated by the OVSYNCH system after the 1st and 2nd ultrasound examination. Therefore, the insemination interval was calculated and in the case of dairy cows, pregnancy detection, also the number of services per conception and the length of open days. Twice performed hormonal treatment of 73.6% of the animals delayed the period by 50.2 days. In all, 202 dairy cows calved in the period from 29th July 2011 to 7th February 2012 were included in this observation. Significant effects of the body condition change on the ovarian activity as documented by sonographic examination and reproductive indicators appeared primarily in the second month of lactation. The best reproductive indicators were found in cows with the lowest body condition change, thus with a small decline or even increase of body condition score (−0.0 to +0.75 points, P < 0.05). On the contrary, the worst level of indicators of recovery of the reproduction functions were documented in the dairy cows with the most marked decline of BCS (P < 0.05).