Progesterone and betahydroxybutyrate in line measurements for a better description and understanding of Holstein cows fertility in field conditions
Résumé
PLF devices allow to follow up large populations of animals in a non-invasive way over long periods of time and under field conditions. The objective of this work was to describe the ovarian activity and metabolic status during the postpartum period in dairy cows and their impact on further fertility in commercial herds. Data from 760 cows housed in 21 French farms were collected over the first 140 days postpartum (dpp). Milk progesterone was assayed on average every 2.7 days from 20 to 140 dpp whereas BHB was assayed every 3- 4 days during the first 21 dpp. Date and success of artificial insemination (AI) were recorded. Overall, 22.9% (174/760) cows resumed cyclicity (progesterone > 5 ng/ml) after 45 dpp (prolonged anovulatory interval postpartum), ovulation was delayed (follicular phase > 14 days) in 27.9% (212/760), luteolysis was delayed (a luteal phase > 20 days) for 26.1% of the cows (199/760) whereas 34.3% (261/760) suffered from an early luteolysis (a short luteal phase < 10 days). A total of 74.3% (565/760) cows showed at least one atypical pattern of cyclicity. The prevalence of biochemical ketosis (BHB> 0.15 mmol/L) is higher in cows with at least one cyclicity abnormality (p-value=0.02). In cows without any atypical pattern, a shortening in calving to first insemination interval (83.2 dpp vs 97.1 dpp; p-value<0.001) and calving to conception interval (120.7 dpp vs 143.6 dpp; p-value<0.001) were observed. Atypical patterns of ovarian activity are thus of high frequency in Holstein cows, associated to metabolic issues and significantly impact on fertility.
