Investigation of the Changes in NEFA during the Transition Period and its Relationship with Reproductive Performance in Holstein Dairy Cows

This study investigate the changes in serum non-esterified fatty acids (NEFA) during the transition period and to evaluate their relationship with the reproductive performance of Holstein dairy cows. Thirty multiparous Holstein cows (parities ۲–۵) from a large industrial dairy herd in Shahrekord were enrolled during the last week of the dry period. Blood samples were collected at ۱۰ and ۳۰ days after calving. Samples were centrifuged at ۱۷۰۰ × g for ۱۵ minutes, and serum was separated and stored at -۲۰°C until analysis. Serum NEFA concentrations were determined using commercial Randox kits (UK). Reproductive data, including calving date, date of first insemination, number of inseminations, and pregnancy outcomes, were recorded. Statistical analyses were performed using SPSS (version ۱۹). Serum NEFA concentrations increased significantly (P < ۰.۰۵) after calving compared with the prepartum period, reaching the highest value at ۱۰ days post-calving and declining thereafter. Mean NEFA levels at one month postpartum were significantly higher in cows that failed to conceive after the first insemination compared to cows that became pregnant (P < ۰.۰۵). At ۱۰ days postpartum, NEFA concentrations were significantly lower (P < ۰.۰۵) in cows that received their first insemination before ۷۵ days compared to those inseminated later, suggesting that elevated NEFA was associated with a prolonged calving-to-first-insemination interval. When cows were categorized by calving-to-conception interval (<۸۰ days, ۸۰–۱۵۰ days, >۱۵۰ days), the lowest NEFA concentrations were observed in the <۸۰-day group, although differences were not statistically significant (P > ۰.۰۵). Similarly, cows conceiving with fewer than three inseminations generally exhibited lower NEFA values. The findings confirm that dairy cows experience negative energy balance during the transition period, reflected by elevated NEFA concentrations. Monitoring NEFA dynamics during this period provides a useful indicator for predicting and improving reproductive performance in dairy herds.

کلیدواژه ها:

dairy cow ، NEFA ، Negative Energy Balance ، reproductive performance ، Transition Period