Evaluation of fat tissue mobilization and postpartum fertilty performance in dairy cows

This study aimed to evaluate the effects of pre- and postpartum changes in back fat thickness (BFT) on metabolic parameters, postpartum disease incidence, and fertility in dairy cows. The research included primiparous (n=120) and multiparous (n=120) Holstein cows, all of which were clinically healthy individuals without systemic disease or fertility problems. BFT measurements were performed at five different time points: 60 days before calving (BFT1), 5 days before calving (BFT2), and on days 21 (BFT3), 40 (BFT4), and 80 (BFT5) postpartum. Based on the difference in fat thickness before and after calving (∆BFT), cows were divided into four equal subgroups: Primiparous Group 1 (max ∆ BFT), Primiparous Group 2 (min ∆ BFT), Multiparous Group 1 (max ∆ BFT), and Multiparous Group 2 (min ∆ BFT). Blood samples were collected at two different time points: five days before and five days after calving. Serum levels of calcium, phosphorus, magnesium, BHBA, NEFA, AST, GGT, glucose, cholesterol, BUN, total protein, and albumin were determined. Additionally, pregnancy rates and the incidence of postpartum diseases such as retained placenta, septic metritis, and ketosis were evaluated by group. According to the findings, an increase in postpartum BHBA (0.995 mmol/L) and NEFA (0.660 mmol/L) levels, and a decrease in glucose (48.2 mg/dL) and calcium (9.15 mg/dL) levels were detected in Multiparous Group 1 cows. In Primiparous Group 1, BHBA (0.891 mmol/L) and NEFA (0.923 mmol/L) levels were also high, and total protein and GGT levels were higher compared to Group 2. Pregnancy rates were 36.6% in Primiparous Group 1 and 41.6% in Multiparous Group 1, while these rates reached 70.0% and 61.6%, respectively, in the corresponding Group 2s. The rates of retained placenta and septic metritis were higher in groups with greater fat loss; the incidence of ketosis was particularly notable in Multiparous Group 1 at 26.0%. In conclusion, prepartum fat reserve levels and the amount of fat loss during the postpartum period may influence metabolic balance and reproductive performance in dairy cows. Accordingly, regular monitoring of back fat thickness can be considered an early risk assessment tool in transition period management. This approach is anticipated to contribute to the prevention of metabolic diseases and support reproductive performance.