Liver functionality and its association with milk production and ovarian activity in dairy cows

Context The liver function index (LFI) is a marker that reflects liver function and could be a tool to identify adequate conditions for ovarian functionality and improve milk production capacity during the transition period in the dairy cow. Aims This study aimed to evaluate LFI according to dietary changes, and its relationship with milk production and the onset of ovarian activity. Methods Thirty dairy cows were randomly selected into two experimental groups: CON (supplemented with concentrate) and MIX (supplemented with corn and soybean plants silage). Blood samples were taken on the 3rd and 28th days after calving and analyzed for bilirubin (mg/dL), cholesterol (mg/dL), and albumin (g/L) to calculate the LFI. The study variables identified were weight loss at 28 days, milk production at 7 (initial) and 28 days, ovarian and follicular size, and days to first estrus. A two-factor split-plot animal design was used. Key results The diets (CON or MIX) did not affect any of the studied variables. However, cows with a LFI greater than zero (LFI > 0) had higher initial and 28-day milk production (r = 0.41 and r = 0.80, respectively). Additionally, LFI was positively correlated with transverse (r = 0.28) and longitudinal (r = 0.52) preovulatory follicle size.. Within the first 90 days in milk (DIM), 89% of cows were in estrus, with an average of 49 days until first estrus after calving. Conclusions The LFI was correlated with initial milk production at 28 days, but not at 100 days. It was shown that an LFI > 0 influenced ovarian and follicular size, with larger longitudinal and transverse measurements compared to animals with LFI values lower than zero (LFI < 0). The same behavior was observed with preovulatory follicles, with 9 mm for LFI > 0 compared at 4.64 mm for LFI < 0. Implications The LFI is a potential tool to predict ovarian functionality in terms of the onset of postpartum ovarian activity.