Influence of herbal supplementation on nutrient digestibility, blood biomarkers, milk yield, and quality in tropical crossbred cows

Herbal supplements containing diverse phytochemicals have been proven to improve digestibility, beneficial serum metabolites, milk yield, and quality in cows. However, the temperature sensitivity of phytochemicals in herbs complicates their practical use as livestock supplements. In response, this study aimed to assess how shade-dried plantain, lemongrass, and their combination influence cow performance, digestibility, serum and milk antioxidants, and milk fatty acids. Forty multiparous mid-lactating Holstein-tropical crossbred cows were randomly assigned to four groups (n = 10) for 63 days in a completely randomized design with covariates adjustment. The control group received a basal diet (14.9% crude protein, 11.0 MJ metabolizable energy/kg dry matter (DM)) without herbs. The herbs-supplemented groups received shade-dried powder (per cow/day) of either 100 g plantain (plantain), 100 g lemongrass (lemongrass), or 50 g each of plantain and lemongrass (combined), along with the basal diet. Compared with the control, the plantain or lemongrass group presented improved performance, i.e., DM consumption (3-4%), milk (10-11%) and its components yield (p ≤ 0.05). Similar to the control, the combined group had no effect on performance or digestibility, whereas the digestibility of all nutrients in the plantain or lemongrass group substantially increased. Herbs-supplementation reduced serum bad-cholesterol and urea-nitrogen while increasing good-cholesterol and albumin compared with the control (p < 0.01). Notably, 4-8% serum and 8-23% milk antioxidants were greater in the herbs-supplemented groups than the control, while the lemongrass had the optimum milk β-carotene. Substantially, herbs-supplementation resulted in a 6-10% higher unsaturated fatty acids (USFAs), whereas the combined group presented a 3.56-fold greater n-3 fatty acids than the control. Significantly, the plantain or lemongrass group presented better benefit‒cost‒ratio than the combined and control. Therefore, shade-dried herbs-supplementation improved the beneficial serum metabolites, serum and milk antioxidants, and milk USFAs in cows. Additionally, shade-dried plantain or lemongrass enhanced cow DM consumption, digestibility, milk yield, and profitability.