Phytochemical Supplementation in Grazing Dairy Cows: Effects on Milk Production, Metabolic Status, Hematology, and Postpartum Ovarian Activity.

This study evaluated the effects of three treatments in dairy cows under pasture-based systems during the transition and early lactation periods: one group supplemented with a phytochemical mix (polyphenols, curcuminoids, piperine, and trans-cinnamaldehyde, PHY), another group supplemented with monensin (MON), and a third group with no additive, used as the control (CTL). Sixty Holstein cows (primiparous and multiparous) were assigned to these treatments from 30 days prepartum to 60 days postpartum. Productive, metabolic, endocrine, hematological, and reproductive parameters were analyzed. Results showed that both PHY and MON increased milk yield in primiparous cows compared to CTL, whereas no treatment differences were observed in multiparous cows. MON supplementation was associated with higher serum cholesterol concentrations, particularly in primiparous cows. Total leukocyte counts did not differ between treatments; however, a treatment effect was observed for monocytes in multiparous cows. Energy balance indicators (nonesterified fatty acids, beta-hydroxybutyrate, and glucose) and calcium and phosphorus were not significantly influenced by treatments and remained within physiological ranges. In conclusion, both MON and the phytochemical mix supported adaptation during the transition period, although their effects differed by parity and physiological response. MON was more closely associated with lipid metabolism, while the phytochemical mix may have contributed to subtle immune-related adjustments, warranting further investigation.