Relationship between milk production and plasma concentrations of oxidative stress markers during hot season in primiparous cows.

摘要

Oxidative stress markers, ascorbic acid and sulfhydryl (SH) residue concn. in primiparous cattle plasma and their relationship to milking performance during hot seasons were investigated. The rectal temp. of cattle correlated negatively with SH residue (r = -0.38, n = 38, P < 0.05) and ascorbic acid (r = -0.34, P < 0.05) concn. in their plasma. The group with a higher concn. of ascorbic acid over the mean value produced significantly more milk (P < 0.05) than did the group with a lower ascorbic acid concn. Although milk production showed a positive correlation with ascorbic acid concn. in plasma (r = 0.47, P < 0.05), the relationship between SH residue concn. and milk yield was not constant. The plasma SH residue concn. during the hot season correlated positively with milk protein percentage (r = 0.38, P < 0.05), lactose percentage (r = 0.35, P < 0.05) and SNF percentage (r = 0.47, P < 0.05), but not with fat percentage. Ascorbic acid concn. in plasma showed negative correlations with milk fat percentage (r = -0.34, P < 0.05) and protein percentage (r = -0.49, P < 0.05), but correlated positively with lactose percentage (r = 0.52, P < 0.05). The produced amount (g/day) of milk protein (r = 0.42, P < 0.05), lactose (r = 0.61, P < 0.05), and SNF (r = 0.56, P < 0.05) showed positive correlations with ascorbic acid concn. in plasma.