Metabolic status of crossbreed F1 Holstein × Gyr dairy cows during the transition period in two different seasons in Brazil

Abstract

Crossbreed F1 Holstein x Gyr cows are proving to be a good alternative for milk production under tropical conditions. In order to contribute to that affirmative, our work focused on clarifying the metabolic patter of F1 Holstein x Gyr dairy cows during the most critical time in the lactation cycle, the transition period, and to compare their performance in two seasons. Blood sampling was performed on 15 cows during summer (January to April) and on 13 cows during winter (May to August), beginning three weeks before the estimated calving date, until 30 days relative to calving. The season had a great influence on the metabolic status. Almost all evaluated metabolites, with exception for aminotransferase (AST), non-esterified fatty acids (NEFA) and beta-hydroxybutyrate (BHBA), that have shown no variation among seasons, demonstrated a different patter between summer and winter. Liver functions were enhanced during the postpartum, with increased liver enzymes activity and increased concentration of cholesterol and BHB. Animals went through negative energy balance (NEB) and an alarming number of animals had experienced subclinical ketosis and high NEFA concentrations.