BLOOD METABOLITES AND IMMUNE STATUS RESPONSE TO THE USE OF ENCAPSULATED CHOLINE CHLORIDE (BYCHOL®) IN TRANSITIONING DAIRY COWS

This study was presented last July at the ADSA (American Dairy Science Association) 2021 annual meeting and was conducted jointly with IRTA. The objective of the study was to evaluate the effect of encapsulated choline chloride (BYCHOL®) supplementation on blood metabolites and immune status of dairy cows during transition.

Sixty Holstein cows randomly distributed in 2 groups were used and exposed for 60 days to 2 treatments. The treatments consisted of supplementation with 60 g/day of Bychol® (CLN) 3 weeks before and after calving, or no supplementation in the control group (CTR). Cows were fed one ration in the dry period (12.2% BW, 57.3% NDF, 1.30 Mcal ENl/kg; DM basis) and another ration in the milk production period (15.3% BW, 32.2% NDF, 1.69 Mcal ENl/kg), twice daily. Peripheral blood samples were taken from all cows on days-4, 3 and 10 relative to calving to determine concentrations of fatty acids (FA), β-hydroxybutyrate (BHB), triglycerides (TG) and very low density lipoproteins (VLDL). To assess immune status, lymphocyte counts and the ratio of T4 to T8 lymphocytes (T4:T8) were determined by flow cytometry.

Plasma GA concentration did not differ between treatments. Plasma BHB content tended (P =0.07) to be lower in the CLN group (0.33 mM) than in the CTR group (0.45 mM). Plasma TG and VLDL concentration was higher (P < 0.05) in CLN cows at day-4 compared with CTR cows, but no differences were observed thereafter. Cows in the CLN group had lower (P = 0.01) blood lymphocyte counts compared to CTR cows throughout the study. Cows in the CLN group had (P= 0.05) higher T4:T8 ratios than CTR cows at day 3 postpartum.

It was concluded that ration supplementation with BYCHOL® during the transition period tended to reduce blood BHB concentration and increased blood T4:T8 ratio at day 3 postpartum