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Biotin, folic acid, and vitamin B12 supplements: Their effects on glucose tolerance in early lactation.

C. L. Girard

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06-22-2020

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Abstract:

M123
Biotin, folic acid, and vitamin B12 supplements: Their effects on glucose tolerance in early lactation.
M. Duplessis, C. L. Girard*. Agriculture and Agri-Food Canada Sherbrooke, QC, Canada.

This study aims to evaluate glucose and insulin metabolism of early lactating multiparous cows receiving biotin (B8), folic acid (B9), and vitamin B12 (B12) supplements. Cows (n = 32) were assigned to either 1 of the 4 treatments from −3 to 3 wk relative to the calving: 1) no vitamin (B8-B9B12-); 2) 20 mg/d of dietary B8 (B8+B9B12-); 3) 2.6 g/d of dietary B9 and weekly intramuscular injections of 10 mg of B12 (B8-B9B12+); 4) B8 with B9B12 (B8+B9B12+). An intravenous glucose tolerance test (IVGTT) was performed at 25 (SD: 2) days in milk after a fasting period of 12 h. Glucose (0.3 g of dextrose/kg of BW) was administered in 7.6 min; blood samples were taken −20, −10, 2, 5, 10, 15, 20, 25, 30, 40, 50, 60, 80, 100, and 120 min post-infusion. Positive incremental method was used to calculate area under the curve (AUC). Data were analyzed with Proc MIXED (SAS) according to a factorial arrangement 2x2 and log-transformed when needed. Basal glucose, nonesterified fatty acid and glucagon plasma concentrations did not differ among treatments (P > 0.16) and averaged 2.96, SE: 0.15 mmol/L, 1,392, SE: 109 �mol/L, and 113, SE: 8 pg/mL, respectively. Supplementary B8 had no effect on basal insulin concentration in B9B12- cows but increased it when B9B12 was given, 1.07, 95% confidence interval (CI): 0.89—1.29 and 1.57, 95% CI: 1.30—1.91 mU/L for B8-B9B12+ and B8+B9B12+, respectively (B8xB9B12 interaction, P = 0.05). Glucose AUC (274, SE: 22 mmol�120 min/L), clearance rate (1.99, SD: 0.2%/min) and time to half-maximal concentration (35.1 SE: 1.0 min) did not differ among treatments (P > 0.57). B8 had no effect on glucose peak height in B9B12- cows but increased it in B9B12+ cows, 12.7, CI: 12.2—13.3 and 13.8, CI: 13.3—14.4 mmol/L for B8+B9B12- and B8+B9B12+, respectively (B8xB9B12 interaction, P = 0.05). Insulin AUC was greater for cows receiving B8 (1,950, SE: 110 mIU�120 min/L) than cows who did not (1,120, SE: 106 mIU�120 min/L; P < 0.0001). Peak insulin concentration was also greater for B8 cows (P = 0.03). The greater insulin release with the B8 supplement suggests that this supplement reduced insulin sensitivity.

Keywords: biotin, folates, cyanocobalamin.