The influence of a supplement of beta-carotene given during the dry period to dairy cows on colostrum quality, and beta-carotene status, metabolites and hormones in newborn calves

摘要

The objectives of the present study were to investigate whether a dietary supplement of beta-carotene given to dairy cows during the dry period was able to: (1) increase their beta-carotene status, (2) increase the amount of beta-carotene in colostrum, (3) increase the concentrations of immunoglobulin Gin colostrum and (4) modify metabolic hormone, enzyme and metabolite status in their calves at birth. Forty Holstein cows were allocated to one of two dietary treatments: a control diet (C, n = 20) or the same diet plus 1 g beta-carotene/cow/day (BC, n = 20) starting on the day of drying-off. The beta-carotene supplement was given individually to the cows throughout the dry period. From week 2 after the start of supplementation, blood concentrations of beta-carotene were higher in BC compared to C cows (P < 0.0001). The beta-carotene concentrations of colostrum were higher in BC than in C cows (3.10 +/- 0.23 mg/l vs. 1.44 +/- 0.24 mg/l, P < 0.001). Colostrum production was not different between groups (BC. 11.11 +/- 1.21 kg vs. C. 10.05 +/- 2.25 kg). The content of IgG in colostrum was not affected by treatment (BC, 82.65 +/- 8.79 mg/ml vs. C, 79.32 +/- 9.02 mg/ml). Blood concentrations of beta-carotene in calves at birth were unaffected by treatment (BC, 1.16 +/- 0.21 mg/l vs. C, 1.27 +/- 0.24 mg/l). A supplement of beta-carotene given during the dry period to dairy cows did not affect metabolite and metabolic hormone concentrations and enzyme activities in newborn calves. The results of this study indicate that a dietary supplement of beta-carotene given in late-gestation was able to increase beta-carotene concentrations in dam blood and in colostrum but was unable to increase colostral IgG. In addition, hormone and metabolite status and enzyme activities in the neonatal calf were also unaffected