Abstract

Effects of vitamin A supplementation during the dry period and early lactation on vitamin A status, milk yield and reproductive performance of dairy cows were studied. Eleven primiparous and 10 multiparous Holstein Friesian cows were assigned into one of three groups: 1) control; 2)700, 000IU of vitamin A supplemented in diet at weekly intervals from 30 days before expected calving ; 3) 700, 000IU of vitamin A supplemented in diet at weekly intervals from 60 days before expected calving. The supplementation was done by mixing with concentrate weekly and lasted for 45 days after calving. Vitamin A supplementation slightly increased the plasma retinol concentrations of cows 1 day after calving. The supplementation had no significant effect on days to first service, days open and services per conception of cows. The supplementation 60 days before the expected calving significantly decreased milk yield 5 and 15 days after calving. The plasma retinol concentrations of multiparous cows were significantly lower than those of primiparous cows 45 and 90 days after calving. The plasma retinol concentrations of cows 90 days after calving were negatively correlated with milk yield of the same length period after calving. 700, 000IU of vitamin A supplemented in diet at weekly intervals from 60 days before calving might have an adverse effect on the milk yield at the beginning of lactation. The lower plasma retinol concentrations of multiparous cows at the peak of lactation were due to large transfer of vitamin A into milk.

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.