Influence of β-carotene and vitamin A supplementation on the ovarian activity of dairy cows with chronic fertility impairment

The aim of this study was to determine the influence of supplemented beta-carotene and vitamin A on the ovarian activity during the periovulatory period in dairy cows with chronic fertility impairment. A total of 46 non pregnant Holstein cows with fertility impairment, at the age of 5-7 years, were selected for this study. The animals in three experimental groups were supplemented with either a combination of beta-carotene and vitamin A, beta-carotene only or vitamin A only. Non supplemented animals served as controls. All animals included in the survey were gynecologically examined; the estrus was synchronized and inseminated. Initial blood levels of beta-carotene as well as the levels at the time of insemination and in the luteal phase as well as the ovarian structures during ovulation and formation of corpus luteum and P-4 and conception rate, were monitored. Significant increases in follicular size as well as luteal tissue growth were found in animals supplemented with beta-carotene and vitamin A combination and vitamin A only. Positive correlation between the serum concentrations of beta-carotene at insemination and at day 7 of the luteal phase and the concentrations of progesterone and the conception rate, lead to a conclusion that periovulatory beta-carotene and and vitamin A supplementation could improve follicular growth and development of the corpora lutea in cows with fertility impairement.