Failure of β-carotene absorption negates any potential effect on ovarian function in mares.

The study evaluates the effect of oral beta-carotene supplementation on ovarian function and plasma progesterone levels in Thoroughbred mares, in light of conflicting evidence regarding beta-carotene’s impact on fertility.

Background

• The research undertakes the task of investigating the effects of oral beta-carotene supplementation on ovarian cyclicity and plasma progesterone levels in Thoroughbred mares. This is stirred by variable results from previous studies regarding the fertility influences of beta-carotene.
• Previous research has indicated that low beta-carotene levels have been associated with lowered fertility rates, ovarian cysts, prolonged estrus, delayed ovulation, and suboptimal luteal function in cattle.
• Holding horses indoors during winter seasons electronically reduces their beta-carotene intake as compared to when they are out in the pasture during summer. Previous reports suggest the existence of a significant variance in blood concentrations of beta-carotene between winter (60 pgA) and summer (1300 pgA) seasons.
• Several studies have demonstrated that oral beta-carotene supplementation while mares are not at grass increases pregnancy rates, reduces cycling disorders, improves the exhibition of estrus, and increases circulating progesterone during diestrus. However, contradicting studies have shown no effect on fertility despite oral or parenteral beta-carotene supplementation.

Research Objectives and Approach

• The primary objective of this research is to systematically investigate the effect of an oral beta-carotene supplement on ovarian cyclicity and plasma progesterone levels in cycling Thoroughbred mares. This inquiry is provoked by the conflicting evidence suggesting the non-effect of beta-carotene supplementation on fertility.
• The research goes further to measure the plasma response to two dose levels of beta-carotene which are administered daily to pony mares. The doses represent one physiological and one pharmacological level.