The effect of dietary protein on reproduction in the mare. IV. Serum progestagen, FSH, LH and melatonin concentrations during the anovulatory, transitional and ovulatory periods in the non-pregnant mare.

This research investigates how the quality and amount of dietary protein consumed by non-pregnant, Anglo-Arab mares influences the levels of certain reproductive hormones at different stages of their reproductive cycle.

Research Methodology

• The study monitored the effect of total protein intake and protein quality on the serum concentrations of reproductive hormones such as serum progestagen, Follicle Stimulating Hormone (FSH), Luteinizing Hormone (LH), and melatonin during the three phases of the horse’s reproductive cycle – anovulatory, transitional and ovulatory periods.
• To investigate these effects, 36 non-pregnant Anglo-Arab mares were selected and their diets manipulated for varying degrees of protein quality. The effects on their reproductive hormones were then measured and analyzed.

Key Findings

• High-quality protein diets were found to stimulate the production of FSH and LH hormones in the mares during the late transitional period.
• The quality of dietary protein did not significantly affect the concentrations of serum progestagen and melatonin during the anovulatory period.
• Mares that were fed a high-quality protein diet exhibited a cyclical pattern of FSH release about 10-14 days earlier and ovulated approximately 3-4 weeks earlier than those mares that were fed a lower quality protein diet.
• Notably, the quality of the protein diet did not considerably impact the concentrations of progesterone during the first estrous cycle following the anovulatory period.

The study concludes that the quality of dietary proteins has a noticeable effect on the production of some reproductive hormones during certain phases, potentially influencing the timing of ovulation. However, it does not affect all hormones or phases of the reproductive cycle. Further research may be necessary to understand the implications of these findings for breeding and fertility among horses.