Oral L-arginine supplementation impacts several reproductive parameters during the postpartum period in mares.

The research article studies the effects of supplementing mares with the amino acid L-arginine during the postpartum period, with an emphasis on its potential impacts on reproductive parameters such as plasma arginine concentrations, follicular dynamics, and blood flow in the ovarian and uterine arteries.

Methodology

• The research was executed in two experiments.
• In the first experiment, the mares were given 100g of L-arginine for one day in the last three weeks of their pregnancy and their plasma samples were taken every hour for the initial four hours, and subsequently every other hour until the twelfth hour.
• The second experiment involved feeding the mares with either a 100g dose of L-arginine or a control diet, starting from 21 days before their expected foaling date and continuing for 30 days postpartum.
• Their reproductive tracts were evaluated by using transrectal Doppler ultrasonography from the first day after giving birth through to the thirtieth day.

Results

• The researchers found that L-arginine supplementation elevated plasma arginine concentrations from the first hour to the eighth hour post feeding, peaking at the sixth hour.
• In the second experiment, it was determined that supplementation with L-arginine had no significant effect on ovarian follicular dynamics or blood flow resistance in the ovarian and uterine arteries.
• However, it was found that vascular perfusion of the wall of the F1 follicle was significantly higher in mares that were given supplements of L-arginine compared to the control group.
• Also, mares that were given L-arginine had smaller uterine bodies and horns and also accumulated less uterine fluid than the control group.

Conclusions and Application

• The study suggests that supplementing with L-arginine does not have any pronounced effect on follicular development but it may contribute to the reduction in uterine fluid accumulation.
• This is a potentially beneficial effect of L-arginine supplementation because a buildup of uterine fluid can inhibit breeding success.
• As such, the study raises the possibility of using L-arginine supplementation as a breeding management tool during the postpartum period, with the intention to increase reproductive success rates in mares.