Effects of body condition and leptin on the reproductive performance of Lusitano mares on extensive systems.

This research study explores how the body condition, body condition changes, and the plasma leptin concentrations of Lusitano broodmares affect their reproductive performance. It was discovered that changes in body condition at the time of conception had a significant effect on fertility and that the growth of offspring was affected by the mothers’ body condition changes during early lactation.

Objective of the Study

The primary objective of this research was to examine how a Lusitano mare’s body condition, the changes in the body condition, and the levels of plasma leptin in their system affected their ability to reproduce successfully within extensive systems. This included understanding how these factors influenced the mares’ overall fertility, the intermission time between births, the duration of gestation, and the growth performance of their offspring.

Methodology

• The researchers gathered data from 119 mares, whose ages ranged from 4 to 22 years, across four consecutive breeding seasons.
• Each case represented one mare that had given birth and bred within a single year.
• The team looked at changes in body condition at the time of conception (ΔBCScon) and how it correlates with the body condition score at conception (BCScon).
• Additionally, they also examined the plasma leptin concentrations in the mares during late gestation and early lactation.
• Another area of focus was how the ΔBCScon influenced the growth performances of the foals when they reached 90 days of age.

Findings

• The researchers noted that changes in body condition at the time of conception significantly affected fertility during the first two postpartum estrous cycles.
• The best fertility was observed when there were positive and greater ΔBCScon, with a predictive value of 91% when BCScon was at 3.0 and ΔBCScon at 0.375.
• The overall foaling rate for the four-year period was 74.5%.
• The average length of gestation decreased as the mares aged and was also impacted by the month of foaling. Furthermore, the number of estimated estrous cycles per live foal was approximately 1.78.
• Leptin was found to have a significant correlation with the body condition score. However, the concentration of plasma leptin during the latter stages of pregnancy and early lactation did not have any influence on fertility.
• Deterioration in the body condition score of the mothers during the initial three months of lactation affected the growth performances of the foals negatively.

Conclusions

The study concluded that alterations in the body condition of broodmares during the early postpartum period significantly influence their reproductive efficiency, as well as the growth of their offspring. These findings provide valuable insights to breeders and can impact feeding and management strategies for Lusitano mares and similar breeds.