Evaluation of environmental effects on reproductive characteristics of Mangalarga Marchador mares in a commercial embryo transfer program.

The study focuses on analyzing the effects of the environment on the embryo recovery rate and pregnancy rate of Mangalarga Marchador horses over five years in Brazil’s tropical climate. The research demonstrated that these horses can reproduce successfully throughout the year.

Research Scope and Procedure

• The study observed the reproductive capacities of both donor and receiver mares of the Mangalarga Marchador breed, a horse species common in Brazil, over a period of five years.
• The research classified the year into different seasons: October to April as the breeding season, May as the transition out of the breeding season, June to August as the non-breeding season, and September as the transition into the breeding season.
• The environmental conditions measured included daily temperature, rainfall, and length of daylight (photoperiod) throughout the months and years of study.
• Reproduction measures such as embryo recovery rate (ERR) and pregnancy rate (PR) were evaluated and their frequencies calculated.

Analysis and Findings

• Chi-square and Kruskal-Wallis statistical tests were used to determine the effects of environmental variables, day of uterine flushing, and hormone treatments (estradiol benzoate and progesterone) on reproduction measures.
• The study found that the year, season, and temperature significantly influenced the ERR, while none of the environmental parameters had a significant effect on the PR.
• The findings also showed that the day of uterine flushing had an impact on the ERR but had no significant effect on the PR.
• Moreover, hormone treatments were found to bolster the pregnancy outcomes of receiver mares during the non-breeding season.
• The results confirmed that Mangalarga Marchador mares could be used in reproduction throughout the year, with good pregnancy rates, even in Brazil’s tropical environmental conditions.

Conclusion and Implications

• The study concluded that Mangalarga Marchador mares can have good pregnancy rates throughout the year in Brazil’s tropical environment. This suggests that the breed is suitable for year-long reproduction in the observed environment.
• The added support offered by hormonal treatment in enhancing the pregnancy rates of recipient mares suggests further scientific possibilities for optimizing horse reproduction even outside their natural breeding season.