Reproductive efficiency of Thoroughbred mares under Indian subtropical conditions: A retrospective survey over 7 years.

This research examines the reproductive efficiency of Thoroughbred mares in India’s northwestern subtropical region over seven consecutive years. The study found that mares aged between 3-7 years old had higher pregnancy and foaling rates, and lower detected pregnancy losses compared to mares aged 18 years or older. Also, mares that faced chronic barrenness and habitual abortions had a lower rate of reproductive efficiency. The study concluded that the lower fertility rates observed might be due to differences in breeding management rather than just the subtropical climate.

Methodology and Data Analysis

The study scrutinized the service records of 253 Thoroughbred mares over a span of seven years. These mares were from nine different organized stud farms located in northwestern India’s subtropical region. These records were used to assess their reproductive efficiency in terms of pregnancy rate per cycle, overall foaling rates, observed pregnancy losses, and the incidence of multiple pregnancies.

• Overall per cycle pregnancy rate: 50.30%
• Overall foaling rate: 68.95%
• Late embryonic losses: 9.86%
• Overall detected pregnancy losses: 19.11%
• Incidence of multiple pregnancies: 5.40%

Age and Reproductive Efficiency

Different age brackets of mares showed significantly varying reproductive rates. Mares aged between 3 to 7 years were more productive, displaying higher pregnancy and foaling rates, and fewer detected pregnancy losses. On the contrary, mares aged 18 years or older showed lower productivity.

Chronic Barrenness and Habitual Abortions

Chronic barren and habitual aborter mares exhibited lower reproductive efficiency. Half of mares that experienced two or more consecutive abortions or barren years continued to abort or remain barren in subsequent seasons. The number of matings per oestrus or the use of exogenous hormonal treatment to induce oestrus or ovulation seemed to have no significant effect on the fertility of the mares.

Multiple Pregnancies and Late Embryonic Losses

The study found that twin pregnancies had a significantly higher rate of late embryonic losses (21.98%) compared to singleton pregnancies (8.64%). The overall incidence of multiple pregnancies was recorded at 5.40%.

Conclusion

The researchers concluded that the relatively lower fertility rates of Thoroughbred mares bred under Indian subtropical conditions might be due to differences in breeding management rather than the environment alone. The comparison drawn against reports from temperate regions suggests that different climatic conditions may not necessarily impact the reproductive efficiency of Thoroughbred mares.