Twinning in mares: A survey of veterinarians and analyses of theriogenology records.

The research article is an investigation into the occurrence of twinning in horses, with an emphasis on influencing factors such as mare type, breeding practices, and genetics. The study utilizes responses from 22 veterinarians and records from three breeding farms.

Methodology and Data Collection

• The research was conducted using a dual approach of collecting data from direct responses of 22 veterinarians through a questionnaire and analysis of records from three broodmare farms.
• The veterinary questionnaire solicited information and opinions regarding twinning in mares, while the farm records provided factual data on occurrences.
• This approach aimed to provide a broad perspective on the issue of twinning, from generic professional opinion to specific empirical data from farms.

Findings and Inferences

• The study found varying multiple ovulation rates among the three farms. Ovulation rates were recorded as 9%, 11% and 22%, indicating that farm-specific practices may influence these rates.
• The data showed that multiple ovulation rates reduced by between 42-67% in mares that had recently given birth compared to maiden and barren mares. This suggests that the physiological state of the mare impacts multiple ovulations.
• Interestingly, the breed of horse seemed to have an influence with Thoroughbreds showing a higher frequency of multiple ovulations (19%) in comparison to Quarter Horses (9%) and Appaloosas (8%).
• Both the questionnaire and farm records pointed towards a high degree of repeatability of multiple ovulations and twin pregnancies within the same mares and within certain familial lines. This evidence points towards some genetic influences.

Breeding Strategies

• Records showed that on two of the farms, breeding was delayed until after the first ovulation when multiple follicles were present. This practice could be aimed at managing or reducing instances of twin pregnancies.
• Findings showed no significant differences in overall reproductive efficiency – including pregnancy and foaling rates – among the three farms. This suggests that the presence of twin pregnancies has no profound effect on these rates.
• The incidence of observed twin abortions or births was low across all thrее farms, thus indicating that twin pregnancies rarely result in viable twin births.