[The effect of the age of stallions and mares on their fertility].

This research explores the impact of the age of stallions and mares on their fertility, using data from the Napajedla Stud Farm of the English Thoroughbred horse spanning from 1888 to 1972. The findings present mixed results without any evident pattern linking parental aging and reduction in fertility.

Study Design and Data

• The research utilized historical data from the Napajedla Stud Farm of the English Thoroughbred horse, covering a period of 84 years, from 1888 to 1972.
• The primary focus was to evaluate the effect of the age of stallions and mares on their fertility, separate from the age of their offspring.

Analysis Method

• A total of 26 studs were evaluated to ascertain the effects of the stallions’ age on fertility.
• A statistical method involving different modifications of the chi2 value was used to evaluate the relationship between the age of the stallion and the mare on fertility.
• The prerequisites for the analyses were the calculation of the global chi2 used jointly for evaluating the variable age of stallions and mares.

Findings

• The research found a significant effect of the age of stallions on their fertility in just four out of the 26 studs evaluated. This signifies that the impact of age was not significant in the majority of the studs.
• The correlation coefficients were found to be negative in 65% of the selected stallions, meaning an inverse relationship between age and fertility, but without statistical significance, thereby lacking reliability.
• The results varied widely between individual stallions without providing a clear basis for generalizing a fertility-decreasing tendency with the higher age of the parents.

Considerations and Implications

• The research analyzed the issue from a physiological viewpoint, although the abstract does not elaborate on these specific physiological factors or implications. It could include aspects like changes in health, vigor, or reproductive capacity with age.
• The lack of definitive results suggests that factors other than just age could be influencing fertility rates in horses. This opens avenues for further investigation into horse fertility.