[Length of gestation of Freiberger mares with mule and horse foals]

In a retrospective study the gestation lengths of two groups, each consisting of 193 "Freiberger" mares, were compared. The mares of the first group were bred by a donkey, those of the second group by a stallion of the "Freiberger" breed. On average, the gestation length of mares with "Freiberger" foals lasted 336.5 days, and that of mares with mule foals 343.1 days. The difference between both groups was significant (p < 0.001). The shortest and longest observed gestation length of mares with "Freiberger" foals was 307 and 361 days, and that of mares with mule foals 315 and 369 days, respectively. Additionally, we examined if the stallion, the mare, the age of the mare, the sex of the foal and the time of mating during the breeding season influenced gestation length of mares with mule foals and if the age of the mare, the sex of the foal and the time of breeding influenced gestation length of mares with "Freiberger" foals. The time of breeding and the mare had a significant (p < 0.05) influence on gestation length.