Reproductive performance of offspring from mares administered altrenogest during gestation

Summary

Thirty light-horses, two-year-olds (15 fillies, 15 colts) were evaluated for reproductive performance. The dams of these offspring had been administered either: 1) 2 ml of neobee oil per 44.5 kg body weight (controls)); or 2) 2 ml of altrenogest (2.2 mg/ml) orally per 44.5 kg body weight.. Treatments were administered daily from day 20 to 320. Interval to first ovulation with estrus and duration of estrus, diestrus and estrous cycle were similar (P>0.05) for treated and control fillies. In addition, pregnancy rate per cycle and after 3 cycles was not different (P>0.05) between groups. Age at puberty was similar (P>0.05) for treated and control stallions. In addition seminal characteristics of the last 9 ejaculates prior to castration as well as sexual behavior were not different (P>0.05) between groups. Testicular weight and size and spermatozoal production was not affected by treatment. Thus, treatment of mares with altrenogest during gestation had no affect on reproductive performance of either female or male offspring.