Reproductive performance of Thoroughbred mares on six commercial stud farms [horses; Australia]

Bruck, I. . Dept. of Reproduction; Anderson, G.A.; Hyland, J.H. . Dept. of Veterinary Science

Reproductive performance of Thoroughbred mares on six commercial stud farms [horses; Australia]

1993

Bruck, I. (Royal Veterinary and Agricultural Univ., Frederiksberg (Denmark). Dept. of Reproduction) | Anderson, G.A. | Hyland, J.H. (Melbourne Univ., Werribee (Australia). Dept. of Veterinary Science)

The records of 1630 mare years from 6 Thoroughbred stud farms in south eastern Australia were analysed for the years 1981 to 1986. Overall pregnancy and foaling rates were 83.9 percent and 69.3 percent, respectively. When calculated per served oestrous cycle, pregnancy and foaling rates were 54.7 percent and 43.1 percent, respectively. Pregnancy and foaling rates were higher for mares 3 to 10 years of age than for older mares. There was no difference in the pregnancy rates of maiden, barren and foaling mares. The foaling rate was significantly higher in mares that became pregnant during the first served oestrous cycle than in mares that needed 2 served oestrous cycles to become pregnant (65.4 percent). Of all diagnosed pregnancies, 19.5 percent were not completed. Pregnancy loss was lower in maiden (12.4 percent) than in barren (19.7 percent) or foaling (20.9 percent) mares. Twins were diagnosed in 7.8 percent of all pregnancies. If one conceptus was lost without external interference, 84.1 percent of pregnancies went to term. If one conceptus was manually crushed, 55.9 percent of pregnancies were maintained. If prostaglandin was used to terminate twin pregnancies, 60 percent of mares so treated produced foals the following year.

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