Fecundity in fat-tailed sheep at two different altitudes in East Java.

Ovulation rates, embryonic mortality and litter sizes at birth were studied in East Java fat-tailed sheep at two different altitudes: Pujon, 1,300 m above sea level and Malang, 500 m above sea level, over a period of one year. In both areas the number of ewes lambing each month was approximately the same. The average litter size at birth in Pujon and Malang was 2.37 and 1.60, respectively. Litters of three or more were almost exclusively found in November, December, January and February and in Pujon only. The relatively low ambient temperatures in Pujon in the period June to October may have influenced ovulation and embryonic survival rates positively. Abattoir data showed that ovulation rates of ewes with three or more foetuses alive 45 to 60 days after mating were much higher than in ewes with one or two foetuses alive. Embryonic mortality was very high in ewes with one live foetus.