How Many Litters of Lambs Does a Small-Tailed Han Sheep Have Per Year? A Detailed Explanation of Ewe Reproductive Performance
Small-Tailed Han sheep can reproduce year-round and have extremely strong fertility, producing three litters in two years, and many produce two litters per year. According to statistics on 2101 births from 1964 to 1991, the Small-Tailed Han sheep is a prolific breed, with an average lambing rate of 281.9%, and a maximum of 9 lambs in a single litter.
Reproductive Performance Characteristics of Small-Tailed Han Sheep
① Within the first four parities, the lambing rate increases substantially as the number of parities increases.
② The triplet rate and quadruplet rate of the third and fourth parities are about twice those of the first and second parities, accounting for more than 40% of the number of lambing ewes.
Sexual Maturity Period of Small-Tailed Han Sheep
The average first estrus of Small-Tailed Han ewes is 186-255 days, and the sexual maturity period varies considerably, mainly because sexual maturity is affected by birth season, litter size, birth weight and growth and development. The body weight of a 6-month-old ewe is 60% of the body weight of a yearling ewe, but its uterus weighs more than 76% of that of a yearling. This shows that early maturity of the reproductive organs is an important germplasm characteristic of highly prolific breeds. Small-Tailed Han rams mature at 5 months of age. Young rams already have sexual desire and mounting behavior at 4 months of age, and show penile erection at 5 months of age. At 5 months of age, 85% mature sperm are found in the vas deferens of rams, and 100% mature sperm can be seen at 6 months of age. At this time, the sperm density in the raw semen is 3 billion/ml, basically reaching the standard for insemination. However, because body maturity is not yet complete at this stage, it is not suitable to participate in mating. An 8-month-old ram can be used for a small amount of mating, but feeding must be strengthened. Generally, a 1-year-old ram is best for mating, provided that its nutritional needs are met.
Estrus Period of Small-Tailed Han Sheep
Small-Tailed Han sheep come into estrus year-round, but most actively in spring and autumn. Their estrous cycle is 17.2±2.17 days, and the duration of estrus is 2.66±1.15 days, with the first estrus having the shortest duration. This is related to age and nutritional status. Adult ewes in good nutritional condition have a short estrous cycle, and the number of days from lambing to estrus is 71.88±23.78 days, longest for the first parity and shortest for the fourth parity.
Gestation Period of Small-Tailed Han Sheep
The gestation period of Small-Tailed Han sheep is 148.6±1.93 days. There is little difference in gestation period among different parities, and very little difference among different lambing types. Certain differences appear due to differences in age and nutritional status, but the differences are not significant.
Non-Seasonal Breeding Characteristics of Small-Tailed Han Sheep
Non-seasonal breeding is a notable characteristic of Small-Tailed Han sheep. According to statistics on 170 ewes, 45 ewes lambed from January to March, accounting for 26.47%; 61 ewes lambed from April to June, accounting for 35.58%; 23 ewes lambed from July to September, accounting for 13.53%; and 41 ewes lambed from October to December, accounting for 24.12%.