Growth and development characteristics 1. Developmental characteristics of weight The weight of the adult ram of the Small Tail Han sheep was 80.50 kg, and that of the adult ewes was 57.30 kg. Male and female ewes had poor body consistency after 5 and 18 months of age, respectively: their gender differences began to increase significantly from the age of the first year, which may be less than the retained male rams, and they can be well-cultivated in the early stages. The age of the sheep is related to factors such as pregnancy and childbirth. The weight of ewes is basically steadily increasing from 1 month of age to adulthood, with the largest monthly increase occurring at the ages of 2, 3 and 10 months, which are 5.8 kg/month, 5.4 kg/month and 4.5 kg/month respectively; Rams The monthly increase in body weight is larger and occurs more often at 2, 3, 6, 9 and 11 months of age, indicating that the ewes are precocious than the rams. 2. Body development characteristics Adult ram height is 90.33 centimeters, body length is 94.33 centimeters, bust 110.33 centimeters, tube circumference 10.50 centimeters; adult ewes height is 80.00 centimeters, body length is 82.96 centimeters, bust is 100.35 centimeters, tube circumference It is 9.04 cm. Compared with body weight, the increase in body size was more uniform and the gender difference was not significant, but the body consistency of ewe's body scales was significantly better than that of rams. Reproductive characteristics 1. Sexual maturity Small Tail Han sheep average ew eeast 186-255 days, sexual maturity difference is greater, mainly due to sexual maturity by the birth season, fetal birth weight, birth weight and growth and development. 6-month-old ewes weigh 60% of their body weight, but their uterus weighs more than 76% of their uterus weight. It can be seen that the early maturing of reproductive organs is an important germplasm characteristic of high fertility varieties. Small Tail Han sheep matured to 5 months of age. The male ram had libido at 4 months of age, had crawling behavior, and had a penis evoked phenomenon at the age of 5 months. The ram found 85% of the mature spermatozoa in the 5-month-old vas deferens, and 100% of the mature spermatozoa were found at 6 months of age. At this time, sperm density in the original sperm was 3 billion/ml, basically reaching the insemination standard. However, maturation of the stage body has not yet been completed, so it is not appropriate to participate in breeding. Eight-month-old rams can be used for breeding in small quantities, but they must be strengthened. The average 1-year-old ram is best to participate in breeding if nutrition needs are met. 2. The estrus of small-tailed Han sheep is perennially estrus, but it is most prosperous in the spring and autumn. Its estrus cycle is 17.22.17 days, and the duration of estrus is 2.661.15 days. The initial duration of estrus is the shortest. This is related to age and nutritional status. Well-fed adult ewes have short estrus cycles and postpartum estrus days are 71.8823.78 days, with the longest first child and the shortest fourth child. 3. The gestation period of gestation period is 148.61.93 days. The difference in gestation between different parity periods is not significant. The difference between different litter types is small. Due to differences in age and nutritional status, the differences were not significant. 4. Non-seasonal breeding Non-seasonal breeding is a significant feature of Small Tail Han sheep. According to statistical data on 170 ewes, 45 ewes were bred from January to March, accounting for 26.47%; 61 were ewes from April to June, accounting for 35.58%; and ewes were bred from July to September. 23 Only accounted for 13.53%; from October to December, 41 ewes were delivered, accounting for 24.12%. 5. The multiple-nest Small Tail Han sheep can breed all year round, with strong fertility, three-year production in two years, and many production in one year. According to the statistical data of 2101 production times from 1964 to 1991, the Small Tail Han sheep is a multi-ravine species with an average lambing rate of 281.9%. A maximum of one child can produce 9 lambs. Its reproductive performance has two notable features. First, within the first four births, the lambing rate increases significantly with the increase of parity; second, the third and fourth parity rates are approximately the same. One and two times the second parity, accounting for more than 40% of the number of ewes. China Agricultural Network Editor