| The fox belongs to Mammalia, Carnivora, a canine animal. Foxes are mainly distributed in the cold northern areas of China, such as Hebei province, Shandong province, Inner Mongolia, northeast of China, and so on. Silver fox, which is also called silver- black fox,is a fur animal whose fur is black and white, and there is a layer of mist- shaped guard hair, which becomes one of the main rare species for people to breed for the fur. There are a number of fox farming enterprises in the north of Anhui province. Natural breeding is generally used in these enterprises, but foxes, estrus is short, only about two month a year, in addition to its low reproductive rate, only 2-3 babies at a birth. Natural reproduction can’t meet the demands of high-speed expansion of reproduction. With the development of technology of artificial insemination, insemination technology becomes more mature. Although the rate of reproduction has been greatly improved, the products are still much lower than that of other fur animals. What’s more, there are many difficulties in tocolysis. How to improve the reproduction rate of fox concerns many researchers. In the breeding industry, demand for female fox is often less than need, so to improve the yield of the female fox is the key for the breeding factory to expand production. Gender segregation before artificial insemination will greatly save time and resources, which will improve the efficiency of the gender control, identification and embryo transfer.The research object in this paper is the silver fox in northern Anhui province. By studying the influence of season on silver fox spermatogenesis, the semen quality, preserving effect at room temperature and X sperm screening and so on, we try to improve the reproduction rate of the fox. Eventually through animal experiments, the gender determination technology will be applied in the silver fox farming industry to lay the foundation for the artificial breeding fertilization rate and meet the need to expand the fox aquaculture industry. The following main aspects were concluded after studying:1. The effect of season on spermatogenesis of the silver fox in the Northern Anhui province is analyzed to find that spermatogenesis showed typical seasonal pattern, which determines the best time of semen collection. Silver fox testicles were taken for the study, measuring testicular volume, weight and other basic parameters in September, November and January of the next year. Testosterone in the testes content is measured by enzyme-linked. Technical analysis was taken by using tissue slice seminiferous tubules in all kinds of raw composition and proportion of sperm cells. Results:In September, November, January of the next year, testicles weight of the silver fox were 0.896 ± 0.002 g,3.365 ± 0.081 g and 5.241 ± 0.100 g, and the volume was 1.215 ± 0.036cm3,5.558 ± 0.794 cm3 and 14.112 ± 2.8543 cm3 and the content of testosterone was 1.215 ±0.036 μg,5.558±0.794 μg, and 14.112±2.8543μg. The results show that testicular volume, weight and testosterone concentrations in different months are with significant difference (P<0.05). The content of testosterone and the weight change are of the positive correlation(correlation coefficient=0.991). In different seasons, the composition and number of the spermatogenic cell in seminiferous tubules changes with the seasons, with the significant difference (P <0.05).Based on the analysis of the semen of the silver fox in the north of Anhui province, a safe, efficient and economical sperm dilution for silver fox was developed which extended the survival time of sperm in vitro, improved the pregnancy rate in artificial insemination and the number of babies every single birth. The results show that the ejaculate volume is 0.5-1.5 ml once, and the sperm density is about 500 million per milliliter. Capacity of sperm in the female fox uterus is about 0.5 ml. Experiments prove that pregnancy rate and the number of pregnancy will not be affected if sperm is diluted about 5 times. However, the dilution quality will directly affect sperm motility and viability, thereby affecting the reproduction rate of the silver fox. An optimal dilution of silver fox sperm was developed in our experiment to store the sperm at room temperature. Based on semen dilution components of other animal such as mink, humans, etc., three liquid dilutions for sperm storage were developed, then the storage effect was observed at the cellular level to obtain the optimal method:2.100ml diluent is made up of Tris 2.13 g, citric acid 1.24 g, D fructose 0.71g, double distilled water 80 ml, egg yolk 10 ml, Ham’s F-10 10ml and penicillin 70,000 IU, after well mixing. In experimental group,15 female foxes with the semen diluents give birth to 6.5 ±1.5 babies on average. The control group used other diluents only gives 4.5 ± 1.5 babies. The result shows that with this semen diluents, silver fox can produce more offspring.3. An optimal X sperm separation technology was established to improve the proportion of female, which provide evidences for improving the reproduction rate of the fox. Taking the silver fox as the research object, the method of gradient centrifugation sediment was used to separate X sperm, and then appraise the ratio of the X sperm, finally using the artificial insemination to make fox be pregnant. The number of new born fox and gender ratio were compared with the traditional method of artificial insemination. Using X sperm isolated from the gender determination technology,10 female foxes after artificial insemination gave birth to 72 babies, among which 61 are female, accounting for 84.7%, while in the control group, female only accounts for 51.6%. |
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