عنوان مقاله [English]
Introduction Identifying the appropriate foreign and indigenous breeds to improve reproductive performance is an essential requirement for self-sufficiency of sheep products.
Reproduction in ruminants is influenced by several factors such as genetics and genetic potential, stage and type of nutrition, factors Environment, day length, animal health and so on. Use of estrus synchronization or ovulation programs The number of estrus animals increases in a short period of time. In the common method, ie observation of estrus and insemination, percentage Fertility is 50%. In the case of synchronization in the new method, the fertility rate is reduced to 32%
Finds. However, in the new method, the total number of pregnancies in the herd increases per year. To further increase the total percentage Herd pregnancy, different methods or changes in methods are used. Estrus synchronization to the farm manager is possible Provides livestock care and insemination as a work plan commensurate with other planning activities required And the time-consuming work of estrus detection is reduced and the reproductive season can be shortened. The benefits of a concurrency system Artificial insemination increases when the rate of estrus detection and pregnancy rate is low. The purpose of this study was to investigate the effects of using CIDR and PMSG as an appropriate method of concomitant with artificial insemination of imported ewes and comparing them with native Iranian ewes on reproductive performance.
Materials and methods 180 ewes with Similar average weighted were divided into 6 groups of 30 rats based on internal and external breeds including: 1- Romanov group 2- Sharouleh group 3- Suffolk 4- Baluchi 5- Mogani group 6- Afshari were selected. Estral synchronization was performed in spring with CIDR. Ewes after CIDR (14 day) extraction and PMSG injection as soon as observed estrus symptoms and Artificial insemination were using the method Transcervical with fresh sperm. The Small Ruminant Nutrition System (SRNS) nutrition program (version 1.8) was adjusted based on the pregnancy diet (Tables 1 and 2). All diets contained equal concentrations of dry matter, metabolizable energy and crude protein. Diets were given to the sheep for 60 days (30 days before and 30 days after shearing) freely and at an appetite level (in two meals at eight in the morning and four in the afternoon). Ultrasonography test with an ultrasonograph (ECM model, made in France) equipped with an 8 MHz bovine probe to check the number of graph follicles (follicles larger than 4 mm), simultaneously with cider removal and estrus, check the number of corpus luteum 10 days later Sider removal was performed 34 days after insemination to diagnose pregnancy. The estrus time of each ewe was determined by viewing the images stored through the CCTV camera at the location of each spring.
Ovulation rate (number of ewes with corpus luteum on number of ewes prone to mating) and pregnancy rate (number of ewes to number of ewes prone to mating) were calculated. Postpartum reproductive parameters such as infertility rate (lambs born to ewe ewes) and twinning (number of twin ewes born to ewes) and stillbirth (dead lambs born to ewe ewes). ) Was calculated.
Results and discussion There were no difference between the experimental groups in terms of estrus symptoms. Results showed that Ovarian ultrasound at day 10 postoperatively showed that the number of lutein in foreign races was higher than other races and significant statistical differences were observed (p < 0.05). Results Ovulation rate, Pregnancy rate, stillbirth rate, was significant difference in fertility rate and twinning rates between the groups (P <0.05). The highest ovulation rate (100%), Pregnancy rate (100%), The fertility rate (160%) and Twinning rates (66%) belonged to the Romanov group and statistical differences were observed (p < 0.05).
Conclusion In general, due to the low productivity of Iranian breeds compared to foreign breeds, it can be suggested that foreign sheep be used to improve breeding efficiency of Iranian sheep for breeding. The use of some new technologies such as estrous cycle control and the use of hormones was effective in this study and increased the average production of lambs per ewe mixed in the herd. The significant difference between Romanov ewes in pregnancy rate, lambing rate and twinning with other breeds indicates the high genetic capacity of this breed of sheep in the success of reproductive performance. The results of this study showed that the use of imported animals such as Romanov that have the highest ovulation rate (100%), pregnancy rate (100%), fertilization rate (160%) and twinning rate (66%) Can be used to breed native Iranian livestock that increase the reproductive efficiency of Iranian sheep.