The effect of the absence or presence of a corpus luteum on the ovarian follicular population and serum oestradiol concentrations during the estrous cycle in Sanjabi ewes |
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| Affiliation: | 1. Department of Animal Science, Faculty of Agriculture, Razi University, Kermanshah, Iran;2. Department of Animal Science, Faculty of Agriculture, Yasouj University, Yasouj, Iran;3. Department of Agronomy & Plant Breeding, Faculty of Agriculture, Razi University, Kermanshah, Iran;1. Faculdade de Veterinária, Universidade Federal Fluminense, Rua Vital Brazil, 64, Niterói, Rio de Janeiro 24320-340, Brazil;2. Embrapa Gado de Leite, Rua Eugênio do Nascimento, 610, Juiz de Fora, Minas Gerais 36038-330, Brazil;3. Fundacion IRAUy, Cno. Cruz del Sur 2250, Montevideo 12200, Uruguay;4. Embrapa Caprinos e Ovinos, Estrada Sobral/Groaíras, km 04, CP 145, Sobral, Ceará 62010-970, Brazil;1. Department of Clinical Sciences, School of Veterinary Medicine, Shiraz University, Shiraz, Iran;2. Department of Animal Health Management, School of Veterinary Medicine, Shiraz University, Shiraz, Iran;3. Animal Science Research Department, Fars Agricultural and Natural Resources Research and Education Center, Agricultural Research, Education and Extension Organization (AREEO), Shiraz, Iran;4. Department of Biochemistry, School of Veterinary Medicine, Shiraz University, Shiraz, Iran;1. Department of Animal Production, Faculty of Agriculture, Alexandria University, Alexandria 21545, Egypt;2. Department of Arid Land Agriculture, Faculty of Meteorology, Environment and Arid Land Agriculture, King Abdulaziz University, Jeddah, Saudi Arabia;1. Department of Physiology and Radiobiology, Faculty of Veterinary Medicine, University of Zagreb, 10 000 Zagreb, Croatia;2. Veterinary Practice Varaždin, 42000 Varaždin, Croatia;3. Department of Animal Nutrition and Dietetics, Faculty of Veterinary Medicine, University of Zagreb, 10 000 Zagreb, Croatia;4. Clinic for Reproduction and Obstetrics, Faculty of Veterinary Medicine, University of Zagreb, 10 000 Zagreb, Croatia;5. Department of Pharmacology and Toxicology, Faculty of Veterinary Medicine, University of Zagreb, 10 000 Zagreb, Croatia;6. Veterinary Practice Đurđevac, Malinov trg 7, 48350 Đurđevac, Croatia;7. Department of Veterinary Biology, Faculty of Veterinary Medicine, University of Zagreb, 10 000 Zagreb, Croatia;1. Department of Large Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, USA;2. Departamento de Ciencias Biológicas, Centro Universitario de los Altos, Universidad de Guadalajara, Tepatitlán, Jalisco, México;3. Animal Science Department, College of Agriculture and Life Sciences, Texas A&M University, College Station, Texas, USA |
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| Abstract: | The aim of this study was to determine if the presence or absence of a corpus luteum (CL) during estrous synchronization in ewes can affect the ovarian follicular population and the serum oestradiol concentrations. The estrous cycles of 197 Sanjabi ewes were synchronized using a 12-day treatment with intravaginal progestagen sponges (Chronogest®). Estrus was detected in 144 ewes, 27–39 h after sponge removal. Blood samples were taken daily from day 2 and continued for 19 days and analyzed for serum oestradiol concentration. Nine ewes were slaughtered on each experimental day (days 1–16 after estrus) for ovary collection. The ovaries per ewe were classified as those without, or with one or two CL's, for each slaughter day. Visible follicles on the surface of the ovaries were classified, based on their diameter, into (i) very small (<2 mm), (ii) small (2–3.4 mm), (iii) medium (3.5–5 mm) and (iv) large (>5 mm) categories, and the respective numbers recorded. Results indicated, the number of ovarian follicles to decrease (P < 0.01) from days 1 to 5 of the cycle and showed a significant increase on day 7. Numbers were high again on day 11 and decreased (P < 0.01) on day 16 of the estrous cycle. The serum oestradiol concentrations were significantly higher (P < 0.001) in the double than in the single ovulating animals (one or two CL's, respectively) on days 2–0. However serum levels were also significantly higher (P < 0.001) in single, than twin ovulating animals on days 4–5 and 12–16 of the estrous cycle. There were no significant differences in the total number of very small follicles between animals without and those with two CL's. The number of small, medium and large follicles in ewes, with or without a CL on the ovary was significantly higher (P < 0.01) than ewes with two ovulations at certain stages of the estrous cycle. The present study provides evidence of differences in the follicular ovarian population in ovaries without CL's and double ovulations. The existence of an intraovarian effect of the CL numbers on follicular population is demonstrated. |
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