Synchronization of estrus with short- and long-term progestagen treatments and the use of GnRH prior to short-term progestagen treatment in ewes |
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| Institution: | 1. Department of Reproduction and Artificial Insemination, Faculty of Veterinary Medicine, Mustafa Kemal University, 31040 Hatay, Turkey;2. Department of Reproduction and Artificial Insemination, Faculty of Veterinary Medicine, Selcuk University, 42075 Konya, Turkey;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 Pathology and Veterinary Clinic, Veterinary School, Fluminense Federal University, Niteroi, RJ 24320-340, Brazil;2. Brazilian Agricultural Research Corporation on Goats and Sheep, Coronel Pacheco, MG 36155-000, Brazil;3. Department of Animal Science, Veterinary School, Fluminense Federal University, Niteroi, RJ 24320-340, Brazil;1. Departamento de Biociencias Veterinarias, Facultad de Veterinaria, Universidad de la República, Lasplaces 1620, Montevideo, 11600, Uruguay;2. Departamento de Medicina Veterinária Preventiva e Reprodução Animal, Faculdade de Ciências Agrárias e Veterinárias, Univ. Estadual Paulista “Júlio de Mesquita Filho”, 14884-900, Jaboticabal, São Paulo, Brazil;3. Departamento de Producción Animal y Pasturas, Facultad de Agronomía, Universidad de la República, Garzón 780, 12400, Montevideo, Uruguay;1. Facultad de Ciencias Veterinarias UNCPBA, Tandil, Argentina;2. Facultad de Ciencias Veterinarias UNLP, La Plata, Argentina;3. Laboratorio SYNTEX, Argentina;1. Departament of Animal Science, Agricultural Research Agency of Sardinia, S.S. Sassari-Fertilia Km., 18, 600 Località Bonassai, 07100 Sassari, Italy;2. International Center for Agricultural Research in the Dry Areas (ICARDA), P.O. Box, 950764 Amman 11195, Jordan;3. Departament of Animal Production and Technologies, Nigde Ömer Halisdemir University, 51240 Ni?de, Turkey |
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| Abstract: | The objective of the present study was to determine the efficacy of the synchronization of estrus using short- and long-term progestagen treatments in ewes at the onset of the breeding season, and to evaluate the effect of the exogenous GnRH administration immediately prior to short-term progestagen treatment on the reproductive performance. A total of 240 Tahirova cross-bred ewes, aged 18–24 months, and 40 rams, aged 2–4 years-old, were used in the trial. Ewes were divided equally into 3 groups (n = 80 per group). Intravaginal progestagen sponges containing FGA (30 mg) were inserted in the ewes for 7 d in the FGA1 (short-term) and GnRH treatment groups, and for 12 d in the FGA2 group (long-term). The ewes in the GnRH group received 10.5 μg busereline acetate i.m. at the time of sponge insertion. Tiaprost tromethamol (PGF2α; 0.294 mg) and eCG (400 IU) were injected i.m. on the 6th day of progestagen treatment in the GnRH and FGA1 groups, and on the 11th day in the FGA2 group following sponge insertion. All ewes were hand-mated once at the detection of estrus. The estrous response, fertility rate, multiple birth rate and litter size recorded was 88.7, 87.3, 51.6% and 1.6 in the FGA1 group, 92.5, 71.6, 50.9% and 1.5 in the FGA2 group, and 96.2, 89.6, 71.0% and 1.8 in the GnRH group, respectively. No significant difference in estrous response between the groups was recorded, but the fertility rate in the FGA1 and GnRH groups was significantly (P < 0.05) higher than in the FGA2 group. The occurrence of multiple births and litter sizes were significantly (P < 0.05) higher in the GnRH group, compared to both the FGA1 and FGA2 groups, with the number of single lambs being significantly (P < 0.05) higher in the FGA1 (48.4%) and FGA2 (49.0%) groups than in the GnRH (29.0%) group. However, the differences recorded between any of the groups in terms of the number of twin and triplet lambs were insignificant. In conclusion, it can be said that estrous synchronization using the 12-d-FGA-eCG-PGF2α regimen could be replaced with the 7-d-FGA-eCG-PGF2α regime in sheep at the onset of the breeding season. However, the combination of GnRH with the latter regimen (7-d-GnRH-FGA-eCG-PGF2α) increased the multiple birth rate and litter size in the ewes. |
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