Relevance of ovarian follicular development to the seasonal impairment of fertility in weaned sows |
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Authors: | Tania P. Lopes Jonatan Sanchez-Osorio Alfonso Bolarin Emilio A. Martinez Jordi Roca |
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Affiliation: | 1. Department of Veterinary Medicine, Federal University of Lavras, Lavras, Minas Gerais, Brazil;2. Department of Animal Science, Federal University of Lavras, Lavras, Minas Gerais, Brazil;3. Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil;1. Department of Animal Medicine and Surgery, University of Murcia, Murcia, Spain;2. Department of Research and Development Selección Batallé S.A., Girona, Spain;1. ReproPel, Campus Capão do Leão, Universidade Federal de Pelotas, 96010-900, Pelotas-RS, Brazil;2. Faculdade de Veterinária, Campus Capão do Leão, Universidade Federal de Pelotas, 96010-900, Pelotas-RS, Brazil;3. Instituto de Biologia, Campus Capão do Leão, Universidade Federal de Pelotas, 96010-900, Pelotas-RS, Brazil;4. Escola de Veterinária, Universidade Federal de Goiás, 74001-970, Goiânia-GO, Brazil |
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Abstract: | A field study was conducted to estimate seasonal differences in follicular development in weaned sows and to evaluate the implication of these differences on seasonal infertility. A total of 110 sows were selected at weaning during winter–spring (WS, n = 58) and summer–autumn (SA, n = 52). Ovaries were scanned once daily from weaning to the onset of oestrus and twice daily from then until ovulation. Six sows during WS were removed from study for not showing growing follicles at weaning. Oestrus was evaluated twice daily from day 1 after weaning to day 14 post-weaning. One of 52 (1.9%) sows in WS and 9/52 (17.3%) in SA showed no signs of oestrus within 14 days of weaning (P < 0.05). The diameters of the follicles at weaning, at the onset of oestrus and just before ovulation were smaller (P < 0.01) in SA sows than in WS sows. There were fewer follicles in SA sows than in WS sows just before ovulation (P < 0.05). Fifty of 51 (98.0%) sows in WS and 31/43 (72.1%) sows in SA experienced a weaning-to-oestrus interval (WOI) of 3–6 days (P < 0.05). Fifty-one of 52 (98.1%) sows in WS and 43/52 (82.7%) sows in SA were inseminated; the percentage of pregnant sows that failed to farrow was lower in WS (1/51, 2.0%) than in SA (5/43, 11.6%; P < 0.05). The percentage of farrowed sows was greater in WS (46/51, 90.2%) than in SA (32/43, 74.4%; P < 0.05). Sows in WS had on average 1.5 more piglets than sows in SA (P < 0.05). Sows with a WOI of 3–6 days had lower rates of pregnancy losses (P < 0.05) and higher farrowing percentages (P < 0.01) than those with a WOI > 6 days, irrespective of season. |
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Keywords: | Pig Weaning Ultrasonography Ovarian follicles Seasonality |
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