Inducción de celos con efecto macho, utilizando carneros vasecomizados asociados o no con ovejas en celo en ovejas Merino durante el anestro estacional: experiencias prácticas en Uruguay
Resumen
En el presente trabajo se plantean resultados prácticos de la utilización del efecto macho para inducir celos y ovulaciones durante el anestro estacional de ovejas Merino en un sistema extensivo. Durante 9 años (2013, 2014, 2015, 2017, 2019, 2020, 2021, 2022 y 2023) se indujo la ciclicidad en total a 15.300 ovejas durante el anestro estacional, mediante la introducción súbita de carneros vasectomizados, con ovejas con celo farmacológico hasta 2020, y sin las mismas a partir de 2021. En todos los casos se utilizó 4,5 % de machos, y hasta 2020 9% de ovejas en celo. A los 15 días se retiraron los animales estimuladores, introduciéndose otros carneros vasectomizados. En el último año, 2023, se utilizó una combinación de carneros vasectomizados con machos castrados tratados con testosterona en lugar de solamente carneros vasectomizados. Se controló el celo diariamente, y las ovejas fueron inseminadas con semen fresco. En total, 13.488 ovejas manifestaron celo (88,16%), con una variación de entre 69,18% y 97,75% de acuerdo al año, aunque en los años de menor incidencia el inicio del control de celos se retrasó, lo que probablemente implicó perder datos de ovejas en celo. Si bien no se identificaron las ovejas que parieron, la tasa de preñez estuvo siempre por encima del 60%. La distribución de los celos, si bien tuvo variaciones menores entre los años, en general correspondió a una distribución bimodal consistente con la respuesta al efecto macho. En conclusión, el uso de carneros vasectomizados tanto con cómo sin ovejas en celo permitió tener una alta incidencia de celos en ovejas Merino en anestro estacional.
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Derechos de autor 2024 Rodolfo Ungerfeld, Eduardo Lorenzelli
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