Effect of the collection method on semen characteristics of Zebu and European type cattle in the tropics.
The effect of the collection method on the characteristics of fresh semen and the recovery of spermatozoa after thawing was studied in 30 Zebu bulls (Bos indicus) and in 30 Brown Swiss (Bos taurus) bulls. Semen was collected by using an artificial vagina and by electroejaculation; the ejaculates were individually evaluated. Semen was diluted for freezing in skimmed milk and stored in 0.5-ml French straws, at a concentration of 30x10(6) spermatozoa. Data were evaluated by analysis of variance using a factorial model which included collection method, breed effect, and interaction between method and breed, with each bull as a block. Higher volume and pH of the semen was obtained following electroejaculation. Conversely, higher concentration prior to freezing and better progressive motility after thawing was observed in semen collected with an artificial vagina. No differences in motility were obtained in fresh semen between methods. Better post-thaw recovery occurred when the semen was collected by an artificial vagina, independently of the breed type.
León
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Departamento de Reproducción, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Apartado postal 22-256 México, D.F. 14000 Mexico.
Porras
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Galina
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CS
Navarro-Fierro
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