Comparison of two methods of progesterone application in a fixed time artificial insemination protocol in beef cows

  • Alfredo Irazábal Facultad deVeterinaria, Udelar,
  • Raquel Pérez Clariget Facultad de Agronomía
  • Carmen de Olarte Facultad de Veterinaria, Udelar
  • Guillermo de Nava Ejercicio liberal Salto y Flores
  • Daniel Cavestany Facultad de Veterinaria, Udelar


Two experiments were conducted at two commercial farms to compare pregnancy rates of nulliparous (n = 178) and primiparous (n = 130; Farm 1), and multiparous (n = 161; Farm 2) Aberdeen Angus cows, when 200 mg s-c of injectable oil-based progesterone (MAD-4) or a 558 mg progesterone releasing intravaginal device (DIV) were used in a fixed time artificial insemination protocol based on estradiol benzoate (EB), prostaglandin (PG), equine chorionic gonadotropin (eCG) and gonadotropin-releasing hormone (GnRH). Primiparous and multiparous cows were weaned 30 d before treatment (60–90 d postpartum). The ovarian status was determined by rectal palpation and the animals classified as cycling or in superficial anoestrus or deep anoestrus. The P4 source affected (P<0.0001) the pregnancy rate of primiparous and multiparous cows, but not that of nulliparous cows (Farm 1: Nulliparous: 51% and 42%; Primiparous: 42% and 10%, DIV and MAD-4, respectively, with a treatment x category interaction (P = 0.0056). Farm 2: DIV: 51% vs. MAD4: 9%, P=0.0001). Independently of the hormonal treatment, the ovarian status influenced pregnancy rates (P<0.0001), cycling cows showed the highest value and cows in deep anoestrus the lowest. No significant treatment x ovarian status interaction was found. It is concluded that replacing the DIV by MAD-4 decreased pregnancy rate of primiparous and multiparous cows, but not that of nulliparous ones.


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Author Biographies

Alfredo Irazábal, Facultad deVeterinaria, Udelar,
Estudiante de posgrado
Raquel Pérez Clariget, Facultad de Agronomía

Prof. Titular Departamento de Producción Animal y Pasturas Facultad de Agronomía, Udelar, Uruguay

Daniel Cavestany, Facultad de Veterinaria, Udelar
Prof titular Departamento de Reproducción Facultad de Veterinaria, Udelar, Uruguay
How to Cite
Irazábal, Alfredo, Raquel Pérez Clariget, Carmen de Olarte, Guillermo de Nava, and Daniel Cavestany. 2014. “Comparison of Two Methods of Progesterone Application in a Fixed Time Artificial Insemination Protocol in Beef Cows”. Latin American Archives of Animal Production 22 (3-4).
Original paper