PMID: 25797292Mar 24, 2015Paper

Influence of category--heifers, primiparous and multiparous lactating cows--in a large-scale resynchronization fixed-time artificial insemination program

Journal of Veterinary Science
Márcio de Oliveira MarquesMarcelo M Seneda

Abstract

This study was conducted to evaluate the influence of category (heifers, primiparous or multiparous cows) on pregnancy rates in a large scale resynchronization ovulation program. Nelore heifers (n = 903), primiparous lactating cows (n = 338) and multiparous lactating cows (n = 1,223) were synchronized using a conventional protocol of estradiol/P4-based fixed-time artificial insemination (FTAI). Thirty days after ultrasonography, females who failed the first FTAI were resynchronized with the same hormonal protocol prior to a second FTAI. The pregnancy status of each cohort was evaluated by ultrasonography 30 days after each FTAI. The average conception rate after the first FTAI and resynchronization was 80.5%. Heifers had a higher conception rate (85%) than primiparous (76%) or multiparous cows (78%; p = 0.0001). The conception rate after the first FTAI was similar among heifers (57%), primiparous cows (51%) and multiparous cows (56%; p = 0.193). After the second FTAI, heifers exhibited a higher conception rate (66%) than primiparous or multiparous cows (51%; p = 0.0001). These results demonstrate the feasibility of resynchronization in large beef herds for providing consistent pregnancy rates in a short period of time. We also ...Continue Reading

References

Sep 16, 2000·Theriogenology·Y Yavas, J S Walton
Dec 10, 2003·Theriogenology·Scott McDougall, Scott H Loeffler
Jul 26, 2005·Theriogenology·M G ColazoR J Mapletoft
Jun 19, 2007·Animal Reproduction Science·F P PereaUNKNOWN Miembros del Grupo de Investigadores de la Reproducción Animal en la Región Zuliana (GIRARZ)

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Citations

Mar 21, 2018·Animal : an International Journal of Animal Bioscience·P S BaruselliG A Bó
Jan 24, 2021·Animal Reproduction Science·Luiz Fellipe Monteiro CoutoWelber Daniel Zanetti Lopes

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