Influence of category-heifers, primiparous and multiparous lactating cows-in a large-scale resynchronization fixed-time artificial insemination program.
10.4142/jvs.2015.16.3.367
- Author:
Marcio de Oliveira MARQUES
1
;
Fabio MOROTTI
;
Camila Bizarro DA SILVA
;
Mario Ribeiro JUNIOR
;
Rubens Cesar Pinto DA SILVA
;
Pietro Sampaio BARUSELLI
;
Marcelo Marcondes SENEDA
Author Information
1. Geraembryo, Cornelio Procopio 86300-000, Brazil.
- Publication Type:Original Article
- Keywords:
Bos indicus;
conception rate;
fixed-time artificial insemination;
hormonal treatment;
resynchronization
- MeSH:
Animals;
Brazil;
Cattle;
Estradiol/*pharmacology;
Estrus Synchronization;
Female;
Fertilization/*drug effects;
Insemination, Artificial/*veterinary;
Lactation;
*Parity;
Pregnancy;
Pregnancy Rate;
Progesterone/*pharmacology
- From:Journal of Veterinary Science
2015;16(3):367-371
- CountryRepublic of Korea
- Language:English
-
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 demonstrated that ovulation resynchronization 30 days after FTAI is particularly effective for heifers, providing a conception rate of up to 66%.
