Influence of category-heifers, primiparous and multiparous lactating cows-in a large-scale resynchronization fixed-time artificial insemination program
Journal of Veterinary Science
;
: 367-371, 2015.
Article
in English
| WPRIM
| ID: wpr-66448
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%.
Full text:
Available
Index:
WPRIM (Western Pacific)
Main subject:
Parity
/
Progesterone
/
Brazil
/
Lactation
/
Insemination, Artificial
/
Pregnancy Rate
/
Estradiol
/
Estrus Synchronization
/
Fertilization
Limits:
Animals
/
Pregnancy
Country/Region as subject:
South America
/
Brazil
Language:
English
Journal:
Journal of Veterinary Science
Year:
2015
Type:
Article
Similar
MEDLINE
...
LILACS
LIS