Use of eCG in progestogen based estrus sinchronization programs for hair ewes

Resumen

Objective: To determine the importance of eCG use in the reproductive management of hair ewes subjected to progestagen based synchronization protocols.
Design/methodology/approach: A total of 120 hair ewes (Blackbelly and Pelibuey) in the peak reproductive season were synchronized using intravaginal sponges containing 20 mg fluorogestone acetate (FGA) and intramuscular equine chorionic gonadotropin (eCG; 200 or 300 IU). Treatments combined eCG dose and timing (200 IU/0 h, 200 IU/−24 h, 300 IU/0 h, and 300 IU/−24 h). Estrus occurrence, interval to estrus, follicular growth, ovulation rate, and number of corpora lutea were analyzed by ANOVA using PROC GLM and PROC MIXED in SAS.
Results: The interaction between eCG dose and timing significantly affected (P < 0.05) estrus occurrence, interval to estrus, and ovulation rate. Regardless of dose and timing, eCG application resulted in an orderly follicular growth pattern similar to that of a natural estrous cycle.
Limitations/implications: Crossbred animals were excluded to meet the study's inclusion criteria.
Findings/conclusions: Incorporating eCG into progestagen based synchronization protocols enhances estrus expression, concentrates estrus onset within a short time frame, and increases ovulatory rate.