Use of protocol with prolonged proestrus with and without eCG in dual purpose dairy Holsteins cows in the Ecuadorian Amazons

Abstract

The objective was to evaluate the effect of eCG on presence estrus, ovulation time, preovulatory follicle diameter and pregnancy rate in Holstein cows treated with a prolonged proestrus protocol in the Ecuadorian Amazon. The project was developed of the Province of Pastaza - Ecuador, from October 2018 to October 2019. The study used 306 Holstein multiparous dairy cows were used, milked once a day producing with an average production of 8 liters of milk per cow / day. Four treatments were used, the cows were artificially inseminated at fixed time on day nine T1: J - Synch + eCG + estrus FTAI 60 hours (n = 92); T2: J - Synch + eCG + without estrus + GnRH FTAI 72 hours (n=61), T3: J - Synch + estrus FTAI 60 hours (n = 70); T4: J - Synch + without estrus + GnRH + FTAI 72 hours (n = 83). The pregnancy rate was 59.8% (T1), 54.1% (T2), 47.1% (T3) and 41.0% (T4). Follicular development and corpus luteum diameter showed significant differences (p≤0.05). For this group of cows and with the production system used, any of the evaluated treatments could be manipulated interchangeably. Although, the J-Synch treatment with eCG and IA 60 hours would show a trend of better pregnancy rate.

Keywords

• estrus
• follicular dynamics
• pregnancy
• progesterone
• cow