Protocolo J-synch con y sin eCG en vacas Brown Swiss y sus cruzas con Bos Indicus en la amazonía ecuatoriana

Abstract

The incorporation of prolonged proestrus protocols under extreme conditions has improved conception. Therefore, the objective of this research was to evaluate the results of the protocol with prolonged proestrus called J-Synch with and without eCG, on follicular dynamics and pregnancy percentage in dual purpose cows in the Ecuadorian Amazon. The study was carried out in the province of Pastaza - Ecuador, from October 2018 to October 2019. We used 448 multiparous cows in production with calves at foot of Brown Swiss breeds and their crosses (Bos indicus). Four treatments were used, cows were artificially inseminated at fixed time on day nine T1: J-Synch, eCG, IATF estrus 60 hours (n= 120); T2: J-Synch and eCG and No Estrus+ GnRH IATF 72 hours (n=118); T3: J-Synch and Estrus IATF 60 hours (n=103); T4: J-Synch plus No Estrus plus GnRH plus IATF 72 Hours (n=107). Pregnancy rates were 55% (T1), 49% (T2), 51% (T3) and 50% (T4) with no significant differences. Follicular development and corpus luteum diameter showed significant differences (p0.05). It is concluded that the J-Synch plus eCG treatments at 60 hours and 72 hours had different behaviour in follicular development and corpus luteum size. Pregnancy percentages did not differ between treatments, although there was a 44.5% greater chance of a cow becoming pregnant with T1 compared to T2. In addition, 22.5% higher pregnancy would be achieved with T1 compared to T3, and 18% higher pregnancy would be achieved with T3 compared to T2.