The difficulty of identification of the estrus in cows and heifers, as well as the late first birth of heifers, warrant the adoption of estrus and ovulation synchronization protocols, in association with a good feed and sanitary management, aiming for the reduction of this problems. The “OVSYNCH” protocol combines treatments that control the luteal and follicular dynamics, with an intramuscular application (IM) of 1.0 mL of FertagylÒ (Gonadorelin, similar to the natural Gonadotrophin Releasing Hormone - GnRH) at day zero, after seven days 2.0 mL IM of PrelobanÒ (Cloprostenol Sodium Salt, similar to the natural Prostaglandin F2a - PGF2a) and after 48 h the second dose (1.0 mL) of FertagylÒ IM. The “CIDR-B” protocol is an intravaginal device with progesterone, that is implanted at day zero associated with 2.0 mL of EstrogenÒ (Estradiol Benzoate - EB) IM; after eight days the implant is removed and we give, by IM, 2.5 mL of FolligonÒ (Hormone Pregnant Mare Serum Gonadotrophin – PMSG or eCG) and 2.0 mL of PrelobanÒ; the next day we give more 1.0 mL of EstrogenÒ, by IM, and after 30 h the artificial insemination (AI) is done. The present study compares the efficiency of these two protocols in Girolando heifers raised in the semi-arid zone of Northeast in Brazil. The “CIDR-B” protocol was the most efficient of them, with conception rates of 60 and 96% and pregnancy rates of 50 and 80% for the first and second artificial insemination, respectively. In this way, it is recommend the use of “CIDR-B” protocol to reduce the age of the first birth in Girolando heifers that are late in puberty.
