Improved fertility in dairy cattle with low body condition using equine chorionic gonadotropin in fixedtime artificial insemination

In order to evaluate the use of equine chorionic gonadotropin (eCG) in a fixed time artificial insemination (FTAI) protocol based on progesterone (P4) and body condition score (BC) on cows fertility kept under a production system traditional (PST), an investigation was developed using a completely randomized design, with a 2×2 factorial arrangement, the factors being BC (3.00 ≤ BC ≤ 2.75) and administration of 400 International Units (IU) of eCG, forming four treatments (T) with 50 animals each, which were T1 synchronized cows with BC ≤ 2.75 without eCG application; T2 synchronized cows with BC ≤ 2.75 and eCG application; T3 synchronized cows with BC ≥ 3.00 without eCG application and, T4 cows synchronized with BC ≥ 3.00 and eCG application. The FTAI protocol was: day (d) zero, intravaginal device (IVD) of Progesterone application, plus 2 miligrames (mg) of Estradiol Benzoate (EB). On 7 d, IVD withdrawal plus 500 microgrames (μcg) of Cloprostenol sodium; 8 d, 1 mg of EB; 9 d, FTAI, 56 hours after having IVD removed. Fertility values observed were T1: 22.0 %; T2: 44.0 %; T3: 46.0 % and, T4: 48.0 %, with statistical differences (P<0.05) between T1 and another T groups. The results indicate that the eCG administration improves cows fertility with low BC, under a dairy PST.