Tratamiento del anestro postparto con progesterona intravaginal mas eCG en vacas mestizas tropicales

In order to evaluate an intravaginal sponge impregnated with progesterone for the treatment of postpartum anestrous, 42 crossbred multiparous acyclic cows, between 90 and 120 days after parturition, with body condition in the range of 3 and 4, in scale 1-5, were randomLy allotted to one the following treatments: PH (n=21), intravaginal sponge (IS) with 250 mg medroxyprogesterone acetate (MEP) during 7 days plus im injection of 50 mg of MEP and 5 mg of 17β-estradiol (17β-E) the day of sponge insertion (day 0) and 500 IU of eCG in the day of sponge removal; Control (GC; n=21), intravaginal sponges without MEP for 7 days plus the im injection of the same volume of saline solution replacing the P and 17β-E. calving first service (PS) and calving to conception (PC) intervals, estrus, ovulation and pregnancy rate were considered as variables in this study. Response to treatment was considered up to 30 days. The work was performed in a commercial farm located in Machiques de Perijá county, Zulia State, Venezuela, in an area of sub-humid tropical forest. Data was analyzed using GLM procedures and Chi-Square test of SAS. The percentage of cows in estrus was similar between treatment (PH: 50%; GC: 36.8%; P>0.05). Group PH had a greater ovulation rate (P<0.01) than the control group (79 vs. 29.4%). The pregnancy rate did not differ between treatments, however there was 18.3% difference between PH and the control group (55 vs. 36.8%). There were not effect of treatment on the PS and PC intervals (P>0.05): PS: 150,6 ± 11,6 y 157,7 ± 13.2; PC: 156,9 ± 8.8 y 162,0 ± 9.0, for PH and control groups, respectively. There were not effect of treatment on the percentage of anestrous cows at 90 days post-treatment, however, the control group was 22.1% greater PH group (42.1 vs. 20,0%).