Uso de dispositivos auriculares de nogestomet en inseminación artificial a tiempo fijo en bovinos doble propósito, con amamantamiento permanente

to evaluate the effectiveness of progesterone ear devices new and second use, rates were determined estrus and pregnancy rates in cycling and anestrous animals by breastfeeding. we used 69 dual-purpose cows (bos taurus by bos indicus) with calf at foot and 60 to 80 days postpartum, a livestock farm, located in the municipality of cimitarra, santander. the animals were implanted for 9 days with 3 mg of norgestomet (crestar？ msd), and were divided randomly into two groups, group 1 (n=35) cows with new devices, group 2 (n=34) cows with implants headset reused, and artificial insemination was performed at fixed time at 56 hours after removal of the devices. the data obtained were tested in a simple anova (anova) with a reliability of 95%. for the variable estrus no differences (p>0.05) between group 1 and 2 (66.4% and 53.4%), respectively. the variables pregnancy and ovarian structures (dominant follicles and corpus luteum), upon synchronization, yielded significant differences (p<0.05) between groups 1 devices new group (53.9,%) vs group 2 devices reused (38,3%), ovarian structures and between group 1 devices new (56,6%) vs. group 2 devices reused (33.2%) respectively, with ovaries without structures. we conclude that progesterone ear devices new and reused, generate similar rates of estrus. also, pregnancy rates are higher in cows cycling versus anestrus cows.