Factors affecting conception rate of hair ewes after laparoscopic insemination with chilled semen under tropical conditions

The objective was to evaluate the effect of some factors on the conception rate of hair ewes using laparoscopic intrauterine insemination with chilled semen under tropical conditions. Data on 1200 inseminations carried out in Pelibuey, Blackbelly, Katahdin and Dorper ewes from 19 farms were used. Estrous was synchronized using vaginal sponges or a controlled intravaginal drug release (CIDR) device by 12 days. At the withdrawal of the device (sponge/CIDR) 200 or 250 IU of equine chorionic gonadotropin (eCG) was applied. Insemination was carried out 54-56 h after withdrawal of the device using chilled semen with 150 million spermatozoa per dose. Ultrasound conception diagnosis was carried out 35-40 d after insemination. The effects of ewe breed, age of ewe (1-4 years), body condition score (low, middle and high), type of device (sponge and CIDR), dose of eCG (200 and 250 IU), year of insemination (2010-2012), season (hot-dry, hot-humid; fresh-humid), inseminator (5 inseminators) and simple interactions on conception rate were determined using binary logistic regression. The overall conception rate was 66.4%. There was not significant interactions of main effects. Only breed, body condition score (BCS) and year of insemination influenced (P < 0.05) conception rate. Blackbelly (73.1%) and Pelibuey (68.9%) ewes had the highest conception rates as compared to Dorper (61.4%) and Katahdin breeds (62.4%). The conception rate was better in the ewes of middle body condition (68.1%) than ewes of low BCS (64.2%). Under the conditions of this study, the conception rate of ewes, using laparoscopic intrauterine insemination with chilled semen was influenced by ewe breed, BCS and year of insemination.