Reproduction performance of Pelibuey ewes in response to estrus synchronization and artificial insemination in northwestern Mexico

Artificial insemination is a valuable technique for improving reproductive performance in sheep as well as providing a resource to introduce new genetics. The purpose of the present study was to evaluate the induction of estrous, gestation length, fertility and prolificacy in Pelibuey ewes in response to Laparoscopic Artificial Insemination (LAI) using frozen semen from 3 hair sheep breeds in a northwest region of Mexico during 2 consecutive years. In year one, 36 Pelibuey ewes were randomly distributed in three groups to be inseminated with three hair sheep breeds (Katahdin, K, n = 11; Dorper, D, n = 13; Pelibuey, P, n = 12). In year two, 43 Pelibuey ewes were randomly distributed in 3 groups using the same breeds (K, n = 14; D, n = 15; P, n = 14). Gestation length and prolificacy were analyzed using analysis of variance and induction of estrus, fertility and fecundity using chi-square tests. All analyses were performed through SAS procedures. Estrus was induced in all ewes of the three different groups. Gestation length was longer (p<0.006) in ewes inseminated with K (147.3 d) than those with D (145.5 d) semen. Gestation lengths of ewes inseminated with P semen (146.4 d) were similar (p>0.05) to those with D and K semen. Fertility rates of ewes inseminated with D semen (65%) were higher (p<0.026) than those with K (40%) or P (62%, p<0.035) semen. There were no differences (p>0.05) in fertility rates between ewes inseminated with D and P semen. Fecundity rate was higher (p<0.05) in ewes inseminated with D (164%) than those with P (131%) or K (108%). Pelibuey ewes inseminated with P semen had the lowest (p<0.05) prolificacy (2.1 lpe) than those with K (2.7) and D (2.6 lpe) semen. These results suggest that estrus synchronization resulted in an efficient technique to induce estrus in Pelibuey ewes. Also, data from LAI in this desert conditions had similar results in fertility than those in other regions of the world. Although differences were observed in prolificacy, more information is needed to evaluate the convenience of introducing new sheep hair breeds using LAI in northwestern Mexico.