INFLUENCIA DE LA PRESINCRONIZACIÓN DEL ESTRO EN VARIABLES REPRODUCTIVAS DE OVEJAS DE LA RAZA KATAHDIN PORTADORAS DEL GEN GDF9

Abstract

<p><strong>Background</strong>: Genetic improvement in the sheep species focuses on increasing the number of offspring per sheep. Heritable characteristics such as ovulation rate, fertility, and prolificacy are desirable. <strong>Objective</strong>: To evaluate the influence of estrus pre-synchronization with PGF2α on the manifestation of estrus, onset and return to estrus (1st and 2nd), pregnancy, lambing, prolificacy, and fertility in Katahdin ewes carrying exon 2 of the gene Factor Growth and Differentiation 9 (<em>GDF9</em>). <strong>Methodology</strong>: Seventy-two ewes were randomized into four treatments (T): T1 (n = 18), ewes without <em>GDF9</em> gene and without estrus pre-synchronization; T2 (n = 17), ewes without <em>GDF9</em> gene and with estrus pre-synchronization; T3 (n = 19) ewes with the <em>GDF9</em> gene and without estrus pre-synchronization, and T4 (n = 18), ewes with the <em>GDF9</em> gene and with estrus pre-synchronization. <strong>Results</strong>: The presence of estrus, the onset of estrus, and returns to estrus, pregnancy, and lambing percentages were not different between treatments (p>0.05). The average pregnancy and lambing in both cases were 86.2% and the average general prolificacy was 1.4 lambs per ewe for all four treatments. There were also no significant differences for the prolificacy or fertility rate (p>0.05). <strong>Implications</strong>: The present study contributes to the understanding of the use of presynchronization with PGF2α and the effect of the presence of exon 2 of the <em>GDF9</em> gene on reproductive variables. <strong>Conclusions</strong>: The presynchronization of estrus with PGF2α and the presence of exon 2 of the <em>GDF9 </em>gene in ewes of the Katahdin breed did not have a significant effect on the reproductive variables evaluated.</p>