Efecto del estadio del desarrollo folicular al momento de la monta sobre la ovulación y supervivencia embrionaria en alpacas

The objective of this study was to evaluate the effect of the stage of the dominant follicle (df) at mating on the ovulation and embryonic survival in alpacas. A total of 116 alpacaswith315 day-post-partum resting period were used and evaluated by transrectal ultrasonography in order to distribute them in 4 groups: G1 (df in growing stage, diameter: 6 mm), G2 (df in growing stage, diameter: 3 7 £ 12 mm), G3 (df in static stage, diameter: 37 mm,) and G4 (df in regression stage, diameter: 37 mm). Subsequently, all alpacas were mated except 5 alpacas of group G1 that rejected the male. Mating day was considered as day 0. Additional ultrasound evaluations were carried out on days 2 (occurrence of ovulation), 9 (presence and size of the corpus luteum); 20, 25, 30 and 35 (presence of embryonic vesicle orembryo). On day 15, a sexual receptiveness test was performed. Ovulation occurred in 97.3% of alpacas that were mated (n=111) but without significant differences (p<0.05) between groups. On day 9, no significant difference in the average size of the corpus luteum was observed among groups. The embryonic survival rate was also not significantly different among the groups, but there was a tendency to a greater rate of survival for group G2(65.5%) on day 35 after mating. These results suggested that the stage of follicular development of the dominant follicle during mating does not have a significant effect on the rate of ovulation and embryonic survival in alpacas.