412 OVARIAN RESPONSE IN ALPACAS (VICUGNA PACOS) TO SUPERSTIMULATORY TREATMENT WITH FOLLICLE-STIMULATING HORMONE AND EQUINE CHORIONIC GONADOTROPIN

Abstract

The objective of this study was to evaluate the ovarian response in alpacas to superstimulatory treatment with FSH and eCG. Alpacas females (n = 49) were examined daily by transrectal ultrasonography using a 7.5-MHz linear-array transducer (Aloka SSD500, Tokyo, Japan) to determine ovarian follicular dynamics. Alpacas (n =41) were selected when a growing follicle ≥7 mm in diameter was detected and were given an i.m. injection of 4 μg of buserelin (Conceptal®, Intervet, Millsboro, MD, USA) on Day 0 (i.e. beginning of treatment). On Day 2, alpacas were assigned to 1 of the following 2 treatments: (1) the FSH group (n = 21), which received a total dose of 200 mg NIH-FSH-P1 of pFSH (Folltropin®-V, Bioniche Animal Health Inc., Belleville, Ontario, Canada) in decreasing dosages of 52, 48, 40, 32, and 28 mg divided in twice-daily i.m. injections for 5 days; and (2) the eCG group (n = 20), which received a single dose of 750 IU of eCG (Folligon®, Intervet, Millsboro, MD, USA). Animals received an i.m. dose of 0.150 mg of triapost (PGF; Iliren, Intervet, Millsboro, MD, USA) on Day 6. On Day 7, ovaries of all alpacas were examined by transrectal ultrasonography, followed by mating and embryo collection on Day 14. Data were analyzed by ANOVA. The mean number of follicles <7 mm in diameter was 5.8 ± 1.0 and 3.2 ± 0.9 for those treated with FSH and eCG, respectively (NS). The number of follicles 7 to 13 mm in diameter was 5.8 ± 1.5 and 9.7 ± 1.2 for the FSH and eCG groups, respectively (P < 0.05). The number of follicles >13 mm in diameter was 0.3 ± 0.4 and 1.0 ± 0.3 for the FSH and eCG groups, respectively (NS). The mean (± SD) follicle diameter was 8.3 ± 0.3 and 9.0 ± 0.2 for the FSH and eCG groups, respectively (NS). The mean (± SD) number of CL was 6.0 ± 1.9 and 8.7 ± 2.3 for the FSH and eCG groups, respectively (NS). Only 82.9% of animals (34/41) were flushed and embryos were recovered in 18 animals (52.9%), with 2.7 ± 0.4 and 2.7 ± 0.7 embryos in the FSH and eCG groups, respectively (NS). Large unovulated follicles (diameter >13 mm) were observed in 34.1% of animals (14/41) on Day 14 and most of them (71.4%) were in the group treated with eCG (10/14; P < 0.05). In conclusion, the use of eCG resulted in a higher number of preovulatory follicles (7-13 mm in diameter) than FSH. However, the percentage of animals with large unovulated follicles was also higher in the eCG-treated group, resulting in no differences in the number of CL counted or embryos obtained per treatment.