A comparative study of the effects of intramuscular administration of gonadorelin, mating and intrauterine infusion of either raw seminal plasma or seminal plasma purified -NGF on luteal development in llamas

Silva Jiménez, Mauricio
Urra, F.
Ulloa-Leal, C.
Ratto, Marcelo
Datos de publicación:
Contents The aim of this study was to compare the effect of the intramuscular administration of 50g of gonadorelin acetate versus natural mating, intrauterine infusion (i.u.) of a physiological relevant dose of either raw llama seminal plasma (SP) or purified beta-nerve growth factor from seminal origin (sp-NGF) on ovulation rate and corpus luteum (CL) development and function in llamas. Females with a follicle (8mm) were assigned to groups: (i) i.m. administration of 50g of gonadorelin acetate (GnRH; positive control; n=4); (ii) single mating (mating; n=6); (iii) i.u. infusion of 4ml of llama SP (SP; n=4); or (iv) i.u. infusion of 10mg of sp-NGF contained in 4ml of PBS (phosphate-buffered saline) (sp-NGF; n=6). Ovaries were examined by power Doppler ultrasonography at 0, 1, 3, 6, 12 and 24hr after treatment to determine preovulatory follicle vascularization area (VA), and additionally every 12hr until Day 2 (Day of treatment=Day 0) to determine ovulation. Afterwards, ovaries were examined every other day until Day 8 to evaluate CL diameter and VA. Blood samples were collected on Days 0, 2, 4, 6 and 8 to determine plasma progesterone (P4) concentration. Ovulation rate did not differ (p=.7) among groups, but treatment affected (p<.0001) preovulatory follicle VA. Neither treatment administration nor treatment by time interaction affected (p.4) CL diameter, VA and plasma P4 concentration. Mating tended (p=.08) to increase CL VA when compared to the seminal plasma group by Day 8. Intrauterine administration of seminal plasma or sp-NGF does not increase CL size and function when compared to i.m. GnRH treatment, suggesting that the administration route of sp-NGF influences its luteotrophic effect in llamas.