SUPEROVULATORY RESPONSE TO A SINGLE SUBCUTANEOUS INJECTION OF FOLLTROPIN-V IN BEEF-CATTLE

A series of 4 experiments were designed to evaluate the feasibility of superstimulation in beef cattle with a single sc injection of the por cine pituitary extract, Folltropin-V. In the preliminary study (Experi ment 1), superovulatory response of cows (n=7) treated with a single s c injection of 400 mg NIH-FSH-P1 Folltropin-V was not different than t hat of cows (n=8) superstimulated with twice daily im injections over 4 d, or a single sc injection plus an injection of eCG (n=12). Experim ents 2 and 3 were designed to determine the optimal site of a single s c injection. In Experiment 2, cows (n=25) with body condition scores ( BCS) of 1 to 2 were used. The mean number of CL counted and ova/embryo s collected was lower (P<0.05) in cows treated with the single sc inje ction in the neck region than in cows treated with a single sc injecti on behind the shoulder, or with the twice daily im injection treatment . In Experiment 3, cows (n=49) with BCS of 3 to 5 were used. There wer e no differences in the number of CL, total ova/embryos collected, fer tilized ova and transferable embryos whether treatments were given in the neck region or behind the shoulder, or whether the cows were impla nted or not implanted with Syncro-Mate-B. Experiment 4 was designed to determine the optimal superstimulatory dosage of Folltropin-V adminis tered by a single sc injection. Superovulatory response of cows treate d with the higher doses (400 mg, 600 mg or 800 mg NIH-FSH-P1) was high er (P<0.05) than those treated with 200 mg NIH-FSH-P1. The number of u novulated (greater than or equal to 10 mm) follicles at the time of ov a/embryo collection was higher (P<0.05) in the 600 and 800 mg groups, and progesterone concentration at estrus was higher (P<0.05) in cows t reated with 800 mg than with 400 or 200 mg. It was concluded that a si ngle, bolus sc injection of 400 mg NIH-FSH-P1 of Folltropin-V is as ef ficacious as the 4-d, twice daily im treatment protocol for inducing s uperovulation in beef cows. The amount of subcutaneous fat and site of injection appeared to affect the efficacy of a single sc injection; a single bolus sc injection of Folltropin-V behind the shoulder resulte d in the most predictable superovulatory response.