A Note on the Use of Prostaglandin-F_2a to Facilitate the Training of Sexually Na've Boars for Semen Collection

Livestock Update, November 2000

Mark Estienne, Swine Research Physiologist, and
Allen Harper, Extension Animal Scientist-Swine, Tidewater AREC

Anecdotal evidence from observations in the field has suggested that the administration of Prostaglandin-F_2--> (PGF_2-->) enhances libido in boars and increases the willingness to display mounting and mating behavior. There are, however, very few published research reports that justify this practice. Hashizume and Niwa (1984) reported that PGF_2--> improved libido to some extent and increased semen volume and the total number of sperm cells in the sperm-rich fraction of ejaculates. However, only three boars were utilized in that study.

Work at the Tidewater Agricultural Research and Extension Center (TAREC) in Suffolk, demonstrated that i.m. treatment with 10 mg PGF_2--> (Lutalyse, Pharmacia & Upjohn Company, Kalamazoo, MI) decreased the number of sessions required to train sexually active boars (i.e., boars experienced with natural mating) to mount an artificial sow and allow semen collection (Estienne and Harper, 2000). In that study, the number of false mounts (mounting artificial sow but not allowing semen collection) and reaction time (elapsed time between entering collection pen and start of ejaculation) were decreased by treatment with Lutalyse (Estienne and Harper, 2000). In contrast, researchers at Oklahoma State University reported that treatment with PGF_2--> did not increase the number of low-libido boars that mounted and mated gilts (Wettemann et al., 1992).

Szurop et al. (1985) reported that treatment of young, sexually na've boars with a PGF_2--> analog increased the number of individuals that mounted an artificial sow at the first training session for semen collection. To extend these findings, we recently conducted an experiment, the objective of which was to determine the effects of PGF_2--> on the ability to train for semen collection, young boars that had not experienced natural mating.

Six littermate boars (Landrace x Yorkshire), each approximately 423 lbs. of body weight and 289 days of age, were used. Boars were moved to a semen collection pen equipped with an artificial sow twice weekly for 5.5 weeks (total of 11 sessions). Each training session lasted a maximum of 15 minutes. Sessions 1 through 9 (Period A) was considered the control period and boars received no treatment. Immediately upon entering the collection pen during the tenth session (Period B) all boars received an i.m. injection of 10 mg Lutalyse. During the eleventh session (Period C), boars received no injection of Lutalyse.

During each training session, boars received a libido score of 1 to 5 using an index developed by Charles Babb, an agricultural supervisor located at TAREC (Table 1).

Table 1. Index used to assess boar libido during training to mount an artificial sow for semen collection.
1	No interest in artificial sow.
2	Slight interest in artificial sow, but did not attempt to mount.
3	Mounted artificial sow, but did not display an erection.
4	Mounted artificial sow and displayed erection; did not allow semen collection.
5	Mounted artificial sow and allowed semen collection.

The percentage of boars that mounted the artificial sow and allowed semen collection was greater (P < .01) during Periods B (100%) and C (100%) compared to Period A (0%) (Figure 1). Average libido score during Period A (1.7 ± .08) was less (P < .01), compared to Periods B (5.0 ± .08) and C (5.0 ± .08) (Figure 1).

Figure 1. Effect of Lutalyse on libido in boars being trained to mount an artificial sow for semen collection. Boars received no treatment during Periods A and C. Lutalyse (10 mg) was administered only during Period B.

Based on our results, it appears that Lutalyse can be used as a tool to expedite the training of young boars for semen collection. Decreasing the number of sessions needed to train boars for semen collection saves time and labor and more than offsets the cost of Lutalyse (approximately $1.00 per injection). However, indiscriminate or routine use of Lutalyse in boars is not recommended. Indeed, in our experiment, Lutalyse was used only to "train" boars for semen collection. In subsequent collections, it was not needed nor used to entice boars to mount. The long-term effects of repeated injections of Lutalyse on boar health, libido and semen quality have not been determined. Finally, Lutalyse injections for enhancing libido in boars is technically an "extra-label" use of the drug and should only be administered after consultation with a producer's herd veterinarian.

References

Estienne, M.J., and A.F. Harper. 2000. PGF_2--> facilitates the training of sexually active boars for semen collection. Theriogenology (In Press).

Hashizume, T. and T. Niwa. 1984. Effect of administration of prostaglandin F_2--> (PGF_2-->) on the properties of sperm rich fraction of boar semen. Japan. J. Anim. Reprod. 30:182.

Szurop, I. et al. 1985. Stimulation of libido in pubertal and mature boars with prostaglandin F_2--> analogs: Clinical observations. Zuchthygiene 20:83.

Wettemann, R.P. et al. 1992. An attempt to stimulate sexual behavior of boars. Oklahoma Agricultural Experiment Station 1992 Animal Science Research Report. Pp. 410-412.

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