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Pig Behavior Studies With Practical Implications for Commercial Swine production - Study I.

Livestock Update, April 1995

Allen Harper, Tidewater AREC

Study I: Influence of penning type and feeding level on sexual behavior and feet and leg soundness in boars. R. R. Hacker et al., 1994 (J. Anim. Sci. 72:2531).

This study, conducted at the University of Guelph in Guelph, Ontario, Canada, sought to determine the effects of housing growing-developing boars individually or in small groups on reproductive behavior of the boars at maturity. Another treatment factor in the study was ad libitum feeding (full feeding) or limit feeding (85% of ad libitum consumption). Ninety-six Yorkshire boars were used in the study. Group housed boars were penned at a stocking density of 8 pigs in 13 ft. X 14 ft. pens equipped with partially slotted, concrete floors. Individually penned boars were in 3 1/4 ft. X 5 1/2 ft. pens also equipped with partially slotted, concrete floors. Average weight of the boars at the onset of the test treatments was 66 lbs. When the boars reached 150 days of age, exposure tests to estrus gilts were begun. Mating behavior and semen characteristics were evaluated. The boars were also evaluated for feet and leg soundness at the end of the trial by a trained evaluator.

Results of the study revealed that individually reared boars required longer to make contact with receptive gilts, and made more "incorrect" mounting attempts than group reared boars. Furthermore, group reared boars had a more favorable mating score and were younger at the time of completing a successful test mating. The individually penned boars were older and larger before successful semen collection, which apparently contributed to a higher sperm count for the individually penned group. Furthermore, group reared boars had more favorable feet and leg soundness scores than individually penned boars, although the incidence of minor injuries (swellings and lesions) was greater among group reared boars.

Full or limited feeding during development did effect semen characteristics with boars that were full-fed throughout the trial producing the greatest volume of semen and highest sperm counts. This appeared to be related to the advanced body size of the full fed boars at the time of semen evaluation. However, the type of feeding strategy had minimal impact on mounting and mating behavior when the boars were exposed to gilts in heat.

The results from this study indicate that the social interaction that occurs in group penning during growth and development of boars is an important factor for establishment of correct mounting and mating behavior at an early age. Penning in small groups with adequate floor space during growth also appears to result in better foot and leg soundness in young boars but more minor injuries are likely to occur.

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