Behavioral responses to intramuscular injections of prostaglandin F(2 alpha) in female pigs

This study investigated the effect of different doses (0-1.25 mg/kg IM) of prostaglandin (PG) F(2 alpha) on the behavior of female pigs (Sus scrofa). Six-month-old cyclic nulliparous sows (gilts) were housed and tested individually in strawed pens (2.8 x 1.7 m). All doses of PGF(2)alpha induced rooting, pawing at the ground, and gathering straw. In the hour following treatment the frequency of pawing increased with increasing dose to reach a maximum level with the highest dose given. The frequency to gather straw was highest in pigs treated with the lowest dose (0.008 mg/kg). The frequency of oronasal contact with the floor and pen walls was unaffected by dose. Scratching, locomotion, and changes in body posture were highest following treatment with the three highest doses of PGF(2 alpha). Many of the behaviors observed following PGF(2 alpha) treatment are characteristic of prepartum nesting behavior in pregnant sows. We conclude that two key components of maternal nest-building behavior, pawing, and gathering straw, are affected differentially by different doses of PGF(2 alpha). The implications of these results on the mechanisms underlying maternal nest building in pigs are discussed.