Effects of Nutrient Supplementation on Pig Sickness Behavior When Infected with Porcine Reproductive and Respiratory Syndrome Virus

Porcine reproductive and respiratory syndrome virus (PRRSV) is a significant respiratory pathogen in grow-finish pigs. The objective of this research was to investigate how nutrient supplements impact pig sickness behavior during a PRRSV infection. Sixty PRRSV naïve pigs were allotted based on BW into 10 pens (6 pigs/pen) housed in a curtain-sided commercial barn during summer months. At 35 kg BW, all pigs were inoculated intranasal and I.M. with a field strain of PRRSV virus and began treatment supplements. Treatments included 1) control, receiving no nutrient supplement (n=3 pens), 2) water nutrient supplement (modified Blue2, TechMix LLC; n=3 pens), and 3) water+feed supplement (modified Blue2 + modified powdered form of Blue2, TechMix LLC; n=4 pens). Pig home-pen behavior was recorded on 4 color cameras positioned above the pens. Video was collected on days post inoculation (dpi) -1, 3, 6, 9, 12, 15, and 18. Video observations were recorded using a 10-min scan sampling interval from 7:00-19:00 hours daily by 1 trained observer. Percent of pigs standing, lying, sitting, eating, and drinking within each pen was recorded. Data were analyzed using the Glimmix procedure of SAS with a beta distribution to evaluate treatment and day differences. Pigs given the water+feed supplement showed an increase in sitting behavior compared to the control and water supplement treatments (P≤0.05). No differences were observed between treatments for lying, standing, eating, or drinking behaviors (P>0.05). On 6 and 9 dpi an increase in lying behavior was observed compared to -1 dpi (P≤0.05). Compared to -1 dpi, a decrease in sitting behavior was observed 9 dpi whereas an increase in sitting behavior was observed 15 dpi (P≤0.05). Standing behavior decreased on 6 and 9 dpi compared to -1 dpi (P≤0.05). On 6 dpi eating behavior decreased compared to -1 dpi whereas on 15 and 18 dpi eating behavior increased compared to -1 dpi (P≤0.05). Compared to -1 dpi, drinking behavior was reduced in pigs on 6–18 dpi (P≤0.05). In conclusion, no differences in sickness behavior were observed until 6 dpi. On 6 and 9 dpi pigs were less active than -1 dpi; however, activity was similar to -1 dpi on 3 and 12–18 dpi. Eating behavior was only decreased on 6 dpi; however, drinking behavior decreased on 6 dpi and did not return to baseline by 18 dpi. Furthermore, the nutrient supplement treatments had minimal effect on sickness behaviors of PRRSV infected pigs.