PSV-18 - Improved performance of PRRSV challenged pigs fed 1-α-glycerol monolaurate

Abstract: Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) and Porcine Enteric Diarrhea (PEDV) has posed a persistent challenge to the swine industry despite vaccinations and biosecurity measures. Feed has been shown to be a carrier for bacterial and viral pathogens (Dee et al.,2020). Feed mitigation using medium chain fatty acids can eliminate the pathogen or reduce the pathogen load below its infectious dose. However, less is known regarding the application of monoglycerides for feed mitigation. The objective of this study was to determine if using only 1-α-glycerol monolaurate (GML) can be an effective feed mitigant against PRRSV compared to untreated control feed. A total of 2 rooms, each with 100 pigs per room, and 6 pens per room were used. The initial weight of the pigs averaged 15 kgs and were sourced from a herd free of PRRSV and PEDV. GML was added to the feed at 2 kgs/mT. The study period was 14 days with starting and end weights measured. An ice block viral challenge as described by Dee, et al., 2020 was used. Briefly, a 500 mL ice cube containing 1x10⁷ 50% tissue culture infectious dose of each virus (PRRSV, PEDV and Senecavirus A (SVA)) was added to 1,300 kg of feed on day 0 and again on day 6. On day 15 pigs were tested for PRRSV (serum), PEDV (rectal swabs) and SVA (tonsil samples). Control and GML fed pigs did not seroconvert to PEDV and SVA, therefore only results for PRRSV are presented. Average daily gain was significantly improved in GML fed pigs (0.50 kg/d vs 0.20 kg/d; P < 0.05). Percentage of PRRSV positive feed samples were decreased (P < 0.05) in GML treated feed from 100% (Ct=32.2) in control feed to 33% (Ct=34.3). The percentage of positive oral fluid samples decreased (P< 0.05) from 100% (Ct=26.1) in control pigs to 17.0% (Ct=33.0) in GML fed pigs. GML fed pigs exhibited no clinical signs of PRRS (dysponea), whereas 100% of the control pigs had clinical signs (P< 0.05). Similarly, GML fed pigs had no PRRSV positive serum samples but 100% of the control pigs had PRRSV positive serum samples. Results from this study show that the use of only GML can be an effective feed mitigant to reduce or eliminant the clinical signs of PRRS in pigs and maintain growth performance.