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A PRRS-PED virus co-infection reduces total tract digestibility in grower pigs
Porcine reproductive and respiratory syndrome (PRRS) and porcine epidemic diarrhea (PED) are two costly diseases to the swine industry. Therefore, our objective was to determine the impact PRRSv and PEDv, alone or combination, had on apparent total tract digestibility (ATTD) and apparent ileal digestibility (AID) coefficients in early grower pigs. Forty-two Choice Genetics gilts (16.8 ± 0.6 kg BW), naïve for PRRS and PED, were selected and randomly assigned to one of four treatments: 1) Control (n=6), 2) PRRS only (n=12), 3) PED only (n=12), 4) PRRS+PED (n=12). Treatments 2 and 4 were inoculated with live PRRSv on day zero (D0) and euthanized on D21. Treatments 3 and 4 were inoculated with PEDv on D14, 7 days prior to euthanasia on D21. PRRSv infection was determined by serum QPCR and seroconversion. PEDv infection was confirmed by fecal PCR. Feces were collected on days 18-20 and ileal digesta was collected at euthanasia (D21). Feed, feces, and digesta were analyzed for DM, OM, and N. Feed and feces were analyzed for energy, and digesta and feed were analyzed for amino acids. Feed intake was used as a covariate for statistical analysis of ATTD and AID. By design, Control pigs remained PRRS and PED negative throughout the study. Compared to control pigs, PRRSv infection did not reduce ATTD or AID of nutrients and energy (P > 0.05). However, PED infection, alone or in combination with PRRS, decreased ATTD of DM and energy by 8% and 12%, respectively (P < 0.05). Although PED alone decreased N and OM ATTD (7% and 2.5%, respectively), they were not significantly different (P = 0.24 and P = 0.35, respectively). Compared to controls, the PRRS+PED group had N and OM ATTD reduced by 13% and 3% respectively (P < 0.05). PED alone or in combination reduced AID DM (14-18%) and OM (6-8%), but not significantly (P > 0.05). AID of Met, Leu, Phe, Arg, and Trp did not differ between virus challenges. However, lysine AID tended to be reduced in PED and PRRS+PED treatments compared to the control (10-12%, P= 0.095). Altogether, the controls and PRRS treatment have similar digestibility coefficients, while the two PEDv challenges reduced ATTD of nutrients and energy. Surprisingly, AID of amino acids was not affected by PEDv or PRRSv challenges in this model.
Keywords: digestibility, PRRS, PED