Impact of Brachyspira hyodysenteriae on intestinal amino acid digestibility and endogenous amino acid losses in pigs

Authors: SCHWEER, WES - Iowa State University; BURROUGH, ERIC - Iowa State University; PATIENCE, JOHN - Iowa State University; Kerr, Brian; GABLER, NICHOLAS - Iowa State University

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/5/2018
Publication Date: 1/1/2019
Citation: Schweer, W.P., Burrough, E.R., Patience, J.F., Kerr, B.J., Gabler, N.K. 2019. Impact of Brachyspira hyodysenteriae on intestinal amino acid digestibility and endogenous amino acid losses in pigs. Journal of Animal Science. 97:257-268. https://doi.org/10.1093/jas/sky393.
DOI: https://doi.org/10.1093/jas/sky393

Interpretive Summary: Brachyspira hyodysenteriae (Bhyo), the classical agent of swine dysentery, affects pigs worldwide and is a reemerging pathogen in U.S. swine industry. Although Bhyo infection is more prominent in finishing pigs, younger pigs can experience the disease with mortality and morbidity approaching 30 and 90%, respectively. Although Bhyo commonly results in decreased growth performance and causes considerable economic loss worldwide, little is known about how Bhyo infection modulates digestive tract function and nutrient and energy digestibility. Therefore, the current study was conducted to determine how Bhyo modulated the digestibility of nutrients, energy, and amino acids in response to Bhyo infection. Data from this experiment suggests that Bhyo, which largely impacts only the hindgut, has minimal impact on basal endogenous losses of amino acids and reduces the standardized ileal digestibility of some amino acids. This indicates that Bhyo did not impact amino acid digestibility in the same way as other enteric pathogens, affecting amino acid digestibility similar to that of a systemic disease challenge. In addition, there was an increase in appearance of nitrogen and gross energy in the hindgut of Bhyo infected pigs which was likely associated with decreased nitrogen and energy balance, which likely attributes to the reduced growth performance commonly seen with Bhyo infection. This information is important for nutritionists at universities, feed companies, and pig production facilities that not all diseases act similarly with regard to amino acid digestibility and metabolism, and consideration should be given to pathogens individually.

Technical Abstract: Brachyspira hyodysenteriae (Bhyo), induces mucohemorrhagic diarrhea in pigs and is an economically significant disease worldwide. Our objectives were to determine the impact of Bhyo on apparent total tract digestibility (ATTD), ileal digestibility (AID), and ileal basal endogenous losses (BEL) in grower pigs. In addition, we assessed the effect of Bhyo on hindgut disappearance of DM, N, and GE. Thirty-two Bhyo negative gilts (38.6 ± 0.70 kg BW) were fitted with a T-cannula in the distal ileum. Over two replicates, pigs were fed a complete diet (7 control, 10 Bhyo pigs) or nitrogen-free diet (NFD; 4 control, 11 Bhyo pigs). The 21 Bhyo pigs (62.6 ± 1.39 kg BW) were inoculated with Bhyo on day post inoculation (dpi) 0, and the 11 control pigs were sham inoculated. Feces were collected from 9 to 11 dpi and ileal digesta collected from 12 to 13 dpi. All pigs were euthanized at 14 to 15 dpi and intestinal tract pathology assessed. Feed, feces, and digesta were analyzed for DM, N, and GE. Feed and digesta were analyzed for AA. Within the complete diet and NFD treatments, data were analyzed to determine pathogen effects. All control pigs remained Bhyo negative, and 5 challenged pigs in each replicate were confirmed Bhyo positive within 9 dpi. Infection with Bhyo reduced ATTD of DM, N, and GE and increased AID of Gly (P < 0.05). No other AA AID differences were observed. Interestingly, only BEL of Pro was reduced (P < 0.05) while Arg, Trp, and Gly tended (P < 0.10) to be reduced by Bhyo infection. When calculated from AID and BEL, Bhyo infection reduced SID of N, Arg, Lys, Ala, Gly, Pro, and Ser (P < 0.05) and tended to reduce Thr SID (P = 0.09). In the hindgut of Bhyo pigs, there was generally an appearance of nutrients rather than disappearance. In pigs fed a complete diet, hindgut appearance of N and GE were increased (P < 0.05) by 58 and nine-fold, respectively, and DM tended to be increased two-fold (P = 0.06). Similarly, in NFD fed pigs, hindgut appearance of N and GE was increased by 172 and 162%, respectively, although high variability led to no significance. Altogether, Bhyo infection has minimal impact on AID of AA, but when corrected for BEL, SID of N, Ar, Lys and some nonessential AA are reduced. Unexpectedly, BEL of several AA were unaffected by Bhyo infection. This may suggest an increased need for AA and energy during a Bhyo challenge.