Impact of mash feeding versus pellets on propionic / butyric acid levels and on total E. coli load in the gastrointestinal tract of growing pigs.

Longpré, J., Fairbrother, J.M., Fravalo, P., Arsenault, W.J., LeBel, P., Laplante, B., Surprenant, C., Massé, D.I., and Letellier, A. (2016). "Impact of mash feeding versus pellets on propionic / butyric acid levels and on total E. coli load in the gastrointestinal tract of growing pigs.", Journal of Animal Science, 94(3), pp. 1053-1063. doi : 10.2527/jas.2015-9617  Access to full text

Abstract

Feed characteristics may influence the bacterial community composition and metabolic activities in the pig gastrointestinal tract, known to be associated with positive effects on the gut. Use of mash feed is associated with reduced Salmonella excretion, but little is known of its effect on the Escherichia coli population or of the mechanism of action. Our objec¬tives were to assess the effect of feed texture combined with feed particle size on VFA profiles and levels, total E.coli count, and the presence of genes encod¬ing virulence factors of pathogenic E.coli strains in the digestive tract along with their impact on pig perfor¬mance of fattening pigs. Pigs (n = 840) on a commercial farm received mash or pellet diets of different particle sizes during the fattening period. Caecal and colon con¬tents from 164 pigs were sampled at the slaughterhouse for enumeration of E.coli by quantitative PCR (qPCR) and for VFA quantification by capillary gas chromatog¬raphy. The yccT gene was used to enumerate total E.coli. Improved pig performances associated with pellet texture and a 500-μm size were observed. Caecal (P = 0.02) and colon (P < 0.01) propionic acid concentra¬tions were lower for pigs receiving pellet rather than mash feed. Similarly, caecal (P = 0.01) and colon (P < 0.001) butyric acid concentrations were also lower for pigs receiving pellet rather than mash feed, as deter¬mined by capillary gas chromatography. Moreover, caecal (P = 0.03) and colon (P < 0.001) butyric acid concentrations were higher for pigs receiving a feed with a 1,250-μm particle size rather than a 500-μm particle size. On the other hand, total caecal and colon E.coli levels were higher for pigs receiving pellet feed than for those receiving mash feed. For total E.coli enumeration, caecal (P < 0.01) and colon (P < 0.01) yccT gene copies were higher for pigs receiving pel¬let rather than mash feed. No effect of particle size on fatty acid concentrations or on E.coli numbers was observed. Virulence gene quantification revealed no trend. Taken together, results showed that mash feed is associated with lower growth performance but with favorable intestinal changes linked to VFA levels and E.coli reduction in the intestine.

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