Effects of dietary protein level and zinc oxide supplementation on performance responses and gastrointestinal tract characteristics in weaner pigs challenged with an enterotoxigenic strain of Escherichia coli

Abstract

The interactive effects of dietary protein level, zinc oxide (ZnO) supplementation and infection with an enterotoxigenic strain of Escherichia coli (ETEC) on performance responses and gastrointestinal tract characteristics were examined. Ninety-six individually housed, 21-day-old pigs (1 : 1 gender ratio) with initial bodyweight (BW) of 7.2 ± 0.69 kg, were used in a split plot experiment, with the whole plot being challenge or no challenge with ETEC and the dietary treatments used as subplots and arranged in a completely randomised 2 × 2 factorial design, with the factors being (i) two dietary protein levels (251 versus 192 g/kg crude protein) and (ii) addition or no addition of 2.5 g/kg ZnO. No antibiotic was added to the diet. The ETEC infection decreased average daily gain (P < 0.001) and increased feed conversion ratio (P < 0.01). Protein level had no effect on performance of pigs while ZnO supplementation increased (P < 0.001) average daily gain and average daily feed intake and hence decreased feed conversion ratio (P < 0.001). There were no 2- or 3-way interactions for growth performance indices (P > 0.05). Feeding a lower protein diet did not influence (P > 0.05) faecal volatile fatty acid concentrations. In non-infected pigs, feeding a lower protein diet caused a lower pH in the jejunum and ileum compared with pigs fed a higher protein diet (P < 0.05 and P < 0.01, respectively). However, feeding ZnO-supplemented diets increased (P < 0.05) the pH in the stomach and caecum compared with feeding diets without ZnO supplementation. Protein level did not alter (P > 0.05) empty BW but dietary supplementation with ZnO increased empty BW (P < 0.05). Neither protein level nor ZnO supplementation modified small intestinal morphology, although a tendency for an interaction (P < 0.1) was detected for jejunal villous height between protein level and ZnO supplementation. The results indicate that feeding ZnO-supplemented diets improved pig performance, and feeding a lower protein diet without ZnO supplementation did not compromise performance nor modify measures of gastrointestinal tract structure and function compared with pigs fed a diet higher in protein after weaning.

Effects of low-protein diets supplemented with indispensable amino acids on growth performance, intestinal morphology and immunological parameters in 13 to 35 kg pigs

“…The decreasing dietary CP level decreased the relative organ weights of liver and pancreas, which is in agreement with the results by Kerr et al (1995) and Heo et al (2010). The reduction in pancreas weight of pigs fed low-CP diets may suggest a reduced amount of pancreatic protease, which would be required to digest the smaller quantity of consumed protein (Heo et al, 2010).…”

“…These results may be ascribed to the lower peptide-bound AA in low-CP diets, which decreased mucosal protein content in the small intestine . However, intestinal morphology was not affected when dietary CP level was reduced from 25.10% to 19.20% (Heo et al, 2010), in which 19.20% CP diet may have proper intact protein or peptidebound AA for pigs, compared with the other studies (Gu and Li, 2004;.…”

“…The reduction in pancreas weight of pigs fed low-CP diets may suggest a reduced amount of pancreatic protease, which would be required to digest the smaller quantity of consumed protein (Heo et al, 2010). Besides, the liver weight has been reported to decrease with decreasing dietary protein level, the lower liver may be due to an adaptation of liver to less AA metabolism in pigs receiving low-CP diet (Kerr et al, 1995).…”

“…Reducing the CP level in diets has been recognized as an effective strategy to reduce the incidence of diarrhea in piglets (Yue and Qiao, 2008;Heo et al, 2010). It is well documented that reducing dietary CP level from 16% to 12%, supplemented with indispensable amino acids (IAA), could maintain similar growth performance as pigs fed control diet (Figueroa et al, 2002 andKerr et al, 2003).…”

Establishment of a linear regression equation for quantification of beta-hemolytic Escherichia coli in different media and survival of hemolytic Escherichia coli after blending with three different media

“…The ETEC serogroup O149; K91; K88 isolated from a clinical case of PWD has been used for experimental infection of young pigs to (sub)clinically express PWD, and trypticase soy broth (TSB) is a commonly used medium for dilution of ETEC after incubation at 37ºC (Heo et al, 2010). However, the lower palatability of TSB during oral administration of ETEC during the infection procedure can cause accidental passage of ETEC into the airways, with death occurring within a few hours after infection.…”