Effects of protein sources and levels in antibiotic-free diets on diarrhea, intestinal morphology, and expression of tight junctions in weaned piglets

摘要

Abstract This study examined effects of dietary protein sources and levels on intestinal health of 21 to 35 d-old weaned piglets fed antibiotics-free diets. A total of 150 weaned piglets (21 d of age) were allotted to 5 dietary treatment groups. Diets were formulated, based on corn-soybean meal, with different protein sources (fish meal and soy protein concentrate) to provide different dietary CP levels. Piglets within 5 dietary treatments were fed diets as follows, respectively: 1) control diet of 17% CP (control); 2) 19% CP diets formulated with more soy protein concentrate (SPC19); 3) fish meal (FM19); 4) 23.7% CP diets formulated with more soy protein concentrate (SPC23); 5) fish meal (FM23). The results showed that piglets from control group had higher ADG and lower incidence of diarrhea compared with those of other groups ( P Keywords Dietary protein ; Weaned piglets ; Diarrhea ; Intestinal health ; Tight junction protein ; Antibiotic-free diets prs.rt("abs_end"); 1. Introduction Early weaning of piglets is often associated with gut disorders such as mucosal inflammation ( Pié et al., 2004 ), intestinal barrier dysfunction ( Wijtten et al., 2011 ) and diarrhea ( Caspary, 1992 and van Beers Schreurs et al., 1992 ). In-feed antibiotics in weaning diets have been used as preventative measures to alleviate these problems for decades ( Cromwell, 2002 ). Increased concerns about negative effects of antibiotics ( Chen et al., 2005 and Jensen, 2006 ), such as antibiotic-resistant bacteria have led to a partial and then a total ban on the preventive use of antibiotics in feed ( Wierup, 2001 and Gallois et al., 2009 ). Accordingly, the control of post-weaning diarrhea requires alternative strategies other than dietary antibiotics. Both dietary protein levels and sources are important causes of diarrhea in weaned piglets ( Pluske et al., 2002 ). Evidence shows that feeding a low-protein diet ( 2. Materials and methods 2.1. Animals, diets, and housing Procedures performed in this experiment were approved by the Animal Care and Use Committee of the Guangdong Academy of Agricultural Sciences. A total of 150 male weaned piglets (Duroc × Landrace × Large White, 21 d of age, initial BW 5.99 ± 0.14 kg) were randomly assigned in the balance of BW to 1 of 5 treatments, each with 6 replicates (pens) of 5 piglets. Diets ( Table 1 ) were formulated to provide 17% CP (control), 19% CP (Chinese recommended level Ministry of Agriculture of the People?s Republic of China, 2004 ), and 23.7% CP (NRC recommended level NRC, 2012 ), respectively, with increasing dietary percentages of soy protein concentrate (SPC19 and SPC23) or fish meal (FM19 and FM23) for the latter two higher CP diets. Control diet contained 17.5% soybean meal and 3% fish meal. All diets were pelleted without any in-feed antibiotics growth promoters and the levels of all essential amino acids met or exceeded the standard of NRC (2012) .