The effects of live yeast Saccharomyces cerevisiae (strain CNCM I-4407, 10(10) cfu/g; Actisaf; Lesaffre Feed Additives, Marcq-en-Baroeul, France) on the severity of diarrhea, immune response, and growth performance in weaned piglets orally challenged with enterotoxigenic Escherichia coli (ETEC) strain O149:K88 were investigated. Live yeast was fed to sows and their piglets in the late gestation, suckling, and postweaning periods. Sows were fed a basal diet without (Control; n = 2) or with (Supplemented; n = 2) 1 g/kg of live yeast from d 94 of gestation and during lactation until weaning of the piglets (d 28). Suckling piglets of the supplemented sows were orally treated with 1 g of live yeast in porridge carrier 3 times a week until weaning. Weaned piglets were fed a basal starter diet without (Control; n = 19) or with (Supplemented; n = 15) 5 g of live yeast/kg feed for 2 wk. Significantly lower daily diarrhea scores (P < 0.05), duration of diarrhea (P < 0.01), and shedding of pathogenic ETEC bacteria (P < 0.05) in feces was detected in the supplemented piglets. Administration of live yeast significantly increased (P < 0.05) IgA levels in the serum of piglets. Evidence indicates that decreased infection-related stress and severity of diarrhea in yeast-fed weaned piglets positively affected their growth capacity in the postweaning period (P < 0.05). The results suggest that dietary supplementation with live yeast S. cerevisiae to sows and piglets in the late gestation, suckling, and postweaning periods can be useful in the reduction of the duration and severity of postweaning diarrhea caused by ETEC.
Yersiniosis belongs to the common foodborne diseases around the world, and frequently manifests as diarrhea that can be treated with probiotics. Colicin FY is an antibacterial agent produced by bacteria and it is capable of specific growth inhibition of Yersinia enterocolitica, the causative agent of gastrointestinal yersiniosis. In this study, recombinant E. coli producing colicin FY were constructed, using both known probiotic strains EcH22 and EcColinfant, and the newly isolated murine strains Ec1127 and Ec1145. All E. coli strains producing colicin FY inhibited growth of pathogenic Y. enterocolitica during co-cultivation in vitro. In dysbiotic mice treated with streptomycin, E. coli strains producing colicin FY inhibited progression of Y. enterocolitica infections. This growth inhibition was not observed in mice with normal gut microflora, likely due to insufficient colonization capacity of E. coli strains and/or due to spatial differences in intestinal niches. Isogenic Y. enterocolitica producing colicin FY was constructed and shown to inhibit pathogenic Y. enterocolitica in mice with normal microflora. Evidence of in vivo antimicrobial activity of colicin FY may have utility in the treatment of Y. enterocolitica infections.
ABSTRACT:The aim of the study was to verify under experimental conditions the hypothesis that a reliable protection of piglets against Actinobacillus pleuropneumoniae (App) infection can be obtained by colostrum-derived antibodies and/or a low-dose infection from sows naturally infected with App. Twenty-eight piglets were allocated into four groups. Piglets of groups 1A and 1B were the progeny of App-seronegative sows, piglets of groups 2A and 2B originated from App-seropositive sows. At the age of 4 weeks, piglets in groups 1A and 2A were exposed to a low infection dose with the pathogenic strain of App serotype 9 (4 × 10 4 CFU/ml). At the age of 8 weeks, all four groups of piglets were exposed to the App serotype 9 challenge (2.5 × 10 7 CFU/ml). We compared the differences in clinical, radiological, pathological changes and cytological findings in blood and bronchoalveolar lavage samples between groups with different levels of antigen-specific immunity after challenge. Piglets that obtained colostrum-derived antibodies and experienced a low-dose App infection were best protected against App challenge. More apparent clinical and pathological changes were observed in groups protected with either only colostrumderived antibodies or active immunity induced by a preceding low-dose infection. However, none of the types of protection prevented developing of the disease and characteristic changes in the lungs. Cell counts changes in blood and lavage gave evidence of only bacterial infection in progress; however, between-group differences were not marked. Antibodies (IgG, IgA) present in the respiratory tract at the time of challenge played a major role in protection against App infection.
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