A standardised challenge model with an enterotoxigenic F4+Escherichia colistrain in piglets assessing clinical traits and faecal shedding offaeandest-IItoxin genes

Abstract

This study evaluated the effect of five feed additives on post weaning diarrhoea (PWD) in piglets challenged 3 d after weaning with an enterotoxigenic Escherichia coli strain (ETEC). In three experimental runs, a total of 84 piglets was weaned at 21 days of age and randomly assigned to seven treatments. As dietary treatment, piglets were fed a basal diet or diets with addition of bovine colostrum (0.2%), pineapple stem extract containing bromelain (0.2%), an autolysed yeast preparation (Saccharomyces cerevisiae) (0.1%), a combination of organic acids (0.7%) and a phytogenic product with thyme essential oil (0.015%). A porcine ETEC, serotype O149:K91:K88ac was given twice via oral infection on day 3 after weaning at 10(10) colony forming units/animal. One group of piglets was fed the basal diet without ETEC challenge. Traits included clinical sores, body temperature, faecal scoring and determination of faecal dry matter and the shedding of fae and est-II ETEC toxin genes. After weaning, non-challenged control piglets did not show signs of diarrhoea or impaired health, while the majority of infected piglets had a drop in body temperature, signs of diarrhoea and impaired general health. Mortality, the decrease of faecal dry matter and shedding of the toxin genes fae and est-II were not affected by the different additives. In conclusion, the ETEC challenge model induced distinct clinical signs of PWD in piglets, but the tested feed additives had no preventive effect under these conditions.

Methodology and application of Escherichia coli F4 and F18 encoding infection models in post-weaning pigs

“…In the study of Kyriakis et al [43], the animals were chosen from a farm with poor environmental and management conditions, and in which the piglets already exhibited the ETEC F4 infection. Other studies, including Trevisi et al [44] and Spitzer et al [45], took piglets from farms in which previous cases of ETEC infection had occurred in order to increase the probability of having ETEC-susceptible animals. Responses to ETEC F4 and F18 infection showed high individual animal variability, which can partially be explained by the animals’ genetic mutations associated with the expression of specific receptors on the intestinal epithelium.…”

“…Preconditioning procedures should be carried out to contain the within variability of the piglets’ response to the ETEC challenge on the basis of their physiological status before the infection. Among preconditioning procedures, pigs can initially be treated with antibiotics, including colistin (50/60 mg per pig) [45, 84–86] or florfenicol (2 mL per pig) [87], in order to keep the animals in a healthy condition before ETEC inoculation or to contrast the effects of the weaning transition. However, this practice poses some risks; in fact, the prolonged administration of antibiotics can reduce the gut microbial variability, compromise the gut eubiosis and impair animal health [88].…”

“…and posFecal score; fecal coliforms count6 dpi[101]48d28NoF4 + O1492 × 10 10 CFU/mLFrom 1 to 2 dpwNADiarrhea, ETEC shedding in feces11 dpi[100]524d28NoF4+ O1496, 8 and 10 mL of 3.44 × 10 8 CFU/mLFrom 5 to 7 dpwNADiarrhea; ETEC fecal shedding7 dpi[112]68d28NoF43 mL of 3 × 10 10 CFU/mL7 dpwNeg. groupDiarrhea; ETEC shedding in feces; Post-mortem examination7 dpi[104]76d 25NoF4% mL of 5 × 10 8 CFU/mLAt weaningNADiarrhea; ETEC shedding in feces7 dpi[99]824d 21NoF46, 8 and 10 mL of 2.16 × 10 8 CFU/mLFrom 3 to 6 dpwNegDiarrhea: haemolytic E. coli fecal shedding11 dpi[103]912d21YesF4ac2 mL of 5.0 × 10 9 CFU/mLFrom 3 to 4 dpwNegGeneral condition scores of pigs behaviour; diarrhea; RT g ; fecal fae and est-II concentrations7 dpi[45]107d28NoF41.5 mL of 10 × 10 10 CFU/mL14 dpwNADiarrhea; E. coli in feces; blood Igs28 dpi[107]1110d24NoF41.5 mL of 10 × 10 8 CFU/mL7 dpwPosDiarrhea; ETEC shedding in feces; blood total IgA and F4ac-specific IgA14 dpi[13]125d21NoF41 mL of 1 × 10 9 CFU/mL7 dpwNeg and PosDiarrhea8 dpi[105]136d21NoF41 mL of 1 × 10 9 CFU/mL9 dpw…”

Animal Enterotoxigenic Escherichia coli

“…This toxin has also been detected in ETEC of human origin (432, 433). STb is recognized as a potent enterotoxin in weaned pigs (292, 434–436). …”

Effects of medium-chain fatty acids on the structure and immune response of IPEC-J2 cells

“…High efforts are carried out in the search of alternatives to substitute or decrease the use of antibiotics in animal production (Allen et al 2013;Seal et al 2013). In pig production, a diverse range of feed additives has been tested like probiotics, zinc, organic acids, plant extracts, microbial by-products or dairy products and others (Roselli et al 2005;González-Ortiz et al 2014;Pluske 2013;Spitzer et al 2014). …”