L. Casini

A tryptophan-enriched diet improves feed intake and growth performance of susceptible weanling pigs orally challenged with Escherichia coli K88

We tested the effect of Trp addition to a standard weaning diet and oral challenge with enterotoxigenic Escherichia coli K88 (ETEC) on growth and health of piglets susceptible or nonsusceptible to the intestinal adhesion of ETEC. Sixty-four pigs weaned at 21 d of age were divided into 3 groups based on their ancestry and BW: a control group of 8 pigs fed a basal diet (B), the first challenged group of 28 pigs fed B diet (BCh), and the second challenged group of 28 pigs fed a diet with Trp (TrpCh). The Trp diet was produced by the addition of 1 g of l-Trp/kg to the basal diet. On d 5, pigs were orally challenged with 1.5 mL suspension containing 10(10) cfu ETEC/mL or placebo, and killed on d 9 or 23. Based on in vitro villus adhesion assay, the pigs (except the B group) were classified as susceptible (s(+)) or nonsusceptible (s(-)) to the intestinal ETEC adhesion. Thus, after the challenge, treatments were B, BChs(-), BChs(+), TrpChs(-), and TrpChs(+). Pigs susceptible to ETEC were 50.0% in the BChs(+) group (3 pigs lost included) and 46.4% in the TrpChs (+) group (1 pig lost included). During the first 4 d after challenge, the challenge reduced ADG (P < 0.05), and this reduction was greater in susceptible pigs (P < 0.05) than nonsusceptible ones. Tryptophan increased ADG and feed intake in susceptible pigs (P < 0.05) from challenge to d 4, but not thereafter. Tryptophan supplementation did not improve the fecal consistency and did not reduce the number of pigs positive for ETEC in feces on d 4 after the challenge. The K88-specific immunoglobulin A activity in blood serum tended to be greater in challenged pigs (P = 0.102) and was not affected by the addition of Trp. Villous height was affected by the addition of Trp and challenge in different ways, depending on the site of small intestine. The need to consider the phenotype for the adhesion of the ETEC in studies with different supply of Trp was clearly evident. When compared with practical weaning standard diets, Trp supplementation allowed susceptible pigs to partially compensate for the effects of ETEC challenge by increasing feed intake and maintaining an adequate BW growth. This is of practical importance for the formulation of diets for pigs selected for lean growth because of the presence of an association between this trait and the susceptibility to the intestinal adhesion of ETEC.

Effect of dietary addition of nitrate on growth, salivary and gastric function, immune response, and excretion of Salmonella enterica serovar Typhimurium, in weaning pigs challenged with this microbe strain

Abstract 64 weaned pigs (24d-old), were fed a control diet or a control plus 1% thymol diet, with or without Salmonella typhimurium challenge. Thymol reduced feed intake but did not affect significantly the final body weight after 29d of trial. Salmonella did not affect the performances. Body temperature was lower in the thymol group before, but also 1d after challenge, when Salmonella increased the values more in unsupplemented pigs. Fecal excretion of S. typhimurium in challenged pigs was not changed by the diet. The thymol group had a higher concentration of immunoglobulin (Ig) in serum before the challenge, but after there was an interaction between diet and challenge. The diet and the challenge did not affect saliva parameters, and ATPase gene expression in the fundic gastric mucosa. Thymol increased the number of parietal cells for 100 µm depth of oxintic gland. In conclusion the important supplementation with thymol reduced the intake, but not performance in the medium period. Some factors of the gut barrier were positively influenced. Salmonella challenge did not reduce significantly the performance of the weaned piglet.

Feed supplemented with 3 different antibiotics improved food intake and decreased the activation of the humoral immune response in healthy weaned pigs but had differing effects on intestinal microbiota.

The aim of this study was to determine the effects of 3 antibiotics used for pulmonary pathologies added in the feed of weaned pigs on growth performance, commensal microbiota, and immune response. At weaning, a total of 72 pigs were randomly assigned by BW and litter to 1 of the following diets: control (typical weaning diet), control + 400 mg of tilmicosin/kg, control + 600 mg of amoxicillin/kg, and control + 300 mg of doxycycline/kg. Individually penned pigs were slaughtered after 3 wk (12 pigs/treatment) or 4 wk (6 pigs/treatment). During the fourth week, all pigs received the control diet to test the residual effect of the antimicrobial supplementation. The antibiotic supplementation increased growth and feed intake during the first week (P < 0.01) and over the first 3 wk combined (P < 0.05). Gain-to-feed ratio tended to improve during the first week (P = 0.076) by the antibiotics compared with the control. Among the antibiotic treatments, no difference was observed in ADG and feed intake, which were also unchanged by the diet in the fourth week. The fecal enterobacteria counts were increased by amoxicillin on d 14 and 21 (P < 0.05 and 0.01, respectively) and were decreased by tilmicosin (P < 0.001) compared with the control. Amoxicillin decreased lactic acid bacteria (P < 0.01) counts compared with the control. The antibiotic supplementation tended to decrease total bacteria variability in the jejunum (Shannon index, P = 0.091) compared with the control. The antibiotic treatment decreased the mean total serum IgM concentration (P = 0.016) after 3 wk and did not change the mucosal histomorphometry of the small intestine. For tilmicosin, the observed positive action on piglet performance and feed intake can originate by the decreased costs of immune activation determined by the action on intestinal microbiota. For amoxicillin and doxycycline, the observation on intestinal and fecal microbiota seems to be not sufficient to explain their growth-promoting effect.

Dietary addition of Lactobacillus rhamnosus GG impairs the health of Escherichia coli F4-challenged piglets.

Lactobacillus rhamnosus GG (LGG) is a probiotic for humans and is normally not found in pigs; however, it has been shown to protect the human-derived intestinal Caco-2 cells against the damage induced by an important intestinal pathogen, enterotoxigenic Escherichia coli F4 (ETEC). An experiment was conducted to test whether the dietary addition of LGG improves the growth and health of weaned pigs when orally challenged by E. coli F4. Thirty-six pigs were weaned at 21 days and assigned to a standard weaning diet with or without 1010 CFU LGG (ATCC 53103) per day. The pigs, individually penned, were orally challenged with 1.5 ml of a 1010 CFU E. coli F4 suspension on day 7 and slaughtered on day 12 or 14. With the addition of LGG, the average daily gain and the average daily feed intake were reduced after the challenge with ETEC and for the entire trial (P < 0.05). The average faecal score tended to worsen from day 11 to the end of the trial and the concentration of ETEC in the faeces tended to increase (P = 0.07) with the LGG supplementation. The counts of lactic acid bacteria, enterobacteria and yeasts in the colonic digesta were not affected. The pH values in ileal, colonic and caecal digesta, and the small intestine size were also unchanged. Regardless of the site of measurement (duodenum, jejunum or ileum), a trend of decreased villus height was seen with LGG (P = 0.10). Crypt depth and villus to crypt ratio were unchanged by the diet. A gradual increase of total seric IgA was seen after 1 week and after the challenge, in the control (P < 0.05), but not in the treated group. After the challenge, the LGG reduced the total IgA in the blood serum (P < 0.05), v. the control. The total IgA in the saliva and in the jejunum secretion were not affected by the diet. The F4-specific IgA activity was not affected by the diet at all the samplings. Our result shows that, the administration of LGG do not prevent or reduce the detrimental effect of the E. coli F4 infection on the growth performance and health status of weaned piglet.

Production performance of dairy cows after the dietary addition of clinoptilolite

Abstract Clays are frequently proposed for the addition to dairy cattle diets to reduce the transfer of mycotoxins in milk. This study examined the effect of the addition of Clinoptilolite to the diet of lactating dairy cows on milk production and milk composition. Thirty-two lactating Holstein cows (average lactation length: 142 d) were blocked according to milk production, parity, and days of lactation for assignment to one of two dietary treatments: control diet; control diet + Clinoptilolite, 200g/d. The control diet was based on corn and alfalfa silages, hay and concentrates, and did not contain aflatoxins above the safe level. The experimental period lasted 76 days. The Clinoptilolite supplementation did not affect milk yield and milk composition other than urea contents. The urea level in milk was negatively affected by Clinoptilolite addition (control group 29.7 mg/100 ml vs Clinoptilolite group 31.3 mg/100ml). The dietary addition of Clinoptilolite did not change pH, ammonia content and VFA molar percentages in the rumen. No dietary effect on mineral contents of blood plasma (Na, K, Zn, and Ca) was observed. In case of clinoptilolite use in dairy cattle feeding, scarce negative effect on milk production and quality are expected.

Effect of dietary addition of free or fat-protected calcium formate on growth, intestinal morphology and health of Escherichia coli k88 challenged weaning pigs

Riassunto Effetto dell’integrazione della dieta con formiato libero o protetto sulla crescita, la morfologia intestinale e la salute di suini in svezzamento stimolati per os con Escherichia coli K88. Sessanta suini, svezzati a 21 giorni (d 0), sono stati divisi in 3 gruppi, bilanciati per numero, peso e nidiata ed alimentati con: dieta standard (C), C + 1,2% calcio formiato, C + 1,2% calcio formiato protetto con grasso. Al giorno 2, i suini sono stati stimolati oralmente con 1,5 ml di una sospensione con 1010 CFU Escherichia coli K88 O148 e sacrificati ai giorni 7 e 8. L’impiego di formiato libero ha migliorato la crescita e l’ingestione, il formiato protetto ho prodotto solo una tendenza al miglioramento. Le due fonti di formiato hanno ridotto l’incidenza di diarrea, l’escrezione fecale di E. coli, le IgA anti E. coli K88 nella saliva e aumentato l’altezza dei villi del piccolo intestino. L’acido formico ha una funzione di promotore di crescita anche in suini stressati con E. coli enterotossigenico. La sua azione è stata però legata principalmente all’effetto sulla persistenza di E. coli totali. Non è emersa una particolare convenienza dall’uso di formiato protetto.

Effect of high oral doses of nitrate on salivary recirculation of nitrates and nitrites and on bacterial diversity in the saliva of young pigs

Ingested nitrate is absorbed in the small intestine, recirculated into the saliva and reduced to nitrite by oral bacteria. In pigs receiving a moderate dietary addition of nitrate, the recirculation into the saliva is modest, so we aimed to assess the effect of higher nitrate doses to find out how the animal reacts to this new situation and to evaluate if a higher nitrate level could enhance the nitrate reduction process, improving the nitrite production Trial 1. Six piglets received 100 g of a commercial diet with 2.45% KNO(3) . In relation to baseline values, nitrate in blood serum and saliva increased 15 times, and declined after 6 h vs. 2 h. Salivary nitrite increased seven times after the addition and declined after 6 h vs. 2 h. Trial 2. Six piglets were fed a diet with or without 1.22% KNO(3) for 2 weeks. Salivary nitrate and nitrite increased with the addition of KNO3: nitrate increased from d0 to the end of the trial, nitrite increased 15 times after 1 week, but decreased after 2 weeks to 4.5-fold the control. After 2 weeks, nitrate reduced Shan diversity index of salivary microbiota. The present results indicate that the long exposure to high quantities of nitrates impairs the oral reduction of nitrate to nitrite and engenders a reduction of the mouths microbiota diversity.

Relevance of immune response against resident and not resident commensal strains for the definition of strategies of probiotic supply in the diet of weaning pigs

Riassunto Importanza della risposta immunitaria nei confronti di commensali residenti e non, per la definizione di strategie d’impiego di probiotici nella dieta del suino in svezzamento. Con l’impiego di probiotici spesso si osserva una maggiore risposta umorale, ma non è documentato se l’animale d’allevamento reagisca anche contro lo stesso probiotico. Sono stati analizzati campioni di sangue e saliva raccolti in due prove di somministrazione di probiotici a suini in svezzamento: A) Lactobacillus rhamnosus GG, non tipico del suino; B) Lactobacillus sobrius 001T, isolato dal suino. Anticorpi probiotico specifici sono stati riscontrati nel siero dei soggetti prima del trattamento (prova A) e nei gruppi di controllo, nonostante l’assenza di DNA ceppo-specifico nel loro contenuto intestinale (prova A e B). Utilizzando un test ELISA su siero o saliva preincubati con uno o l’altro dei lattobacilli, si è visto che ciascuno di questi lega parte delle IgA specifiche per l’altro. Quindi batteri con differente affinità per il suino possono presentare attività immunologia crociata reciproca. Nella definizione dell’impiego di un probiotico nella dieta del suinetto si deve valutare con attenzione la presenza di anticorpi già attivi prima della sua somministrazione.

Effect of different butyrate supplementations on growth and health of weaning pigs challenged or not with E. coli K88

Abstract In a full factorial design (4 diets X challenge, Yes/No), 72 weaning pigs were assigned to one of the diets: Control; experimental diets, obtained with the addition of 2 g/kg free sodium butyrate (fNaB), or 0.6 g/kg fat-protected sodium butyrate (pNaB), or 2 g/kg INVE commercial mixture (Mix, based on 75 g/kg protected butyrate). Oral challenge with Escherichia coli K88 was done on 2/3 of pigs on d 7. Pigs were slaughtered on d 13. The mortality in challenged pigs, tended to be higher in control group (50.0%) than in the three supplemented groups (23.5%). Growth tended to be increased averagely by the supplements (P=0.100) after the challenge, that also significantly reduced growth. In general the diet did not affect the fecal shedding of Escherichia coli and Lactobacilli, the K88-specific IgA activity in blood, the morphology of oxyntic mucosa and the expression of H+/K+-ATPase gene. The supplementations tended to increase villous length of jejunum (P=0.101). On the whole, growth, villous height and surviving rate can be positively affected either when the supplementation is done by free butyrate, by protected butyrate or by the special Inve Nutri-Ad product and these effects are distributed both on pigs infected or not with Escherichia coli K88.