Effects of dietary protein supply, weaning age and experimental enterotoxigenic Escherichia coli infection on newly weaned pigs: health

Weaning is often associated with post-weaning colibacillosis (PWC), caused by enterotoxigenic Escherichia coli (ETEC). The objective was to investigate the effects of manipulating dietary protein supply and increasing weaning age on enteric health and ETEC shedding of newly weaned pigs exposed to an experimental ETEC challenge. The experiment consisted of a complete 2 × 2 × 2 factorial combination of weaning age (4 v. 6 weeks), dietary protein content (H, 230 g crude protein (CP)/kg v. L, 130 g CP/kg) and experimental ETEC challenge (+ v. -); all foods were free from in-feed antimicrobial growth promoters (AGP). An additional four treatments were added to allow the effect of protein source (DSMP, dried skimmed milk powder v. SOYA, soybean meal) and AGP inclusion (yes v. no) to be investigated in challenged pigs of both weaning ages. On day 3 post-weaning challenged pigs were administered per os with 109 cfu ETEC O149. A subset of pigs was euthanased on days 0 and 6 post weaning to assess enteric health and small intestine morphology. Both weaning age and dietary protein content affected the consequences of ETEC challenge. ETEC excretion persisted longer in the 4-week-weaned pigs than those weaned at 6 weeks. Although not significant, the numbers of ETEC shed in the faeces post infection (days 4 to 14) were higher on the H than L diet, especially in the 4-week-weaned pigs (P = 0.093). Lowering CP level led to significantly firmer faeces post challenge (days 3 to 6) and decreased colonic digesta pH. Protein level had no effect on small intestine villous heights or crypt depths. There was no significant effect of protein source on ETEC excretion or enteric health. Results suggest that increasing weaning age and decreasing the level of dietary protein, especially in earlier weaned pigs, may help to maintain enteric health and minimise the effects of PWC.     

Effect of increasing the dietary tryptophan to lysine ratio on plasma levels of tryptophan,kynurenine and urea and on production traits in weaner pigs experimentally infected with an enterotoxigenic strain of Escherichia coli‡

This experiment examined if immune system stimulation of weaner pigs, initiated by inoculation an enterotoxigenic strain of Escherichia coli (ETEC), increased the requirement for dietary tryptophan (Trp), modulated the inflammatory response, altered plasma levels of Trp and its metabolite kynurenine (Kyn) and effected post-weaning diarrhoea. Individually housed pigs (n = 72) weaned at 21 d of age were allocated to one of six treatments (n = 12) according to a two by three factorial arrangement of (1) with or without ETEC infection and (2) three dietary ratios of standardised ileal digestible (SID) Trp to lysine (Lys) (SID Trp:Lys) of 0.16, 0.20 or 0.24, in a completely randomised block design. Pigs had ad libitum access to diets (per kg 14.13 MJ ME, 12.4 g SID Lys, 195 g crude protein) for 3 weeks after weaning. Pigs were infected with ETEC (O149:K98:K88) at 72, 96 and 120 h after weaning and then bled on day 3, 11 and 19. An increased dietary Trp:Lys ratio increased plasma Trp and Kyn (p < 0.001) without effect of infection. On day 3, pigs fed 0.24 SID Trp:Lys had lower levels of plasma urea than at 0.20 Trp:Lys (p = 0.047) and on day 11, plasma urea was lower at 0.20 than at 0.16 SID Trp:Lys (p = 0.007). Infection increased (p = 0.039) the diarrhoea index and deteriorated faecal consistency from day 4–10 (p < 0.05). Treatments did not affect haptoglobin and acid soluble glycoprotein levels or daily gain and feed intake. However, 0.24 SID Trp:Lys improved (p = 0.021) feed efficiency without an effect of infection. In conclusion, in the absence of dietary antibiotic growth promotants, increasing the dietary SID Trp:Lys ratio to 0.24 improved feed conversion ratio after weaning and increased plasma levels of Trp and Kyn regardless of infection with E. coli.     

Early Weaning Stress in Pigs Impairs Innate Mucosal Immune Responses to Enterotoxigenic E. coli Challenge and Exacerbates Intestinal Injury and Clinical Disease

Background and Aims

The clinical onset and severity of intestinal disorders in humans and animals can be profoundly impacted by early life stress. Here we investigated the impact of early weaning stress in pigs on intestinal physiology, clinical disease, and immune response to subsequent challenge with enterotoxigenic F18 E. coli (ETEC).

Methodology

Pigs weaned from their dam at 16 d, 18 d, and 20 d of age were given a direct oral challenge of F18 ETEC at 26 d of age. Pigs were monitored from days 0 to 4 post-infection for clinical signs of disease. On Day 4 post-ETEC challenge, ileal barrier function, histopathologic and inflammatory cytokine analysis were performed on ileal mucosa.

Results

Early weaned pigs (16 d and 18 d weaning age) exhibited a more rapid onset and severity of diarrhea and reductions in weight gain in response to ETEC challenge compared with late weaned pigs (20 d weaning age). ETEC challenge induced intestinal barrier injury in early weaned pigs, indicated by reductions in ileal transepithelial electrical resistance (TER) and elevated FD4 flux rates, in early weaned pig ileum but not in late weaned pigs. ETEC-induced marked elevations in IL-6 and IL-8, neutrophil recruitment, and mast cell activation in late-weaned pigs; these responses were attenuated in early weaned pigs. TNF levels elevated in ETEC challenged ileal mucosa from early weaned pigs but not in other weaning age groups.

Conclusions

These data demonstrate the early weaning stress can profoundly alter subsequent immune and physiology responses and clinical outcomes to subsequent infectious pathogen challenge. Given the link between early life stress and gastrointestinal diseases of animals and humans, a more fundamental understanding of the mechanisms by which early life stress impacts subsequent pathophysiologic intestinal responses has implications for the prevention and management of important GI disorders in humans and animals.     

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.     

Impact of early inoculation of probiotics to suckling piglets on postweaning diarrhoea – A challenge study with Enterotoxigenic E. Coli F18

Postweaning diarrhoea caused by Enterotoxigenic Escherichia coli (ETEC) is a threat to the pig industry. With an intensified focus on finding alternatives to the use of medical zinc oxide and antibiotics in newly weaned pigs, the objective of this study was to investigate the effect of early inoculation of probiotics to suckling piglets on subsequently ETEC faecal shedding and immune parameters in ETEC F18-challenged weaned piglets. Sixty pigs weaned on day 28 of age were assigned to three treatment groups: (i) Negative Control (non-challenged), (ii) Positive Control (challenged) and (iii) Probiotic (challenged and inoculated with a multi-species probiotic product during suckling). On days 1 and 2 postweaning, pigs in the Positive Control and Probiotic groups were challenged with 5 × 10⁸ colony-forming unit ETEC F18/pig/day, whereas pigs in the Negative Control group were provided with NaCl. Growth and diarrhoea incidence were not significantly affected by ETEC challenge or probiotic administration. ETEC F18 shedding and C-reactive protein concentration in plasma were significantly lower in the Negative Control group, confirming a successful challenge model. Pigs in the Probiotic group had a significantly reduced number of pigs shedding ETEC F18 and STb toxin in faeces compared with the Positive Control group. Probiotic application did not significantly impact the concentration of C-reactive protein, haptoglobin and cytokines in plasma nor haematology numbers. In conclusion, weaned pigs administered with a multi-species probiotic product early in life had a more rapid response towards the pathogen challenge and a faster clearance of ETEC compared with the Positive Control group. Administration of a multi-species probiotic to newborn piglets may thus promote resilience in the newly weaned pig. However, further studies with pigs subjected to a more severe pathogen challenge are needed to confirm these results and to investigate the mechanism of action of the probiotic intervention.     

Increased number of intestinal villous M cells in levamisole -pretreated weaned pigs experimentally infected with F4ac+ enterotoxigenic Escherichia coli strain

Immunoprophylaxis of porcine postweaning colibacillosis (PWC) caused by enterotoxigenic Escherichia coli (ETEC) expressing F4 fimbriae is an unsolved problem. Just as ETEC strains can exploit intestinal microfold (M) cells as the entry portal for infection, their high transcytotic ability make them an attractive target for mucosally delivered vaccines, adjuvants and therapeutics. We have developed a model of parenteral/oral immunization of 4-weeks-old pigs with either levamisole or vaccine candidate F4ac⁺ non-ETEC strain to study their effects on de novo differentiation of antigen-sampling M cells. Identification, localization and morphometric quantification of cytokeratin 18 positive M cells in the ileal mucosa of 6-weeks-old pigs revealed that they were: 1) exclusively located within villous epithelial layer, 2) significantly numerous (P< 0.01) in levamisole pretreated/challenged pigs, and 3) only slightly, but not significantly numerous in vaccinated/challenged pigs compared with non-pretreated/challenged control pigs. The fact that levamisole may affect the M cells frequency by increasing their numbers, makes it an interesting adjuvant to study development of an effective M cell-targeted vaccine against porcine PWC.Key words: M cells, levamisole, E. coli vaccine, weaned pigs.     

Small intestine growth and morphometry in piglets weaned at 7 days of age. effects of level of energy intake

Two trials involving a total of 56 pigs were conducted to examine the effects of weaning at 7 d of age (trial 1) and of energy intake level and length of post-weaning underfeeding period (trial 2) on small intestinal (SI) development and morphometry. At 3 d after weaning, weight of the SI and mucosa (g/kg body weight) and villous height along SI were reduced by 20, 36 and 41%, respectively, compared to the day of weaning. Intestinal morphometrical changes are dependent on SI site and days post-weaning. Villous atrophy on d 3 and recovery on d 14 post-weaning were greater and occurred earlier in the proximal than in the medial and distal SI. Villous height was dependent on the level of energy intake which explains 56% of the variations in proximal SI villous height in weaned pigs and 73% when data of the sow-reared pigs were included in the analysis. Moreover, after 4 d of refeeding, underfed piglets showed similar villous characteristics to piglets fed a continuously high feeding level after weaning stressing that capacities of intestinal restoration were not affected by the length of the post-weaning underfeeding period. Overall, the present results suggest a spatial and temporal effect of weaning on villous atrophy and recovery, and that the level of energy intake is a major factor accounting for the post-weaning villous height.     

Effect of rearing environment and dietary zinc oxide on the response of group-housed weaned pigs to enterotoxigenic Escherichia coli O149 challenge

A 2 × 2 factorial experiment was conducted to determine the effects of rearing environment (indoor (In) v. outdoor (Out)) and dietary zinc oxide (ZnO) supplementation (0 (-Zn) v. 3100 (+Zn) mg/kg feed) on the response of weaned pigs to a challenge infection with enterotoxigenic Escherichia coli (ETEC). Pigs from the two rearing environments were weaned onto trial diets at 4 weeks of age, moved into conventional accommodation and infected 3 days later with 109 CFU ETEC per os. Faecal ETEC shedding was determined before and after challenge. After 7 days of ETEC infection, all pigs were euthanized for gut lactic acid bacteria (LAB)-to-coliform ratio, pH and small intestine morphological measurements. Both ZnO and outdoor rearing reduced ETEC excretion, and these effects were additive. Outdoor rearing increased small intestine and colon tissue weight. ZnO increased villus height and goblet cell number in the upper small intestine, LAB-to-coliform ratio (through reduced coliforms) in the lower small intestine and proximal colon, and improved growth performance. There were interactive effects of rearing environment and ZnO supplementation on upper small intestine villus height and daily gain, as outdoor rearing conferred advantages on these variables only with ZnO dietary supplementation. Daily gains were 233, 174, 277 and 347 (s.e.m. 27.2) g/day for the In - Zn, Out - Zn, In + Zn and Out + Zn, respectively. These results suggest different, but complementary mechanisms of intestinal health and performance in outdoor-reared pigs and those offered ZnO supplemented diets. The results indicate that the benefits of ZnO to the weaned pig extend beyond suppression of ETEC and appear mediated through altered development of the small intestine mucosa.     

A glucocorticoid receptor agonist improves post-weaning growth performance in segregated early-weaned pigs

While beneficial for sow reproductive efficiency and biosecurity, segregated early weaning (SEW) leads to a systemic immune response that adversely affects the digestive physiology and post-weaning growth of pigs. Two experiments were conducted to evaluate the effects of a glucocorticoid receptor agonist (GA) on growth performance, measures of immune function and intestinal integrity of SEW pigs. In both experiments, pigs were fed corn-soybean meal-based starter diets. In the first experiment, 48 pigs (initial BW 4.8 ± 0.7 kg) were weaned at 21 ± 1 days and randomly assigned to three GA treatment groups: 0, 0.2 and 0.6 mg GA/kg of BW injected intramuscularly. Treatments were administered one day before weaning. Pigs in the 0 mg GA group received sterile saline in place of GA. Body weight was measured daily from one day before to 7 days post-weaning, and then weekly until 28 days post-weaning. Piglets treated with 0.2 mg GA had a higher BW than piglets in other treatment groups during the 28-day course of the study (P <0.02). To further explore the mechanisms behind this result, a second experiment was performed in which a total of 18 gilts (BW 5.6 ± 0.85 kg) were randomly assigned into three treatment groups: suckling plus saline (UWS), weaned treated with GA (WGA; 0.2 mg GA/kg BW) and weaned plus saline (CON). Treatments were administered one day before and 3 days post-weaning. The WGA and CON groups were weaned at 23 ± 2 days, while the UWS group remained with sow for the duration of the study. Body weight was measured daily and blood plasma was collected at 0, 1, 4 and 5 days post-weaning. All gilts were euthanized 5 days after weaning and jejunum samples were collected for mucosal scrapings, histomorphological analysis and gene expression analysis. Plasma levels of interleukin-1β (IL-1β) and haptoglobin were lower in WGA pigs compared with CON (P <0.02), while plasma total antioxidant capacity was higher in WGA pigs compared with both CON and UWS groups (P <0.01). Relative to CON, GA downregulated IL-18 gene expression in the jejunum, as assessed by both tissue homogenate and mucosal scrapings, but it upregulated claudin-IV gene expression only in the tissue homogenate (P <0.01). These results suggest that GA treatment improves the growth performance of SEW pigs in part by mitigating the negative effects of systemic inflammation. However, the effect of GA on barrier integrity requires further investigation.     

The effect of zinc oxide supplementation on the stability of the intestinal flora with special reference to composition of coliforms in weaned pigs

The effect of a dietary supplementation of zinc oxide (ZnO) on the stability of the intestinal flora and on the composition of coliforms in weaned pigs was investigated. Faecal floras were characterized by their metabolic activities and fermentative capacity (FC) using the Phene Plate generalized microplate. Coliforms were characterized by conventional enumeration and by the Phene Plate-RS plates. The latter measured FC, phenotypic diversity, persistence of each coliform strain in piglets, and similarity among the coliform populations within groups. From weaning onwards, the control pigs (n = 5) were fed a basal diet ad libitum, while experimental pigs (n = 5) were given the same food supplemented with 2500 ppm ZnO. Metabolic fingerprinting of faecal floras indicated marked differences between the composition of floras of treated and control pigs during the first 2 weeks post-weaning. The FC of faecal flora in both groups decreased as pigs aged, but it was significantly (P 相似文献   

Health-promoting effects of Lactobacillus-fermented barley in weaned pigs challenged with Escherichia coli K88 +

Fermented feeds are being considered as practical alternatives to antimicrobial growth promoters (AGP) supplemented in nursery pig diets. This study aimed to investigate health-promoting effects of fermented barley in weaned pigs challenged with Escherichia coli K88 ⁺. A total of 37 piglets were weaned at 21 ± 1 day of age (6.41 ± 0.47 kg of BW) and assigned to either of the following five treatment groups: (1) unchallenged control (UCC; n = 7), (2) challenged control (CC; n = 7), (3) AGP (CC + 0.1% AGP; n = 7), (4) Ferm1 (challenged and fed homofermentative Lactobacillus plantarum (Homo)-fermented barley; n = 8) and (5) Ferm2 (challenged and fed heterofermentative L. buchneri (Hetero)-fermented barley; n = 8). The control diet included unfermented barley. Barley was fermented with either Homo or Hetero for 90 days under anaerobic conditions. On day 10, all pigs except those in UCC group were orally inoculated with E. coli K88 ⁺ (6 × 10⁹ colony forming units/ml). The pre-planned orthogonal test was performed to compare (1) UCC and CC, (2) CC and AGP, (3) CC and Ferm1 + Ferm2, as well as (4) Ferm1 and Ferm2. Challenged control pigs showed shorter (P < 0.05) villus height (VH) in the duodenum and deeper (P < 0.05) crypt depth (CD) in the jejunum than UCC pigs. The AGP group had higher (P < 0.05) VH and lower (P < 0.05) IL-6 gene expression in the jejunum compared with CC group. Compared to CC, Ferm1 and Ferm2 had decreased (P < 0.05) CD in the duodenum, IL-6 gene expression in the jejunum and rectal temperature at 24 h post-challenge. Pigs fed fermented barley diets showed greater (P < 0.05) faecal abundance of Clostridium Cluster IV and Lactobacilli than those fed UCC diet. Ferm2-fed pigs showed lower (P < 0.05) concentrations of band cells, eosinophils and lymphocytes at 6, 24 and 48 h after challenge, respectively, and lower (P < 0.05) faecal abundance of Enterobacteriaceae 24 h after challenge than the Ferm1-fed pigs. In conclusion, the substitution of unfermented barley with fermented barley in a nursery diet showed similar results as those shown by AGP supplementation in terms of enhancing the intestinal morphology and modulating faecal microbiota composition, as well as down-regulating the pro-inflammatory cytokines; therefore, fermented barley can be a possible nutritional strategy for managing nursery pigs fed diets without in-feed AGP.     

Partial replacement of triticale for corn grain in starter diet and its effects on performance,structural growth and blood metabolites of Holstein calves

The primary objective of this study was to examine the effects of different inclusion rates of dietary triticale replacing corn grain in starter rations of dairy calves on feed intake, average daily gain (ADG), feed efficiency, skeletal growth, fecal score, and selected blood and ruminal parameters. In all, 30 4-day-old Holstein calves (15 female and 15 male) were blocked by gender and birth weight, and then randomly allotted to three treatment groups (n=10 calves/treatment) and received either a corn-based diet without triticale (T0), or a diet containing 16% (T16) or 32% (T32) triticale (25% and 50% corn replaced by triticale, respectively) for 10 weeks. Calves were weaned on day 43 of study and remained on the study until day 70. During post-weaning period, calves fed T32 had the lowest starter intake (1.78 kg/day; P=0.02). In contrast, ADG was not affected in pre-weaning and overall periods, but calves fed T32 had a lower ADG (P=0.04) as compared with calves fed T0 in post-weaning period. No dietary effect was detected for feed efficiency. Dietary treatment did not affect heart girth and body length; however, height at wither and hip at weaning increased in calves fed triticale compared with T0. No detectable effects were observed in serum glucose and β-hydroxybutyrate. No difference was detected in blood urea nitrogen on day 35 either but on day 50 and day 70 the greatest concentration was recorded for calves fed T16. Compared with the control, ruminal ammonia concentration was increased for calves fed T32 (4.34 v. 7.50 mmol/l) and T16 (4.01 v. 8.12 mmol/l) on day 35 and day 50. No difference was detected in ruminal pH on day 35 or day 50; however, calves fed T32 had the lowest pH (6.11) at 70 days. No significant effect was detected in days scoured, respiratory score and general appearance. Under our experimental conditions, it appears that triticale at 16% dry matter (i.e. replacing corn grain up to 25%) in the starter diet does not have adverse effects on the performance and intake of calves. Therefore, substituting corn partially with triticale in calf starter diets may prove beneficial in places where corn is less abundant or its price is prohibitive. The low number of calves per treatment however may have limited the statistical power to detect significant differences among treatments, possibly affecting the results, which should be interpreted with caution.     

Comparative fibre-degrading capacity in foals at immediate and late post-weaning periods

Total tract apparent digestibility of dietary fibrous components and parameters of the faecal digestive ecosystem were compared at immediate and late post-weaning periods using five foals. The foals were abruptly weaned (day 0) from their mares at 6 months of age. Immediately (day 0 to day 14) and later (day 131 to day 194) after weaning, foals received the same basal diet consisting of hay and pellets. Pellets were fed at 0.36% BW. Hay was offered ad libitum and corresponded to 120% of the average voluntary hay intake measured individually during the immediate (days 1 to 4) and late (days 180 to 183) post-weaning periods. Total feed intake was measured during the two post-weaning periods (from days 7 to 10 and from days 187 to 190). Total tract apparent digestibility of DM, organic matter (OM), NDF and ADF was assessed using a 4-day partial collection of faeces (from days 8 to 11 and from days 188 to 191). Major bacterial groups in faeces, Fibrobacter succinogenes, DM, pH and volatile fatty acids were quantified at days −1, 1, 3, 7, 14 and 180. During the post-weaning period, minor changes were observed in the composition and activity of the faecal microbiota. The amylolytic count in faeces decreased immediately after weaning (between days 1 and 7) (P<0.05). Later (from days 14 to 180), the molar proportion of propionate decreased (P=0.03). The limited alteration seen in the hindgut ecosystem was probably due to the fact that the foals had undergone a gradual dietary transition from milk to solid feed before weaning. Such conclusions have also been reported in other animal species. Between the immediate and late post-weaning periods, the average daily feed intake and the digestibility coefficients of DM, OM, NDF and ADF increased (P<0.05). These results could suggest an increase in the fibre-degrading capacity of foals after weaning.     

Effects of weaning age and formic acid-based feed additives on pigs from weaning to slaughter

Two hundred and forty piglets were used in a 2 x 6 factorial experiment to study the effects of weaning age (26 or 36 d) and four formic acid-based feed additives on the performance of pigs from weaning to slaughter. Either formic acid (F) or a mixture of formic acid, propionic acid, and potassium sorbate (FPS) or a mixture of formic acid, propionic acid, and sodium benzoate (FPB) or formic acid in a diatomaceous earth carrier (FD) were added to the diets of weaned piglets (from weaning to 60 d of age) and growing (18-46 kg) and finishing pigs (46-107 kg) to provide 8, 6, and 6 g acid per kg feed, respectively. The negative control treatment's (C) diets contained no growth promoters, whereas the positive control treatment's weaner and grower diets were supplemented with 40 mg/kg of avilamycin (A). The piglets weaned at the age of 26 and 36 d weighed 7.6 and 10.7 kg at weaning (p < 0.001), and 18.5 and 17.9 kg at the age of 60 d (p > 0.05), respectively. There was a weaning age x feed additive interaction in the weight gain of piglets after weaning (p < 0.05). The weight gain of piglets weaned on day 26 was enhanced by A, FPS, and FD (p < 0.05), and that of piglets weaned on day 36 by A and FPB (p < 0.05). The feed conversion ratio was not affected by weaning ages but was decreased in groups A, F, FBS, and FPB (p < 0.05). The severity of post-weaning diarrhoea was less in groups A, F, FPS, and FD than in C (p < 0.05). In piglets weaned on day 26, faecal water content and the total Escherichia coli count were highest 9 d after weaning. The total E. coli count was reduced only by FD (p < 0.05). Increased faecal water content was characterized by increased faecal Na+ and decreased K+ concentrations. Weaning age did not influence performance or carcass quality in the growing-finishing pigs. Feed additives did not affect weight gain in the growing pigs, but FPS and FPB enhanced weight gain during finishing period and total fattening (p < 0.05). In summary, the pigs' growth performance from weaning to slaughter was not affected by weaning age but it was enhanced by mixtures of formic and propionic acids with small amounts of sorbate or benzoate.     

Nutritionally induced adipose hypertrophy in young pigs is transient and independent of changes in the expression of the obese and peroxisome proliferator activated receptor genes

Previous studies have shown that piglets weaned to a liquid milk replacer (MR), rather than a typical dry diet (DD) regimen, have improved growth rates and deposit more energy as body fat. In the present study, we used this model to determine whether changes in the expression of genes linked to the regulation of adiposity were related to the accelerated fat accretion. We also determined whether the increase in body fat was sustained throughout a substantial proportion of the growth curve. At weaning (19 plus minus 2 days of age), 96 piglets were placed in 12 replicate pens per diet (4 pigs per pen, 2 barrows and 2 gilts), and fed a liquid MR or conventional DD regimen for 5 weeks. Thereafter, 6 barrows and 6 gilts pigs from each diet were killed for determination of whole body chemical composition (less gastrointestinal contents). The remaining pigs were assigned randomly to weight target groups (60, 85, and 110 kg), placed in individual pens, and fed a conventional dietary regimen until killed at their respective weight targets for tissue sampling and determination of whole body chemical composition. Over the 5-week period in which the MR was fed, the growth rate of the pigs consuming the MR exceeded that of the pigs fed the DD by 36% (P <.05). Fat gain in these pigs was increased to 1.8 times that of the pigs fed the DD, and percentage body fat was 45% greater (P <.05). Acetyl Co-A carboxylase (ACC) activity (per mg of adipose extract protein) was not different between the two diet groups at the conclusion of the 5-week period, or at 110 kg body weight. During the MR period, actual protein gain was increased (P <.05) 22% in the pigs fed the MR as well. By 110 kg of body weight, body fat was reduced (P <.05) by 7.7% (total fat mass) and 8.3% (percentage of body weight basis) in the pigs fed MR vs. the DD group. The expression of the peroxisome proliferator activated receptors (PPAR) alpha and gamma was not influenced by diet or by body weight. Expression of the obese gene was independent of diet, but was greater (P <.09) in pigs at 110 kg body weight than at 60 kg. These data provide additional evidence that piglets weaned to liquid diets have greater rates of growth and deposit more body fat, but that this difference subsides quickly when a typical dry dietary regimen is imposed. Furthermore, the biochemical changes responsible for the increased adiposity are independent of changes in the expression of the obese or PPAR genes, at least at the mRNA level.     

Histomorphometric evaluation of intestinal cellular immune responses in pigs immunized with live oral F4ac+ non-enterotoxigenic E. coli vaccine against postweaning colibacillosis

Enterotoxigenic Escherichia coli (ETEC) infection is the most common type of porcine postweaning colibacillosis (PWC). Among fimbriae of porcine ETEC strains the best studied family of fimbriae are the members of F4 adhesins, existing in at least three variants: ab, ac, ad. Active immunization against porcine PWC is difficult due to: i) ETEC strains are only one of the essential predisposing factors, ii) the success of vaccinal antigen uptake depends on the presence of enterocyte receptors for F4 adhesins, iii) the intestinal immune system may react with tolerance or hypersensitivity to the same antigens depending on the dose and form of the vaccinal immunogen, and iv) kinetics of the specific immune responses may be different in the case of F4 (earlier) and the other ETEC adhesins, particularly F18 (later). The aim of this study was to test the effectiveness of a live attenuated F4ac⁺ non-ETEC vaccine against porcine PWC by analyzing quantitative differences in the small intestinal lymphoid and myeloid cell subsets of immunized (with or without levamisole given as an adjuvant) vs control non-immunized pigs. Four week-old pigs were intragastrically immunized with a vaccine candidate F4ac ⁺ non-ETEC strain 2407 at day 0, challenged 7 days later with a virulent F4ac⁺ strain ETEC 11-800/1/94, euthanatized at day 13 and sampled for immunohistology. Non-immunized pigs received saline at day 0 and were processed as the principals. Immunophenotypes of lymphoid and myeloid cell subsets were demonstrated within jejunal and ileal mucosa by immunohistochemical avidinbiotin complex method and corresponding morphometric data were analyzed using software program Lucia G for digital image analyses. Monoclonal antibodies reactive with surface molecules on porcine immune cells such as CD3, CD45RA, CD45RC, CD21 and SWC3 enabled clear insight into distribution patterns and amount of these cells within the gut-associated lymphoid tissues (GALT) examined. The numbers of jejunal and ileal cell subsets tested were significantly increased (at P<0.5 or lower) in both principal groups (vaccinated or levamisole primed-vaccinated) of pigs, compared to those recorded in the control non-vaccinated pigs. Based on the histomorphometric quantification of porcine intestinal immune cells from the GALT compartments tested, it is possible to differentiate the responses of pigs immunized by an experimental mucosal vaccine from those of non-immunized pigs.Key words: adjuvanted/nonadjuvanted E. coli vaccine, intestinal immune cells, pigs.     

Evaluation of microbially enhanced soybean meal as an alternative to fishmeal in weaned pig diets

An experimental, microbially enhanced soybean product (MEPRO) was evaluated as a replacement for fishmeal (FM). Assessment of feedstuffs should include estimation of digestibility as well as pig performance and in combination with dietary additives. Digestibility values determined in growing pigs may not apply to nursery pigs; thus, standardized ileal digestibility (SID) of amino acids (AA) in MEPRO and FM were determined using 30±1.6 kg BW ileal-cannulated barrows (n=6) and 9.8±1.2 kg BW barrows (n=37; serial slaughter). Experimental diets included MEPRO, FM and nitrogen free where FM and MEPRO were included as the sole protein source. The SID of AAs was 3% to 5% lower in MEPRO than FM when fed to 30 kg pigs. The SID of arginine and methionine was greater (P<0.05) in MEPRO than FM when fed to 10 kg pigs. The SID of AAs was 12% to 20% lower in FM when fed to 10 v. 30 kg pigs but only 3% to 9% lower in MEPRO. A total of 336 barrows and gilts were weaned at 21 days of age (initial BW=6.1±0.8 kg) and used in a performance trial. Pens of pigs were assigned to one of the six experimental diets (8 pens/diet in two blocks). Treatment diets were fed in Phase I (7 days) and Phase II (14 days) with all pigs fed a common Phase III diet (14 days). Experimental diets included (1) negative control (NEG) containing corn, soybean meal and whey, (2) NEG+acidifier, (3) NEG+FM (POS), (4) POS+acidifier (POS A+), (5) NEG+MEPRO (MEPRO) and (6) MEPRO+acidifier. The FM and MEPRO were included at 7.5% and 5.0% in Phase I and II diets, respectively. Diets were formulated to meet the standard nutrient requirements for weaned pigs. Pig BW and feed disappearance was measured weekly and fecal scores were measured daily for the first 14 days post-weaning as an indicator of post-weaning diarrhea syndrome (PWDS). Performance (BW, daily gain, feed intake and gain : feed) was not significantly different among treatments. Treatment for PWDS occurred on different days in each block. Analysis of fecal score was completed separately by block. Pigs fed the NEG diets had higher (P=0.02) fecal scores than pigs fed the POS diets on days 2 and 3 (block 1) and higher (P<0.05) than pigs fed MEPRO or POS diets and diets with dietary acidifier on days 6 and 3 (block 2). The MEPRO holds promise as an alternative to FM in nursery pig diets.     

A reduced CP level without medicinal zinc oxide does not alter the intestinal morphology in weaned pigs 24 days post-weaning

The use of medicinal zinc oxide (ZnO) to prevent diarrhoea post-weaning will be banned in the EU from 2022. Therefore, new alternatives are needed to avoid an increase in diarrhoea and higher antibiotic use. A low dietary CP level has shown to lower the frequency of diarrhoea in pigs, due to lower microbial protein fermentation in the colon as well as improved conditions in the small intestine after weaning. The objective of this study was to examine the effect of decreased CP levels post-weaning as an alternative to medicinal ZnO on gut morphology and histopathology. Five hundred and sixty pigs were randomly assigned into one of six groups receiving a two-phase diet from 5.5 to 15 kg: positive control group (PC) with medicinal ZnO and standard levels of protein (19.1–18.4% CP), negative control group (NC) without medicinal ZnO and standard levels of protein (19.1–18.4% CP). The remaining four low protein groups were a low-standard (LS) CP level (16.6–18.4% CP), a low-low (LL) CP level (16.6–16.2% CP), a very low-high (VLH) CP level (14–19.3% CP) and a very low-medium (VLM) CP level (14–17.4% CP). Individual BW was recorded at day 0, 10 and 24 post-weaning, and all antibiotic treatments were recorded. Tissue samples from the small intestine (mid-jejunum) for morphological and histopathologic analysis, organ weights, blood and urine samples were collected at day 10 and 24 post-weaning from a total of 90 sacrificed weaners. The results demonstrated no differences in intestinal morphology between groups, but the histopathology showed a damaged brush border score in VLM and VLH pigs . In addition, a lower blood urea nitrogen in VLM pigs at 24 days was found. The LL and VLM pigs had a significantly decreased average daily gain in the overall trial period compared to PC and NC pigs. Conclusively, intestinal brush border was damaged by the very low protein diet at 24 days post-weaning, but intestinal morphology was unaffected by dietary strategy.     

Effects of feeding low protein diets to piglets on plasma urea nitrogen, faecal ammonia nitrogen, the incidence of diarrhoea and performance after weaning

This study evaluated the effects of feeding pigs low protein (LP) diets for different lengths of time after weaning on indices of protein fermentation, the incidence of postweaning diarrhoea (PWD), growth performance, and total-tract apparent digestibility. Sixty weaner pigs weighing 6.1 +/- 0.13 kg (mean +/- SEM) were used in a completely randomised design having five treatments: (i) a high protein diet (HP, 243 g/kg CP) fed for 14 d after weaning (HP14); (ii) a low protein diet (LP, 173 g CP/kg) fed for 5 d after weaning (LP5); (iii) LP diet fed for 7 d after weaning (LP7); (iv) LP diet fed for 10 d after weaning (LP10), and (v) LP diet fed for 14 d after weaning (LP14). All diets were supplemented with lysine, methionine, tryptophan and threonine, with all LP diets additionally fortified with crystalline isoleucine and valine to conform to a proposed ideal amino acid (AA) pattern. A second-stage diet (215 g CP/kg) was fed to pigs at the conclusion of each treatment. None of the diets contained antimicrobial compounds. Feeding a LP diet, regardless of duration of feeding, decreased plasma urea nitrogen (p < 0.001) and faecal ammonia-nitrogen (p < 0.001) contents. Feeding a LP diet, irrespective of feeding duration, decreased the incidence of PWD at day 8 after weaning (p = 0.044), and pigs fed diets LP7, LP010 and LP14 had firmer faeces (p = 0.030, p = 0.047 and p = 0.007, respectively) between days 10 and 12 after weaning. Treatments LP5, LP7, LP10 and LP14 did not reduce (p > 0.05) growth performance up to 106 days after weaning compared to pigs fed the HP diet. Total-tract apparent digestibility of dry matter, energy and crude protein were similar (p > 0.05) between treatments. Our data suggest that feeding a LP diet, supplemented with AA to conform to an ideal AA pattern, for 7-10 days after weaning can reduce PWD in pigs fed antibiotic-free diets without compromising production.     

Bacteriophage cocktail and multi-strain probiotics in the feed for weanling pigs: effects on intestine morphology and targeted intestinal coliforms and Clostridium

Two experiments were conducted to investigate the effects of dietary supplementation of bacteriophage cocktail, probiotics and a combination of these two supplements on performance and gut health of weanling pigs. In Experiment 1, 150 weaned piglets were randomly allotted to three treatments on the basis of BW. The dietary treatments included a basal diet supplemented with 0 (control), 1.0 and 1.5 g/kg bacteriophage cocktail. Pigs fed 1.0 and 1.5 g/kg bacteriophage product had greater (P<0.05) average daily gain (ADG), apparent total tract digestibility of dry matter from day 22 to 35, ileal Lactobacillus spp., villus height (duodenum and jejunum), and fewer coliforms (ileum) and Clostridium spp. (ileum). In Experiment 2, 200 weaned piglets were randomly allotted to four treatments. Dietary treatments included basal diet, basal diet supplemented with 3.0 g/kg fermented probiotic product (P), 1.0 g/kg bacteriophage cocktail (B) and combination of 1.0 g/kg bacteriophage cocktail and 3.0 g/kg fermented probiotic product. Pigs fed bacteriophage cocktail diets had greater (P<0.05) overall ADG, gain to feed ratio (G:F), fecal score from day 8 to day 21, and pigs fed bacteriophage cocktail diets had fewer coliforms (ileum) Clostridium spp. (ileum and cecum). Probiotics significantly increased G:F, colonization of Lactobacillus spp. in ileum. At day 35, bacteriophage treatment group showed greater (P<0.05) villus height of the duodenum, but a deeper crypt in duodenum. The present results indicate that the bacteriophage cocktail had a potential to enhance the performance and gut health of weanling pigs, however their combination with probiotics did not show an interaction.