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

Increasing weaning age of piglets from 4 to 7 weeks reduces stress, increases post-weaning feed intake but does not improve intestinal functionality

This study tested the hypothesis that late weaning and the availability of creep feed during the suckling period compared with early weaning, improves feed intake, decreases stress and improves the integrity of the intestinal tract. In this study with 160 piglets of 16 litters, late weaning at 7 weeks of age was compared with early weaning at 4 weeks, with or without creep feeding during the suckling period, on post-weaning feed intake, plasma cortisol (as an indicator of stress) and plasma intestinal fatty acid binding protein (I-FABP; a marker for mild intestinal injury) concentrations, intestinal morphology, intestinal (macro)molecular permeability and intestinal fluid absorption as indicators of small intestinal integrity. Post-weaning feed intake was similar in piglets weaned at 4 weeks and offered creep feed or not, but higher (P < 0.001) in piglets weaned at 7 weeks with a higher (P < 0.05) intake for piglets offered creep feed compared with piglets from whom creep feed was witheld. Plasma cortisol response at the day of weaning was lower in piglets weaned at 7 weeks compared with piglets weaned at 4 weeks, and creep feed did not affect cortisol concentration. Plasma I-FABP concentration was not affected by the age of weaning and creep feeding. Intestinal (macro)molecular permeability was not affected by the age of weaning and creep feeding. Both in uninfected and enterotoxigenic Escherichia coli-infected small intestinal segments net fluid absorption was not affected by the age of weaning or creep feeding. Creep feeding, but not the age of weaning, resulted in higher villi and increased crypt depth. In conclusion, weaning at 7 weeks of age in combination with creep feeding improves post-weaning feed intake and reduces weaning stress but does not improve functional characteristics of the small intestinal mucosa.

Gastrointestinal health and function in weaned pigs: a review of feeding strategies to control post-weaning diarrhoea without using in-feed antimicrobial compounds

For the last several decades, antimicrobial compounds have been used to promote piglet growth at weaning through the prevention of subclinical and clinical disease. There are, however, increasing concerns in relation to the development of antibiotic-resistant bacterial strains and the potential of these and associated resistance genes to impact on human health. As a consequence, European Union (EU) banned the use of antibiotics as growth promoters in swine and livestock production on 1 January 2006. Furthermore, minerals such as zinc (Zn) and copper (Cu) are not feasible alternatives/replacements to antibiotics because their excretion is a possible threat to the environment. Consequently, there is a need to develop feeding programs to serve as a means for controlling problems associated with the weaning transition without using antimicrobial compounds. This review, therefore, is focused on some of nutritional strategies that are known to improve structure and function of gastrointestinal tract and (or) promote post-weaning growth with special emphasis on probiotics, prebiotics, organic acids, trace minerals and dietary protein source and level.

Dietary zinc oxide affects the expression of genes associated with inflammation: Transcriptome analysis in piglets challenged with ETEC K88

The post-weaning growth check in commercial pig production systems is often associated with gastrointestinal infection, in particular that caused by enterotoxigenic Escherichia coli (ETEC) K88. Pharmacological doses of zinc oxide (ZnO) in the post-weaning diet reduce the incidence of diarrhoea and improve piglet performance. In the present study, piglets reared indoors or outdoors and weaned onto diets with or without pharmacological levels of ZnO were orally challenged with ETEC K88. Quantitative real-time PCR was performed on RNA extracted from jejunal lamina propria and Peyer's patch samples, to compare expression of a variety of candidate genes between treatments. Candidate genes were selected from an initial microarray study using pooled RNA to identify differentially expressed genes. Dietary treatment with ZnO was associated with significant differences in the transcript abundance of several genes. Zinc supplementation was associated with a marked decrease in expression of immune response genes concerned with inflammation, and possibly related to the stage of infection. Interestingly, evidence was also obtained that a reduced level of MUC4 (a proposed ETEC K88 receptor) was associated with zinc supplementation suggesting a mechanism that might influence ETEC infection. These findings indicate that zinc oxide supplementation may reduce the level of inflammation caused by ETEC challenge.

Effects of dietary protein level and zinc oxide supplementation on performance responses and gastrointestinal tract characteristics in weaner pigs challenged with an enterotoxigenic strain of Escherichia coli

The interactive effects of dietary protein level, zinc oxide (ZnO) supplementation and infection with an enterotoxigenic strain of Escherichia coli (ETEC) on performance responses and gastrointestinal tract characteristics were examined. Ninety-six individually housed, 21-day-old pigs (1 : 1 gender ratio) with initial bodyweight (BW) of 7.2 ± 0.69 kg, were used in a split plot experiment, with the whole plot being challenge or no challenge with ETEC and the dietary treatments used as subplots and arranged in a completely randomised 2 × 2 factorial design, with the factors being (i) two dietary protein levels (251 versus 192 g/kg crude protein) and (ii) addition or no addition of 2.5 g/kg ZnO. No antibiotic was added to the diet. The ETEC infection decreased average daily gain (P < 0.001) and increased feed conversion ratio (P < 0.01). Protein level had no effect on performance of pigs while ZnO supplementation increased (P < 0.001) average daily gain and average daily feed intake and hence decreased feed conversion ratio (P < 0.001). There were no 2- or 3-way interactions for growth performance indices (P > 0.05). Feeding a lower protein diet did not influence (P > 0.05) faecal volatile fatty acid concentrations. In non-infected pigs, feeding a lower protein diet caused a lower pH in the jejunum and ileum compared with pigs fed a higher protein diet (P < 0.05 and P < 0.01, respectively). However, feeding ZnO-supplemented diets increased (P < 0.05) the pH in the stomach and caecum compared with feeding diets without ZnO supplementation. Protein level did not alter (P > 0.05) empty BW but dietary supplementation with ZnO increased empty BW (P < 0.05). Neither protein level nor ZnO supplementation modified small intestinal morphology, although a tendency for an interaction (P < 0.1) was detected for jejunal villous height between protein level and ZnO supplementation. The results indicate that feeding ZnO-supplemented diets improved pig performance, and feeding a lower protein diet without ZnO supplementation did not compromise performance nor modify measures of gastrointestinal tract structure and function compared with pigs fed a diet higher in protein after weaning.

Evaluation of Lactobacillus rhamnosus GG using an Escherichia coli K88 model of piglet diarrhoea: Effects on diarrhoea incidence, faecal microflora and immune responses

Probiotic bacterium Lactobacillus rhamnosus GG (LGG) has been demonstrated to adhere to pig intestinal mucus, and is able to displace and inhibit pathogens, including Escherichia coli (E. coli), in vitro. However, currently there are few data concerning the effects of LGG on piglet health. The objectives of this study were to assess the effectiveness of LGG in reducing the incidence and severity of post-weaning diarrhoea in piglets, and to investigate its mechanisms of action. Eighteen weaned barrows were allocated to nonchallenged control (NCN), challenged control (CCN) and LGG treatment (LGG) groups. Diarrhoea incidence was significantly lower in group LGG than group CCN after E. coli challenge. Faecal coliform bacteria counts were significantly increased, while lactobacilli and bifidobacteria counts were decreased, in group CCN compared with the other groups after challenge. In the jejunum and ileum, secretory immunoglobin A (SIgA) concentrations were significantly higher in group LGG than in group CCN. In group LGG, administration of short-term LGG before E. coli infection attenuated the elevation of serum IL-6 induced by E. coli. Significantly higher concentrations of TNF-alpha were observed in group LGG than NCN and CCN at 6h. IL-1beta concentrations in group NCN were significantly higher than LGG at 6h and higher than CCN at 24h. In conclusion, LGG was effective in ameliorating diarrhoea in post-weaning piglets induced by E. coli K88, possibly via modulation of intestinal microflora, enhancement of intestinal antibody defence, and regulation of production of systemic inflammatory cytokines.

The effect of weaner diet protein content and diet quality on the long-term performance of pigs to slaughter

Short and long-term effects of manipulating dietary CP content and diet quality in weaner diets on health and performance of pigs were investigated in a 2 x 2 factorial combination of CP inclusion (high-CP, 230 g of CP/kg vs. low-CP, 170 g of CP/kg) and diet quality (high-quality, cooked cereals, and animal protein vs. low-quality, raw cereals, and plant protein). Diets were fed ad libitum for 14 d postweaning to pigs weaned at 29.4+/-3.1 d of age and 9.9+/-1.0 kg of BW. From d 14 to slaughter at 104+/-3 kg, all pigs were fed the same series of standard commercial diets. There were 15 replicates per treatment in the weaner phase (<30 kg) and 5 replicates per treatment in the grower-finisher phase (>30 kg). High-quality diets promoted gut health as indicated by improved fecal lactobacilli to coliform ratio (P=0.002) and decreased fecal enterotoxigenic Escherichia coli counts on d 11 postweaning (P=0.028), reducing the risk of postweaning diarrhea and improving pig health from weaning to the end of the weaner phase. Reducing CP content had no effect on gut health. High-CP (P=0.053) and high-quality (P=0.025) diets independently increased ADG during the first 14 d postweaning compared with low-CP and low-quality diets, respectively. There were no interactions between dietary CP content and quality on any of the response criteria investigated. Despite differences in the immediate postweaning period, there was no effect of manipulating diet quality or CP content for 2 wk postweaning on lifetime performance with pigs reaching slaughter weight in 128+/-7 d. These results indicate that high-quality diets may protect pig gut health during the immediate postweaning period. However, it may be possible to use less expensive, decreased quality weaner diets without any adverse effects on long-term performance when weaning older, heavier pigs and where health status, environmental control, and stock management are all maintained to a high standard.