Effect and interaction between wheat bran and zinc oxide on productive performance and intestinal health in post-weaning piglets. Br J Nutr. 2011;105:1592-1600. [PMID: 21477404 DOI: 10.1017/S0007114510004575]

The assessment of chemical composition and biological activity of faba bean pods as a potential feed additive utilized in piglets nutrition

The study addresses the utilization of food waste by-products from faba bean (Vicia faba L.) pods (FBP) as an alternative feed supplement to promote sustainable piglet growth by reducing antimicrobial use. Objectives include evaluation of FBP in terms of nutritional components (proximate composition, fibres, minerals), phytochemical composition (total phenols, HPLC-MS profiling), and in vitro biological activities. Air-dried FBP from the cultivar 'Bizon' contained high levels of crude protein (144 g/kg), dietary fibre (413 g/kg), potassium (27.8 g/kg), and iron (126 mg/kg). Phytochemical analysis of methanolic extract from FBP revealed significant levels of polyphenols, including vestitol, piscidic acid, hydroxyeucomic acid, quercetin, and kaempferol glycosides with no detectable tannins. The extract showed negligible activity against porcine digestive enzymes (α-amylase, lipase, and trypsin) (IC50 > 4 mg/mL) and demonstrated a dose-dependent antibacterial activity against Escherichia coli and Salmonella enterica in concentrations of 1-8 mg/mL. The extract had low cytotoxicity (IC50 = 432.6 µg/mL) against IPEC-J2 - cells derived from porcine jejunal epithelium. The results indicate that FBP 'Bizon' is a valuable source of bioactive compounds with antibacterial properties, without adverse effects on porcine enzymes or IPEC-J2 cells, supporting its potential as a sustainable feed in piglet nutrition, in line with circular economy concepts.

Nutritional guide to feeding wheat and wheat co-products to swine: a review

Inclusion of wheat grain can offer feeding opportunities in swine diets because of its high starch, crude protein (CP), amino acid (AA), and phosphorus (P) content. High concentrations of starch within wheat grain makes it a good energy source for swine. Mean energy content of wheat was 4,900 and 3,785 kcal/kg dry matter (DM) for digestible energy and metabolizable energy, respectively. CP concentration can vary based on the class of wheat which include hard red winter, hard red spring, soft red winter, hard white, soft white, and durum. The average CP of all wheat data collected in this review was 12.6% with a range of 8.5% to 17.6%. The AA concentration of wheat increases with increasing CP with the mean Lys content of 0.38% with a standardized ileal digestibility (SID) of 76.8%. As CP of wheat increases, the SID of AA in wheat also increases. Mean P of wheat was 0.27% and median P was 0.30%. Off-quality wheat is often associated with sprouts, low-test weight, or mycotoxin-contamination. Sprouted and low-test weight wheat are physical abnormalities associated with decreased starch within wheat kernel that leads to reductions in energy. The assumed energy value of wheat grain may need to be reduced by up to 10% when the proportion of sprouted to non-sprouted wheat is up to 40% whereas above 40%, wheat's energy may need to be reduced by 15% to 20%. Low-test weight wheat appears to not influence pig performance unless it falls below 644 kg/m3 and then energy value should be decreased by 5% compared to normal wheat. Deoxynivalenol (DON) contamination is most common with wheat grain. When content is above the guidance level of 1 mg/kg of DON in the complete diet, each 1 mg/kg increase in a DON-contaminated wheat-based diet will result in a 11% and 6% reduction in ADG and ADFI for nursery pigs, and a 2.7% and 2.6% reduction in ADG and ADFI, in finishing pigs, respectively. Wheat co-products are produced from the flour milling industry. Wheat co-products include wheat bran middlings, millrun, shorts, and red dog. Wheat co-products can be used in swine diets, but application may change because of differences in the final diet energy concentration due to changes in the starch and fiber levels of each wheat co-product. However, feeding wheat co-products are being evaluated to improve digestive health. Overall, wheat and wheat co-products can be fed in all stages of production if energy and other nutrient characteristics are considered.

Dietary nutrition, intestinal microbiota dysbiosis and post-weaning diarrhea in piglets

Weaning is a critical transitional point in the life cycle of piglets. Early weaning can lead to post-weaning syndrome, destroy the intestinal barrier function and microbiota homeostasis, cause diarrhea and threaten the health of piglets. The nutritional components of milk and solid foods consumed by newborn animals can affect the diversity and structure of their intestinal microbiota, and regulate post-weaning diarrhea in piglets. Therefore, this paper reviews the effects and mechanisms of different nutrients, including protein, dietary fiber, dietary fatty acids and dietary electrolyte balance, on diarrhea and health of piglets by regulating intestinal function. Protein is an essential nutrient for the growth of piglets; however, excessive intake will cause many harmful effects, such as allergic reactions, intestinal barrier dysfunction and pathogenic growth, eventually aggravating piglet diarrhea. Dietary fiber is a nutrient that alleviates post-weaning diarrhea in piglets, which is related to its promotion of intestinal epithelial integrity, microbial homeostasis and the production of short-chain fatty acids. In addition, dietary fatty acids and dietary electrolyte balance can also facilitate the growth, function and health of piglets by regulating intestinal epithelial function, immune system and microbiota. Thus, a targeted control of dietary components to promote the establishment of a healthy bacterial community is a significant method for preventing nutritional diarrhea in weaned piglets.

Dietary fiber and its role in performance, welfare, and health of pigs

Dietary fiber (DF) is receiving increasing attention, and its importance in pig nutrition is now acknowledged. Although DF for pigs was frowned upon for a long time because of reductions in energy intake and digestibility of other nutrients, it has become clear that feeding DF to pigs can affect their well-being and health. This review aims to summarize the state of knowledge of studies on DF in pigs, with an emphasis on the underlying mode of action, by considering research using DF in sows as well as suckling and weaned piglets, and fattening pigs. These studies indicate that DF can benefit the digestive tracts and the health of pigs, if certain conditions or restrictions are considered, such as concentration in the feed and fermentability. Besides the chemical composition and the impact on energy and nutrient digestibility, it is also necessary to evaluate the possible physical and physiologic effects on intestinal function and intestinal microbiota, to better understand the relation of DF to animal health and welfare. Future research should be designed to provide a better mechanistic understanding of the physiologic effects of DF in pigs.

Review on Preventive Measures to Reduce Post-Weaning Diarrhoea in Piglets

In many countries, medical levels of zinc (typically as zinc oxide) are added to piglet diets in the first two weeks post-weaning to prevent the development of post-weaning diarrhoea (PWD). However, high levels of zinc constitute an environmental polluting agent, and may contribute to the development and/or maintenance of antimicrobial resistance (AMR) among bacteria. Consequently, the EU banned administering medical levels of zinc in pig diets as of June 2022. However, this may result in an increased use of antibiotic therapeutics to combat PWD and thereby an increased risk of further AMR development. The search for alternative measures against PWD with a minimum use of antibiotics and in the absence of medical levels of zinc has therefore been intensified over recent years, and feed-related measures, including feed ingredients, feed additives, and feeding strategies, are being intensively investigated. Furthermore, management strategies have been developed and are undoubtedly relevant; however, these will not be addressed in this review. Here, feed measures (and vaccines) are addressed, these being probiotics, prebiotics, synbiotics, postbiotics, proteobiotics, plants and plant extracts (in particular essential oils and tannins), macroalgae (particularly macroalgae-derived polysaccharides), dietary fibre, antimicrobial peptides, specific amino acids, dietary fatty acids, milk replacers, milk components, creep feed, vaccines, bacteriophages, and single-domain antibodies (nanobodies). The list covers measures with a rather long history and others that require significant development before their eventual use can be extended. To assess the potential of feed-related measures in combating PWD, the literature reviewed here has focused on studies reporting parameters of PWD (i.e., faeces score and/or faeces dry matter content during the first two weeks post-weaning). Although the impact on PWD (or related parameters) of the investigated measures may often be inconsistent, many studies do report positive effects. However, several studies have shown that control pigs do not suffer from diarrhoea, making it difficult to evaluate the biological and practical relevance of these improvements. From the reviewed literature, it is not possible to rank the efficacy of the various measures, and the efficacy most probably depends on a range of factors related to animal genetics and health status, additive doses used, composition of the feed, etc. We conclude that a combination of various measures is probably most recommendable in most situations. However, in this respect, it should be considered that combining strategies may lead to additive (e.g., synbiotics), synergistic (e.g., plant materials), or antagonistic (e.g., algae compounds) effects, requiring detailed knowledge on the modes of action in order to design effective strategies.

Effect of fiber source and crude protein level on nursery pig performance and fecal microbial communities

Reduction in dietary crude protein and addition of fiber could mitigate the incidence and severity of post-weaning diarrhea, a common gastrointestinal condition in newly weaned pigs. Therefore, 360 weanling pigs, initially 5.0 ± 0.10 kg, were used to evaluate the effects of crude protein (CP) level and fiber source on growth performance and fecal microbial communities. At weaning, pigs were randomly assigned to pens and allotted to 1 of 8 dietary treatments in a 2 × 4 factorial with main effects of CP (21 or 18%) and fiber source (none, coarse wheat bran, oat hulls, or cellulose). There were 5 pigs per pen and 9 pens per treatment. Experimental diets were formulated in two dietary phases from d 0 to 10 and 10 to 24, with a common post-treatment diet fed from 24 to 45. The 21% CP diets contained 1.40% standardized ileal digestible (SID) Lys in phase 1 and 1.35% SID Lys in phase 2. By using a maximum SID Lys:digestible CP ratio of 6.35%, the 18% CP diets contained 1.25% SID Lys in both phases. Diets containing a fiber source were formulated to the level of insoluble fiber provided by 4% coarse wheat bran, resulting in the addition of 1.85% oat hulls and 1.55% cellulose. No fiber source × CP level interactions (P > 0.05) were observed. Decreasing CP (and subsequently SID lysine) decreased (P = 0.05) ADG and G:F during the experimental period. From d 0 to 45, ADG decreased (P = 0.05) for pigs fed 18% CP diets compared to pigs fed 21% CP. No effect of fiber source was observed for growth performance. Fecal DM on d 17 increased (P < 0.001) for pigs fed 18% CP diets compared to pigs fed 21% CP diets. Pigs fed diets with added cellulose had increased (P < 0.05) fecal dry matter during the experimental period compared to pigs fed no fiber source or wheat bran. Bacterial community structure was investigated by sequencing the V4 region of the 16S rRNA gene. Analysis indicated a significant difference between CP content at d 24 (P = 0.023) using a Weighted UniFrac distance matrix. Further investigation identified five differential Amplicon Sequence Variants associated with CP content at d 24. In conclusion, reducing crude protein (and subsequently SID Lys) decreased growth performance but increased fecal dry matter content. The source of dietary fiber in nursery diets had no impact on growth performance; but pigs fed added cellulose had increased fecal DM compared with other treatments. Microbial analysis identified differential taxa associated with CP content.

Effects of fermented wheat bran and yeast culture on growth performance, immunity, and intestinal microflora in growing-finishing pigs

This study was conducted to evaluate the effects of feeding fermented wheat bran (FWB) and yeast culture (YC) on growth performance, immune levels, and intestinal microflora in growing-finishing pigs. In total, 96 crossbred pigs were randomly distributed into four treatments with four replicates pens and six pigs per pen. This study was performed using a 2 × 2 factor design: 1) CON (basal diet), 2) FWB (basal diet + 5% FWB), 3) YC (basal diet + 2% YC), and 4) FWB + YC (basal diet + 5% FWB + 2% YC). Dietary FWB supplementation significantly increased the average daily gain and significantly decreased the feed gain ratio of growing-finishing pigs (P < 0.05). Supplementation of FWB and YC improved the immune capacity and reduced the inflammation level of growing-finishing pigs (P < 0.05). In addition, pigs fed FWB, YC, and FWB + YC diets showed better intestinal development and morphology compared with those CON pigs. The relative abundance of Streptococcus in the FWB group was significantly lower than that in the CON group (P < 0.05), and the relative abundance of probiotics (unclassified_f_Lachnospiraceae, Turicibacter) increased significantly (P < 0.05). Furthermore, the relative abundance of probiotics (Lactobacillus, norank_f_Muribaculaceae) in the YC group was significantly increased compared with the CON group (P < 0.05). The results of this study observed positive effects of FWB and YC on growing-finishing pigs, which provides insights into the application of biological feed in swine industry.

The effects of pharmacological levels of zinc, diet acidification, and dietary crude protein on growth performance in nursery pigs

This experiment was conducted to evaluate potential replacements for pharmacological levels of Zn (provided by Zn oxide), such as diet acidification (sodium diformate) and low dietary crude protein (CP: 21 vs 18%) on nursery pig performance and fecal dry matter (DM). A total of 360 weaned pigs (Line 200 × 400, DNA, Columbus, NE; initially 5.90 ± 0.014 kg) were used in a 42-d growth study. Pigs were weaned at approximately 21 d of age and randomly assigned to pens (five pigs per pen). Pens were then allotted to one of eight dietary treatments with nine pens per treatment. Experimental diets were fed in two phases: phase 1 from weaning to day 7 and phase 2 from days 7 to 21, with all pigs fed the same common diet from days 21 to 42. The eight treatment diets were arranged as a 2 × 2 × 2 factorial with main effects of Zn (110 mg/kg from days 0 to 21 or 3,000 mg/kg from days 0 to 7, and 2,000 mg/kg from days 7 to 21), diet acidification, (without or with 1.2% sodium diformate), and dietary CP (21% or 18%, 1.40% and 1.35% in phases 1 and 2 vs. 1.20% standardized ileal digestible Lys, respectively). Fecal samples were collected weekly from the same three pigs per pen to determine DM content. No 2- or 3-way interactions (P > 0.05) were observed throughout the 42-d study for growth performance; however, there was a Zn × acidifier × CP interaction (P < 0.05) for fecal DM on day 7 and for the overall average of the six collection periods. Reducing CP without acidification or pharmacological levels of Zn increased fecal DM, but CP had little effect when ZnO was present in the diet. From days 0 to 21, significant (P < 0.05) main effects were observed where average daily gain (ADG) and gain:feed (G:F) increased for pigs fed pharmacological levels of Zn, sodium diformate, or 21% CP (P < 0.065). In the subsequent period (days 21 to 42) after the experimental diets were fed, there was no evidence of difference in growth performance among treatments. Overall (days 0 to 42), main effect tendencies were observed (P < 0.066) for pigs fed added Zn or sodium diformate from days 0 to 21, whereas pigs fed 21% CP had greater G:F than those fed 18% CP. Pig weight on day 42 was increased by adding Zn (P < 0.05) or acidifier (P < 0.06) but not CP. In summary, none of the feed additives had a major influence on fecal DM, but dietary addition of pharmacological levels of Zn or sodium diformate independently improved nursery pig performance.

Effect of Zinc Source and Level on Growth Performance and Zinc Status of Weaned Piglets

The aim of this study was to evaluate the effect of zinc (Zn) supplementation in different commercial forms on the growth performance, health status, and Zn balance of weaners in field conditions. The animals were fed pre-starter (from the 28th to 47th day of life) and starter (from the 48th to 74th day of life) mixtures differing in Zn form and concentration. Group I was given ZnSO4 at 150 mg kg-1; Group II received pre-starter zinc oxide (ZnO) at 3000 mg kg-1 and starter at 150 mg kg-1; and Group III was given 150 mg kg-1 of zinc oxide nanoparticles (nZnO). We found that the average daily gain in Group I was significantly lower, compared to Groups II and III. A commonly accepted level of Zn (150 mg kg-1) as nZnO can be recommended, instead of therapeutic doses of Zn preparations with the same efficiency. Moreover, a lower level of Zn in the diet can prevent the excessive accumulation of this element in waste and, thus, reduce environmental damage.

Effects of feeding diets containing low crude protein and coarse wheat bran as alternatives to zinc oxide in nursery pig diets

Two experiments were conducted to determine the effects of crude protein (CP) level in diets containing coarse wheat bran (CWB) with or without pharmacological levels of Zn (provided by zinc oxide: ZnO) on growth performance and fecal DM of nursery pigs. In experiment 1, 360 barrows (Line 200 × 400, DNA, Columbus, NE, initially 5.6 kg) were allotted to 1 of 6 dietary treatments from d 0 to 21 after weaning with 5 pigs per pen and 12 pens per treatment. Treatments included a positive control diet (21% CP) with 3,000 mg/kg Zn in phase 1 and 2,000 mg/kg in phase 2; negative control (21% CP) with 110 mg/kg added Zn, and 4 diets containing 4% CWB and 110 mg/kg added Zn formulated to contain 21%, 19.5%, 18%, or 16.5% CP. The 2 control diets and 21% CP CWB diet contained 1.40% standardized ileal digestible (SID) Lys in phase 1 and 1.35% SID Lys in phase 2, while the 19.5%, 18%, and 16.5% CP diets contained 1.33, 1.25 and 1.20% Lys, respectively, in both phases. Pigs fed the positive control diet containing pharmacological ZnO had increased (P < 0.05) ADG and G:F compared with the negative control and the 21% CP CWB diet. Reducing CP (concurrently with SID Lys) in diets containing CWB decreased ADG and G:F (linear, P = 0.002); however, fecal DM increased (linear, P = 0.005). In experiment 2, two groups of 300 and 350 pigs, initially 7.0 and 6.2 kg, respectively, were used with 5 pigs per pen and 26 pens per treatment. The objective was to determine if adding back essential AA would improve growth performance of pigs fed the low CP diets. All dietary treatments were fed for 13 days, contained 4% CWB, and consisted of: (1) positive control with 2,000 mg/kg of Zn and 21% CP (1.35% SID Lys); (2) no ZnO and 21% CP; and 3 diets with no ZnO formulated to 18% CP and (3) 1.2% SID Lys; (4) 1.35% SID Lys by the addition of feed grade amino acids (AA), and (5) diet 4 with non-essential amino acids (NEAA; Gly and Glu). Pigs fed 21% CP with ZnO had increased (P = 0.001) ADG compared to those fed 18% CP (1.35% SID Lys) with high levels of feed grade amino acids or those fed the reduced SID Lys (1.2%) diet. Overall, G:F was improved (P < 0.001) for pigs fed 21% CP diets and those fed the 18% CP diet with NEAA compared to pigs fed 1.2% SID Lys and pigs fed high levels of feed grade amino acids. Fecal DM was increased for pigs fed the reduced SID Lys diet. In summary, pharmacological levels of Zn improve pig growth performance, but reducing CP (and subsequently SID Lys) decreased nursery pig growth performance.

Physiological function and application of dietary fiber in pig nutrition: A review

Dietary fiber (DF), divided into soluble dietary fiber (SDF) and insoluble dietary fiber (IDF), has attracted increasing attention in the field of pig nutrition. Although DF reduces nutrient digestibility and inhibits energy deposition in most cases, fiber-rich feeds have been widely used in pig diets. This is not only because of lower feed costs, but also from the continuous discovery about the nutritional value of DF, mainly including the improvement of piglet intestinal health and sow reproductive performance. The addition timing has also been further considered, which potentially enables the nutritional value of DF to be accurately used in applicable pig models. Furthermore, fiber degrading enzymes have been shown to alleviate the anti-nutritional effects of DF and have ensured the improvement effect of fiber on intestinal health in young piglet models. However, the regulatory effect of fiber on pork quality is still unclear, which requires consideration of the wide range of fiber sources and the complexity of the basic diet composition, as well as the impact of pig breeds. Taken together, future research needs to gain more insight into the combined effects of SDF and IDF, processing methods, and addition timing to improve the nutritional value of DF, and further explore the physiological functions and regulatory mechanisms of DF fermentation products short-chain fatty acids in pigs.

Fibre supplementation to pre-weaning piglet diets did not improve the resilience towards a post-weaning enterotoxigenic E. coli challenge

Dietary fibre (DF) is implicated in gastrointestinal health of weaned piglets, either through its physiochemical properties, through modulation of gut microbiota and (or) improved gut integrity. We aimed to study the effect of DF enriched supplemental diets fed to suckling piglets ('creep feed') on health and performance after weaning when challenged with an enterotoxigenic E. coli (ETEC). Seventy-two piglets originating from 28 litters had been fed four creep diets, that is a low-fibre control (CON); a diet containing 2% long-chain arabinoxylans from wheat (lc-AXOS) or 5% purified cellulose (CELL) or a diet containing the high fermentable and the low-fermentable fibre source (i.e. 2% lc-AXOS and 5% CELL). Upon weaning, piglets were individually housed and all fed the same diet. On days 7, 8 and 9, animals received an oral dose of ETEC (5 ml containing 107 to 108  CFU/ml). Besides growth performance, faecal and skin scores were recorded daily. Gut permeability was assessed by urinary excretion of Co-EDTA prior and post-ETEC challenge. Repeated measures in time were statistically evaluated with generalized linear mixed models. We used a binominal distribution for evaluating the faecal and skin scores. Feed intake and body weight gain did not differ between treatments (p > .05). Piglets on CELL decreased gain:feed ratio in week 2 + 3 week compared to CON (p = .035). Prior to ETEC challenge, gut permeability tended to increase for lc-AXOS (p = .092). Moreover, lc-AXOS as main effect increased intestinal permeability before ETEC challenge (p = .013), whereas the low-fermentable fibre lead to elevated intestinal permeability after ETEC challenge (p = .014). The incidence of diarrhoea was higher for lc-AXOS + CELL compared with lc-AXOS (p = .036), while skin condition was unaffected. In conclusion, neither the high fermentable nor the low-fermentable fibre source improved post-weaning growth or gastrointestinal health of the piglets.

Towards Zero Zinc Oxide: Feeding Strategies to Manage Post-Weaning Diarrhea in Piglets

Simple Summary

Zinc oxide (ZnO) supplementation at pharmacological doses in post-weaning piglets is a consolidated practice that allows efficient control of post-weaning diarrhea (PWD), a condition exacerbated by Escherichia coli F4 (K88) infections. Far from being completely elucidated, the multifactorial ZnO mechanism of action is in all likelihood exerted at the gastrointestinal level. However, increasing environmental concerns are arising from prolonged ZnO use. This article reviews the utilization of ZnO in piglets, the biological rationale behind its powerful activity, and the emerging threats that are leading towards a significant reduction in its use. Finally, a wide analysis of the strengths and weaknesses of innovative alternative strategies to manage PWD at the nutritional level is given.

Abstract

Zinc oxide (ZnO) at pharmacological doses is extensively employed in the pig industry as an effective tool to manage post-weaning diarrhea (PWD), a condition that causes huge economic losses because of its impact on the most pivotal phase of a piglet’s production cycle. In a multifactorial way, ZnO exerts a variety of positive effects along the entire gastrointestinal tract by targeting intestinal architecture, digestive secretions, antioxidant systems, and immune cells. ZnO also has a moderate antibacterial effect against Escherichia coli F4 (K88), the main causative agent of PWD. However, the environmental impact of ZnO and new emerging threats are posing serious questions to the sustainability of its extensive utilization. To work towards a future free from pharmacological ZnO, novel nutritional approaches are necessary, and many strategies have been investigated. This review article provides a comprehensive framework for ZnO utilization and its broad mode of action. Moreover, all the risks related to pharmacological ZnO levels are presented; we focus on European institutions’ decisions subsequently. The identification of a novel, complete solution against PWD should be accompanied by the adoption of holistic strategies, thereby combining good management practices to feeding approaches capable of mitigating Escherichia coli F4 (K88) infections and/or lowering ZnO utilization. Promising results can be obtained by adjusting diet composition or employing organic acids, natural identical compounds, polyphenol-rich extracts, prebiotics, and probiotics.

Evaluation of the combined effects of different dose levels of Zinc oxide with probiotics complex supplementation on the growth performance, nutrient digestibility, faecal microbiota, noxious gas emissions and faecal score of weaning pigs

This study was conducted to assess the effects of different dose levels of zinc oxide (ZnO) combined with probiotics complex supplementation on the growth, performance, nutrient digestibility, faecal lactobacillus and Enterobacteria counts, noxious gas emissions and faecal score of weaned piglets. A total of 180 crossbred weaning pigs ([Yorkshire × Landrace] × Duroc; 6.61 ± 1.29 kg [mean ± SE]; 28 days old) were used in a 42-day trial. All pigs were randomly allotted to 1 of 4 treatment diets based on initial BW and sex (9 replicate pens/treatment; 2 gilts and 3 barrows/pen). Dietary treatment groups were as follows: CON, basal diet +ZnO 3,000 ppm; BZS, basal diet +ZnO 2,100 ppm +0.1% SynerZymeF10; BZS1, basal diet +ZnO 1,200 ppm +0.1% SynerZymeF10; BZS2, basal diet +ZnO 300 ppm +0.1% SynerZymeF10. During the phase 3, decreasing the ZnO concentration led to a linear reduction in ADG (p = 0.044), and the ADG was lower (p < 0.05) in BZS2 compared with CON treatment during the whole experimental period. The effects of dietary ZnO with probiotics complex were not detected (p > 0.05) on nutrient digestibility, Lactobacillus and E. coli counts, faecal gas emissions and faecal scores. In conclusion, the diet supplementation of ZnO (1,200 ppm) with probiotics complex has been shown to have comparable efficacy to ZnO (3,000 ppm) diet on growth performance, nutrient digestibility, faecal microbiota, noxious gas emissions and faecal score of weaning pigs.

Overall assessment of antibiotic substitutes for pigs: a set of meta-analyses

Background

Antibiotic growth promoters are widely used to improve weight gain. However, the abuse of antibiotics can have many negative effects on people. Developing alternatives to antibiotics is an urgent need in livestock production. We aimed to perform a meta-analysis and network meta-analysis (NMA) to investigate the effects of feed additives as potential antibiotic substitutes (ASs) on bacteriostasis, growth performance, intestinal morphology and immunity. Furthermore, the primary, secondary, and tertiary ASs were defined by comparing their results with the results of antibiotics.

Results

Among 16,309 identified studies, 37 were summarized to study the bacteriostasis effects of feed additives, and 89 were included in the meta-analysis and NMA (10,228 pigs). We summarized 268 associations of 57 interventions with 32 bacteria. The order of bacteriostasis effects was as follows: antimicrobial peptides (AMPs) ≈ antibiotics>organic acids>plant extracts>oligosaccharides. We detected associations of 11 feed additives and 11 outcomes. Compared with a basal diet, plant extract, AMPs, probiotics, microelements, organic acids, bacteriophages, lysozyme, zymin, and oligosaccharides significantly improved growth performance (P < 0.05); organic acids, probiotics, microelements, lysozyme, and AMPs remarkably increased the villus height:crypt depth ratio (V/C) (P < 0.05); and plant extracts, zymin, microelements, probiotics, and organic acids notably improved immunity (P < 0.05). The optimal AMP, bacteriophage, lysozyme, microelements, oligosaccharides, organic acids, plants, plant extracts, probiotics, and zymin doses were 0.100%, 0.150%, 0.012%, 0.010%, 0.050%, 0.750%, 0.20%, 0.040%, 0.180%, and 0.100%, respectively. Compared with antibiotics, all investigated feed additives exhibited no significant difference in effects on growth performance, IgG, and diarrhoea index/rate (P > 0.05); AMPs and microelements significantly increased V/C (P < 0.05); and zymin significantly improved lymphocyte levels (P < 0.05). Furthermore, linear weighting sum models were used to comprehensively estimate the overall impact of each feed additive on pig growth and health.

Conclusions

Our findings suggest that AMPs and plant extracts can be used as primary ASs for weaned piglets and growing pigs, respectively. Bacteriophages, zymin, plants, probiotics, oligosaccharides, lysozyme, and microelements can be regarded as secondary ASs. Nucleotides and organic acids can be considered as tertiary ASs. Future studies should further assess the alternative effects of combinational feed additives.

Evaluation of Anthocyanin Content, Antioxidant Potential and Antimicrobial Activity of Black, Purple and Blue Colored Wheat Flour and Wheat-Grass Juice against Common Human Pathogens

The present study aimed to analyze the antioxidant and antimicrobial activity of anthocyanins extracted from colored wheat flour and wheat-grass juice against human pathogens. The total anthocyanin content and antioxidant potential in colored wheat flour and wheat-grass juice extracts were significantly higher than white flour and wheat-grass juice extracts. Ultra-performance liquid chromatography showed the maximum number of anthocyanin peaks in black wheat, with delphinidin-3-o-galactoside chloride, delphinidin-3-o-glucoside chloride, and cyanindin-3-o-glucoside chloride as the major contributors. Among flour extracts, maximum zones of inhibition against Staphylococcus aureus (MTCC 1934), Pseudomonas aeruginosa (MTCC 1434), Escherichia coli, and Candida albicans (MTCC 227) were produced by black flour extract, having the highest anthocyanin content. It exhibited a minimum microbicidal concentration (MMC) of 200 mg/mL against E. coli and C. albicans; and 100 and 150 mg/mL against S. aureus and P. aeruginosa, respectively. Black and purple flour extracts exhibited a minimum inhibitory concentration (MIC) of 50 mg/mL against S. aureus and P. aeruginosa. White flour extracts did not show MMC against E. coli and C. albicans. Among wheat-grass juice extracts, black wheat-grass was most effective and showed an MIC of 100-150 mg/mL against all pathogens. It exhibited an MMC of 200 mg/mL against S. aureus and P. aeruginosa. Hence, anthocyanin-rich colored wheat could be of nutraceutical importance.

Chestnut extract but not sodium salicylate decreases the severity of diarrhea and enterotoxigenic Escherichia coli F4 shedding in artificially infected piglets

The development of alternatives to antibiotics is crucial to limiting the incidence of antimicrobial resistance, especially in prophylactic and metaphylactic use to control post-weaning diarrhea (PWD). Feed additives, including bioactive compounds, could be a promising alternative. This study aimed to test two bioactive compounds, sodium salicylate (SA) and a chestnut extract (CE) containing hydrolysable tannins, on the occurrence of PWD. At weaning, 72 piglets were assigned to four treatments that combined two factors: CE supplementation (with 2% of CE (CE+) or without (CE-)) and SA supplementation (with 35 mg/kg BW of SA (SA+) or without (SA-)). Then, 4 days after weaning, all piglets were infected with a suspension at 10⁸ CFU/ml of enterotoxigenic Escherichia coli (ETEC F4ac). Each piglet had free access to an electrolyte solution containing, or not, SA. This SA supplementation was administered for 5 days (i.e., from the day of infection (day 0) to 4 days post-infection (day 4). During the 2 weeks post-infection, supplementation with SA had no effect (P > 0.05) on growth performances nor on fecal scores. A significant SA × time interaction (P < 0.01) for fecal scores and the percentage of diarrhea indicated that piglets with SA did not recover faster and did have a second episode of diarrhea. In contrast to SA treatment, inclusion of CE increased (P < 0.05) growth performances and feed intake. In the first week post-infection, CE decreased (P < 0.001) the overall fecal scores, the percentage of piglets with diarrhea, the days in diarrhea, and ETEC shedding in the feces. There was a SA×CE interaction (P < 0.05) for ETEC shedding, suggesting a negative effect of combining SA with CE. This study highlighted that, in contrast to SA, CE could represent a promising alternative to antibiotics immediately after weaning for improving growth performance and reducing PWD.

Applicability of an Unmedicated Feeding Program Aimed to Reduce the Use of Antimicrobials in Nursery Piglets: Impact on Performance and Fecal Microbiota

Simple Summary

The need for a reduction in the use of antibiotics in livestock to safeguard their efficacy requires the development of alternatives. In this line, the use of alternative by-products or ingredients, with functional properties brings the opportunity to improve pig health and thus, reduce medicalization. Therefore, in the present study, we aimed to evaluate the impact of an alternative feeding program based on unmedicalized diets formulated with fibrous by-products and functional feed ingredients on performance and fecal microbiota of young pigs compared to a common weaner diet supplemented with antibiotics. The alternative feeding program could anticipate the gut development of young piglets, which at the end of the nursery period presented a fecal microbiota more similar to that found in fattening animals. Moreover, piglets in the unmedicalized diets showed a trend to reduce the course of diarrhea immediately after weaning. The alternative feeding program showed, however, a reduced growth efficiency during the nursery period that needs to be discussed in the frame of the costs-benefits analysis of reducing antibiotics.

Abstract

This study aimed to assess the impact of two different feeding programs, including or not antimicrobials, on gut microbiota development at early ages in commercial pigs. For this, 21-day-old weaned piglets were distributed into 12 pens (6 replicates with 26 pigs each) and fed ad libitum until fattening with: standard commercial formula with antibiotics and zinc oxide (2400 ppm) (AB), and alternative unmedicated feed formula (UN). Subsequently, the animals were moved to the fattening unit (F) receiving a common diet. Pigs were weighed, and feed consumption and diarrhea scores registered. Feces were collected on days 9 (pre-starter), 40 (starter) and 72 (fattening) post-weaning and microbial DNA extracted for 16S rDNA sequencing. Piglets fed UN diets had a worse feed efficiency (p < 0.05) than AB during nursery; however, UN pigs spent less time scouring after weaning (p = 0.098). The structure of fecal community evolved with the age of the animals (p = 0.001), and diet also showed to have a role, particularly in the starter period when UN microbiomes clustered apart from AB, resembling the ecosystems found in the fattening animals. Fibrolytic genera (Fibrobacter, Butyrivibrio, Christellansellaceae) were enriched in UN piglets whereas Lactobacillus characterized AB piglets (adjusted p < 0.05). Overall, this alternative feeding program could anticipate the gut development of piglets despite a lower feed efficiency compared to standard medicalized programs.

Effect of fibre sources on performance, serum parameters, intestinal morphology, digestive enzyme activities and microbiota in weaned pigs

This study was conducted to evaluate the effects of wheat bran (WB) as insoluble fibre source, and sugar beet pulp (SBP) as soluble fibre source, on performance, serum parameters and intestinal health in weaned pigs. A total of 90 weaned pigs (BW: 7.33 ± 1.24 kg) were randomly assigned to three dietary treatments: (1) a control diet (CON) based on corn and soybean meal; (2) CON + 6% WB; (3) CON + 6% SBP. Each treatment had five replicate pens with six pigs per pen. The experimental period was divided into two phases (d 0 to 14 and d 14 to 28). Pigs in group WB tended to have greater avarage daily gain than those in group SBP. Compared with CON, SBP reduced (p < 0.05) the apparent total tract digestibility (ATTD) of dry matter, organic matter (OM), gross energy and neutral detergent fibre on d 14 and 28, while WB decreased (p < 0.05) the ATTD of OM on d 28. Pigs in group SBP had higher (p < 0.05) glucagon-like peptide 1 concentration than the other groups on d 14 and 28. The villus height to crypt depth (V:C) ratio of duodenum and jejunum in pigs fed diet WB were greater (p < 0.05) than in group SBP. The WB increased (p < 0.05) the V:C ratio of ileum compared with CON or SBP. Compared with SBP, WB increased (p < 0.05) the sucrase activity in the duodenum. Moreover, pigs in WB had higher (p < 0.05) activities of maltase and sucrase in the jejunum compared with CON or SBP. The abundances of Ruminococcaceae and Prevotellaceae were increased (p < 0.05) in WB, while the Lachnospiraceae abundance was increased (p < 0.05) in SBP. WB increased (p < 0.05) concentrations of acetate, butyrate and total short-chain fatty acids (SCFA), while SBP increased (p < 0.05) concentrations of acetate and total SCFA when compared with CON. In conclusion, WB was beneficial to performance in weaned pigs by improving morphology, enzyme activities and microbiota when compared with SBP, highlighting that effects of fibre depends on the fibre sources.

Comparative effects of low zinc oxide dose with or without probiotics relative to high zinc oxide dose on the performance, nutrient digestibility, blood metabolites, and noxious gases emission in weaned piglets

The objective of this study was to assess the effects of low-dose zinc oxide (ZnO) supplemented with or without probiotic complex compared with pharmacological ZnO (3000 mg kg−1) on the performance, digestibility, blood metabolites, fecal Lactobacillus and enterobacteria counts of weaned piglets. One-hundred and twenty crossbred piglets were randomly allocated to three treatments based on their initial body weight (BW). Treatments consisted of corn–soybean-meal-based basal diet supplemented with 3000 mg kg−1 ZnO as positive control (ZH), basal diet supplemented with 300 mg kg−1 ZnO as negative control (ZL), and ZL + 0.1% probiotic complex (ZLP). At the end of the experiment, fecal samples were collected by direct rectal massage to determine nutrient digestibility, Lactobacillus and enterobacteria counts, and gas emission, whereas blood samples were taken via jugular venipuncture for determination of blood metabolites. The BW of piglets at week 6, and the average daily gain (ADG) at week 6 and during overall period were higher (P < 0.05) in pigs fed ZH diet compared with those fed ZL diet. The supplementation of ZLP increased the ADG during week 6 and overall making it comparable with ZH diet (P < 0.05). However, other parameters described above were comparable with ZH in pigs fed ZLP diet.

The use of inulin and wheat bran only during the starter period or during the entire rearing life of broilers: effects on growth performance, small intestinal maturation, and cecal microbial colonization until slaughter age

Inulin and wheat bran were added to broiler diets during the starter period or during the entire rearing period to investigate whether the effects of using these ingredients remained until slaughter age. Diets containing no inulin and no wheat bran (CON), 2% inulin (IN), 10% wheat bran (WB), or 2% inulin + 10% wheat bran (IN+WB) were provided until day 11. Thereafter, each dietary treatment was further divided into a continued diet with supplementation or a control diet, resulting in 7 groups (CON, IN/IN, IN/CON, WB/WB, WB/CON, IN+WB/IN+WB, or IN+WB/CON). On day 40, 12 chickens per group were euthanized. The IN/IN group increased the cecal molar ratio of butyrate but had a lower relative abundance of Lactobacillus (P < 0.05). Additionally, the cecal molar ratio of propionate was higher in the IN/CON group compared to the IN/IN group (P = 0.034). The WB/CON group had the best results on BW and feed conversion ratio (FCR) (P < 0.05). Only the cecal molar ratio of iso-butyrate was higher in the WB/WB group (P = 0.013). Moreover, compared to the CON group, both WB/WB and WB/CON groups reduced the relative abundances of Bifidobacterium and Escherichia coli, and only the WB/WB group reduced the relative abundance of Enterobacteriaceae (P < 0.05). Both IN+WB/IN+WB and IN+WB/CON groups increased BW until day 21 and lowered the relative abundance of Bifidobacterium (P < 0.05). The IN+WB/IN+WB group increased the cecal molar ratio of butyrate but reduced the molar ratio of propionate with a higher relative abundance of Enterobacteriaceae (P < 0.05). In conclusion, the lack of positive effects induced by inulin might be explained by the dose being too high. The beneficial effects on BW, FCR, and microbiota induced by wheat bran during the starter period were lasting when supplementation was stopped, suggesting that wheat bran could be a favorable ingredient during the starter period.

A comparison of various bulking materials as a supporting matrix in composting blackwater solids from vacuum toilets

This study discusses the influence of six bulking materials (peat, bark, oat husks, sawdust, food waste, and wheat bran) on the composting of blackwater solids (feces, urine and toilet paper) from low flush vacuum toilets (0.8 L/flush). The focus was on faecal indicator reduction, nutrient recycling, and carbon dioxide and methane emissions. In a composting experiment lasting 60 days, bulking materials were combined and mixed with blackwater solids, composted without stirring and with controlled aeration in a bench scale experiment. The bulking materials combination of oat husks, wheat bran and bark and of oat husks and wheat bran composted with blackwater solids showed the best results in terms of faecal indicator reduction (2.8 log10 reduction of Escherichia coli and 3.2 log10 reduction of faecal streptococci, respectively). Oat husks, bark and wheat bran combination had the smallest nutrient losses of 7.5% total nitrogen, 3.8% total phosphorus and 28% total potassium, while the highest accumulation in total phosphorus was 76.4% occurred in the mixture with oat husks and wheat bran. Peat and food waste improved the sorption of ammonia. The highest methane emissions (average 15.4%) were detected after 28 days of composting in the mixture with bran and food waste. Methane and carbon dioxide levels decreased in all the mixtures towards the end of composting indicating high organic matter degradation. Our findings show that a variety of natural and inexpensive materials can be used and adapted when composing blackwater in remote and sensitive areas.

High dosage of zinc modulates T-cells in a time-dependent manner within porcine gut-associated lymphatic tissue

Zn serves as a powerful feed additive to reduce post-weaning diarrhoea in pigs. However, the mechanisms responsible for Zn-associated effects on the adaptive immune responses following feeding of a very high dosage of Zn remain elusive. In this study, we examined the T-cell response in gut-associated lymphatic tissues of seventy-two weaned piglets. Piglets received diets with 57 mg Zn/kg (low Zn concentration, LZn), 164 mg Zn/kg (medium Zn concentration, MZn) or 2425 mg Zn/kg (high Zn concentration, HZn) mg Zn/kg feed for 1, 2 or 4 weeks. We observed that feeding the HZn diet for 1 week increased the level of activated T-helper cells (CD4+ and CD8α dim) compared with feeding MZn and LZn (P<0·05). In addition, we observed higher transcript amounts of interferon γ and T-box 21 (TBET) in the HZn group compared with the MZn and LZn groups (P<0·05). A gene set enrichment analysis revealed an over-representation of genes associated with 'cytokine signalling in immune system'. Remarkably, feeding of a very high Zn dosage led to a switch in the immune response after 2 weeks. We detected higher relative cell counts of CD4+CD25high regulatory T-helper cells (P<0·05) and a higher expression of forkhead box P3 (FOXP3) transcripts (P<0·05). After 4 weeks of feeding a high-dosage Zn diet, the relative CD4+ T-cell count (P<0·05) and the relative CD8β + T-cell count (P<0·1) were reduced compared with the MZn group. We hypothesise that after 1 week the cellular T-helper 1 response is switched on and after 2 weeks it is switched off, leading to decreased numbers of T-cells.

Purified natural pig immunoglobulins can substitute dietary zinc in reducing piglet post weaning diarrhoea

Enteric infectious disease in weaner piglets, including postweaning diarrhoea (PWD), are usually treated and/or prevented with antibiotics and/or zinc oxide in the piglet feed. However extensive use of antibiotics and zinc oxide in intensive animal production is unwanted as it may promote microbial antibiotic resistance and pose environmental problems. Recently, in an experimental model of PWD, we observed that oral administration of purified porcine immunoglobulin G (ppIgG) from pooled natural pig plasma could reduce enteric infection. In the present study we were able to reproduce these results as it was observed that oral ppIgG accelerated clearance of faecal haemolytic bacteria in pigs challenged with E. coli in comparison with pigs not receiving ppIgG. This effect was observed upon feeding ppIgG for seven days postweaning suggesting that ppIgG does not have to be used prophylactically for several days preweaning. Furthermore, the effect of oral administration of ppIgG for seven days postweaning was equal to or better than that of dietary zinc oxide in reducing diarrhoea symptoms and in clearing faecal haemolytic bacteria for 14days postweaning. These observations warrant future trials of dietary ppIgG in intensive swine production units to establish its performance as an alternative to dietary antibiotics and zinc oxide for preventing PWD.

Elevated dietary zinc oxide levels do not have a substantial effect on porcine reproductive and respiratory syndrome virus (PPRSV) vaccination and infection

Background

Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most important infectious agents for the swine industry worldwide. Zinc (Zn) salts, which are widely used as a dietary supplement in swine nutrition, have shown antiviral effects in vitro as well as in vivo. The purpose of this study was to determine the influence of dietary zinc oxide supplementation on vaccination and challenge infection with PRRSV.

Findings

The clinical course of PRRS and the success of vaccination with an experimental inactivated vaccine were compared between animals receiving a conventional diet (50 ppm Zn, control group) and diets supplemented with Zn oxide (ZnO) at final Zn concentrations of 150 or 2,500 ppm. Pigs receiving higher dietary Zn levels showed a tendency towards higher neutralizing antibody levels after infection, while dietary Zn levels did not substantially influence the number of antiviral IFN-gamma secreting cells (IFN-gamma-SC) or percentages of blood immune cell subsets after infection. Finally, feeding higher dietary Zn levels reduced neither clinical symptoms nor viral loads.

Conclusions

Our results suggest that higher levels of dietary ZnO do not have the potential to stimulate or modulate systemic immune responses after vaccination and heterologous PRRSV infection to an extent that could improve the clinical and virological outcome.

Electronic supplementary material

The online version of this article (doi:10.1186/1743-422X-11-140) contains supplementary material, which is available to authorized users.

Effect of seaweed-derived laminarin and fucoidan and zinc oxide on gut morphology, nutrient transporters, nutrient digestibility, growth performance and selected microbial populations in weaned pigs

In the present study, two experiments were conducted to (1) evaluate the effect of laminarin and/or fucoidan on ileal morphology, nutrient transporter gene expression and coefficient of total tract apparent digestibility (CTTAD) of nutrients and (2) determine whether laminarin inclusion could be used as an alternative to ZnO supplementation in weaned pig diets. Expt 1 was designed as a 2 × 2 factorial arrangement, comprising four dietary treatments (n 7 replicates, weaning age 24 d, live weight 6·9 kg). The dietary treatments were as follows: (1) basal diet; (2) basal diet+300 ppm laminarin; (3) basal diet+240 ppm fucoidan; (4) basal diet+300 ppm laminarin and 240 ppm fucoidan. There was an interaction between laminarin and fucoidan on the CTTAD of gross energy (GE) (P< 0·05) and the expression of sodium-glucose-linked transporter 1 (SGLT1/SLC5A1) and GLUT1/SLC2A1 and GLUT2/SLC2A2 (P< 0·05) in the ileum. The laminarin diet increased the CTTAD of GE and increased the expression of SGLT1, GLUT1 and GLUT2 compared with the basal diet. However, there was no effect of laminarin supplementation on these variables when combined with fucoidan. Expt 2 was designed as a complete randomised design (n 8 replicates/treatment, weaning age 24 d, live weight 7·0 kg), and the treatments were (1) basal diet, (2) basal diet and laminarin (300 ppm), and (3) basal diet and ZnO (3100 ppm, 0-14 d, and 2600 ppm, 15-32 d post-weaning). The laminarin diet increased average daily gain and gain:feed ratio compared with the basal diet during days 0-32 post-weaning (P< 0·01) and had an effect similar to the ZnO diet. These results demonstrate that laminarin provides a dietary means to improve gut health and growth performance post-weaning.

Effect of the interaction of seaweed extracts containing laminarin and fucoidan with zinc oxide on the growth performance, digestibility and faecal characteristics of growing piglets

Seaweed extracts (SWE) rich in laminarin and fucoidan have shown promise as a supplement for weaned piglets. However, successful application in pig nutrition depends on their bioactivity in the presence of additives such as ZnO. In the present study, a 2 × 2 factorial experiment was carried out to investigate the effect of the interaction between SWE and ZnO on the growth performance, digestibility and faecal characteristics of 192 weaned piglets (6·5 kg). The piglets were penned in groups of 4 (n 12 pens). The study consisted of two phases after weaning: a starter diet period from the day of weaning (0 d) to 21 d and a transition diet period from 21 to 40 d. The dietary treatments were as follows: (1) control diet; (2) control diet+ZnO; (3) control diet+SWE; (4) control diet+ZnO+SWE. Diets containing ZnO improved the faecal consistency of the piglets throughout the experimental period (0-40 d). An effect of the interaction between ZnO and SWE on several variable was observed. The diet containing only SWE or ZnO improved the feed conversion efficiency of the piglets during the transition diet period; however, this effect was not observed when the diet containing both ZnO and SWE was fed. The diet containing only SWE increased the N and organic matter digestibility of the piglets; however, this effect was not observed in the presence of ZnO. An interaction between ZnO and SWE was observed, whereby the faecal counts of Escherichia coli were decreased when piglets were fed the diet containing only SWE, but not when fed the diet containing both SWE and ZnO. In summary, SWE and ZnO improve growth performance when given alone, but not when given in combination. The biological effect of SWE on selected digestibility and faecal characteristics was markedly different when compared with that of ZnO.

Dietary Enterococcus faecium NCIMB 10415 and zinc oxide stimulate immune reactions to trivalent influenza vaccination in pigs but do not affect virological response upon challenge infection

Swine influenza viruses (SIV) regularly cause significant disease in pigs worldwide. Since there is no causative treatment of SIV, we tested if probiotic Enterococcus (E.) faecium NCIMB 10415 or zinc (Zn) oxide as feed supplements provide beneficial effects upon SIV infection in piglets. Seventy-two weaned piglets were fed three different diets containing either E. faecium or different levels of Zn (2500 ppm, Zn^high; 50 ppm, Zn^low). Half of the piglets were vaccinated intramuscularly (VAC) twice with an inactivated trivalent SIV vaccine, while all piglets were then infected intranasally with H3N2 SIV. Significantly higher weekly weight gains were observed in the E. faecium group before virus infection, and piglets in Zn^high and E. faecium groups gained weight after infection while those in the control group (Zn^low) lost weight. Using ELISA, we found significantly higher H3N2-specific antibody levels in the E. faecium+VAC group 2 days before and at the day of challenge infection as well as at 4 and 6 days after challenge infection. Higher hemagglutination inhibition (HI) titers were also observed in the Zn^high+VAC and E. faecium+VAC groups at 0, 1 and 4 days after infection. However, there were no significant differences in virus shedding and lung lesions between the dietary groups. Using flow cytometry analysis significantly higher activated T helper cells and cytotoxic T lymphocyte percentages in the PBMCs were detected in the Zn^high and E. faecium groups at single time points after infection compared to the Zn^low control group, but no prolonged effect was found. In the BAL cells no influence of dietary supplementation on immune cell percentages could be detected. Our results suggest that feeding high doses of zinc oxide and particularly E. faecium could beneficially influence humoral immune responses after vaccination and recovery from SIV infection, but not affect virus shedding and lung pathology.

Diets high in heat-treated soybean meal reduce the histamine-induced epithelial response in the colon of weaned piglets and increase epithelial catabolism of histamine

We examined the influence of dietary fermentable protein (fCP) and fermentable carbohydrates (fCHO) on the colonic epithelial response to histamine in pigs. Thirty-two weaned piglets were fed 4 diets in a 2 × 2 factorial design with low fCP/low fCHO, low fCP/high fCHO, high fCP/low fCHO and high fCP/high fCHO. After 21-23 days, the pigs were killed and tissue from the proximal colon was stimulated with carbachol, histamine, PGE2 or sodium hydrogen sulphide in Ussing chambers. Changes in short-circuit current and tissue conductance were measured. Diamine oxidase, histamine N-methyltransferase, stem cell growth factor receptor, Fc-epsilon receptor I and cystic fibrosis transmembrane conductance regulator gene expression was determined. Activities of diamine oxidase and histamine N-methyltransferase and numbers of colonic mast cells were measured. The change in the short-circuit current in response to histamine was lower (P = 0.002) and tended to be lower for PGE2 (P = 0.053) in high fCP groups compared to low fCP groups, irrespective of fCHO. Additionally, the change in tissue conductance after the application of histamine was lower (P = 0.005) in the high fCP groups. The expression of histamine N-methyltransferase mRNA (P = 0.033) and the activities of diamine oxidase (P = 0.001) and histamine N-methyltransferase (P = 0.006) were higher with high fCP in comparison with low fCP. The expression of mast cell markers, stem cell growth factor receptor (P = 0.005) and Fc-epsilon receptor I (P = 0.049) was higher with high fCP diets compared to diets low in fCP, whereas the mast cell count did not differ between groups. The expression of the cystic fibrosis transmembrane conductance regulator was reduced (P = 0.001) with high fCP diets compared to low fCP diets. The lower epithelial response to histamine and PGE2 and elevated epithelial histamine inactivation suggests an adaptation to high fCP diets.

Screening the ability of natural feed ingredients to interfere with the adherence of enterotoxigenicEscherichia coli(ETEC) K88 to the porcine intestinal mucus

The inhibition of the attachment of bacteria to the intestine by receptor analogues could be a novel approach to prevent enterotoxigenicEscherichia coli(ETEC) K88-induced diarrhoea in piglets. The objective of the present study was to screen the ability of different feed ingredients (FI) to bind to ETEC K88 (adhesion test, AT) and to block its attachment to the porcine intestinal mucus (blocking test, BT) usingin vitromicrotitration-based models. In the AT, wheat bran (WB), casein glycomacropeptide (CGMP) and exopolysaccharides exhibited the highest adhesion to ETEC K88 (P< 0·001). In the BT, WB, CGMP and locust bean (LB) reduced the number of ETEC K88 attached to the intestinal mucus (P< 0·001). For WB and LB, fractionation based on their carbohydrate components was subsequently carried out, and each fraction was evaluated individually. None of the WB fractions reduced the adhesion of ETEC K88 to the mucus as did the original extract, suggesting that a protein or glycoprotein could be involved in the recognition process. With regard to the LB fractions, the water-extractable material reduced the adhesion of ETEC K88 (P< 0·001) to the mucus similar to the original extract (P< 0·001), indicating, in this case, that galactomannans or phenolic compounds could be responsible for the recognition process. In conclusion, among the FI screened, the soluble extracts obtained from WB, LB and CGMP exhibited the highest anti-adhesive properties against ETEC K88 in the BT. These results suggest that they may be good candidates to be included in diets of weaned piglets for the prevention of ETEC K88-induced diarrhoea.

Zinc as an agent for the prevention of biofilm formation by pathogenic bacteria

AIMS

Biofilm formation is important for the persistence of bacteria in hostile environments. Bacteria in a biofilm are usually more resistant to antibiotics and disinfectants than planktonic bacteria. Our laboratory previously reported that low concentrations of zinc inhibit biofilm formation of Actinobacillus pleuropneumoniae. The aim of this study is to evaluate the effect of zinc on growth and biofilm formation of other bacterial swine pathogens.

METHODS AND RESULTS

To determine the effect of zinc on biofilm formation, biofilms were grown with or without zinc in 96-well plates and stained with crystal violet. At micromolar concentrations (0-250 μ mol l(-1)), zinc weakly inhibited bacterial growth and it effectively blocked biofilm formation by A. pleuropneumoniae, Salmonella Typhymurium and Haemophilus parasuis in a dose-dependent manner. Additionally, biofilm formation of Escherichia coli, Staphylococcus aureus and Streptococcus suis was slightly inhibited by zinc. However, zinc did not disperse preformed biofilms. To determine whether zinc inhibits biofilm formation when poly-N-acetylglucosamine (PGA) is present, PGA was detected with the lectin wheat germ agglutinin. Only A. pleuropneumoniae and Staph. aureus biofilms were found to contain PGA.

CONCLUSION

Zinc used at nonbactericidal concentrations can inhibit biofilm formation by several Gram-negative and Gram-positive bacterial swine pathogens.

SIGNIFICANCE AND IMPACT OF STUDY

The antibiofilm activity of zinc could provide a tool to fight biofilms, and the nonspecific inhibitory effect may well extend to other important human and animal bacterial pathogens.

No protective effects of high-dosage dietary zinc oxide on weaned pigs infected with Salmonella enterica serovar typhimurium DT104

Twenty-eight-day-old weaned pigs were fed diets with a low (LZn), medium (MZn), or high (MZn) Zn concentration (50 to 80, 150, or 2,500 mg Zn/kg of diet, respectively) provided as zinc oxide (ZnO)(24 pigs per group). They were infected orally with Salmonella enterica serovar Typhimurium DT104 on day 32. Salmonellae were cultivated from feces (up to 42 days postinfection [dpi]) and organs (2 and 42 dpi). Activation of the adaptive systemic and mucosal immune systems was investigated by recording anti-Salmonella IgG levels and levels of B and T lymphocyte subpopulations in blood and gut-associated lymphatic tissue. Growth performance was recorded as well. Salmonellae were shed at higher levels and for longer periods in the HZn group (P < 0.05), with no differences in the tissues. At 2 dpi, the relative percentages of CD4(+) T helper cells (P < 0.01) and of CD2(+) T and NK cells (P < 0.01) in blood were reduced from the relative cell counts obtained at 0 dpi, irrespective of the Zn group. The lowest percentage of cytotoxic T cells was found 14 dpi in the HZn group relative to the MZn (P < 0.05) and LZn (P < 0.01) groups. Supplementation of the feed with 2,500 mg Zn/kg of diet immediately after weaning could positively affect the immune responses of piglets infected with Salmonella Typhimurium, but for a short period only. After 2 weeks, all positive effects disappeared, and rather negative effects, such as higher shedding of salmonellae, lower T cell frequencies, and worse performance, occurred. Thus, supplementation with ZnO at high levels in the pig industry should be limited to 2 to 3 weeks.

Use of nano-oxide materials as anti-diarrhea agents in piglets

Diarrhea is a common intestinal disease with high morbidity and mortality, seriously affecting the growth performance and survival of piglets. Due to the restricted use of antibiotics, new feed additives or drugs have been paid more and more attention. This article reviews the use of nano-zinc oxide and montmorillonite as anti-diarrhea agents in piglets.

Influence of a microbial phytase and zinc oxide on young pig growth performance and serum minerals

Crossbred pigs (n=288; average age=21±3 d and BW=7.1±0.2 kg) were used in a 42-d trial to determine the influence of a microbial phytase and various doses of ZnO on growth performance and serum minerals. Pigs (6 castrated males or females/pen) were randomly allotted to treatments in a 2×3 factorial arrangement with 2 dietary levels of a microbial phytase (0 or 2,500 phytase units/kg) and 3 dietary levels of supplemental ZnO [0, 1750, or 3,500 mg/kg ZnO (72% Zn)] with 4 pens of castrated males and 4 pens of females per treatment. Diets were formulated to exceed all nutrient requirements, including Ca and P from d 0 to 21 (phase 1) and d 22 to 42 (phase 2). Growth performance, serum Zn, and serum P were not influenced (P>0.05) by a ZnO×phytase interaction during phase 1, phase 2, or overall (d 0 to 42). Phytase increased (P=0.01) ADFI and improved (P=0.02) ADG in phase 1 and improved (P=0.01) overall ADG, regardless of the level of ZnO supplemented. Zinc oxide supplementation linearly reduced (P=0.05) ADG, and ZnO at 3,500 mg/kg reduced (quadratic, P=0.04) G:F in pigs (phase 2). During phase 1, phytase increased serum Ca, but only in the absence of ZnO supplementation, which resulted in a ZnO×phytase interaction (P=0.02). Serum Zn was increased (linear, P<0.001) and serum P was decreased (linear, P=0.05) as ZnO supplementation increased in the diet (phase 1). In phase 2, serum Ca was reduced (linear, P=0.04) and serum Zn was increased (linear, P=0.02) as ZnO supplementation increased in the diet. Phytase supplementation increased (P=0.009) serum Zn and increased (P=0.003) serum P (phase 1). There was no influence of phytase supplementation on serum minerals in phase 2. In summary, supplemental ZnO reduced growth performance in this experiment. Phytase supplementation improved ADG in Ca- and P-adequate diets regardless of the level of ZnO supplemented, which may be attributed to the reduction of phytate as an antinutrient. In addition, through phytate hydrolysis, phytase reduced phytate-Zn interactions and increased serum Zn, Ca, and P. However, supplementing ZnO increased serum Zn, which reduced serum P and Ca, indicating Ca-Zn-P precipitation. In addition, phytase increased serum Ca, but only in the absence of Zn, further indicating a complex interaction between Zn, Ca, and P in the blood.

Coarse, but not finely ground, dietary fibre increases intestinal Firmicutes:Bacteroidetes ratio and reduces diarrhoea induced by experimental infection in piglets

Using dietary fibre to control childhood diarrhoea has rarely been discussed. However, dietary fibre is being proposed to prevent diarrhoea in piglets. The present study aimed to study the effects of introducing fibre in the post-weaning piglet diet and its particle size on the intestinal ecosystem before and after an experimental infection with Escherichia coli. A total of thirty-six post-weaning piglets were assigned to four experimental diets: a negative control (NC) diet, the same diet with 4 % wheat bran coarse (WBc) particle size or finely milled (WBF) and a positive control (PC) diet with an antibiotic. On day 9, animals were challenged with E. coli. Faecal and digesta samples were obtained before and after the experimental infection and changes in the microbial ecosystem were measured. Animals fed the WBc and the PC diets showed a significant reduction in the faecal score compared with the NC diet. The inclusion of WBc in the diet increased total volatile fatty acid concentration, reduced Bacteroidetes in the faeces before and after the experimental infection compared with the NC diet and increased Firmicutes at the end of the experiment. Based on the results, diarrhoea scours and the composition of the pig gut microbial community are modified by the inclusion of a relatively small amount of wheat bran in the diet, being the physical presentation of the fibre a determinant of that difference.

Influence of dietary ingredients on in vitro inflammatory response of intestinal porcine epithelial cells challenged by an enterotoxigenic Escherichia coli (K88)

Enterotoxigenic Escherichia coli (ETEC) K88 is the main bacterial cause of diarrhea in piglets around weaning and the adhesion of ETEC to the intestinal mucosa is a prerequisite step for its colonization. In this study, the adhesion of a fimbriated ETEC and a non-fimbriated E. coli (NFEC) to the intestinal cells and the activation of the innate immune system were evaluated using a porcine intestinal epithelial cell line (IPEC-J2). The impact of several feedstuffs (wheat bran (WB); casein glycomacropeptide (CGMP); mannan-oligosaccharides (MOS); locust bean extract (LB) and Aspergillus oryzae fermentation extract (AO)) on ETEC attachment and the inflammatory response were also studied. The gene expression of TLR-4; TLR-5; IL-1β; IL-8; IL-10 and TNF-α were quantified using Cyclophilin-A, as a reference gene, and related to a non-challenged treatment. The fimbriated strain was markedly better than the non-fimbriated strain at adherence to intestinal cells and inducing an inflammatory response. All the feedstuffs studied were able to reduce the adhesion of ETEC, with the greatest decrease with CGMP or MOS at highest concentration. Regarding the inflammatory response, the highest dose of WB promoted the lowest relative expression of cytokines and chemokines. All tested feedstuffs were able to reduce the adhesion of ETEC to IPEC-J2 and interfere on the innate inflammatory response; however WB should be further studied according to the beneficial results on the intestinal inflammatory process evidenced in this study.