Dietary zinc oxide in weaned pigs--effects on performance, tissue concentrations, morphology, neutrophil functions and faecal microflora

Comparative effects of level of dietary fiber and sanitary conditions on the growth and health of weanling pigs

There are conflicting results on the growth and health of weanling pigs (Sus scrofa) fed high-fiber diets, and responses may differ according to sanitary conditions. This study was conducted to explore the growth, health, and fecal microbiota of weanling pigs fed either low- or high-fiber diets in 2 different sanitary conditions. Forty-eight pigs weaned at 28 d of age were individually housed in "good" (clean) or "poor" (unclean) sanitary conditions. During 2 consecutive phases, pigs were fed 2 diets containing a low (control) or high level of fiber: 121 or 169 g/kg total dietary fiber (TDF) for Phase I and 146 or 217 g/kg for Phase II, which lasted 15 and 20 d, respectively. This led to 4 experimental treatments in Phase I in a 2 × 2 factorial arrangement (2 sanitary conditions × 2 diets) and 8 experimental treatments in Phase II in a 2 × 2 × 2 factorial arrangement (2 sanitary conditions × 2 diets in Phase I × 2 diets in Phase II). The poor sanitary conditions led to a reduced G:F (0.617 vs. 0.680 for poor and good sanitary conditions, respectively; P = 0.01) over the entire experimental period. The number of pigs with diarrhea in Phase I tended to be greater in the poor sanitary conditions with the high-fiber diet than the control diet (7 vs. 3 pigs, P = 0.07). Enterococcus was prominent in feces of these diarrheic pigs. At 5 wk after weaning, compared with good sanitary conditions, the fecal microbiota of pigs housed in poor sanitary conditions was characterized by more Lactobacillus (9.24 vs. 8.34 log cfu/g, P < 0.001), more Enterobacteria (6.69 vs. 5.58 log cfu/g, P < 0.001), and less anaerobic sulfite bacteria (3.72 vs. 5.87 log cfu/g; P < 0.001). The feces of pigs in poor sanitary conditions contained more total VFA and proportionally more butyrate (9.7 vs. 5.7% for poor and good conditions, respectively, independently of dietary treatment, P < 0.001). At 5 wk after weaning, feces of pigs fed the high-fiber diet during Phase II contained less Enterococcus bacteria than pigs fed the control diet (4.06 vs. 4.56 log cfu/g; P = 0.05), and more total VFA with a decreased proportion of branched-chain fatty acids (5.0 vs. 6.1%; P = 0.006). To conclude, feeding pigs a high-fiber diet in the immediate period after weaning is probably an additional risk factor for slower BW gain, especially in poor sanitary conditions.

Regulatory responses to excess zinc ingestion in growing rats

The growth of weaning piglets is effectively improved by feeding a high-Zn diet (3000 mg Zn/kg of diet). The present study examined whether feeding a diet supplemented with Zn (1016-3000 mg/kg) for 10 d induces growth benefits in rats. In addition, tissue weight, Zn content of tissues and expression of Zn transporters were examined in these rats. Zn supplementation did not significantly increase body weight. Breaking line model analyses indicated that the weight of the pancreas, the organ most sensitive to excess Zn, significantly decreased with increasing Zn intake beyond 15·2 mg/d. Excess Zn has been suggested to accumulate in the liver, kidney and bone in order to protect the pancreas. Zn concentrations in the plasma, liver, kidney and femur increased with increasing Zn intake up to approximately 30 mg/d, whereas those in the pancreas increased up to 8·4 mg/d and decreased by Zn intake beyond 8·4 mg/d. The expression levels of the Zn transporters Zip4 and ZnT1 in the intestinal epithelium were significantly lower in rats fed a diet supplemented with 1016 mg/kg Zn compared to those fed the basal diet. The present study reveals that (1) excess Zn intake does not accelerate growth in rats, but is detrimental to the pancreas, (2) the excess Zn is effectively accumulated in the liver, kidney and bone, without sufficient protection of the pancreas and (3) expression of Zn transporters is down-regulated in response to excess Zn intake.

Bar-coded pyrosequencing of 16S rRNA gene amplicons reveals changes in ileal porcine bacterial communities due to high dietary zinc intake

Feeding high levels of zinc oxide to piglets significantly increased the relative abundance of ileal Weissella spp., Leuconostoc spp., and Streptococcus spp., reduced the occurrence of Sarcina spp. and Neisseria spp., and led to numerical increases of all Gram-negative facultative anaerobic genera. High dietary zinc oxide intake has a major impact on the porcine ileal bacterial composition.

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.

Nutritional influences on some major enteric bacterial diseases of pig

There are several enteric bacterial diseases and conditions of pigs that require control to prevent overt disease, to reduce morbidity and mortality, and to improve the efficiency of production. Traditionally, veterinarians, feed manufacturers and producers have relied upon antibiotics and minerals (for example, ZnO, CuSO4) in diets for a large part of this control. However, recent trends, particularly in Europe, are to reduce antimicrobial use and seek alternative or replacement strategies for controlling enteric bacterial diseases. The majority of these strategies rely on 'nutrition', taken in its broadest sense, to reduce the susceptibility of pigs to these diseases. Evidence to date suggests that specific dietary interventions, for example feeding very highly-digestible diets based on cooked white rice, can reduce the proliferation of a number of specific enteric bacterial infections, such as post-weaning colibacillosis. No simple and universal way to reduce susceptibility to pathogens in the gastrointestinal tract has been identified, and the underlying basis for many of the reported positive effects of 'nutrition' on controlling enteric infections lacks robust, scientific understanding. This makes it difficult to recommend dietary guidelines to prevent or reduce enteric bacterial diseases. Furthermore, some diseases, such as porcine intestinal spirochaetosis caused by Brachyspira pilosicoli, are sometimes associated with other pathogens (co-infections). In such cases, each pathogen might have different nutrient requirements, ecological niches and patterns of metabolism for which a variety of dietary interventions are needed to ameliorate the disease. Greater understanding of how 'nutrition' influences gut epithelial biology and immunobiology, and their interactions with both commensal and pathogenic bacteria, holds promise as a means of tackling enteric disease without antimicrobial agents. In addition, it is important to consider the overall system (i.e. management, housing, welfare) of pig production in the context of controlling enteric bacterial diseases.

Dietary supplementation with zinc oxide stimulates ghrelin secretion from the stomach of young pigs

Dietary supplementation with zinc is known to enhance food intake and growth in young children. However, the underlying mechanisms remain largely unknown. Ghrelin, a peptide derived mainly from stomach, plays an important role in food-intake regulation. The present study was conducted with the piglet model to test the hypothesis that zinc may increase gastric ghrelin secretion. In Experiment 1 (Exp. 1) , thirty-six 28-day-old weaned pigs were assigned to two groups (18 pigs/group), receiving four-week supplementation of 0 or 2000 mg/kg Zn (as ZnO) to the basal diet containing 100 mg/kg Zn. In Experiment (Exp. 2), sixteen 28-day-old piglets were assigned to the same treatments (n=8/group) as in Exp. 1, except that they were pair-fed an equal amount of diet. At the end of the experiments, blood, stomach and duodenum samples were obtained for biochemical analysis, including assays of ghrelin protein and insulin-like growth factor-I (IGF-I) in plasma, as well as quantification of ghrelin and IGF-I mRNA levels in the duodenum and gastric mucosa. Further, gastric mucosal cells from unsupplemented piglets were cultured with 0-0.5 mM ZnO for 2-24 h for assays of ghrelin production and gene expression. Dietary Zn supplementation increased plasma concentrations of ghrelin, IGF-I and cholecystokinin; IGF-I gene expression in the duodenum as well as food intake and piglet growth (Exp. 1). The effects of ZnO on plasma levels of ghrelin, intestinal IGF-I expression and piglet growth were independent of food intake. Addition of ZnO to culture medium enhanced ghrelin production from gastric mucosal cells without affecting ghrelin mRNA levels. Collectively, our results indicate that ZnO stimulates ghrelin secretion from the stomach at the post-transcriptional level. This novel finding aids in elucidating the cellular and molecular mechanism for a role of zinc in promoting food intake and growth of young children.

Use of mannanoligosaccharides and zinc chelate as growth promoters and diarrhea preventative in weaning pigs: Effects on microbiota and gut function1

The efficacy of a commercial source of mannanoligosacharides (BM), organic zinc (BP), or their combination to enhance performance, gastrointestinal health, and immune response in weaned pigs was evaluated. A total of 128 piglets, weaned at 20 +/- 2 d, were housed in 32 pens. Animals received 1 of 4 dietary treatments: a control diet (CT) to which 0.2% of BM, 80 mg/kg of Zn as BP, or both additives (BMP) were added. The experiment lasted for 5 wk including a prestarter period of 2 wk and a starter period of 3 wk. Body weight was recorded and daily feed intake was calculated. Fecal consistency was monitored for the first 21 d. After 2 wk, 32 animals were killed, digesta samples from the stomach, ileum, and cecum were collected, and pH and the short-chain fatty acid profile were determined. Microbiological counts for enterobacteria and lactobacilli were evaluated using quantitative PCR. Histological parameters in the jejunum and immunoglobulin concentrations in serum and ileal digesta were also measured. Both additives improved G:F during the starter period (0.63, 0.69, 0.67, and 0.68 for CT, BM, BP, and BMP, respectively; P < 0.04). Mean fecal score values for the first 21 d were improved by BM and BP, showing decreased values compared with the CT diet (1.22, 0.89, 0.87, and 1.06 for CT, BM, BP, and BMP, respectively; P = 0.002). The addition of BM decreased enterobacteria counts in the jejunum (9.13, 8.05, 8.87, and 7.89 log 16S rRNA gene copies/g of matter for CT, BM, BP, and BMP, respectively; P = 0.05). Empty ileal weight, defined as the segment including the continuous Peyer's patch, tended (P = 0.08) to increase with BP treatment (8.9, 9.6, 11.9, and 10.3 g/kg of BW for CT, BM, BP, and BMP, respectively). Crypt depths in the jejunum were lower in animals fed the combination of the additives (BPM) compared with those fed the control diet (281 vs. 235; P < 0.03). No significant differences were registered in pH, short-chain fatty acids, or serum and ileal immunoglobulin concentrations. The results suggest that the use of BM or BP can improve the efficiency of gain during the starter period.

Changes in caecal microbiota and mucosal morphology of weaned pigs

An experiment was designed to monitor the changes in caecal microbiota associated with early weaning. Twelve piglets (20+/-2 days) from six different litters were selected from a commercial source. For the two experimental groups, one animal from each litter was weaned onto a post-weaning diet (W) and the other remained with the sow (S). After 1 week, animals were sacrificed and caecal samples taken. Microbial counts for total bacteria, enterobacteria and lactobacilli populations were determined by quantitative PCR using SYBR Green dye. Microbial profiles were assessed by terminal restriction fragment length polymorphism (t-RFLP). Weaning promoted an increase in the enterobacteria:lactobacilli ratio (0.27 versus 1.67 log/log 16S rRNA gene copy number, P=0.05). Total bacteria and richness of the caecal microbial ecosystem (number of peaks) were similar in both experimental groups (49.3 for S and 53.4 for W, respectively, P=0.22), although the band patterns were clearly grouped in two different clusters by dendogram analysis. Weaning was also associated with a decrease in crypt density, an increase in mytotic index and a decrease in the number of goblet cells. A reduced immunological response was also observed and was manifested by an increase in intraepithelial lymphocytes and lymphocyte density in the lamina propria. Weaning appears to be critical in the establishment of the caecal microbiota in pigs with important changes, particularly in microbial groups and in caecal mucosal architecture.

Minimal prophylactic concentration of dietary zinc compounds in a mouse model of swine dysentery

Dietary supplementation with 6000 mg of Zn2+/kg of feed has been shown to modify the clinicopathologic expression ofBrachyspira hyodysenteriaeinfection in a laboratory mouse model of swine dysentery. However, this concentration impaired the body weight gain of the mice. The purpose of the present study was to determine a minimal prophylactic concentration of feed-grade zinc compounds that would not affect the growth of mice challenge-exposed withB. hyodysenteriae. A total of 440, 6- to 8-week-old, C3H/HeN mice were allocated randomly to groups and fed either a defined diet or a defined diet containing either 1000, 2000 or 4000 mg/kg ZnO, ZnSO4or zinc-methionine for 7 days before intra- gastric inoculation withB. hyodysenteriae. From days 7 to 35 after inoculation, mice in each group were necropsied at weekly intervals for determination of body weight, presence ofB. hyodysenteriaein the cecum, and histological assessment of cecal lesions. Only ZnO fed at 2000 mg/kg had a prophylactic effect againstB. hyodysenteriaeinfection without affecting the body weight gain of the mice. The prophylactic effect of Zn2+against infection withB. hyodysenteriaewas also affected by the relative concentration of Fe2+and Zn2+/Fe2+ratio of the diet.

Dietary supplementation with zinc oxide increases Igf-I and Igf-I receptor gene expression in the small intestine of weanling piglets

This study was conducted to investigate the mechanism for the effect of elevated levels of dietary zinc oxide (ZnO) in enhancing the intestinal growth of weanling piglets. In Experiment 1, 4-wk-old (8.1 +/- 0.6 kg) crossbred barrows (n = 36) were assigned randomly to 1 of the 2 dietary groups, with 6 pens/group (3 pigs/pen). One group was fed the basal diet containing 100 mg Zn/kg diet. The other group was fed the basal diet supplemented with ZnO to provide 3000 mg Zn/kg diet. Pigs consumed their feed ad libitum for 14 d. In Experiment 2, 4-wk-old (7.6 +/- 0.16 kg) crossbred barrows (n = 16) were housed individually and assigned to 1 of the 2 dietary groups (8 pigs/group) as in Experiment 1, except that the 2 groups were pair-fed the same amount of feed. At the end of a 14-d treatment period, all of the pigs in both Experiments 1 and 2 were weighed, feed consumption was measured, and blood samples were collected for assays of insulin-like growth factor-I (IGF-I). In addition, 1 pig from each pen in Experiments 1 and 2 was selected randomly to obtain the small-intestinal mucosa for analyzing IGF-I and IGF-I receptor (IGF-IR) gene expression and to determine the small-intestinal morphology. In Experiment 1, dietary supplementation of ZnO increased (P < 0.05) the daily body weight gain and daily feed intake. In Experiment 2, dietary supplementation of ZnO increased (P < 0.05) the daily body weight gain and feed conversion efficiency. In both experiments, the villous height of the small-intestinal mucosa and both the mRNA and protein levels for IGF-I and IGF-IR in the small intestine were markedly enhanced (P < 0.05) by feeding elevated levels of Zn. Serum IGF-I levels did not differ between the control and Zn-supplemental groups in either experiment. Collectively, these results suggest that dietary Zn supplementation exerts its beneficial effects on the intestinal growth of weanling piglets through increasing IGF-I and IGF-IR expression in the small-intestinal mucosa.

Comparison of growth performance and zinc absorption, retention, and excretion in weanling pigs fed diets supplemented with zinc-polysaccharide or zinc oxide1

Fifty weanling crossbred pigs averaging 6.2 kg of initial BW and 21 d of age were used in a 5-wk experiment to evaluate lower dietary concentrations of an organic source of Zn as a Zn-polysaccharide (Zn-PS) compared with 2,000 ppm of inorganic Zn as ZnO, with growth performance, plasma concentrations of Zn and Cu, and Zn and Cu balance as the criteria. The pigs were fed individually in metabolism crates, and Zn and Cu balance were measured on individual pigs (10 replications per treatment) from d 22 to 26. The basal Phase 1 (d 0 to 14) and Phase 2 (d 14 to 35) diets contained 125 or 100 ppm added Zn as Zn sulfate, respectively, and met all nutrient requirements. Treatments were the basal Phase 1 and 2 diets supplemented with 0, 150, 300, or 450 ppm of Zn as Zn-PS or 2,000 ppm Zn as ZnO. Blood samples were collected from all pigs on d 7, 14, and 28. For pigs fed increasing Zn as Zn-PS, there were no linear or quadratic responses (P > or = 0.16) in ADG, ADFI, or G:F for Phases 1 or 2 or overall. For single degree of freedom treatment comparisons, Phase 1 ADG and G:F were greater (P < or = 0.05) for pigs fed 2,000 ppm Zn as ZnO than for pigs fed the control diet or the diet containing 150 ppm Zn as Zn-PS. For Phase 2 and overall, ADG and G:F for pigs fed the diets containing 300 or 450 ppm of Zn as Zn-PS did not differ (P > or = 0.29) from pigs fed the diet containing ZnO. Pigs fed the diet containing ZnO also had a greater Phase 2 (P < or = 0.10) and overall (P < or = 0.05) ADG and G:F than pigs fed the control diet. There were no differences (P > or = 0.46) in ADFI for any planned comparison. There were linear increases (P < 0.001) in the Zn excreted (mg/d) with increasing dietary Zn-PS. Pigs fed the diet containing ZnO absorbed, retained, and excreted more Zn (P < 0.001) than pigs fed the control diet or any of the diets containing Zn-PS. In conclusion, Phase 2 and overall growth performance by pigs fed diets containing 300 or 450 ppm Zn as Zn-PS did not differ from that of pigs fed 2,000 ppm Zn as ZnO; however, feeding 300 ppm Zn as Zn-PS decreased Zn excretion by 76% compared with feeding 2,000 ppm Zn as ZnO.

Influence of dietary zinc oxide and copper sulfate on the gastrointestinal ecosystem in newly weaned piglets

Dietary doses of 2,500 ppm ZnO-Zn reduced bacterial activity (ATP accumulation) in digesta from the gastrointestinal tracts of newly weaned piglets compared to that in animals receiving 100 ppm ZnO-Zn. The amounts of lactic acid bacteria (MRS counts) and lactobacilli (Rogosa counts) were reduced, whereas coliforms (MacConkey counts) and enterococci (Slanetz counts, red colonies) were more numerous in animals receiving the high ZnO dose. Based on 16S rRNA gene sequencing, the colonies on MRS were dominated by three phylotypes, tentatively identified as Lactobacillus amylovorus (OTU171), Lactobacillus reuteri (OTU173), and Streptococcus alactolyticus (OTU180). The colonies on Rogosa plates were dominated by the two Lactobacillus phylotypes only. Terminal restriction fragment length polymorphism analysis supported the observations of three phylotypes of lactic acid bacteria dominating in piglets receiving the low ZnO dose and of coliforms and enterococci dominating in piglets receiving the high ZnO dose. Dietary doses of 175 ppm CuSO(4)-Cu also reduced MRS and Rogosa counts of stomach contents, but for these animals, the numbers of coliforms were reduced in the cecum and the colon. The influence of ZnO on the gastrointestinal microbiota resembles the working mechanism suggested for some growth-promoting antibiotics, namely, the suppression of gram-positive commensals rather than potentially pathogenic gram-negative organisms. Reduced fermentation of digestible nutrients in the proximal part of the gastrointestinal tract may render more energy available for the host animal and contribute to the growth-promoting effect of high dietary ZnO doses. Dietary CuSO(4) inhibited the coliforms and thus potential pathogens as well, but overall the observed effect of CuSO(4) was limited compared to that of ZnO.

Development of Post-weaning Diarrhoea in Piglets. Relation to Presence of Escherichia coli Strains and Rotavirus

Weaning of piglets complicated with an exposure to pathogenic strains of Escherichia coli was scrutinized in two sets. The first set comprised 20 animals representing two litters and the second set included 30 animals from five litters. The piglets were either left as controls or exposed to one or three pathogenic strains of E. coli. Aiming to simulate a natural exposure the challenge strains were spread on the floor of the pens at weaning. In addition the pigs experienced several non-infectious stress factors commonly occurring at that occasion. Some groups were given adrenocorticotropic hormone (ACTH), aiming to simulate a stressful weaning. The balance and the composition of the faecal coliform populations, measured by a metabolic fingerprinting method, was disturbed among all animals following weaning. This disturbance was more pronounced and lasted longer among piglets exposed to pathogenic strains of E. coli. All piglets exposed to pathogenic E. coli shed these strains in faeces. Diarrhoea was induced in the groups exposed to E. coli, but not among the control animals. Pigs not treated with ACTH and subjected to a single pathogenic strain of E. coli became infected but did not develop diarrhoea unless if coinciding with shed of rotavirus. Control pigs excreting rotavirus had no diarrhoea. Diarrhoea was most frequent in the groups exposed to three pathogenic strains of E. coli, and in these groups diarrhoea was seen in the absence of rotavirus. ACTH administration amplified the clinical signs. The litter of origin influenced the development of post-weaning diarrhoea.

Zinc Oxide Protects Cultured Enterocytes from the Damage Induced by Escherichia coli

There is some evidence that zinc oxide (ZnO) protects against intestinal diseases. However, despite the suggestions that ZnO may have an antibacterial effect, the mechanisms of this protective effect have not yet been elucidated. We investigated the potential benefits of ZnO in protecting intestinal cells from damage induced by enterotoxigenic Escherichia coli (ETEC, strain K88) and the related mechanisms, using human Caco-2 enterocytes. Cell permeability, measured as transepithelial electrical resistance (TEER), was unaffected by 0.01 and 1 mmol/L ZnO treatments and moderately increased by 5 mmol/L ZnO, compared with untreated cells. Transfer of (14)C-inulin was slightly increased by 5 mmol/L ZnO compared with untreated cells; transfer was unaffected by lower concentrations. The TEER and (14)C-inulin transfer were lower in ETEC-infected cells than in uninfected cells. Treatment of ETEC exposure with 0.2 mmol/L ZnO prevented disruption of membrane integrity. The ETEC was able to adhere to enterocytes and, to some extent, invade the cells. The ZnO treatment reduced bacterial adhesion and blocked bacterial invasion. The ETEC infection upregulated the expression of the inflammatory cytokines interleukin-8, growth-related oncogene-alpha and tumor necrosis factor-alpha, and reduced that of the anti-inflammatory cytokine transforming growth factor-beta, compared with uninfected cells. The addition of 0.2 or 1 mmol/L ZnO counteracted the alteration of cytokine mRNA levels caused by ETEC. The protective effects of ZnO were not due to any antibacterial activity, because the viability of ETEC grown in a medium containing ZnO was unaffected. In conclusion, ZnO may protect intestinal cells from ETEC infection by inhibiting the adhesion and internalization of bacteria, preventing the increase of tight junction permeability and modulating cytokine gene expression.

Extensive profiling of a complex microbial community by high-throughput sequencing

Complex microbial communities remain poorly characterized despite their ubiquity and importance to human and animal health, agriculture, and industry. Attempts to describe microbial communities by either traditional microbiological methods or molecular methods have been limited in both scale and precision. The availability of genomics technologies offers an unprecedented opportunity to conduct more comprehensive characterizations of microbial communities. Here we describe the application of an established molecular diagnostic method based on the chaperonin-60 sequence, in combination with high-throughput sequencing, to the profiling of a microbial community: the pig intestinal microbial community. Four libraries of cloned cpn60 sequences were generated by two genomic DNA extraction procedures in combination with two PCR protocols. A total of 1,125 cloned cpn60 sequences from the four libraries were sequenced. Among the 1,125 cloned cpn60 sequences, we identified 398 different nucleotide sequences encoding 280 unique peptide sequences. Pairwise comparisons of the 398 unique nucleotide sequences revealed a high degree of sequence diversity within the library. Identification of the likely taxonomic origins of cloned sequences ranged from imprecise, with clones assigned to a taxonomic subclass, to precise, for cloned sequences with 100% DNA sequence identity with a species in our reference database. The compositions of the four libraries were compared and differences related to library construction parameters were observed. Our results indicate that this method is an alternative to 16S rRNA sequence-based studies which can be scaled up for the purpose of performing a potentially comprehensive assessment of a given microbial community or for comparative studies.

Aspects on feed related prophylactic measures aiming to prevent post weaning diarrhoea in pigs

The ability of feed related measures to prevent or reduce post weaning diarrhoea (PWD) was examined in a split litter study including 30 pigs from 6 litters allotted into 5 groups. Four groups were exposed to 3 pathogenic strains of E. coli via the environment at weaning. Three of them were given zinc oxide, lactose+fibres or non-pathogenic strains of E. coil as probiotics. The challenged and the unchallenged control groups were given a standard creep feed. Diarrhoea was observed in all challenged groups but not among uninfected animals, and the incidence of diarrhoea was lower in the group given nonpathogenic E. coli compared to all other challenged groups. The severity of PWD also differed between litters. When corrected for mortality due to PWD, a decreased incidence of diarrhoea was also seen in the groups given zinc oxide or lactose+fibres. The dominating serotype of E. coil within faecal samples varied from day to day, also among diarrhoeic pigs, indicating that diarrhoea was not induced by one single serotype alone. The diversity of the faecal coliform populations decreased in all piglets during the first week post weaning, coinciding with an increased similarity between these populations among pigs in the challenged groups. This indicated an influence of the challenge strains, which ceased during the second week. The group given lactose+fibres was least affected with respect to these parameters. In conclusion feed related measures may alleviate symptoms of PWD.