Peadar G. Lawlor

A Five-Strain Probiotic Combination Reduces Pathogen Shedding and Alleviates Disease Signs in Pigs Challenged with Salmonella enterica Serovar Typhimurium

ABSTRACT Salmonella spp. infection is a major cause of gastroenteritis, with many thousands of cases reported in the European Union every year. The use of probiotics offers the potential to improve this situation. Here, we investigate the effects of oral treatment of pigs with a defined lactic acid bacteria culture mixture on both clinical and microbiological signs of Salmonella enterica serovar Typhimurium infection. Fifteen weaned pigs blocked by sex and weight were administered control milk or a mixture of five probiotic strains as either a milk fermentate or milk suspension for a total of 30 days. The mixture consisted of two strains of Lactobacillus murinus and one strain each of Lactobacillus salivarius subsp. salivarius, Lactobacillus pentosus, and Pediococcus pentosaceous. Following probiotic administration for 6 days, animals were challenged orally with serovar Typhimurium; the health of the animals and the microbiological composition of their feces were monitored for 23 days postinfection. Animals treated with probiotic showed reduced incidence, severity, and duration of diarrhea. These animals also gained weight at a greater rate than control pigs administered skim milk. Mean fecal numbers of Salmonella were significantly reduced in probiotic-treated animals at 15 days postinfection (P = 0.01). The administered probiotic bacteria improved both the clinical and microbiological outcome of Salmonella infection. These strains offer significant benefit for use in the food industry and may have potential in human applications.

Effect of pig manure to grass silage ratio on methane production in batch anaerobic co-digestion of concentrated pig manure and grass silage

Anaerobic co-digestion of concentrated pig manure (PM) with grass silage (GS) at five different PM to GS volatile solid (VS) ratios of 1:0, 3:1, 1:1, 1:3 and 0:1 was evaluated by examining operation stability and methane (CH(4)) production potentials. The highest specific CH(4) yields were 304.2 and 302.8 ml CH(4)/g VS at PM to GS ratios of 3:1 and 1:1, respectively. The digestion systems failed at the ratio of 0:1. The lag phase lasted 29.5, 28.1, 24.6 and 21.3 days at the ratios of 1:0, 3:1, 1:1 and 1:3, respectively. The daily methane yield was linearly correlated with the acetic acid concentration, indicating methane production was probably associated with acetoclastic methanogenesis. The hydrolysis constant linearly decreased with increasing the fraction of GS in the feedstock. This study recommends applying the PM to GS ratio of 1:1 in practice due to a high specific methane yield and a short lag phase.

Metabolic activity of the enteric microbiota influences the fatty acid composition of murine and porcine liver and adipose tissues

BACKGROUND Recent reports suggest that the metabolic activity of the gut microbiota may contribute to the pathogenesis of obesity and hepatic steatosis. OBJECTIVE The objective was to determine whether the fat composition of host tissues might be influenced by oral administration of commensal bifidobacteria previously shown by us to produce bioactive isomers of conjugated linoleic acid (CLA). DESIGN Murine trials were conducted in which linoleic acid-supplemented diets were fed with or without Bifidobacterium breve NCIMB 702258 (daily dose of 10(9) microorganisms) to healthy BALB/c mice and to severe combined immunodeficient mice for 8-10 wk. To ensure that the observations were not peculiar to mice, a similar trial was conducted in weanling pigs over 21 d. Tissue fatty acid composition was assessed by gas-liquid chromatography. RESULTS In comparison with controls, there was an increase in cis-9, trans-11 CLA in the livers of the mice and pigs after feeding with linoleic acid in combination with B. breve NCIMB 702258 (P < 0.05). In addition, an altered profile of polyunsaturated fatty acid composition was observed, including higher concentrations of the omega-3 (n-3) fatty acids eicosapentaenoic acid and docosahexaenoic acid in adipose tissue (P < 0.05). These changes were associated with reductions in the proinflammatory cytokines tumor necrosis factor-alpha and interferon-gamma (P < 0.05). CONCLUSIONS These results are consistent with the concept that the metabolome is a composite of host and microbe metabolic activity and that the influence of the microbiota on host fatty acid composition can be manipulated by oral administration of CLA-producing microorganisms.

Relative Ability of Orally Administered Lactobacillus murinus To Predominate and Persist in the Porcine Gastrointestinal Tract

ABSTRACT Five porcine-derived Lactobacillus or Pediococcus isolates administered to pigs (n = 4), either singly or as a combination at ∼1010 CFU per day varied with respect to intestinal survival and persistence. Two Lactobacillus murinus strains survived best and were excreted at ∼107 to 108 CFU/g of feces. In contrast, Pediococcus pentosaceus DPC6006 had the lowest fecal count at ∼105 CFU/g and was excreted at a significantly lower level than both L. murinus strains. Fecal L. murinus DPC6003 counts were also significantly higher than both Lactobacillus salivarius DPC6005 and Lactobacillus pentosus DPC6004 (∼106 CFU/g). The L. murinus strains persisted for at least 9 days postadministration in both the feces and the cecum. Animals fed a combination of all five strains excreted ∼107 CFU of the administered strains/g, with L. murinus predominating, as determined by randomly amplified polymorphic DNA PCR. Postadministration, variation was observed between animals fed the strain combination, but in general, L. murinus DPC6002 and DPC6003 and L. pentosus DPC6004 predominated in the feces and the cecum while P. pentosaceus DPC6006 was detected only in the cecum. Fifteen days after the start of culture administration, mean fecal Enterobacteriaceae counts were significantly lower in some of the treatment groups. In addition, when mean preadministration counts were compared with those obtained after 21 days of culture administration, Enterobacteriaceae counts were reduced by ∼87 to 98% in pigs fed L. salivarius DPC6005, P. pentosaceus DPC6006, L. pentosus DPC6004, and the culture mix. In conclusion, the porcine intestinal isolates have potential as probiotic feed additives for pigs, with differences in strain performance highlighting the advantages of using culture combinations.

Characterization of compost produced from separated pig manure and a variety of bulking agents at low initial C/N ratios.

The aim of this study was to investigate the composting of separated pig manure solids with or without a variety of bulking agents at a low initial C/N ratio (12.5-23.3). Compost stability was investigated using an oxygen uptake rate (OUR) test and compost maturity was investigated using a germination index test. All treatments showed typical patterns of compost temperature. Temperatures above 60°C were achieved by Day 2, followed by a thermophilic phase (50-60°C), which lasted for 1 to 2 weeks followed by a cooling phase. The stability of one of treatments which did not contain any bulking agent - OUR of 25 mmol O(2) kg(-1) OM hour(-1) - was negatively affected by its initial high water content (69%). The addition of a bulking agent and initial water content below 60% were necessary to compost the separated solid fraction of pig manure at a low initial C/N ratio.

Effect of Lactobacillus salivarius Bacteriocin Abp118 on the Mouse and Pig Intestinal Microbiota

Lactobacilli are Gram-positive bacteria that are a subdominant element in the human gastrointestinal microbiota, and which are commonly used in the food industry. Some lactobacilli are considered probiotic, and have been associated with health benefits. However, there is very little culture-independent information on how consumed probiotic microorganisms might affect the entire intestinal microbiota. We therefore studied the impact of the administration of Lactobacillus salivarius UCC118, a microorganism well characterized for its probiotic properties, on the composition of the intestinal microbiota in two model animals. UCC118 has anti-infective activity due to production of the bacteriocin Abp118, a broad-spectrum class IIb bacteriocin, which we hypothesized could impact the microbiota. Mice and pigs were administered wild-type (WT) L. salivarius UCC118 cells, or a mutant lacking bacteriocin production. The microbiota composition was determined by pyrosequencing of 16S rRNA gene amplicons from faeces. The data show that L. salivarius UCC118 administration had no significant effect on proportions of major phyla comprising the mouse microbiota, whether the strain was producing bacteriocin or not. However, L. salivarius UCC118 WT administration led to a significant decrease in Spirochaetes levels, the third major phylum in the untreated pig microbiota. In both pigs and mice, L. salivarius UCC118 administration had an effect on Firmicutes genus members. This effect was not observed when the mutant strain was administered, and was thus associated with bacteriocin production. Surprisingly, in both models, L. salivarius UCC118 administration and production of Abp118 had an effect on Gram-negative microorganisms, even though Abp118 is normally not active in vitro against this group of microorganisms. Thus L. salivarius UCC118 administration has a significant but subtle impact on mouse and pig microbiota, by a mechanism that seems at least partially bacteriocin-dependent.

Effects of thermo-chemical pre-treatment of grass silage on methane production by anaerobic digestion.

Dried grass silage (GS) was pre-treated at different NaOH loading rates (1%, 2.5%, 5% and 7.5% by volatile solids (VS) mass in grass silage) and temperatures (20 °C, 60 °C, 100 °C and 150 °C) to determine effects on its bio-degradability in terms of the hydrolysis yield and degradation of ligno-cellulosic materials for biogas production. At 100 °C and the four NaOH loadings, up to 45% of the total COD was solubilised and up to 65.6%, 36.1% and 21.2% of lignin, hemicellulose and cellulose were removed, respectively; biological methane production potentials obtained were 359.5, 401.8, 449.5 and 452.5 ml CH₄/g VS added, respectively, being improved by 10-38.9% in comparison with untreated GS. VS removals following anaerobic digestion were 67.6%, 76.9%, 85.3%, 95.2% and 96.7% for untreated GS and GS treated at the four NaOH loadings, respectively. 100 °C and the NaOH loading rate of 5% is recommended as a proper GS pre-treatment condition.

Predominance of a bacteriocin-producing Lactobacillus salivarius component of a five-strain probiotic in the porcine ileum and effects on host immune phenotype.

Relative predominance of each of five probiotic strains was investigated in the ileum of weaned pigs, compared with that in feces, when administered in combination at c. 5 x 10(9) CFU day(-1) for 28 days. Probiotic was excreted at 10(6)-10(9) CFU g(-1) feces, while ileal survival ranged from 10(2) to 10(6) CFU g(-1) digesta. In contrast to the feces, where Lactobacillus murinus DPC6002 predominated, the bacteriocin-producing Lactobacillus salivarus DPC6005 dominated over coadministered strains both in the ileum digesta and in mucosa. Probiotic administration did not alter counts of culturable fecal Lactobacillus or Enterobacteriaceae but higher ileal Enterobacteriaceae were observed in the ileal digesta of probiotic-fed pigs (P<0.05). We observed decreased CD25 induction on T cells and monocytes (P<0.01) and decreased CTLA-4 induction (P<0.05) by the mitogen phytohemagglutinin on CD4 T cells from the probiotic group. Probiotic treatment also increased the proportion of CD4+ CD8+ T cells within the peripheral T-cell population and increased ileal IL-8 mRNA expression (P<0.05). In conclusion, superior ileal survival of L. salivarius compared with the other coadministered probiotics may be due to a competitive advantage conferred by its bacteriocin. The findings also suggest that the five-strain combination may function as a probiotic, at least in part, via immunomodulation.

Measurements of the acid-binding capacity of ingredients used in pig diets

Some feed ingredients bind more acid in the stomach than others and for this reason may be best omitted from pig starter foods if gastric acidity is to be promoted. The objective of this study was to measure the acid-binding capacity (ABC) of ingredients commonly used in pig starter foods. Ingredients were categorised as follows: (i) milk products (n = 6), (ii) cereals (n = 10), (iii) root and pulp products (n = 5), (iv) vegetable proteins (n = 11), (v) meat and fish meal (n = 2), (vi) medication (n = 3), (vii) amino acids (n = 4), (viii) minerals (n = 16), (ix) acid salts (n = 4), (x) acids (n = 10). A 0.5 g sample of food was suspended in 50 ml distilled de-ionised water with continuous stirring. This suspension was titrated with 0.1 mol/L HCl or 0.1 mol/L NaOH so that approximately 10 additions of titrant was required to reach pH 3.0. The pH readings after each addition were recorded following equilibration for three minutes. ABC was calculated as the amount of acid in milliequivalents (meq) required to lower the pH of 1 kg food to (a) pH 4.0 (ABC-4) and (b) pH 3.0 (ABC-3). Categories of food had significantly different (P < 0.01) ABC values. Mean ABC-4 and ABC-3 values of the ten categories were: (i) 623 (s.d. 367.0) and 936 (s.d. 460.2), (ii) 142 (s.d. 79.2) and 324 (s.d. 146.4), (iii) 368 (s.d. 65.3) and 804 (s.d. 126.7), (iv) 381 (s.d. 186.1) and 746 (s.d. 227.0), (v) 749 (s.d. 211.6) and 1508 (s.d. 360.8), (vi) 120 (s.d. 95.6) and 261 (s.d. 163.2), (vii) 177 (s.d. 60.7) and 1078 (s.d. 359.0), (viii) 5064 (s.d. 5525.1) and 7051 (s.d. 5911.6), (ix) 5057 (s.d. 1336.6) and 8945 (s.d. 2654.1) and (x) -5883 (s.d. 4220.5) and -2591 (s.d. 2245.4) meq HCl per kg, respectively. Within category, ABC-3 and ABC- 4 values were highly correlated: R2 values of 0.80 and greater for food categories i, iv, v, vi, vii and viii. The correlation between predicted and observed ABC values of 34 mixed diets was 0.83 for ABC-4 and 0.71 for ABC-3. It was concluded that complete diets with low ABC values may be formulated through careful selection of ingredients. The final pH to which ABC is measured should matter little as ABC-3 and ABC-4 are highly correlated.

Effects of restricted feeding and antioxidant supplementation on pig performance and quality characteristics of longissimus dorsi muscle from Landrace and Duroc pigs

The present study was designed to evaluate the effects of compensatory growth diets with or without antioxidant inclusion (α-tocopheryl acetate (TA) or green tea catechins (GTC)) on pig performance and quality characteristics of longissimuss dorsi (LD) muscle from Landrace or Duroc pigs. Breed did not influence pig performance but had a significant effect on pork quality. Duroc muscle had higher intramuscular fat, ash and monounsaturated fatty acid levels and lower levels of moisture compared to Landrace. Lipid and pigment oxidation levels were higher in meat from Landrace pigs at initial stages of the study. Pigs fed restricted diets had reduced growth rates and lower back fat thickness. Decreasing the duration of energy restriction or significantly increasing dietary energy prior to slaughter resulted in compensatory growth. Supplementing diets with α-TA increased α-tocopherol levels in m. LD. Lipid oxidation levels (TBARS values) remained low throughout refrigerated storage. Dietary treatments did not affect colour stability or compositional analysis. Overall, lipid oxidation was highest in meat from pigs fed diets with greatest energy restriction and lowest in meat from pigs fed diets supplemented with α-TA or GTC.