In vivo assessment of the antiparasitic effects of Allium sativum L. and Artemisia absinthium L. against gastrointestinal parasites in swine from low-input farms.

BACKGROUND: Ethno-veterinary practices could be used as a sustainable developmental tool by integrating traditional phytotherapy and husbandry. Phytotherapeutics are available and used worldwide. However, evidence of their antiparasitic efficacy is currently very limited. Parasitic diseases have a considerable effect on pig production, causing economic losses due to high morbidity and mortality. In this respect, especially smallholders and organic producers face severe challenges. Parasites, as disease causing agents, often outcompete other pathogens in such extensive production systems. A total of 720 faecal samples were collected in two farms from three age categories, i.e. weaners, fatteners, and sows. Flotation (Willis and McMaster method), modified Ziehl-Neelsen stained faecal smear, centrifugal sedimentation, modified Blagg technique, and faecal cultures were used to identify parasites and quantify the parasitic load. RESULTS: The examination confirmed the presence of infections with Eimeria spp., Cryptosporidium spp., Balantioides coli (syn. Balantidium coli), Ascaris suum, Oesophagostomum spp., Strongyloides ransomi, and Trichuris suis, distributed based on age category. A dose of 180 mg/kg bw/day of Allium sativum L. and 90 mg/kg bw/day of Artemisia absinthium L. powders, administered for 10 consecutive days, revealed a strong, taxonomy-based antiprotozoal and anthelmintic activity. CONCLUSIONS: The results highlighted the therapeutic potential of both A. sativum and A. absinthium against gastrointestinal parasites in pigs. Their therapeutic effectiveness may be attributed to the content in polyphenols, tocopherols, flavonoids, sterols, sesquiterpene lactones, and sulfoxide. Further research is required to establish the minimal effective dose of both plants against digestive parasites in pigs.

Impact of Dietary Sodium Butyrate and Salinomycin on Performance and Intestinal Microbiota in a Broiler Gut Leakage Model.

Unfavorable alterations of the commensal gut microbiota and dysbacteriosis is a major health problem in the poultry industry. Understanding how dietary intervention alters the microbial ecology of broiler chickens is important for prevention strategies. A trial was conducted with 672 Ross 308 day-old male broilers fed a basic diet (no additives, control) or the basic diet supplemented with 500 mg/kg encapsulated butyrate or 68 mg/kg salinomycin. Enteric challenge was induced by inclusion of 50 g/kg rye in a grower diet and oral gavage of a 10 times overdose of a vaccine against coccidiosis. Compared to control and butyrate-supplemented birds, salinomycin supplementation alleviated growth depression. Compared to butyrate and non-supplemented control, salinomycin increased potentially beneficial Ruminococcaceae and reduced potentially pathogenic Enterobacteriaceae and counts of Lactobacillus salivarius and Clostridium perfringens. Further, salinomycin supplementation was accompanied by a pH decrease and succinic acid increase in ceca, while coated butyrate (0.5 g/kg) showed no or limited effects. Salinomycin alleviated growth depression and maintained intestinal homeostasis in the challenged broilers, while butyrate in the tested concentration showed limited effects. Thus, further investigations are required to identify optimal dietary inclusion rates for butyrate used as alternative to ionophore coccidiostats in broiler production.

Effect of serum anti-phage activity on colibacillosis control by repeated phage therapy in broilers.

Anti-phage activity of serum is of importance in repeated phage therapy. Higher serum anti-phage activity has been associated with greater susceptibility of phages to neutralisation and phage therapy failure. In this study, in vivo and in vitro survivability and immunogenicity of four coliphages (TM1, TM2, TM3 and TM4) were investigated in naive chickens and chickens pre-immunised with phage TM1. Furthermore, two phages that displayed different survivability and immunogenicity (TM1 and TM3) were compared with respect to their efficacy in treating naive or pre-immunised (TM1) chickens suffering from colibacillosis. The efficacy of the treatments was evaluated based on body weight, relative organ weights, mortality, E. coli counts in the lungs as well as severity and frequency of internal organ lesions. At the end of the experiment, both naive and pre-immunised chickens treated with TM3 showed significantly lower mortality and higher body weights than untreated chickens and those treated with TM1. The same trend was observed in incidence and severity of organ lesions as well as relative spleen weight. However, naive chickens treated with TM1 also showed a shortened inflammation period as indicated by spleen weights. E. coli counts in the lungs of chicken treated with TM3 were lower than those of chickens treated with TM1 on days 3 and 10 post challenge. These data indicate that the outcome of phage therapy and the impact of serum anti-phage activity are highly phage-type dependent in broilers.

Influence of silver nanoparticles on growth and health of broiler chickens after infection with Campylobacter jejuni.

BACKGROUND: Silver nanoparticles (AgNP) have gained much attention in recent years due to their biomedical applications, especially as antimicrobial agents. AgNP may be used in poultry production as an alternative to the use of antibiotic growth promoter. However, little is known about the impact of oral administration of AgNP on the gut microbiota and the immune system. The aim of the present study was to investigate the effects of AgNP on growth, hematological and immunological profile as well as intestinal microbial composition in broilers challenged with Campylobacter jejuni (C. jejuni). RESULTS: AgNP did not affect the intestinal microbial profile of birds. The body weight gain and the relative weights of bursa and spleen were reduced when supplemented with AgNP. There was no difference with respect to packed cell volume. However, the plasma concentrations of IgG and IgM were lower in birds receiving AgNP compared to the non-supplemented control group. The expression of TNF-α and NF-kB at mRNA level was significantly higher in birds receiving AgNP. CONCLUSIONS: The application of AgNP via the drinking water in the concentration of 50 ppm reduced broiler growth, impaired immune functions and had no antibacterial effect on different intestinal bacterial groups, which may limit the applicability of AgNP against C. jejuni in broiler chickens.

The influence of selenium and selenoproteins on immune responses of poultry and pigs.

Selenium is an essential nutrient for poultry and pigs, and is important for a number of physiological processes including regulation and function of the immune system. Through its incorporation into selenoproteins, Se is involved in the regulation of oxidative stress, redox mechanisms, and other crucial cellular processes involved in innate and adaptive immune response. This review provides current knowledge on the mechanisms by which selenium can modulate the resilience to infectious diseases, and how this micronutrient can influence the capacity of the bird or the pig to maintain its productivity during an infectious challenge. In relation to the most frequent and economically important infectious diseases in poultry and pig production, the present paper considers the influence of different selenium sources (organic vs. inorganic Se) as well as dietary concentrations on the immune responses of poultry and pigs with major emphasis on the potential beneficial impact on animal resilience to common infectious diseases.

Influence of feeding crimped kernel maize silage on the course of subclinical necrotic enteritis in a broiler disease model.

This experiment was carried out with 375 male broilers (Ross 308) from days 1 to 28 to evaluate the influence of crimped kernel maize silage (CKMS) on the manifestation of subclinical necrotic enteritis, microbiota counts, organic acid production and relative weights of gastrointestinal segments. A necrotic enteritis disease model was applied. Birds were allocated into 3 different dietary treatments: a maize-based feed (MBF, control diet), and 2 diets supplemented with 15% (CKMS15) or 30% (CKMS30) of crimped ensiled kernel maize. The disease model involved a 10-time overdose of an attenuated live vaccine against coccidiosis given orally on day 17, followed by oral inoculation of Clostridium perfringens Type A (S48, 108 to 109 bacteria/bird) twice daily on days 18, 19, 20 and 21. Scoring of intestinal lesions was performed on days 22, 23, 25 and 28. Ileal and caecal digesta samples were collected for the quantification of selected bacterial groups and organic acids. The results showed that there was no effect of dietary treatments on small intestinal lesion scores (P > 0.05). Lesions scores peaked on days 23 and 25 and decreased again on day 28 (P = 0.001). No effect of age on microbiota counts was observed, but feeding of CKMS30 reduced the number of coliforms in ileal contents (P = 0.01). Dietary treatments did not affect organic acid concentrations in ileum and caeca, but there was an effect of age; butyric acid was higher on days 22, 23 and 25 than on day 28 (P = 0.04). Acetic acid and propionic acid concentrations in caeca were the highest on days 22 and 28 but the lowest on days 23 and 25. Relative gizzard and caeca weights were increased, and relative ileum weights were decreased when birds were fed CKMS30 (P < 0.05). In conclusion, the inclusion of CKMS in broiler diets had no effects on the course of necrotic enteritis but had potential benefits in terms of inhibition of potentially harmful microorganisms.

The influence of feeding crimped kernel maize silage on growth performance and intestinal colonization with Campylobacter jejuni of broilers.

An infection trial and a production trial over 35 days were conducted in parallel to study the influence of feeding crimped kernel maize silage (CKMS) on the intestinal Campylobacter jejuni colonization and broiler performance, respectively. The CKMS was used at dietary inclusion levels of 15% and 30% in maize-based diets. Broilers were orally inoculated with 2 × 10(5) log cfu/ml C. jejuni on day 14. Four birds from each pen were randomly selected and killed by cervical dislocation on days 3, 6, 9, 14 and 21 post infection and intestinal contents from ileum, caeca and rectum as well as liver samples were taken. Body weight and feed consumption of broilers were registered on days 13, 22 and 35. On day 35, litter dry matter (DM) was measured and the condition of the foot pads was evaluated. There was no significant effect of CKMS on the colonization of C. jejuni. Body weight of the broilers supplemented with 15% CKMS was comparable with the control maize-based feed, whereas addition of 30% CKMS reduced broiler body weight (P < 0.001). However, DM intake and feed conversion ratio were the same in all three dietary treatments. Furthermore, the foot pad condition of broilers significantly improved with the inclusion of CKMS on broiler diets as a result of a higher DM content in the litter material. It is concluded that CKMS did not influence intestinal Campylobacter colonization, but improved the foot pad health of broilers.

Bacterial Succession in the Broiler Gastrointestinal Tract.

A feeding trial was performed with broilers receiving a diet of wheat-based feed (WBF), maize-based feed (MBF), or maize-based concentrates supplemented with 15% or 30% crimped kernel maize silage (CKMS-15 or CKMS-30, respectively). The aim of the study was to investigate the bacterial community compositions of the crop, gizzard, ileum, and cecum contents in relation to the feeding strategy and age (8, 15, 22, 25, 29, or 36 days). Among the four dietary treatments, bacterial diversity was analyzed for MBF and CKMS-30 by 454 pyrosequencing of the 16S rRNA gene. Since the diets had no significant influence on bacterial diversity, data were pooled for downstream analysis. With increasing age, a clear succession of bacterial communities and increased bacterial diversity were observed.Lactobacillaceae(belonging mainly to the genus Lactobacillus) represented most of the Firmicutesat all ages and in all segments of the gut except the cecum. The development of a "mature" microbiota in broilers occurred during the period from days 15 to 22. Striking increases in the relative abundances of Lactobacillus salivarius(17 to 36%) and clostridia (11 to 18%), and a concomitant decrease in the relative abundance of Lactobacillus reuteri, were found in the ileum after day 15. The concentration of deconjugated bile salts increased in association with the increased populations of L. salivarius and clostridia. Both L. salivarius and clostridia deconjugate bile acids, and increases in the abundances of these bacteria might be associated with growth reduction and gastrointestinal (GI) disorders occurring in the critical period of broiler life between days 20 and 30.

Bioassay-Guided Chromatographic Isolation and Identification of Antibacterial Compounds from Artemisia annua L. That Inhibit Clostridium perfringens Growth.

Clostridium perfringens is the causative agent of necrotic enteritis leading to significant losses in the poultry industry. Dichloromethane and n-hexane extracts of aerial parts of Artemisia annua (Asteraceae) exhibited activity against C. perfringens with minimum inhibitory concentrations (MIC) of 185 and 270 µg/mL, respectively. Bioassay-guided fractionation of the extracts gave several active fractions (MIC between 75 and 600 µg/mL). Investigations of the most active fractions resulted in the isolation and characterization of the polyacetylene ponticaepoxide (MIC between 100 and 200 µg/mL) and (+)-threo-(5E)-trideca-1,5-dien-7,9,11-triyne-3,4-diol (MIC between 400 and 800 µg/mL), the flavonols chrysosplenol D (MIC between 200 and 400 µg/mL) and casticin (slight inhibition at 800 µg/mL), and 2,4-dihydroxy-6-methoxyacetophenone (slight inhibition at 800 µg/mL). Also, the coumarin scopoletin and the sesquiterpene lactone artemisinin were isolated from active fractions but showed no inhibition of C. perfringens growth at 800 and 2000 µg/mL, respectively. Fractions containing essential oil components with camphor constituting >60% did not show inhibition of C. perfringens up to 1600 µg/mL. Extracts and some active fractions showed higher antibacterial effect than individual bioactive compounds, suggesting that synergistic effects may underlie the observed antibacterial effect. The present study adds new valuable information on the antibacterial effect of A. annua against C. perfringens.

Methylotrophic methanogenic Thermoplasmata implicated in reduced methane emissions from bovine rumen.

Rumen methanogens are major sources of anthropogenic methane emissions, and these archaea are targets in strategies aimed at reducing methane emissions. Here we show that the poorly characterised Thermoplasmata archaea in bovine rumen are methylotrophic methanogens and that they are reduced upon dietary supplementation with rapeseed oil in lactating cows. In a metatranscriptomic survey, Thermoplasmata 16S rRNA and methyl-coenzyme M reductase (mcr) transcripts decreased concomitantly with mRNAs of enzymes involved in methanogenesis from methylamines that were among the most abundant archaeal transcripts, indicating that these Thermoplasmata degrade methylamines. Their methylotrophic methanogenic lifestyle was corroborated by in vitro incubations, showing enhanced growth of these organisms upon methylamine supplementation paralleled by elevated methane production. The Thermoplasmata have a high potential as target in future strategies to mitigate methane emissions from ruminant livestock. Our findings and the findings of others also indicate a wider distribution of methanogens than previously anticipated.

Effect of silver nanoparticles on growth performance, metabolism and microbial profile of broiler chickens.

This study evaluated the potential of silver nanoparticles (AgNano) as an antimicrobial growth-promoting supplement for broiler chickens. One hundred forty-four seven-day-old broiler chicks were distributed randomly to AgNano treatments at 0, 10 and 20 mg/kg (Control, Group AgNano10, and Group AgNano20, respectively) provided via the drinking water from day 7 to 36 post-hatching. Body weight and feed consumption were measured weekly. In addition, balance and respiration experiments were carried out to determine nitrogen (N) utilisation and energy retention. At days 22 and 36, blood samples and intestinal content were collected to evaluate the effects of AgNano on plasma concentration of immunoglobulins and the intestinal microflora, respectively. The provision of water solutions containing different concentrations of AgNano had no effect on postnatal growth performance and the energy metabolism of broiler chickens. However, in Group AgNano10 N intake (p = 0.05) and retention (p = 0.03) was increased, but N excretion and efficiency of utilisation was not affected. The populations of bacteria in the intestinal samples were not affected by AgNano supplementation. The concentration of immunoglobulin (IgG) in the blood plasma of broilers supplemented with AgNano decreased at day 36 (p = 0.012). The results demonstrated that AgNano affects N utilisation and plasma IgG concentration; however, it does not influence the microbial populations in the digestive tract, the energy metabolism and growth performance of chickens.

The effect of Artemisia annua on broiler performance, on intestinal microbiota and on the course of a Clostridium perfringens infection applying a necrotic enteritis disease model.

The aerial parts of the plant Artemisia annua contain essential oils having antimicrobial properties against Clostridium perfringens Type A, the causal agent for necrotic enteritis in broilers. In two experiments, the influence of increasing dietary concentrations of dried A. annua leaves (0, 5, 10 and 20 g/kg) and n-hexane extract from fresh A. annua leaves (0, 125, 250 and 500 mg/kg) on broiler performance was investigated. Dried plant material decreased feed intake and body weight in a dose-dependent manner, and 10 and 20 g/kg diet tended to improve the feed conversion ratio. The n-hexane extract also reduced feed intake, but broiler weight tended to decrease only at the highest dietary concentration. The feed conversion ratio tended to improve when birds received 250 and 500 mg/kg n-hexane extract. In a third experiment, a necrotic enteritis disease model was applied to investigate the effect of the dietary addition of dried A. annua leaves (10 g/kg on top) or n-hexane extract of A. annua (250 mg/kg) on the severity of the disease in broilers. The addition of n-hexane extract reduced the intestinal C. perfringens numbers and the severity of the disease-related small intestinal lesions. Over the infection period from day 17 to day 27, birds supplemented with the n-hexane extract gained more weight than both the challenged control birds and birds receiving dried plant material. The results indicate that n-hexane extracts derived from A. annua can modulate the course of necrotic enteritis and compensate to a certain extent for the disease-associated weight losses.

Effects of sodium butyrate and salinomycin upon intestinal microbiota, mucosal morphology and performance of broiler chickens.

The effect of dietary sodium butyrate (SB) or salinomycin (SAL) or both additives on performance, small intestinal morphology and microbial ecology of broiler chickens was studied. A growth trial was conducted with 96 Ross 308 female broilers from 1 to 30 days of age. Four treatment groups were fed with a non-supplemented control diet or three experimental diets supplemented with i) 300 mg SB (Adimix 30 coated) per kg, ii) 60 mg SAL (Sacox) per kg or iii) both additives in combination. Feed intake and body-weight gain decreased and gain-to-feed ratio increased due to SAL supplementation, while addition of SB did not affect performance in comparison with the control diet but positively affected feed intake and body-weight gain in comparison with birds fed the SAL-supplemented diet. Villus height in jejunum decreased, while crypt depth increased due to SAL supplementation. Addition of SB increased crypt depth in jejunum. No significant effect of either additive was observed in ileum morphology. Total short-chain organic acids concentration in ileal digesta decreased with SAL supplementation, mainly due to lower lactic acid concentration, but no effects were observed in the caeca. The SAL supplementation was accompanied by a pH increase in ileum and a pH decrease in caecum. No significant effect of SB addition was observed for these parameters. Total bacterial numbers and Lactobacillus [lactic acid bacteria (LAB)] counts in ileal and caecal contents were lower in birds fed with SAL-supplemented diet in comparison with birds fed with control or SB diet. DNA fingerprints revealed SAL supplementation to affect the microbial population by suppressing dominating LAB, potentially L. aviarius. The presented results show that dietary SAL, supplemented alone or in combination with SB, suppressed the microbial activity and altered the microbial community structure mainly in ileum. SAL alone negatively affected feed intake and body-weight gain; however, the effect was ameliorated by SB supplementation.

The effect of pectin, corn and wheat starch, inulin and pH on in vitro production of methane, short chain fatty acids and on the microbial community composition in rumen fluid.

Methane emission from livestock, ruminants in particular, contributes to the build up of greenhouse gases in the atmosphere. Therefore the focus on methane emission from ruminants has increased. The objective of this study was to investigate mechanisms for methanogenesis in a rumen fluid-based in vitro fermentation system as a consequence of carbohydrate source (pectin, wheat and corn starch and inulin) and pH (ranging from 5.5 to 7.0). Effects were evaluated with respect to methane and short chain fatty acid (SCFA) production, and changes in the microbial community in the ruminal fluid as assessed by terminal-restriction fragment length polymorphism (T-RFLP) analysis. Fermentation of pectin resulted in significantly lower methane production rates during the first 10 h of fermentation compared to the other substrates (P = 0.001), although total methane production was unaffected by carbohydrate source (P = 0.531). Total acetic acid production was highest for pectin and lowest for inulin (P < 0.001) and vice versa for butyric acid production from pectin and inulin (P < 0.001). Total propionic acid production was unaffected by the carbohydrate source (P = 0.791). Methane production rates were significantly lower for fermentations at pH 5.5 and 7.0 (P = 0.005), sustained as a trend after 48 h (P = 0.059), indicating that there was a general optimum for methanogenic activity in the pH range from 6.0 to 6.5. Decreasing pH from 7.0 to 5.5 significantly favored total butyric acid production (P < 0.001). Principle component analysis of T-RFLP patterns revealed that both pectin and pH 5.5 resulted in pronounced changes in the microbial community composition. This study demonstrates that both carbohydrate source and pH affect methane and SCFA production patterns, and the microbial community composition in rumen fluid.

In vitro production of necrotic enteritis toxin B, NetB, by netB-positive and netB-negative Clostridium perfringens originating from healthy and diseased broiler chickens.

The Clostridium perfringens necrotic enteritis toxin B, NetB, was recently proposed as a new key virulence factor for the development of necrotic enteritis (NE) in broilers. The aim of the present study was to investigate the presence of the netB gene and the in vitro production of the NetB toxin in a well characterized collection of 48 C. perfringens Type A isolates, obtained from Danish broiler flocks. The investigation revealed netB gene prevalences of approx. 50% and 60% among isolates from diseased (NE) and healthy flocks, respectively. Only minor nucleotide variations were observed between the isolates in the coding sequence (CDS) of the netB gene, and the promoter region was observed to be completely conserved. However, in vitro NetB production was only observed in 4 out of 14 netB-positive C. perfringens isolates recovered from healthy birds, whereas 12 out of 13 netB-positive isolates from NE birds were shown to produce the NetB toxin. It is therefore proposed that genotype, i.e. presence of the netB gene, in itself is inadequate for predicting virulence of C. perfringens, and future investigations should focus on the bacterial phenotypes; the regulatory mechanisms involved in the expression of NetB, and potentially also other toxins, and its implications for the virulence of individual C. perfringens strains.

Sequence variation in the alpha-toxin encoding plc gene of Clostridium perfringens strains isolated from diseased and healthy chickens.

The aim of the present study was to analyse the genetic diversity of the alpha-toxin encoding plc gene and the variation in alpha-toxin production of Clostridium perfringens type A strains isolated from presumably healthy chickens and chickens suffering from either necrotic enteritis (NE) or cholangio-hepatitis. The alpha-toxin encoding plc genes from 60 different pulsed-field gel electrophoresis (PFGE) types (strains) of C. perfringens were sequenced and translated in silico to amino acid sequences and the alpha-toxin production was investigated in batch cultures of 45 of the strains using an enzyme-linked immunosorbent assay (ELISA) approach. Overall, the truncated amino acid sequences showed close similarity (>98% at the amino acid level) to previously reported sequences from chicken-derived C. perfringens isolates. Variations were however observed in 23 out of 379 aa positions leading to the definition of 26 different alpha-toxin sequence types among the 60 strains. Moreover, a type II intron of 834 non-coding nucleotides was identified in the plc gene of three of the investigated strains. The in vitro alpha-toxin production investigated in 45 of the strains, including the three harbouring the intron, revealed no correlation between PFGE type, alpha-toxin sequence type, health status of the host chickens and level of alpha-toxin production. It is therefore concluded that neither plc gene type nor alpha-toxin production level seems to correlate to origin (healthy or diseased chicken) of the C. perfringens strains.

Rye bread enhances the production and plasma concentration of butyrate but not the plasma concentrations of glucose and insulin in pigs.

The present investigation was undertaken to study the gastrointestinal and physiologic properties of diets based on soft and crisp wheat and rye breads similar in dietary fiber (DF; 230-235 g/kg dry matter) but with different proportions of the main DF polymers: in wheat, cellulose, and in rye, arabinoxylans (AX). The 2 diets provided all macronutrients; consequently, they had lower fat and sugar contents and a higher DF content than human mixed diets. The nutritional properties were studied in experiments in which pigs with cannulated ilea and catheterized portal veins and mesenteric arteries served as models for humans. The characteristics studied were degradation of nutrients, flow at the ileum, fecal output, absorption of nutrients deriving from the assimilation of cereal carbohydrates, and the insulin response. Apparent viscosity at the terminal small intestine, the ileal flow of water, flow and digestibility of noncarbohydrate constituents, but not of carbohydrates at the terminal ileum or the plasma concentrations of glucose and insulin, were higher when pigs consumed the rye compared with the wheat diet. The 2 diets provided approximately equal amounts of carbohydrates available for fermentation in the large intestine but because AX from the rye diet was more degradable than cellulose from the wheat diet, the quantitative degradation in the large intestine was more than twice as high when pigs consumed the former compared with the latter diet. The consequences included moister feces and significantly enhanced gut production and plasma concentrations of butyrate when pigs consumed the rye diet compared with the wheat diet.

Dietary antibiotic growth promoters enhance the bioavailability of alpha-tocopheryl acetate in broilers by altering lipid absorption.

The influence of intestinal microbial bile salt deconjugation on absorption of fatty acids and alpha- and gamma-tocopherol was investigated in a trial with Ross 208 broilers. Birds (n = 1600) were assigned to 4 dietary treatments: no supplementation or supplementation of antibiotics (salinomycin, 40 mg/kg feed and avilamycin, 10 mg/kg feed), and inclusion of either animal fat (10 g/100 g feed) or soybean oil (10 g/100 g feed) in the diet. At d 7, 14, 21, and 35 of age, the intestinal number of the bile salt hydrolase-active bacteria Clostridium perfringens, the concentration of conjugated and unconjugated bile salts, the ileal absorption of fatty acids and tocopherols, and the blood plasma concentrations of tocopherols were measured. All variables were significantly influenced by bird age. C. perfringens counts were lower and bile salt concentrations were greater in birds fed soybean oil. The supplementation of antibiotics reduced the numbers of C. perfringens in the small intestine and reduced the concentration of unconjugated bile salts. The ileal absorption of fatty acids and alpha-tocopherol, as well as the plasma concentration of alpha-tocopherol, was greater in birds fed antibiotics. The absorption and plasma concentration of gamma-tocopherol were not influenced by antibiotics. Unlike gamma-tocopherol, which is present solely as the free alcohol, the major proportion of dietary alpha-tocopherol is present as alpha-tocopheryl acetate, which requires a bile salt-dependent enzymatic hydrolysis before absorption. In conclusion, proper digestion of lipid-soluble compounds is highly dependent on an adequate concentration of bile salts in the small intestine to provide proper lipid emulsification and activation of lipolytic enzymes.

Pancreatic lipase activity as influenced by unconjugated bile acids and pH, measured in vitro and in vivo.

The relation between pancreatic lipase activity, unconjugated bile acids and pH was studied in vitro and in vivo. Lipase activity was assayed in vitro using automatic titration, where the fatty acids liberated from the hydrolysis of glycerol tributyrate (GTB) were measured. The lipase activity was determined at different ratios of conjugated to unconjugated bile acids (100:0, 75:25, 50:50, 25:75, 0:100) in response to pH 6.6, 6.8, 7.0 and 7.5. The in vivo study involved 96 one-day-old male broiler chickens. The chickens were assigned randomly, in pens of six animals, into two dietary treatments (8 replicate blocks), composing a non-supplemented diet (A(-)) and a diet supplemented (A(+)) with avilamycin (10 mg/kg feed) and salinomycin (40 mg/kg feed). After 35 days, the chickens were killed and content of the proximal part of the small intestine was collected and analyzed for bacterial counts, pH, bile acid concentration, and lipase activity. Evidence for a significant pH-dependent inhibition of lipase activity by unconjugated bile acids was provided in vitro and confirmed in vivo. Due to a reduction in nutrient fermentation, the pH in the small intestine of antibiotic-fed chickens was significantly higher than in chickens fed the non-supplemented diet. The high pH in the small intestine of chickens fed the A(+)diet was accompanied by a significant increase in lipase activity, and coincided with a significantly lower concentration of unconjugated bile acids and a higher ratio of conjugated to unconjugated bile acids. This study emphasizes the important influence of unconjugated bile acids on lipase activity at physiological pH-values.

Effects of dietary fat source and subtherapeutic levels of antibiotic on the bacterial community in the ileum of broiler chickens at various ages.

The effect of dietary fat source (soy oil or a mixture of lard and tallow) and dietary supplementation with antibiotics (a combination of avilamycin at 10 mg kg of feed(-1) and salinomycin at 40 mg kg of feed(-1)) on the bacterial community in the ileum of broiler chickens at different ages (7, 14, 21, and 35 days) was studied using PCR with denaturing gradient gel electrophoresis (DGGE) analysis and bacteriological culture. The bacterial origin of fragments in DGGE profiles was identified by sequencing. Bacterial enumeration results, together with PCR-DGGE profiles, showed that the composition of the microflora was age dependent and influenced by dietary fat source and antibiotic supplementation. An increased incidence of streptococci, enterobacteria, and Clostridium perfringens with age of the chickens was demonstrated. Lactobacilli and C. perfringens were the bacterial groups most strongly affected by the dietary treatments. Moreover, different strains (clonal variants of the alpha-toxin gene) of C. perfringens type A were detected in response to age, dietary fat source, and dietary supplementation with antibiotics.