Real-Time Quantitative PCR Measurement of Ileal Lactobacillus salivarius Populations from Broiler Chickens To Determine the Influence of Farming Practices

A real-time quantitative PCR assay targeting a 16S-23S intergenic spacer region sequence was devised to measure the sizes of populations of Lactobacillus salivarius present in ileal digesta collected from broiler chickens. This species has been associated with deconjugation of bile salts in the small bowel and reduced broiler productivity. The assay was tested as a means of monitoring the sizes of L. salivarius populations from broilers fed diets with different compositions, maintained at different stocking densities, or given the antimicrobial drugs bacitracin and monensin in the feed. Stocking densities did not influence the numbers of L. salivarius cells in the ileum. A diet containing meat and bone meal reduced the size of the L. salivarius population relative to that of chickens given the control diet, as did administration of bacitracin and monensin in the feed. These changes in the target bacterial population were associated with improved broiler weight gain.     

Cottonseed Meal Bioactive Peptides as an Alternative to Antibiotic Growth Promoters in Broiler Chicks

The aim of this experiment was to evaluate the effects of bioactive peptides derived from enzymatic hydrolysis of cottonseed meal (CSBP) compared with zinc bacitracin, as an antibiotic growth promoter (AGP), on productive traits, serum lipid profile, and ileal microbial population in broiler chickens. A total number of 240-day-old broiler chicks (Ross 308) were allocated into 4 treatments, replicated 5 times based on a completely randomized design. The dietary treatments included a basal diet serving as control group, basal diet?+?40 mg/kg zinc bacitracin as AGP group, and the basal diet supplemented with 15 or 20 g/kg CSBP substituting equal quantity of maize and soybean meal. Performance traits, including daily weight gain, feed intake, feed conversion ratio (FCR), and livability were recorded. At the end of the study, serum lipid parameters, ileal microbial population, and economical indices were determined. The results indicated that feed intake and FCR increased (P?<?0.05) in birds receiving 20 g/kg CSBP over the entire period (1–35 days), but there was no significant effect of CSBP on body weight, although numerically higher than the control group. However, the antibiotic group showed a significant increase (P?<?0.05) in body weight and feed intake. Livability, European Production Efficiency Factor (EPEF), and European Broiler Index (EBI) significantly improved in broiler chickens fed antibiotic and 15 g/kg CSBP supplement (P?<?0.05). Adding 20 g/kg of CSBP to the diet significantly increased serum triglycerides and decreased low-density lipoproteins (LDL) compared to the control and antibiotic groups on day 35. The relative weight of abdominal fat and LDL to HDL ratio were significantly lower for CSBP and antibiotic treatments than the control group (P?<?0.05). Supplementation of antibiotic and both graded levels of CSBP decreased the ileum population of Escherichia coli (P?<?0.05). The current findings suggest that including CSBP in broiler diets may benefit production through improving growth rate of broilers and balancing gut microbiota population. In addition, CSBP could be considered as a potential alternative to antibiotics in an AGP free production system.

     

The effect of site of starch digestion on performance of broiler chickens

A growth trial with 420 broiler chickens (35 per experimental unit) was conducted in order to evaluate whether bird performance (Days 0–38) is affected by site of starch digestion. Two diets were formulated with the same calculated apparent metabolisable energy, digestible lysine, and digestible starch content. The diets contained starch sources with known amounts of rapidly digestible starch (RDS, starch digested until the posterior jejunum) and slowly digestible starch (SDS, starch digested in the ileum). Diets were either high (H) or low (L) in SDS content. RDS and SDS contents were 298 and 52 g/kg for the H diet and 345 and 7 g/kg for the L diet, respectively. Starch in the H diet was supplied by waxy maize, peas and sorghum and starch in the L diet was supplied by tapioca and common maize. Birds receiving the H diet consumed more feed (P<0.10), grew faster (P<0.01) and had a lower feed conversion ratio (P<0.01) than birds receiving the L diet. The results suggest that broiler chickens perform better on diets containing a minimal amount of slowly digestible starch. Future experiments are necessary to investigate the relation between amount of slowly digestible starch and performance of broiler chickens.     

Effects of dietary antibiotics on intestinal microflora in broiler chickens

Changes were examined in the intestinal microflora in broiler chickens fed a diet containing antibiotics to obtain fundamental information on the mechanisms of beneficial effect of the antibiotics upon livestock production. Three antibiotics (colistin, bacitracin, and enramycin) were employed as feed additives. Experiments were conducted with broiler chickens in two ways. In one way dietary antibiotics were fed continually at levels approved for use as feed additives for a long term. In the other they were fed the same antibiotics for a short term. Significant changes in microflora were observed mainly in such bacterial groups as aerobic bacteria and Lactobacillus. In the long term administration, three possible modes of variance in the bacterial flora were postulated: Changes directly related to the antibacterial spectrum of antibiotics. Antagonistic changes related to an ecological balance in the bacterial flora. Changes in quantitative balance of bacteria constituting each bacterial group. The change in the intestinal microflora during administration of the antibiotic diet was expressed as a complex form of these transition modes. In the short term administration, it was demonstrated that the effect of the antibiotic diet lingered even 7 days after administration. This suggests that antibiotics used as feed additives may possibly affect the stability of the intestinal microflora.     

Insights on the Host Stress,Fear and Growth Responses to the Deoxynivalenol Feed Contaminant in Broiler Chickens

Mycotoxins pose an important danger to human and animal health. Poultry feeds are frequently contaminated with deoxynivalenol (DON) mycotoxin. It is thus of great importance to evaluate the effects of DON on the welfare related parameters in poultry industry. In the present study, the effects of contamination of broiler diet with 10 mg DON/kg feed on plasma corticosterone and heterophil to lymphocyte (H/L) ratio as indicators of stress, tonic immobility duration as an index for fear response and growth performance of broiler chickens were studied. In addition, the effect of a microbial feed additive either alone or in combination with DON contamination on these different aspects was also evaluated. The results showed that DON feeding significantly affected the welfare related parameters of broiler chickens. The feeding of DON contaminated diet resulted in an elevation of plasma corticosterone, higher H/L ratio and increased the fear levels as indicated by longer duration of tonic immobility reaction. Furthermore, DON reduced the body weight and body weight gain during the starter phase definitely at the second and third week. However, during grower phase, feeding of DON decreased the body weight at the fourth week and reduced the body gain at the fifth week. Addition of the microbial feed additive, a commercial antidote for DON mycotoxin, was able to overcome DON effects on stress index (H/L ratio), fearfulness and growth parameters of broilers. In conclusion, we showed for the first time that the DON feeding increased the underlying fearfulness and physiological stress responses of broilers and resulted in a reduction in the welfare status as indicated by higher plasma corticosterone, higher H/L ratio and higher fearfulness. Additionally, feeding the microbial feed additive was effective in reducing the adverse effects of DON on the bird''s welfare and can improve the performance of broiler chickens.     

Impact of feed supplementation with antimicrobial agents on growth performance of broiler chickens, Clostridium perfringens and enterococcus counts, and antibiotic resistance phenotypes and distribution of antimicrobial resistance determinants in Escherichia coli isolates

The effects of feed supplementation with the approved antimicrobial agents bambermycin, penicillin, salinomycin, and bacitracin or a combination of salinomycin plus bacitracin were evaluated for the incidence and distribution of antibiotic resistance in 197 commensal Escherichia coli isolates from broiler chickens over 35 days. All isolates showed some degree of multiple antibiotic resistance. Resistance to tetracycline (68.5%), amoxicillin (61.4%), ceftiofur (51.3%), spectinomycin (47.2%), and sulfonamides (42%) was most frequent. The levels of resistance to streptomycin, chloramphenicol, and gentamicin were 33.5, 35.5, and 25.3%, respectively. The overall resistance levels decreased from day 7 to day 35 (P < 0.001). Comparing treatments, the levels of resistance to ceftiofur, spectinomycin, and gentamicin (except for resistance to bacitracin treatment) were significantly higher in isolates from chickens receiving feed supplemented with salinomycin than from the other feeds (P < 0.001). Using a DNA microarray analysis capable of detecting commonly found antimicrobial resistance genes, we characterized 104 tetracycline-resistant E. coli isolates from 7- to 28-day-old chickens fed different growth promoters. Results showed a decrease in the incidence of isolates harboring tet(B), bla(TEM), sulI, and aadA and class 1 integron from days 7 to 35 (P < 0.01). Of the 84 tetracycline-ceftiofur-resistant E. coli isolates, 76 (90.5%) were positive for bla(CMY-2). The proportions of isolates positive for sulI, aadA, and integron class 1 were significantly higher in salinomycin-treated chickens than in the control or other treatment groups (P < 0.05). These data demonstrate that multiantibiotic-resistant E. coli isolates can be found in broiler chickens regardless of the antimicrobial growth promoters used. However, the phenotype and the distribution of resistance determinants in E. coli can be modulated by feed supplementation with some of the antimicrobial agents used in broiler chicken production.     

Selection of lactobacilli for chicken probiotic adjuncts

During inhibitory activity screening of 296 strains of lactic acid bacteria from the gastro-intestinal tract of chicks, 77 strains showed inhibition against enteric indicator strains ( Salmonella enteritidis and Escherichia coli ). Eight different strains identified as Lactobacillus salivarius were selected for the following attributes: their ability to inhibit all the indicator strains; a high adhesion efficiency to the epithelial cells of chickens and also their resistance to a number of antibiotics, monensin, bile salts and pH 3·0. The inhibitory action was not affected by the addition of catalase and no inhibition was detected after neutralizing the supernatant culture fluid. The competitiveness of the most promising strains, Lact. salivarius CTC2183 and CTC2197, was assessed in chicken feed mixture and in vivo . It was concluded that both strains were capable of becoming predominant over the indigenous flora in the incubated chicken feed mixture. In vivo tests showed that Lact. salivarius CTC2197 was able to colonize and overcome Lact. salivarius CTC2183 and the indigenous flora in the crop and caecum of the inoculated chicks.     

Selection of lactobacilli for chicken probiotic adjuncts

During inhibitory activity screening of 296 strains of lactic acid bacteria from the gastro-intestinal tract of chicks, 77 strains showed inhibition against enteric indicator strains (Salmonella enteritidis and Escherichia coli). Eight different strains identified as Lactobacillus salivarius were selected for the following attributes: their ability to inhibit all the indicator strains; a high adhesion efficiency to the epithelial cells of chickens and also their resistance to a number of antibiotics, monensin, bile salts and pH 3.0. The inhibitory action was not affected by the addition of catalase and no inhibition was detected after neutralizing the supernatant culture fluid. The competitiveness of the most promising strains, Lact. salivarius CTC2183 and CTC2197, was assessed in chicken feed mixture and in vivo. It was concluded that both strains were capable of becoming predominant over the indigenous flora in the incubated chicken feed mixture. In vivo tests showed that Lact. salivarius CTC2197 was able to colonize and overcome Lact. salivarius CTC2183 and the indigenous flora in the crop and caecum of the inoculated chicks.     

Proportion of insoluble fibre in the diet affects behaviour and hunger in broiler breeders growing at similar rates

With a view to alleviate the feeling of hunger in broiler breeders, different types of fibre sources were used in high-fibre diets to increase feed quantity while limiting growth to industry recommended levels. Using scatter feeding, three diets (C1: commercial control diet, 1 × fibre content, 80% insoluble fibre (ISF); H2: 2 × fibre content, 89% ISF; and L2: 2 × fibre content, 71% ISF) were each fed to 10 groups of 16 broiler breeder chickens. Similar growth rates were obtained on different quantities of food with all birds reaching commercial target weight at 15 weeks of age. In a hunger test, birds fed C1 ate significantly faster and showed a higher compensatory feed intake than birds on diets H2 and L2, indicating that the two high-fibre diets did reduce the level of hunger experienced by the birds. Behavioural observations carried out at 14 weeks of age showed high levels of tail pecking in birds fed C1 and almost none in birds fed L2, whereas birds fed H2 were intermediate. Stereotypic pecking at fixtures was seen twice as frequently in birds fed C1. Birds on diet L2 displayed behavioural signs indicative of discomfort, and the high water usage on this diet created problems with litter quality. Birds on diet H2 continued to show foraging behaviour throughout the day, and were more frequently engaged in dust bathing and other comfort behaviour. This experiment indicates that high-fibre diets can alleviate the feeling of hunger currently experienced by broiler breeders, and a high ratio of ISF may improve the well-being of the birds.     

Identification of the Most Abundant Lactobacillus Species in the Crop of 1- and 5-Week-Old Broiler Chickens

Bacteria from crops of 1- and 5-week-old broiler chickens fed with two brands (diets A and B) of wheat-based diets were isolated on Lactobacillus-selective medium and identified (n = 300) based on partial 16S rRNA gene sequence. The most abundant Lactobacillus species were L. reuteri (33%), L. crispatus (18.7%), and L. salivarius (13.3%). Regardless of farm and feed, L. reuteri was the most abundant species (P < 0.005) in the crops of the younger chickens. However, the amount of L. reuteri was significantly reduced in the crops of the 5-week-old chickens regardless of the feed (P = 0.016). The diversity of L. reuteri isolates was studied by fatty acid analysis, and the 94 L. reuteri isolates could be arranged into several clusters. The nisin sensitivities of the L. reuteri isolates were determined because nisin is a candidate coccidiostat. Sensitive isolates were found more frequently in younger chickens (77%) than in 5-week-old chickens (23%), whereas chickens fed with commercial feed B had a higher proportion of nisin-resistant isolates (73%) than did chickens fed with feed A (45%). Nisin-resistant strains are potential candidates for adjunct cultures for maintaining L. reuteri in its natural niche in the crop and are potential targets for genetic engineering with nisin-selectable food-grade vectors. The diversity of the L. reuteri population suggested that one should consider including several strains representing different clusters and nisin resistance phenotypes in candidate probiotic feed supplements for chickens.     

Effects of Xylo-Oligosaccharides on Broiler Chicken Performance and Microbiota

In broiler chickens, feed additives, including prebiotics, are widely used to improve gut health and to stimulate performance. Xylo-oligosaccharides (XOS) are hydrolytic degradation products of arabinoxylans that can be fermented by the gut microbiota. In the current study, we aimed to analyze the prebiotic properties of XOS when added to the broiler diet. Administration of XOS to chickens, in addition to a wheat-rye-based diet, significantly improved the feed conversion ratio. XOS significantly increased villus length in the ileum. It also significantly increased numbers of lactobacilli in the colon and Clostridium cluster XIVa in the ceca. Moreover, the number of gene copies encoding the key bacterial enzyme for butyrate production, butyryl-coenzyme A (butyryl-CoA):acetate CoA transferase, was significantly increased in the ceca of chickens administered XOS. In this group of chickens, at the species level, Lactobacillus crispatus and Anaerostipes butyraticus were significantly increased in abundance in the colon and cecum, respectively. In vitro fermentation of XOS revealed cross-feeding between L. crispatus and A. butyraticus. Lactate, produced by L. crispatus during XOS fermentation, was utilized by the butyrate-producing Anaerostipes species. These data show the beneficial effects of XOS on broiler performance when added to the feed, which potentially can be explained by stimulation of butyrate-producing bacteria through cross-feeding of lactate and subsequent effects of butyrate on gastrointestinal function.     

Carcass and meat quality traits of chickens fed diets concurrently supplemented with vitamins C and E under constant heat stress

The objective of this study was to determine if a diet supplemented simultaneously with vitamins C and E would alleviate the negative effects of heat stress, applied between 28 and 42 days of age, on performance, carcass and meat quality traits of broiler chickens. A total of 384 male broiler chickens were assigned to a completely randomized design, with a 2×3 factorial arrangement (diet with or without vitamin supplementation and two ambient temperatures plus a pair-feeding group) and 16 replicates. Chickens were kept in thermoneutral conditions up to 28 days of age. They were then housed in groups of four per cage, in three environmentally controlled chambers: two thermoneutral (22.5 and 22.6°C) and one for heat stress (32°C). Half the chickens were fed a diet supplemented with vitamins C (257 to 288 mg/kg) and E (93 to 109 mg/kg). In the thermoneutral chambers, half of the chickens were pair-fed to heat stressed chickens, receiving each day the average feed intake recorded in the heat stress chamber in the previous day. Meat physical quality analyses were performed on the pectoralis major muscle. No ambient temperature×diet supplementation interaction effects were detected on performance, carcass, or meat quality traits. The supplemented diet resulted in lower growth performance, attributed either to a carry-over effect of the lower initial BW, or to a possible catabolic effect of vitamins C and E when supplemented simultaneously at high levels. Heat stress reduced slaughter and carcass weights, average daily gain and feed intake, and increased feed conversion. Growth performance of pair-fed chickens was similar to that of heat stressed chickens. Exposure to heat stress increased carcass and abdominal fat percentages, but reduced breast, liver and heart percentages. Pair-fed chickens showed the lowest fat percentage and their breast percentage was similar to controls. Heat stress increased meat pH and negatively affected meat color and cooking loss. In pair-fed chickens, meat color was similar to the heat stressed group. Shear force was not influenced by heat stress, but pair-fed chickens showed the tenderest meat. In conclusion, reduction in growth performance and negative changes in meat color in heat stressed chickens were attributed to depression in feed intake, whereas negative changes in body composition, higher meat pH and cooking loss were credited to high ambient temperature per se. Diet supplementation with vitamins C and E as antioxidants did not mitigate any of these negative effects.     

Effects of concurrent administration of monensin and selenium on erythrocyte glutathione peroxidase activity and liver selenium concentration in broiler chickens

Different toxic doses of selenium and monensin preparations were administered to broiler chickens. The two substances were given by oral route, alone or concurrently, for variable periods. Erythrocyte glutathione peroxidase. (GSH-Px) activity was found to be elevated after the administration of the drugs. This increase was considerably higher when selenium and monensin were administered concurrently, indicating the occurrence of strong interaction between them. Administration of selenium led to a rapid increase in the liver selenium concentration. This increase, in turn, was enhanced by concurrent application of monensin. Monensin given alone did not have any significant effect on the changes of liver selenium concentration. Further results suggest that administration of monensin increases erythrocyte GSH-Px activity, even in the absence of supplemental selenium or during increased liver selenium concentration.     

A small variation in diet influences the Lactobacillus strain composition in the crop of broiler chickens

Feed composition has the potential to influence the activities of bacteria that colonize the digestive tract of broiler chickens with important consequences for animal health, well being, and food safety. In this study, the gut microbiota of two groups of broiler chickens raised in immediate vicinity but fed either a standard corn/soybean meal ration (corn–soy, CS) or a ration high in wheat middlings (high wheat, HW) was characterized. The findings revealed that this small variation in feed composition did not influence the distribution of microbial species present in the microbial community throughout the digestive tract. However, diet variation markedly influenced the Lactobacillus strain composition in the crop. Most striking, the dominant type in birds on the CS diet (Lactobacillus agilis type R5), which comprised 25% of the isolates, was not detected in birds fed the HW diet. The latter birds harbored a different strain of L. agilis (type R1) in a significantly higher ratio than birds on the CS diet. Several other strains were also specific to the particular diet. In conclusion, this study showed that a small variation in the composition of chicken feed that does not result in detectable differences in species composition can still have an impact on which microbial strains become dominant in the digestive tract. This finding has relevance in the application of probiotics and other direct-fed microbials in poultry husbandry.     

Effects of two probiotic Lactobacillus strains on jejunal and cecal microbiota of broiler chicken under acute heat stress condition as revealed by molecular analysis of 16S rRNA genes

We examined the effects of probiotic Lactobacillus strains of Lactobacillus agilis JCM 1048 and Lactobacillus salivarius subsp. salicinius JCM 1230 on jejunal and cecal microbiota of broiler chicken under heat stress condition using terminal restriction fragment length polymorphism (T-RFLP) analysis. The jejunal bacterial community was limited to a few bacterial groups, mostly Lactobacillus spp. A relatively abundant and higher prevalence of Lactobacillus spp. were observed in the jejunal and cecal microbiota of the probiotic chickens compared with those of the control chickens under heat stress condition. In general, the probiotic strains did not significantly affect the abundance of L. agilis and L. salivarius in chicken intestine but clearly contributed to increasing their prevalence in the probiotic chickens. The probiotic Lactobacillus strains enriched the diversity of Lactobacillus flora in chicken jejunum and cecum by increasing the abundance and prevalence of Lactobacillus spp. inhabiting the intestine. The richness of Lactobacillus species tended to be similar among the jejunal and cecal microbiota. The bacterial community of cecum was complex and age-dependent. The major components of the cecal microbiota were clostridia and lactobacilli. The Clostridium subcluster XIVa was the most predominant group in chicken cecum. Probiotic Lactobacillus strains restored the microbial balance and maintained the natural stability of indigenous bacterial microbiota following heat stress-induced changes.     

Eucalyptus leaves powder,antibiotic and probiotic addition to broiler diets: effect on growth performance,immune response,blood components and carcass traits

The study was conducted to investigate the effects of different levels of eucalyptus powder (EP), virginiamycin and probiotic on performance, immunity, blood components and carcass traits of broiler chickens. A total of 250, 1-day-old male broiler chickens (Ross 308) were randomly allocated to five treatments with five replicates and 10 chicks each, as a completely randomized design. The dietary treatments consisted of: basal diet (BD), BD+0.25% EP, BD+0.5% EP, BD+0.01% of diet probiotic (Protexin), BD+0.02% of diet antibiotic (virginiamycin). Dietary supplementation did not affect feed intake, BW gain (BWG) and feed conversion ratio (FCR) during starter and grower phases, but BWG and FCR were affected during the finisher and whole periods (P<0.05).The highest BWG and lowest FCR were obtained in birds fed with virginiamycin and 0.5% EP. Dietary supplementation significantly increased the relative weight of carcass and breast (P<0.05). Treatments had no effect on relative weights of internal organs and small intestine except for bursa that increased by treatments. Relative length of jejunum also increased by treatments (P<0.05). Antibody production against sheep red blood cells did not changed in primary titer (day 35), but it significantly increased in secondary titer (day 42) by 0.5% EP. White blood cell counts were increased and cholesterol decreased by dietary supplementation (P<0.05). In conclusion, the results of this study showed that 0.5% EP served as a useful replacement for antibiotic and would improve performance and immune response of broiler chickens.     

Lactobacillus salivarius CTC2197 prevents Salmonella enteritidis colonization in chickens.

A rifampin-resistant Lactobacillus salivarius strain, CTC2197, was assessed as a probiotic in poultry, by studying its ability to prevent Salmonella enteritidis C-114 colonization in chickens. When the probiotic strain was dosed by oral gavage together with S. enteritidis C-114 directly into the proventriculus in 1-day-old Leghorn chickens, the pathogen was completely removed from the birds after 21 days. The same results were obtained when the probiotic strain was also administered through the feed and the drinking water apart from direct inoculation into the proventriculus. The inclusion of L. salivarius CTC2197 in the first day chicken feed revealed that a concentration of 10(5) CFU g(-1) was enough to ensure the colonization of the gastrointestinal tract of the birds after 1 week. However, between 21 and 28 days, L. salivarius CTC2197 was undetectable in the gastrointestinal tract of some birds, showing that more than one dose would be necessary to ensure its presence till the end of the rearing time. Freeze-drying and freezing with glycerol or skim milk as cryoprotective agents, appeared to be suitable methods to preserve the probiotic strain. The inclusion of the L. salivarius CTC2197 in a commercial feed mixture seemed to be a good way to supply it on the farm, although the strain showed sensitivity to the temperatures used during the feed mixture storage and in the chicken incubator rooms. Moreover, survival had been improved after several reinoculations in chicken feed mixture.     

Prevention of intestinal Campylobacter jejuni colonization in broilers by combinations of in‐feed organic acids

Aim: We have tested the effect of various combinations of formic acid and sorbate on Campylobacter jejuni colonization in broiler chickens to reduce the colonization of this zoonotic pathogen in broiler chicken flocks. Methods and Results: Chickens were offered feed supplemented with different concentrations and combinations of formic acid and/or potassium sorbate. We found little or no effect on the Camp. jejuni colonization levels in chickens that were given feed supplemented with formic acid alone. A combination of 1·5% formic acid and 0·1% sorbate reduced the colonization of Camp. jejuni significantly, while a concentration of 2·0% formic acid in combination with 0·1% sorbate prevented Camp. jejuni colonization in chickens. This inhibition was replicated in two independent trials with a combination of three different Camp. jejuni strains. Conclusions: Our results show a novel and promising intervention strategy to reduce the incidence of Camp. jejuni in poultry products and to obtain safer food. Significance and Impact of the Study: To ensure food safety, a reduction of the carcass contamination with Camp. jejuni through reduced colonization of this pathogen in broiler chicken flocks is important. A range of organic acids as additives in feed and drinking water have already been evaluated for this purpose. However, no studies have yet shown a complete inhibition of Camp. jejuni colonization in broiler chickens.     

Effect of Antibiotic Growth Promoters and Anticoccidials on Growth of Clostridium perfringens in the Caeca and on Performance of Broiler Chickens

The effects of the growth promoters avoparcin and avilamycin and the ionophore anticoccidials maduramicin, narasin and monensin on the growth of Clostridium perfringens (Cp) in the ceaca and on performance of broiler chickens were tested in 2 experiments. The supplements were fed as single feed additives or in some combinations. No clinical signs or lesions caused by coccidia were observed in any of the studies. All supplements had an antibacterial effect on Cp and improved growth rate significantly. Carcass yield of birds fed growth promoters avilamycin or avoparcin was significantly higher compared with birds fed anticoccidials. These data indicate that, what concerns bird performance, during good hygienic conditions supplementation with antibiotic growth promoters may not be necessary when the diet is supplemented with an anticoccidial with antibacterial effects.     

The effects of xylanase supplementation on performance, characteristics of the gastrointestinal tract, blood parameters and gut microflora in broilers fed on wheat-based diets

The aim of this study was to investigate the effects of xylanase supplementation on performance, characteristics of the gastrointestinal tract, blood parameters and gut microflora in broilers fed on wheat-based diets. The experimental diets consisted of a wheat-based diet supplemented with 0 or 1 g/kg enzyme preparation (xylanase activity was 1218 U/g). The diets were fed between 7 and 49 days of age. Enzyme supplementation (ES) improved (P<0.05) growth performance and feed conversion efficiency. The addition of enzyme to a wheat-based diet reduced the relative weights of the duodenum, jejunum, pancreas (P<0.05) and colon (P<0.01) in 21-day-old broiler chickens. Enzyme preparation reduced digesta viscosity in the proventriculus and jejunum of 21-day-old broiler chickens (P<0.05) and in colon of 49-day-old broiler chickens (P<0.05). The pH of the digesta in the crop, duodenum and jejunum was increased (P<0.05) in 21-day-old broiler chickens and was reduced in the caecum of 49-day-old broiler chickens (P<0.05) with enzymes. There was no significant difference between the two experimental groups in counts of lactobacillus and coliform bacteria in the caecum. Enzyme supplementation increased the concentration of blood insulin-like growth factor I (IGF-I) (P<0.01) of 21-day-old broilers, triiodothyronine (T₃) and insulin (P<0.05) at 49 days. ES reduced the concentrations of blood thyroxine (T₄) (P<0.01) and uric acid (P<0.05) at 49 days, but had no effect on glucose concentration (P>0.05). In conclusion, ES can improve performance and digestive parameters and can change some blood parameters in broiler chickens fed a wheat-based diet.