A study was conducted to evaluate lignin and mannan oligosaccharides as potential alternatives to antibiotic growth promoters in broilers. Dietary treatments included an antibiotic-free diet (CTL-), a positive control (CTL+, 11 mg/kg of virginiamycin), and an antibiotic-free diet containing BioMos (MOS, 0.2% to 21 d and 0.1% thereafter) or Alcell lignin at 1.25% (LL) or 2.5% (HL) of the diet. Each treatment was randomly assigned to 4 floor pen replicates (40 birds each). Body weight and feed conversion were recorded weekly throughout 42 d. Jejunum histology was analyzed at d 14, 28, and 42. At d 28 and 42, cecal contents were assayed for Escherichia coli, Salmonella, lactobacilli, and bifidobacteria, and the litter was analyzed for E. coli and Salmonella. Birds fed the CTL- diet were heavier (P<0.05) than those fed the other dietary treatments, but feed conversion was not affected by dietary treatments. Birds fed MOS and LL had increased jejunum villi height and a higher number of goblet cells per villus (P<0.05) when compared with those fed the CTL+ diet. At d 42, birds fed MOS, LL, or HL had greater lactobacilli numbers than those fed the CTL+ diet. Compared with the CTL+ diet, the MOS diet increased the populations of bifidobacteria (P<0.05) in the ceca. Litter E. coli load was lower in birds fed MOS (P<0.05) than in birds fed the CTL+ diet but comparable to that of birds fed the LL or HL diet. Broiler performance was similar in birds fed antibiotics or antibiotic-free diets containing either MOS or lignin. However, birds fed MOS and LL had a comparative advantage over birds fed antibiotics as evidenced by an increased population of beneficial bacteria in the ceca, increased villi height and number of goblet cells in the jejunum, and lower population of E. coli in the litter.

The effects of 2 levels of mannanoligosaccharide (MOS) in feed were compared with antibiotic growth promoters on growth performance, intestinal morphology, cecal and litter microbial populations, and carcass parameters in broilers raised in a sanitary environment. Dietary treatments included: 1) antibiotic growth promoter-free diet (control), 2) VIRG (diet 1 + 16.5 mg/kg of virginiamycin), 3) BACT (diet 1 + 55 mg/kg of bacitracin), 4) LMOS (diet 1 + 0.2% MOS), and 5) HMOS (diet 1 + 0.5% MOS). Birds were randomly assigned to 3 replicate pens/treatment (n = 55/pen). Body weight and feed intake were recorded weekly throughout 38 d. At d 14, 24, and 34, a 1-cm segment of duodenum, jejunum, and ileum was used in morphological analysis (n = 9 birds/d per treatment). At the same bird ages, cecal contents were assayed for lactobacilli, bifidobacteria, Salmonella, Campylobacter, and Escherichia coli, whereas litter was analyzed for Salmonella, Campylobacter, and E. coli. Carcass yields (breast fillet and tenders, thigh, drumstick, and wing) were determined at d 38. Body weight, feed conversion, and carcass yields did not differ among treatments. In contrast to birds fed VIRG or BACT, LMOS and HMOS consistently increased (P < 0.05) villi height and goblet cell number per villus in all intestinal segments at d 24 and 34. Bifidobacteria concentrations were higher (P < 0.05) in LMOS- and HMOS-fed birds at all time points. Birds and litter from all treatments were free of Salmonella. At d 14 and 24, cecal E. coli and Campylobacter counts were not different among treatments. In comparison to birds fed control, at d 34, BACT, LMOS, and HMOS significantly reduced (P < 0.05) cecal E. coli concentrations, whereas Campylobacter counts were reduced (P < 0.05) by VIRG, BACT, and LMOS. Litter bacterial counts were not altered by dietary treatments. In conclusion, under conditions of this study, MOS conferred intestinal health benefits to chickens by improving its morphological development and microbial ecology. But, there were no additional benefits of the higher MOS dosage.

A galacto-oligosaccharide (GOS) prebiotic was prepared by reacting a high concentration of lactose (40% wt/vol) with a beta-galactosidase enzyme for 24 h at 37 degrees C. The enzyme was produced from recombinant Pichia pastoris X-33 cells. The study aimed at evaluating the effects of the prebiotic, a Bifidobacterium lactis-based probiotic, and the combination of these dietary additives on BW, feed intake, feed conversion ratio, and fecal counts of total anaerobic bacteria, lactobacilli, and bifidobacteria in broiler chickens. No significant differences in BW, feed intake and feed conversion ratio were found among the various groups. The study showed that GOS selectively stimulated the fecal microflora of broiler chickens. Total anaerobic bacteria and lactobacilli were increased by 3.4- and 3.56-fold, respectively, in chickens fed the diet containing GOS (3 kg per 25 kg) and B. lactis for 40 d compared with those fed the control diet. The bifidobacteria population in chickens fed the diet containing GOS (3 kg per 25 kg) and B. lactis significantly increased 21-fold in comparison to the control-fed birds. In particular, increasing the dietary concentration of GOS was accompanied by significant increases (P < 0.05) in bifidobacteria counts. The detectable population of bifidobacteria was also greater (P < 0.05) in chickens fed the diet containing GOS and bifidobacteria when compared with chickens fed a bifidobacteria-containing ration only. These results suggest that using GOS in combination with a B. lactis-based probiotic favored intestinal growth of bifidobacteria in broiler chickens.

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Two experiments were conducted to evaluate lignin and mannanoligosaccharides as alternatives to antibiotic growth promoters in broilers. Dietary treatments for the 2 studies were 1) negative control (CTL-, antibiotic free); 2) positive control (CTL+, diet 1 + 11 mg of virginiamycin/kg); 3) mannanoligosaccharide (MOS; diet 1 + BioMos: 0.2% to 21 d and 0.1% thereafter); 4) LL (diet 1 + 1.25% Alcell lignin); and 5) HL (diet 1 + 2.5% Alcell lignin). In experiment 1, each treatment was assigned to 4 pen replicates (52 birds each). Body weight and feed intake were recorded weekly for 38 d. At 28 and 38 d, cecal contents were assayed for lactobacilli and bifidobacteria. Body weight and feed intake did not differ among dietary treatments. At d 38, the lactobacilli population was greatest (P < 0.05) in birds fed MOS, whereas LL-fed birds had greater (P < 0.05) lactobacilli load than those fed CTL+. Bifidobacteria load was greater (P < 0.05) in birds fed MOS or LL compared with those fed CTL+ at both d 28 and 38. However, at d 28 and 38, lactobacilli and bifidobacteria loads were lowest (P < 0.05) in CTL+ or HL-fed birds. In experiment 2, 21-d-old birds from the initial flock were transferred to cages for oral Escherichia coli (O2 and O88 serotypes) challenge (12 birds/treatment). After 3, 6, and 9 d, cecal loads of E. coli were determined. Birds fed HL had a lower E. coli load (P < 0.05) than birds fed CTL- or CTL+ at d 3, and lower than birds fed CTL- at d 6. At d 9, the E. coli load was lower (P < 0.05) in birds fed MOS or HL than in those fed the CTL- or CTL+ diets; LL-fed birds had lower E. coli load than those fed CTL-. Birds fed MOS or LL had a comparative advantage over CTL+ birds in increasing populations of lactobacilli and bifidobacteria and lowering E. coli loads after challenge.

The primary aim of this study was to determine whether distinct gastrointestinal tract (GIT) microbial communities are established within ingesta and on mucosal surfaces of dairy calves and chickens to evaluate whether the principle of microbial segregation is of broad biological significance. Multivariate analysis of the predominant bacterial PCR-denaturing gradient gel electrophoresis profiles and estimated bacterial populations were compared in rumen, jejunum, ileum, cecum, and colon ingesta and matching mucosal tissues. Samples collected from 3-week old (n = 8) and 6-month old (n = 8) calves revealed that the predominant mucosa-associated bacteria were distinct from those inhabiting ingesta, and bacterial diversity varied significantly among the GIT regions. The estimated bacterial populations displayed significant regional differences for bovine mucosal (P = 0.05) and for ingesta (P = 0.03) only at 6 months of age. This indicates an established segregation of the enteric bacterial population throughout the GIT in weaned calves. Analysis of ileal and cecal bacterial profiles in chickens confirmed that the segregation of commensal bacteria between ingesta and the mucosal tissue was a common biological phenomenon. Our study provides some fundamental understanding of the impact of sample type (mucosa vs. ingesta), region, and host age on commensal bacterial establishment and segregation throughout the GIT.

Twenty Holstein cows were used in a Latin square design experiment with a 2×2 factorial arrangement to determine the effects of extruded flaxseed (EF) supplementation with 2 different forage to concentrate ratios on the performance of dairy cows. Extruded flaxseed diets contained 9% (dry matter basis) EF product which consisted of 75% EF and 25% ground alfalfa meal. Four lactating Holsteins cows fitted with rumen fistulae were used to determine the effects of dietary treatments on ruminal fermentation. Intakes of dry matter and crude protein were not influenced by dietary treatments. However, neutral detergent fiber intake was greater for the high-forage (8.4 kg/d) than the low-forage (7.8 kg/d) diet. Milk yield (average 40.2 kg/d) was similar for all dietary treatments. However, cows fed the high-forage diets produced milk with higher fat (3.76 vs. 2.97%) and total solids (12.58 vs. 11.95%) concentrations, but lower protein (3.19 vs. 3.33%) and lactose (4.66 vs. 4.72%) contents. Ruminal pH and total volatile fatty acid concentration were not affected by dietary treatments. However, feeding high forage relative to low forage diets increased molar proportion of acetate but decreased that of propionate. Ruminal NH3-N was reduced by feeding high forage relative to low forage diets. Milk fatty acid composition was altered by both forage level and EF supplementation. Feeding diets containing EF or low forage reduced the concentrations of saturated fatty acids and increased those of mono-unsaturated fatty acids. Concentrations of poly-unsaturated fatty acids were increased by feeding EF or low-forage diets. Extruded flaxseed supplementation increased milk fat α-linolenic acid content by 100% and conjugated linoleic acid by 54%. It was concluded that differences in animal performance and ruminal fermentation observed in this study were mostly due to differences in forage to concentrate ratio. However, EF supplementation caused most of the differences observed in milk fatty acid composition.

There is an increasing movement against use of antibiotic growth promoters in animal feed. Prebiotic supplementation is a potential alternative to enhance the host's natural defense through modulation of gut microbiota. In the present study, the effect of mannan oligosaccharide (MOS) and virginiamycin (VIRG) on cecal microbial ecology and intestinal morphology of broiler chickens raised under suboptimal conditions was evaluated. MOS and VIRG induced different bacterial community structures, as revealed by denaturing gradient gel electrophoresis of 16S rDNA. The antibiotic treatment reduced cecal microbial diversity while the community equitability increased. A higher bacterial diversity was observed in the cecum of MOS-supplemented birds. Quantitative polymerase chain reaction results indicated that MOS changed the cecal microbiota in favor of the Firmicutes population but not the Bacteroidetes population. No difference was observed in total bacterial counts among treatments. MOS promoted the growth of Lactobacillus spp. and Bifidobacterium spp. in the cecum and increased villus height and goblet cell numbers in the ileum and jejunum. These results provide a deeper insight into the microbial ecological changes after supplementation of MOS prebiotic in poultry diets.