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.