ates in the intestine upward of 106 bacteria per gram of gut content. Although
other predisposing conditions can occur, such as issues with diet formulation
[large amounts of animal-origin protein
or nonstarch polysaccharide (NSP)
cereal base without enzymes to break
down NSP], 6 changes in the immune
status caused by mycotoxins, 7 or viral
disease, the most common predisposing
factor is coccidiosis. 7 During coccidiosis
infection, lesions are formed in the intestine, creating a suitable environment
for C. perfringens to proliferate and produce toxins. This secondary infection
further damages the intestine, leading to
necrosis. 8 Necrotic enteritis induced by
coccidiosis can reduce short-term and
overall body weight gain compared with
healthy birds, limits digestion potential,
and increases body-weight variability
through market age. 9 The implications
of decreased uniformity within a flock
due to necrotic enteritis and therefore
carcass variability become important for
mechanical efficiency during processing.
Some work has been done assessing the
presence of foodborne pathogens including Salmonella and Campylobacter in
the intestines of broilers provided feed
with or without antibiotics. A study
looking at the presence or absence of
bacitracin dimethyl salicylate (BMD)
found no differences in cecal Salmonella
or ileal Campylobacter prevalence but
observed less ileal Salmonella and more
cecal Campylobacter at processing age
from birds fed with BMD antibiotic
added. 10
Alternative feed ingredients such as
prebiotics and probiotics are being used
as replacements for antibiotics. Prebiotics are feed ingredients that cannot be
digested by the bird but instead selectively stimulate the growth of beneficial
bacteria, thus improving bird health.
Some of these include nondigestible
oligosaccharides (manno-, fructo-, and
galacto-oligosaccharides; MOS, FOS,
GOS). The beneficial bacteria selected
for stimulated growth or activity include Bifidobacteria and Lactobacillus
spp., which fall into the category of
lactic acid-producing bacteria (LAB).
Prebiotics such as MOS can work by
blocking binding sites on the intestinal
epithelium for pathogens, including Sal-
monella Typhimurium. 11 Feed additives
such as organic acids, inorganic acids,
fermentation products, essential oils,
and plant extracts can also be added to
the diet and/or drinking water to reduce
pathogens, including Salmonella. 12 Pro-
biotics, or direct-fed microbials (DFMs),
on the other hand, are defined as live
microbial feed supplements, which can
benefit the bird by improving intestinal
microbial balance. 13 Common DFMs
include combinations of LABs includ-
ing Lactobacillus and Bacillus strains with
particular lines of species that have been
shown to reduce pathogens and poten-
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