Many feed additives have been used to promote
animal health and improve growth performance and
utilisation of nutrients in poultry production.1 The use
of antibiotics as growth promoters and for prevention
and treatment of diseases has become commonplace
as poultry producers have adopted intensive farming
systems. However, there is growing concern regarding
the possible build-up of antibiotic residues in animal
products, which can be harmful to consumers, and
the development of drug-resistant bacteria, attributed
to continuous feeding of antibiotics at sub-therapeutic
levels. These have resulted in increased interest being
paid to valuable alternatives for in-feed antibiotics in
the poultry industry. The modern alternative feed
additives that are being used or studied include
(i) feed acidifiers, which contain blends of organic
and inorganic acids that can enhance growth of broiler
chickens by reducing the pH value of both the feed
and the forepart of the intestinal tract, thus controlling
harmful bacteria and improving the digestion of
nutrients,2,3 (ii) prebiotics, which are non-digestible
substrates that beneficially affect the host by selectively
stimulating growth and/or activity of one or a limited
number of bacteria in the colon,4 and (iii) probiotics
(direct fed microbials) such as Lactobacillus culture in
poultry production.5
Probiotics are characterised as ‘live microbial feed
supplements that can benefit the host by improving its
intestinal balance’.6 Probiotic micro-organisms have to
be viable to accomplish their putative beneficial effects
such as producing antimicrobial factors, inhibiting
undesirable organisms and competing for receptor
sites on the gut epithelial tissue.7 Feeding chickens on
diets containing Lactobacillus cultures has been shown
to improve growth, feed efficiency, carcass yield and
cut-up meat parts.8–10 These investigators ascribed
such improvements in productive and quantitative
Many feed additives have been used to promote
animal health and improve growth performance and
utilisation of nutrients in poultry production.1 The use
of antibiotics as growth promoters and for prevention
and treatment of diseases has become commonplace
as poultry producers have adopted intensive farming
systems. However, there is growing concern regarding
the possible build-up of antibiotic residues in animal
products, which can be harmful to consumers, and
the development of drug-resistant bacteria, attributed
to continuous feeding of antibiotics at sub-therapeutic
levels. These have resulted in increased interest being
paid to valuable alternatives for in-feed antibiotics in
the poultry industry. The modern alternative feed
additives that are being used or studied include
(i) feed acidifiers, which contain blends of organic
and inorganic acids that can enhance growth of broiler
chickens by reducing the pH value of both the feed
and the forepart of the intestinal tract, thus controlling
harmful bacteria and improving the digestion of
nutrients,2,3 (ii) prebiotics, which are non-digestible
substrates that beneficially affect the host by selectively
stimulating growth and/or activity of one or a limited
number of bacteria in the colon,4 and (iii) probiotics
(direct fed microbials) such as Lactobacillus culture in
poultry production.5
Probiotics are characterised as ‘live microbial feed
supplements that can benefit the host by improving its
intestinal balance’.6 Probiotic micro-organisms have to
be viable to accomplish their putative beneficial effects
such as producing antimicrobial factors, inhibiting
undesirable organisms and competing for receptor
sites on the gut epithelial tissue.7 Feeding chickens on
diets containing Lactobacillus cultures has been shown
to improve growth, feed efficiency, carcass yield and
cut-up meat parts.8–10 These investigators ascribed
such improvements in productive and quantitative
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