ABSTRACT
A sixty three (63) day experiment
was carried out to bio-appraise different non-antibiotic growth enhancers using
one hundred and twenty day-old broiler chicks (DOC). The DOC were randomly
assigned to four treatments of 30 birds per group, each with three replications
(10 birds per replicate), in a completely randomized design (CRD). T1
served as the control (CT), whereas T2, T3 and T4
had commercially procured ElRox (EX), PolaMix (PX) and MaxiGrowth (MX) growth
promoters incorporated at 400g/100kg, 500g/100kg and 600g/100kg respectively.
Data were collected weekly on body weight, body weight gain, daily feed intake,
feed conversion ratio, protein efficiency ratio and feed cost per Kg gain.
Carcass yields of the experimental groups were also evaluated at the end of the
experiment. Biochemical parameters of the bird were also determined at the end
of the experiment. These were protein profile, liver enzymes, bilirubin, lipid
profile and serum arsenics. Results of this study showed that the
non-antibiotic growth enhancers used in the study had a significant (P<0.05)
effect on the performance characteristics of the experimental birds. The birds
that received ElRox (T2) had better results in the overall
performance indices of the experimental animals, including feed cost/Kg gain.
Birds on the ElRox in-feed diet had significantly (P<0.05) the best edible
meat parts. However, there was no significant (P>0.05) difference in the
liver enzymes and bilirubin levels. Effect of treatments on the serum arsenic
levels was significant (P<0.05). It was higher in the birds that consumed
in-feed MaxiGrowth. Treatments effects on the protein profile of the birds were
significant (P<0.05). Birds on control diet had the highest protein level
while those on the PolaMix had the least. The urea and creatinine levels were
not significantly (P>0.05) affected by treatments. In the same vein, lipid
profile (CHOL, HDL, VLDL, and TRIG) were also not significantly (P>0.05)
affected except LDL. The highest level of LDL was recorded in birds on the
control diet, with PolaMix as the least. The results of the overall experiment
indicated that, of all the non-antibiotic growth enhancers examined, only ElRox
promoted a significant weight increase with better cost benefit return. It is
concluded that feeding ElRox (400g/100kg) to broilers resulted in better
performance of the birds.
CHAPTER ONE
1.0 INTRODUCTION
1.1 Background Information.
The importance of meat in the diet
of man cannot be overemphasized. Apart from other dietary roles meat plays,
they remain one of the sources of most essential amino-acids for normal growth.
Livestock farmers in an attempt to improve the growth of their animals have
used substances that can enhance growth and sustain their animals on a healthy
status. One of such substances that has been widely used is antibiotics.
Antibiotics are used at low doses
in animal feeds, and are considered to improve the quality of the product with
a lower percentage of fat and higher protein content in the meat (Brussels,
2005; Hughes and Heritage, 2003). Antibiotics have been used to prevent and
control bacterial infections as well as growth promoters. Prevention and
control of bacterial infections have been achieved by a therapeutic,
metaphylactic or prophylactic application of antibiotics. Other benefits of the
use of antibiotic growth promoters include control of zoonotic pathogens such
as campylobacter, E. coli, and enterococei (Brussels, 2005).
According to the National Office
of Animal Health (NOAH, 2001), antibiotic growth promoters are used to “help
growing animals digest their food more efficiently, get maximum benefit from it
and allow them to develop into strong and healthy individuals”. More clearly
the term “antibiotic growth promoters” describes any medicine that destroys or
inhibits bacteria, and is administered at a low, sub-therapeutic dose (Casewell
et al., 2003). The use of anti-biotic growth Promoters in the European
Union was approved by the Council Directive of 23 November 1970 concerning feed
additives (FDA, 2013).
However, there has been
controversy surrounding the use of antibiotics as growth promoters in animal
nutrition (Hughes and Heritage, 2003). It has caused a number of negative
changes. It influenced, among others, development of drug resistance in
bacteria. Livestock are a major reservoir of bacteria resistant to antibiotics.
These pathogens contained in animal meat entered human body and quickly spread
in human society.
The European Union banned on the
application of antibiotic growth promoters in feeds for animals bred for
consumption in 2006. The ban was introduced at the same time in all countries
of the Union. Since that time, antibiotics have been allowed to be used as
drugs only in medicinal animal feeds or in prophylactic additives. The
Regulation EC No 1831/2003 of the European Parliament and Council dated 22
August 2003, on the additives used in animal nutrition, includes, among others,
probiotics as feed additives alternative to antibiotic growth promoters
(Casewell et al., 2003).
Alternatives to antibiotics
therefore are probiotics, phytogenics, organic acids growth enhancers etc.
Lilly and Stillwell (1965) described probiotics as microorganisms stimulating
the growth of other microorganisms. The term was used by Parker (1974) for
organisms and substances that contribute to balancing the intestinal micro
flora of the host. Many bio-active ingredients according to Wang et al.
(1998) and Wenk (2000) which include alkaloids, bitter flavonoids, glycosides, mucilage, saponins and
tanins are new generation growth promoters. As herbs and plant extracts, they
act on the appetite and intestinal micro flora, stimulate the pancreatic
secretions to increase endogenous activity and immune system.
Prebiotics on the other hand are
non-digestible food components/ingredients which have positive effect on host
in their selective growth and/or activation of certain number of bacterial
strains present in intestines (Gibson and Roberfroid, 1995).
Synbiotics on its part is a
relatively recent term among additive used in poultry nutrition. They are
combination of probiotics and prebiotic as well as other promoting substances
which together exhibit joint effect in regard to health of digestive tract,
digestibility and performance of broilers (Fuller, 1989). Investigation showed
that combinations used in synbiotic are often more efficient in relation to
individual additives (Li et al., 2008).
Acidifiers have been used in
poultry nutrition especially the organic acids. The organic acids reduce the pH
value of food and in this way act as conserving agents and prevent micro
biological/ microbial contamination of food, and this effect is exhibited also
in digestive tract of poultry (Eidelsburger and Kirchgessner, 1994; Freitag et
al., 1995)......
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