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="" birds.="" birds="" characteristics="" effect="" elrox="" experimental="" of="" on="" performance="" received="" sub="" that="" the="">2
) 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="" best="" edible="" however="" meat="" no="" parts.="" significant="" the="" there="" was="">0.05) difference in the liver enzymes and bilirubin levels. Effect of treatments on the serum arsenic levels was significant (P<0 .05="" and="" birds="" consumed="" control="" creatinine="" diet="" effects="" had="" higher="" highest="" in-feed="" in="" it="" least.="" level="" levels="" maxigrowth.="" not="" of="" on="" polamix="" profile="" protein="" significant="" significantly="" that="" the="" those="" treatments="" urea="" was="" were="" while="">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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