ABSTRACT
Two feeding trials were conducted to evaluate growth performance, carcass characteristics, nutrient digestibility, haematological and serum biochemical parameters of broiler chickens fed graded levels of onion (Allium cepa) and onion with Bactofort® as eubiotics. Two hundred and forty (240) day old Ross 308 strain broiler chicks were allotted into five different dietary treatments with 0, 100, 200, 300 and 400g Allium cepa levels/100kg diet in the first experiment and 0, 15, 30, 45 and 60g Bactofort® levels added to 200g Allium cepa/100kg diet in the second experiment. Each treatment had 16 birds per pen replicatedthree times in a completely randomized design. Feed and water were given ad libitum while vaccination and other daily routine managements were duly observed throughout the experimental period. Data collected were subjected to analysis of variance using Statistical Analysis System and means were compared using Dunnett’s package. Results of the first trial showed an insignificant (P>0.05) difference in performance parameters measured during starter period. At the finisher phase, final body weight (2137.47 – 2223.25g) and weight gain (1462.05 – 1548.10g) were significantly (P<0.05) higher in treatments receiving Allium cepa additions compared to the control (0g Allium cepa addition level) which had2121.53g and 1445.53g respectively while feed intake and feed conversion ratio (FCR) were similar. Mortality was also higher in the control compared to Allium cepa treatment groups. 200g Allium cepa addition level had significantly (P<0.05) higher live weight (2191.78g), dressed weight (1541.11g) and dressing percentage (75.16%) compared to the other treatment groups. However, there were no significant (P>0.05) differences in all haematological and serum biochemical indices across the treatments except for albumin, creatinine, aspartate aminotransferase, alkaline phosphatase and total cholesterol. Percent apparent nutrient digestibilities were also insignificant except for crude fibre and crude protein. Crude fibre digestibility (87.12%) was better in the treatment receiving 200g Allium cepa addition level compared to the control (82.99%). The proximate compositions of meatwere significant (P<0.05) except ash across the treatment means. The meat quality characteristics were also insignificant. There was a reduction in ceacal and ileal microbial populations of Allium cepa treated group compared to the control. In the second experiment, the treatment group fed Allium cepa based diet (200g/100kg) with 45g Bactofort® addition had better (P<0.05) final weight (2575.00g), weight gain (2529.80g), and FCR (1.89) compared to the rest of the treatment groups. Carcass parameters were all significant (P<0.05) except for percentages of organs weight and dressing percentage. Treatment groups fed 0 and 60g Bactofort® addition to the Allium cepa based diet (200g/100kg) had significantly (P<0.05) higher total cholesterol (402.86 and 401.56mg dl-1) and low-density lipoproteins (263.08 and 250.08mg dl-1) compared to the other treatment groups. There were significant (P<0.05) differences in all digestibility parameters. The net profit return was better in the treatment group fed 45g Bactofort® addition levels to the Allium cepa based diet (200g/100kg). Moreover, gut microbial populations of coliform, salmonella and E. coli were lower in the treatment group with 45g Bactofort® addition level. It can be concluded that 200g/100kg dietary onion powder improved performance, meat quality and modulates gut microbiota in broiler chickens while Bactofort® addition at 45g/100kg Allium cepa based diet, similarly enhance performance, nutrient digestibility and cost efficiency in broiler production.
CHAPTER ONE
1.0 INTRODUCTION
Cost-effective poultry meat production is reliant on many vital factors. Securing optimum digestibility and assimilation of nutrients for improvement of broiler performance is certainly one of the most important elements. In this respect, the gastrointestinal tract needs special attention, because any impairment of the secretion of enzymes or disturbance of the microbiological equilibrium in the gut can negatively affect the digestibility of the feed, resulting in reduced growth rate or impaired feed conversion of growing birds. Various feed additive concepts, called eubiotics have been proposed to improve the nutrient utilization and to maintain gut health, which ultimately should result in improved performance (Wenk, 2002). Eubiotics as described by Broz and Paulus (2015) are groups of some feed additives (such as probiotics, prebiotics, essential oils e.t.c) which are used for the purpose of maintaining intestinal eubiosis (optimal balance of microflora in the gastrointestinal tract), thereby resulting in an improved health status and performance of farm animals.
Prebiotics are non-digestible feed components that beneficially affect the host by selectively altering the composition and metabolism of the gut microbiota (Huyghebaert et al., 2011). Prebiotics may provide energy for the growth of favourable endogenous bacteria in the gut, such as bifidobacteria and lactobacilli, thus improving the host microbial balance (Das et al., 2012). Prebiotics are found naturally in a variety of foods and can also be synthesized enzymatically. Commonly used prebiotics are oligosaccharides i.e., fructo-oligosaccharides (FOS), mannan oligosaccharides (MOS), lactulose, inulin (Brijesh et al., 2013). Inulin is present in significant quantities in vegetables such as onions, artichokes, asparagus, leeks, and garlic. A substantial amount of FOS is also found in suc vegetables and some cereals such as barley, and wheat (Espinosa-Martos et al., 2006; Judprasong et al., 2011).
The genus Allium includes about 550 species. A few of these are important as food plants and as drugs in human medicine, notably onion (Allium cepa L.) and garlic (Allium sativum L.). Onion is a bulbous plant widely cultivated in almost every country of the world withChina, India and United States leading in production (Ebesunun et al., 2007). Most of the plant parts contain compounds with proven antibacterial, antiviral, anti-parasitic, antifungal properties and have antihypertensive, hypoglycemic, antithrombotic, anti-hyperlipidemic, anti-inflammatory and anti-oxidant activity (Lampe, 1999). Administration of onion extract in rabbits significantly reduced serum, liver and aorta triglycerides and serum and liver proteins as reported by Sebastian et al. (1979). Aji et al. (2011) observed the beneficial influence of onion bulbs on growth performance of broiler chickens.
Probiotics are single or mixed culture of living microorganisms which when administered in adequate numbers exert health benefits for the host by improving the host intestinal microbial balance, enhancing of colonization resistance against pathogens and improving the immune responses (Brisbin et al., 2010; Cencic and Chingwaru, 2010; Das et al., 2012). The species of microorganisms currently being used in probiotic preparations are varied, and lactose fermenting bacteria (LAB) i.e., Lactobacillus bulgaricus, Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus helveticus, Lactobacillus lactis, Lactobacillus salivarius, Lactobacillus plantarum, Streptococcus thermophilus, Enterococcus faecium, Enterococcus faecalis, Bifidobacterium spp., are the most common types of bacteria used as probiotics(Khaksefidi and Rahimi, 2005; Kabir, 2009). Recently, the emphasis has been on selection and preparation of mixed strains of microorganisms as probiotics (Chateau et al., 1994).
Khaksefidi and Rahimi (2005) reported lower numbers of Coliform and Campylobacter in the gut of broiler chickens fed probiotics (mixed strains). Competition with pathogenic E. coli has also been documented (Watkins et al., 1982), and an increase in production ofantibodies at the systemic and local (intestinal) level (Haghighi et al., 2006). The combination of prebiotics and probiotics (symbiotic) has not been well studied, but their beneficial effects might be additive or even synergistic (El-banna et al., 2010).
1.1 Justification
Antibiotic feed additives have been used in the poultry industry for many years to improve the productivity in terms of weight gain and feed conversion ratio by helping to control infections in the gut mucosa. However, the use of dietary antibiotics has resulted in common problems such as the development of drug-resistant bacteria (Van Boeckel et al., 2015), drug residues in the body of the birds and imbalance of normal micro flora (Andremont, 2000; Kabir, 2009). As a consequence, it has become necessary to develop alternatives using either beneficial microorganisms or non-digestible ingredients that enhance the growth of beneficial micro organisms. Intensive studies have been conducted to find alternatives and to solve this problem, some components such as probiotics, prebiotics, organic acids and phytogenic feed additives are introduced instead of antibiotics (Patterson and Burkholder, 2003; Ricke, 2003). The beneficial influence of onion bulbs on growth performance of broiler chickens as a substitute for antibiotics has also been reported (Aji et al., 2011). Factors such as tolerance to bile and low gastrointestinal pH are needed to be considered in using any probiotic material. Resistance to bile and acidic gastrointestinal conditions are the important characteristic that enables Lactose-fermenting bacteria to survive and grow in the intestinal tract (Jin et al., 1998). It has been suggested that probiotics and prebiotics are much more efficient when used in combinations than singly (Alloui et al., 2013)
1.2 Aim and Objectives of the Experiments
The aim of this study was to evaluate the effect of dietary addition of Onion (Allium cepa) and Onion with Bactofort® on performance of broiler chickens. The specific objectives were to determine:
