ABSTRACT
A preliminary study was carried out to determine the prevalence of Aflatoxin B1 (AfB1) contamination and common moulds growing in some selected poultry feed ingredients in Zaria town, Nigeria. Twenty-five (25) samples of five different feed ingredients, which included Maize (MZ), soybean cake (SBC), groundnut cake (GNC), brewers dried grain (BDG) and maize offal (M/O) were collected. Samples were collected in March from four commercial feed mills and the open market. The common moulds isolated from the samples were Mucor spp., Aspergillus s pp., Fusarium spp., Penicillum spp., Curvularia spp. and Rhizopus spp. Aflatoxin B1 contamination showed that maize and soya bean cake were less than the 20 parts per billion (ppb) permissible limits for AfB1 in poultry feed ingredients, while BDG, M/O and GNC were 40, 60 and 80 % respectively above 20 ppb permissible limits. Three feeding trials were conducted using broiler chickens. The first experiment was conducted to evaluate the effect of four levels of Mycofix® in diets of broiler chickens, experiment two evaluated the response of broiler chickens fed diets containing four levels of
Biotronic ® SE and experiment three evaluated the response of broiler chickens fed diets containing single and combined levels of Mycofix® and Biotronic ® SE. In experiment one; 330 day old Ross broiler chicks were used for the feeding trial. The chicks were allotted in a completely randomized design (CRD) to five dietary treatments replicated thrice with 22 chicks per replicate. Treatment one was the control diet without Mycofix®, while treatments 2, 3, 4 and 5 had Mycofix® included at the rate of 100, 200, 300 and 400 g / 100kg diet respectively. In experiments two and three, a total of 396 day old Ross chicks each were used. In experiment 2, Treatment one was the positive control diet without Biotronic® SE and Oxytetracycline, treatments, 2, 3, 4, 5 had Biotronic® SE at the rate of 200, 300, 400, 500g Biotronic® SE / 100kg diet and Tretment 6 (negative control) had 100g Oxytetracycline/100kg feed. Experiment 3, Treatment one was the postive control diet without Mycofix®, Biotronic® SE and Oxytetracycline, treatments 2, 3, 4, 5 had 400g Mycofix®, 500g Biotronic® SE, 200gMycofix® + 250 Biotronic® SE, 400g Mycofix®+ 400g Biotronic® SE and treatment 6 (negative control) 100g Oxyteracycline/ 100kg of feed respectively. The diets were formulated to meet standard requirements for starter and finisher broiler chickens. Feed and water were given to the birds ad libitum for the experimentl periods. Data collected included the average of body weight gain, feed intake, feed conversion ratio, carcass percentage, nutrient digestibility; others were haematological, biochemical indices, kidney function test, microbial analysis of digesta, drug residue in meat samples and villi morphometerics. Data collected were subjected to Analysis of Variance (ANOVA) using General Linear Model procedure of SAS and significant differences among treatment means were compared using Dunnette test of significance. Experiment One, starter phase showed that dietary treatments had significant effect (P
0.05) on final weight gain, feed conversion ratio, feed cost and feed cost per kilogram gain. Birds fed 400g/100kg diet Mycofix® had the best final body weight gain at both starter (839.67g) and finisher phases (2350.34g) respectively. The feed conversion ratio at the starter phase was significantly (P<0.05) lower in the experimental treatments and at the finisher phase, 400g Mycofix® treatment had a significantly (P<0.05) lower feed conversion ratio. There were no significant differences (P<0.05) across treatments for cut parts and organ weights of carcass. Haematological and biochemical indices were not significantly affected by dietary treatments as parameters were within the normal reference range for broiler chickens. Nutrient digestibility was significantly improved at 400g inclusion. Experiment Two
starter phase results showed similar (P>0.05) weight gain in birds on 500g Biotronic® SE and100g Oxytetracycline. The birds fed 500g Biotronic® SE had the best feed conversion ratio (1.7) and feed cost per kilogram gain (₦151.42) values. The finisher phase result showed no significant (P>0.05) differences in weight gain among Treatments 3, 4, 5 and 6. Birds on 400g Biotronic® SE had a lower (P > 0.05) FCR and feed cost per kilogram gain.The dressing percentage for the carcass was best in 500g Biotronic® SE and Oxytetracycline treatments. Prime cuts: breast, drumstick and wings were better in birds on 400g Biotronic® SE. Haematological parameters were not affected by dietary treatments. The values of alkaline phosphatase (ALP) were significantly (P>0.05) higher in the experimental treatments, alanine amino transferase (ALT) values was significantly (P>0.05) higher in the antibiotic treatment while aspartate aminotransferase (AST) values was significantly (P > 0.05) higher in birds on 400g Biotronic® SE and Oxytetracycline group. The crude protein values (86.54, 89.31 and 94.50 %) for nutrient digestibility was significantly (P<0.05) higher in 200, 300 and 400g Biotronic® SE groups respectively. The crude fibre (76.43 %) and ether extract (89.82 %) values were significantly (P<0.05) lower across treatments. The levels of Biotronic® SE was more effective in increasing aerobic plate count and coliform counts in both ileum and ceacum of broiler chicks. Birds fed the control diet showed no drug detected, while birds fed 200, 300, 400 and 500g Biotronic® SE were low and Oxytetracycline treatment showed high concentration of drug. In experiment three, results of the starter phase showed no significant (P>0.05) differences in most of the parameters measured across treatments. Birds on Oxytetracycline treatment had a significantly (P <0.05) higher feed intake (1920.44g) from the rest treatment groups and control. At the finisher phase, birds on 100g Oxytetracycline had a significantly (P
0.05) higher weight gain, average daily weight gain and feed conversion ratio and least feed cost /kilogram gain Carcass result showed better breast weight for birds fed diets with Oxytetracycline and better drum stick for birds fed diets with 400g Biotronic® SE. No significant (P>0.05) differences for organ weights across treatments. No significant (P>0.05) differences were recorded across treatments for haematological profile, liver and Kidney function tests. Nutrient digestibility for birds fed 400g Biotronic® SE was better (P<0.05) in its percentage composition for dry matter, crude protein, crude fibre and ash content across treatments but similar to control. Results of villi morphometrics of sections of the jejunum showed that birds fed 400g® Mycofix and 400g Biotronic® SE had a significantly (P<0.05) higher villi crypt across treatment groups and control. Villi roundness for birds on control diet was significantly (P<0.05) higher other rest treatment groups. The study concludes the growth of fungi spp. in feed ingredients samples and presence of AfB1. The findings of the feeding trials concludes that the use of Mycofix® a toxin binder, improved performance significantly at both starter and finisher phases at the rate of 4kg/tone which was above the recommended level of 2-3kg /tone. The use of Biotronic® SE as a gut acidifier gave a better result for all the growth performance parameters above the control; at 500g/100kg for starter phase and 400g/kg at finisher phase. It had a positive effect on maintenance of normal microbial activity of ileum and ceacum and no residues in meat samples. The combined and single use of Mycofix® and Biotronic® SE did not significantly improve growth of broiler chickens, but performed comparable to the antibiotic treatment in all the parameters measured. The combinations had no adverse effect on measured performance parameters, haematological parameters, liver and kidney function tests and improved villi crypt an evidence of a positive synergy in their combination. It is recommended that Mycofix® can be singly used at 400g/100kg and 500g/100kg feed of Biotronic ® SE as a means of alleviating the incidences of mycotoxins in feed and improving gut health.The combined inclusion recommended is at 200g Mycofix® and 200g Biotronic ® SE/100kg feed.
CHAPTER ONE
1.0 INTRODUCTION
Feed represents the greatest single expenditure associated with poultry production. Nutritional research in poultry has therefore centered on issues related to identifying barriers to effective digestion, utilization of nutrients, and on approaches for improving feed utilization (Ravindran, 2010). The quality of feed ingredients is very important as this will determine the quality of the feed and the end-products.Hence a more precise evaluation of the quality of dietary raw materials is needed (Kersten et al., 2005). Feed materials may be contaminated at any time during growing, harvesting, processing, storage and distribution of the feed. Feeds may contain diverse microflora that are acquired from multiple environmental sources, including dust, soil, water, and insects (Maciorowski et al., 2006).
Mycotoxins are a historical problem in poultry, first recognised in the 1960s as the cause of ‘turkey X disease’ in England which resulted in the death of 100,000 turkey poults and many ducks, chickens and pheasants (Siska, 2013). Mycotoxins are toxins formed during fungi growth, myco means mould and toxin represents poison (Annongu, 2012). Mycotoxins are highly toxic secondary metabolic products of mould on almost all agricultural commodities worldwide. They occur under natural conditions in feed. Several studies proved that economic losses occur at all levels of food and production, including crop and animal production, processing and distribution (Robens and Cardwell, 2003; Wu, 2007; Bryden, 2012). According to the Food and Agriculture Organization (FAO), 25% of the world‟s crop harvests are contaminated with mycotoxins (FAO, 2012). There are currently more than 400 mycotoxins known. There are six major classes of mycotoxins that frequently occur namely, aflatoxins, trichothecenes, fumonisins, zearalenone, ochratoxin and ergot alkaloids (CAST 2003). They are formed by different kinds of fungi and each fungi species can produce more
than one type of mycotoxin. Surveys of mycotoxin levels in poultry feeds often reveal the presence of a number of different toxins; most samples in a recent survey contained at least 10 contaminants. Contamination of feeds with mycotoxins is a worldwide problem, in poultry particularly those produced by the genera, Fusarium, Aspergillus and Penicillium (Siska, 2013).
Mycotoxin binders or adsorbents are substances that bind to mycotoxins and prevent them from being absorbed through the gut and into the blood circulation (Jacela et al., 2010). The addition of mycotoxin binders to poultry diets has been considered the most promising dietary approach to reduce the effects of mycotoxins (Galvano et al., 2001). The theory is that the binder decontaminates mycotoxins in the feed by binding them strongly enough to prevent toxic interactions when the animal consumes the feed and to prevent mycotoxin absorption across the digestive tract.
Nutritional researchers have therefore implored the use of toxin binders as an approach to salvaging feed contamination with mycotoxins and protecting animals from disease problems and losses in performance. Another approach by researchers is the use of dietary supplementation with acidifiers, which are organic acids used to reduce bacterial growth. It helps to reduce colonization of pathogens on the intestinal wall, thus preventing damage to the epithelial cells. Acidifiers enhance increase in body weight and feed conversion ratio in broiler chicken (Skinner et al., 1991).
The Mycofix® product line from BIOMIN is a range of specially developed feed additives that protect animal health by deactivating mycotoxins found in contaminated feed. Its modular system consists of three strategies: Adsorption – Elimination of toxins, Biotransformation – Elimination of toxicity and Bioprotection – Elimination of toxic effects. Mycofix is one of
the new promising mycotoxins adsorbent that was successfully used to alleviate the negative effects of T-2 toxins in broilers (Aziz, 2005; Omar, 2010).
Biotronic® SE is a powerful combination of synergistically acting organic acid and their salts combined on a Sequential Release Medium (SRM). Besides decreasing pH, the selected acids penetrate the cell wall of gram – negative bacteria. The use of Biotronic® SE is indicated for the control of gram – negative bacteria including E. coli and Salmonella in other to promote animal growth in pig and poultry. This highly effective synergism ensures its full economic benefit (Poultry Site, 2014).
1.1 Justification for the Study
One subject receiving much attention from researchers at present is that of mycotoxicity. It is an issue which has important implications for the global feed industry, bird performance and potential with negative consequences for the food chain (Stephen, 2008). Nigeria does not have standard regulationsand control on mycotoxins in poultry feed, consequently the risk of mycotoxins exists in the Nigerian poultry sector since the common feed ingredients, such as maize and groundnut cake, are known to contain high levels of mycotoxins (Kpodo and Bankole, 2008). Fungi are major spoilage agents of foods and feedstuffs. The proliferation of various fungi species in agricultural products leads to reduction in yield and quality with significant economic losses (Adejumo and Adejoro, 2014).
The poultry industry witnessed a tremendous growth with the best application of nutritional technologies. Today, animal feed production has been paid attention; however, feed safety is a concern for achieving productivity. Mycotoxin contamination of feed is a recurring problem, however the effective control is a challenge because the mycotoxins contamination occurs through various feed raw materials, which are used in poultry feed. Nevertheless the
contamination of mycotoxins can come from the dust and leftover feed in the feeding channel; hence a rational approach has to be adopted for effective control of feed mycotoxins (Bhat, 2011).
On the other hand, gut health is currently gaining much more attention in literature especially in poultry and has been applied to coordinate the working efficiency of the gut (Laudadio et al., 2012). The gut is the most extensive exposed surface and is constantly exposed to a wide variety of potentially beneficial, non-infectious as well as harmful infectious pathogens (Lievin-Le Moal and Servin, 2006). This has necessitated the need to tackle the microbial population in the gut of the chicks as early as they are hatched in favour of the beneficial microorganism in the host. This is achievable by the use of acidifiers which plays the role of lowering the pH of the gut, thereby inhibiting the proliferation of pathogenic micro-organisms hence, reducing their adverse effect on the host animal.
The use of a toxin binder to mitigate the effect of mycotoxins present in feed and an acidifier to improve the gut health as a way of improving performance was considered in the study
1.2 Objectives of the Study
The objectives of the study were to;
- determine fungi species and Aflatoxin B1 contamination in some common feed ingredients used in poultry finished feed.
- know the optimum inclusion levels of Mycofix® and Biotronic® SE singly and in combination on growth performance, haematological parameters, serum biochemical indices and carcass characteristics, gut morphology and nutrient digestibility of broiler chickens.
- evaluate the effects of various inclusion levels of Biotronic® SE on intestinal microbioata and drug residue in the meat of broiler chickens.
1.3 Research Hypotheses
Null Hypothesis (Ho): Some common feed ingredients used in poultry finished feed are not contaminated with fungi species and Aflatoxin B1.
Null Hypothesis (Ho): Inclusion of Mycofix® and Biotronic® SE as a toxin binder and organic acid respectively in the diets of broiler chickens do not enhance growth performance, apparaent nutrient digestibility, haematological profile, serum biochemical indices and carcass characteristics.
Null hypothesis (Ho): Inclusion of different levels of Biotronic® SE in the diets of broiler chickens does not enhance growth performance, apparent nutrient digestibility, haematological profile, biochemical indices, carcass ch aracteristics and growth of beneficial intestinal biodata.
Null hypotheses (Ho): Inclusion of single and different levels of Biotronic® SE, Mycofix® in the diets of broiler chickens does not enhance growth performance, apparent nutrient digestibility, haematological profile, liver function test, kidney function test, carcass characteristics and intestinal gut morphology of broiler chicken