ABSTRACT
A 35-day experiment was carried out in a completely randomized design to determine the efficacy of two phytogenic feed additives as veritable alternatives to antibiotics using 320 day- old unsexed commercial Ross 308 broiler chicks. The chicks were randomly divided into four groups of 80 birds each and assigned to four isocaloric (12.60, 13.2 and 13.4 MJ/Kg AMEn) and isonitrogenous (25.0, 22.5 and 20.07 % CP levels) diets designated as follows: diet 1- maize- soybean based diet without additives (negative control), diet 2- maize-soybean based diet containing 10% tylosin (positive control), diet 3-maize-soybean based diet containing phytonutrient (product 1) and diet 4-maize-soybean based diet containing phytonutrient (product
2). Diet 2 contained 200g/ton of antibiotics, while diets 3 and 4 contained 1L/ton each of phytogenic feed additives. Each treatment was replicated 8 times with 10 birds per replicate. Birds had adlib access to feed and water. At 35th day of the experiment, 8 birds per treatment, one from each replicate pens were randomly selected, electrically stunned at 70V and killed by cervical dislocation for meat quality, carcass and organ weights determinations. The birds had their left and right tibias removed for bone strength and mineral assessment. Eight birds per treatment were also randomly selected and euthanized according to standard ethical procedures and used for assessment of haematological parameters. Inclusion of phytogenic feed additives (products 1 and 2) resulted in significant reduction (p<0.05) in feed intake and significantly (p<0.05) enhanced performance of birds at week 7 of the trial. Birds fed diets containing phytogenic feed additives product 2 had significantly higher (p<0.05) thigh weights. The inclusion of phytogenic feed additives (products 1 and 2) in some of the diets reduced fat content of meat significantly (p<0.05) compared to the control groups. Treatments did not have significant (p >0.05) effect on bone parameters. Dietary inclusion of phytogenic feed additives (products 1 and 2) significantly improved broiler feed efficiency in week 1, reduced broiler meat fat content and improved the immune status of broiler birds. Treatments had no significant (p
>0.05) effect on white blood cells (WBC), neutrophils, eosinophil, red blood cells (RBC), haemoglobin concentration (Hb), haematocrit value (HCT), mean corpuscular value (MCV), mean heamoglobin count (MCH), mean cell haemaglobin concentration (MCHC), red blood cell distribution width (RDW) and platelet count. Leucocyte differential values such as lymphocytes, monocytes and basophils were significantly (p<0.05) affected by treatments.
CHAPTER ONE
1.0 INTRODUCTION
1.1 BACKGROUND OF THE STUDY
Rearing ruminant animals is exorbitant and time demanding. These have prompted a paradigm shift towards early maturing and fast growing poultry such as broiler chickens. Chickens are one of the major sources of meat and this has made broiler farming a profitable venture due to increased consumer demand for broiler meat. In other words, broilers, apart from fast growth are priced highly by humans as a result of the high protein quality of their meat. Hence, the aim of producing broilers on a commercial scale over the years has been to increase performance within the shortest possible time. This increase in performance is directly correlated with performance indices like daily gain, feed intake and feed conversion ratio (Longo et al., 2005).
Low animal protein intake has remained a major human nutritional problem in Nigeria, especially for the non-wage and low income earners (Amaefule et al., 2009). According to Schonfeldt and Hall (2012), dietary energy is an index of diet composition. Unlike the developed countries of the world whose two main sources of protein are animal products and cereals, low income countries still derive most of their dietary protein from cereal based staple food, with only
3% of the total dietary energy coming from meat and offal (FAO, 2008). Although, the production of livestock has increased in recent times in developing countries, nevertheless, low protein intake is continuously increasing. Hence, under nutrition, including insufficient consumption of protein remains a persistent problem in most developing countries of the world (Schonfeldt and Hall 2012). In the light of the aforementioned facts, the problem of inadequate protein supply in most developing countries like Nigeria can be solved to a large extent if more intensive commercial broiler production is encouraged and embarked upon.
1.2 PROBLEM STATEMENT
The poultry industry has for decades achieved the aim of improved performance and fast growth in broiler chickens with antibiotic growth promoters (AGPs) (Niewold, 2007; Hajati and Rezaie, 2010). These AGPs reputed for growth promoting and disease control activities have been used at low, sub-therapeutic doses to improve growth performance, feed efficiency and health condition of poultry species. However, long-term use poses serious threats to the health of these birds and may also have carcinogenic effects on human consumers. Pathogenic resistance to
antibiotics and imbalance in normal beneficial intestinal micro flora of poultry birds is also on the increase. To this end, the use of AGPs in poultry nutrition has aroused researchers, consumers and government regulators to advocate for alternative measures. In view of this, the search for unconventional botanical feed additives as alternatives to antibiotics is imperative (Niewold, 2007; Hajati and Rezaie, 2010; Sen et al., 2012). These botanical feed additives are also known as phytobiotic or phytogenic substances, and are regarded as natural growth promoters due to naturally occurring phyto-constituents that abound in them.
1.3 OBJECTIVES OF THE STUDY
The broad objective of this research was to ascertain the performance, bone mineralization and haematological indices of broilers fed phytogenic feed additives. Specific objectives were to:
1. Determine the performance of broiler birds to diets containing two phytogenic feed additives.
2. Determine the effect of phytogenic feed additives on meat quality, carcass characteristics and skeletal parameters of broiler chickens.
3. Determine the organ weights and gizzard erosion scores of broilers fed diets containing two phytogenic feed additives.
4. Determine the effect of phytogenic feed additives on haematological parameters ofbroiler chickens.
1.4 JUSTIFICATION OF THE STUDY
In view of the ban on antibiotics by the European Union in 2006, the use of phytogenic feed additives has received increased attention as veritable alternatives to antibiotics in poultry nutrition. It has been reported that these feed additives, commonly known as phytobiotics (ie plant antibiotics), botanicals or phytogenic feed additives are safe, affordable and contain important pharmacologically- active substances such as curcumin, allicin, papain and a host of others. Among the spectrum of phytogenic feed additives that have received increased attention as alternatives to antibiotic growth promoters, acidifiers, probiotics, prebiotics, exogenous enzymes, non- starch polysaccharides (NSP), essential oils, and various classes and blends of medicinal plants and resins seem to be the most researched (Hajati and Rezaei, 2010). Phytogenic feed additives (PFA) have been implicated in exerting beneficial effects in animal nutrition, particularly in appetite stimulation, improvement of endogenous digestive enzyme secretion, activation of immune responses and numerous other therapeutic and pharmacological potentials (Toghyani et al., 2010,
2011). Due to the biochemical constituents of these additives, they are able to play essential roles in improving growth performance of animals, particularly in livestock and poultry (Windisch et al.,
2008; Jacela et al., 2010). These additives are made up of diverse groups of herbs, spices and products derived thereof, and are mainly essential oils.
According to (Huyghaebaert et al., 2011), antibiotic growth promoters function in such a way that stimulates antibacterial action and as a result lead to a reduction in the incidence and severity of subclinical infections. Subsequently, the microbial usage of nutrients decreases but their absorption from the intestine is improved as a result of thinning of the intestinal mucosal. This indirect impact of AGPs mode of action translates into higher growth rate. Hypothetically, AGPs do not exert growth promoting effect in germ-free animals. In view of these facts, for any phytogenic feed additive to effectively replace antibiotics in livestock nutrition it is expected that they have the same beneficial effects as AGPs when included in the diets. It is expected also that just like AGPs, these alternative compounds should have modulatory effects on the gut microbiota and immune system (Huyghaebaert et al., 2011). To this end, a number of these plant-based substances have been found to possess qualities comparable to antibiotics, thus making them potent alternatives. However, there are reports that the mode of action of most of the phytogenic feed additives is not very clear.
The place of phytogenic feed additives as alternative compounds cannot be over-emphasized particularly with reference to their role in poultry nutrition. Exploring these additives in feeding of poultry species is not only beneficial to the animals but also to the human consumers. Different phytogenic feed additives have been used in broiler nutrition with varying results. A study was conducted to ascertain the effect of varying dietary levels (0.0, 0.25, 0.5 and 0.75%) of turmeric rhizome powder (TRP), and 50mg/kg vitamin E on the thigh meat of broiler chickens after slaughter. It was reported that the content of Malondialdehyde in the thigh meat of both birds fed medium (0.5%) turmeric rhizome powder, and those fed 50mg/kg vitamin E were much lower when compared to the groups whose diets were free of TRP. From the research findings it was evident that dietary inclusion of 5mg/kg TRP can increase the thigh meat shelf-life storage and quality in broiler chickens after slaughter (Daneshyar, 2012). Daneshyar et al. (2011) also reported that dietary supplementation of turmeric rhizome powder has the potential to reduce the concentrations of saturated fatty acids and triglycerides in thigh meat and improve the meat quality of broiler meat. Dietary supplementation of garlic meal reduced the population of pathogenic coliform in the gut of broiler chickens as evident in the reports of Sarica et al. (2005). It is reported that garlic has the
ability to lower the cholesterol and triglyceride levels of poultry meat and egg products, and also prevent atherosclerosis. Garlic is also reported to possess anti-thrombotic, anti-platelet, anti- hypertensive, anti-lipidemia properties (Amagase, 2006; Rahman and Lowe, 2006; Rahman, 2007). Acamovic et al. (2007) assessed the effects of dietary inclusion of 5 different culinary herbs or their essential oils on the growth, digestibility and intestinal microflora status of 165 female broiler chicks from 0-28 days of age. The authors reported that use of 10g/kg of these plant extracts (thyme, rosemary herb, oregano, marjoram) and/or 1g/kg of their essential oils affected the performance, gut health and endogenous secretions of the broiler birds. However, it is important to ascertain the chemical composition of the extract before optimal benefits can be obtained.
Against these backdrops, this study was conducted to investigate the performance, bone mineralization and haematological indices of broilers fed phytogenic feed additives.
This material content is developed to serve as a GUIDE for students to conduct academic research
PERFORMANCE BONE MINERALIZATION AND HAEMATOLOGICAL INDICES OF BROILERS FED PHYTOGENIC FEED ADDITIVES
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