GROWTH CARCASS YIELD AND BLOOD PROFILES OF BROILER BIRDS FED HIGH FIBRE DIETS CONTAINING DIFFERENT LEVELS OF AN EXOGENOUS ENZYME

ABSTRACT

This experiment was conducted to investigate the effects of using Nutrizyme (an exogenous enzyme) on the performance of broilers fed high fibre diets. One hundred and forty four broiler chicks aged 7 days were divided into nine groups of sixteen birds each. Each group was replicated twice with eight birds per replicate which were assigned to nine experimental diets where spent grain replaced maize at 0, 6 and 12% at the starter phase and 0, 7 and 12% at the finisher phase. The diets were supplemented with Nutrizyme at 0, 0.5 and 0.8g/kg at both phases.  A 3×3 factorial arrangement in a completely randomized design was used for the experiment which lasted 8 weeks during which Average Daily Weight Gain (ADWG), Average Daily Feed Intake (ADFI), Feed Conversion Ratio (FCR), Feed Cost per Kg Gain (FCKgG) and Carcass yield were measured while their blood profile was evaluated. Results showed   that   Nutrizyme  supplementation   of   high   fibre  diets   improved   weight   gain significantly (p<0.05) at the finisher phase. At the starter phase, weight gain, feed conversion ratio  and  average daily  feed  intake  were not  significantly  (p>0.05)  affected  by  enzyme supplementation. Feed cost per weight gain was positively significant (p<0.05) at the finisher phase, while carcass yield of finisher broilers were significantly improved by enzyme supplementation. Red blood cells, haemoglobin and total protein were significantly(p<0.05) higher with 0.5 and 0,8g/kg enzyme supplementation at the finisher phase but at the starter phase, blood profile of broiler birds were not significantly affected by enzyme supplementation. There was significant (p<0.05) interaction of nutrizyme and spent grain in ADWG, ADFI, FCR, and Carcass yield at 7% spent grain and 0.8g/kg enzyme levels at the finisher phase. It was concluded that enzyme supplementation at 0.8g/kg significantly improved weight gain over unsupplemented diets at 7% spent grain inclusion level at the finisher phase.

CHAPTER ONE

INTRODUCTION

1.1. Background

Rapid human population growth and low protein intake are some of the major problems facing developing countries like Nigeria. Nearly half of the world population are underfed and two third of these underfed people are located in the countries of South and Central America, Africa and Asia (FAO, 2010). In these countries, daily intake of protein is far below requirement. Africa is only meeting 15g of the daily 65g total protein requirement (FAO, 2002). Food and Agricultural Organization has recommended that one third of the daily protein intake should be of animal origin. In Nigeria an average individual consumes 8g of animal protein per day which is about 27g less than the minimum requirement recommended by the Food and Agricultural Organization (FAO, 2006).

The future situation suggests a galloping deficit unless urgent actions are taken. To arrest the situation, it is necessary to increase the quantity of available animal protein by increasing our level of production. Poultry production is the surest and fastest means of bridging the animal protein supply needs of any nation.

Poultry refers to all birds of economic importance to man e.g. Chickens, turkeys, guinea fowl all of which belongs to the family of Aves. Poultry meat is favoured over beef because of its higher protein and lower calorie content in addition to such favourable meat quality as tenderness (Smith, 2001; Sam, 2010). Also poultry has a higher reproductive rate and a shorter generation interval and free from religious taboos, social, economic and climatic constraints. One of the sources of poultry meat is through broiler production. However, the major constraint facing poultry production in Nigeria is high cost of feed. Feed remains the most important cost of animal production accounting for over 70% of  the total cost of production (Madubuike, 2012). The need for feed ingredients which will reduce the cost of production is the basis for most new ingredients that are being brought into limelight in livestock feed and production research. This is because man and his livestock are in competition for basic ingredients which are not usually produced in sufficient quantities locally. Cereal grains and their milling by- products are important sources of energy in poultry nutrition, while oil seed cakes are used as sources of protein (Wachira, 2006). Cereal milling

by-products  and  by-products  of  brewery  industries  such  as  wheat  offal,  rice  offal,  and distillers spent grain are usually high in NSPs content associated with their high fibre levels. The  by-products  are  nevertheless  popular  ingredients  for  poultry  feeds  in  developing countries due to their low cost in comparison with whole grains. In Africa, the tendency is to use feedstuffs high in  fibre or NSPs because of low availability and high cost of maize grain,soybean meal et.c(Sonaiya, 2008).

Non starch polysaccharides (NSPs) affect poultry performance by lowering the nutritive value of feedstuff in poultry diets. High levels of NSPs can result in increased viscosity in the small intestine of chickens and depress nutrients utilization and performance (Choct and Annison, 1992a).The effect of NSPs on poultry performance has been widely studied in barley, rye, and wheat (Choct and Annison, 1992b). Results from studies by these researchers have shown that NSPs causes depression in growth, sticky droppings and reduction in available metabolizable energy (AME) to the birds. Poultry naturally produces a wide range of enzymes to aid in digestion but the range is not comprehensive and most of the NSPs are not digested. While animal protein sources used for poultry feeding can easily be digested by broilers, plants materials and their by-products have certain inherent residues that are not digested by broilers due to absence of a spectrum of appropriate enzymes (Ferket and Middleton, 1999).

Exogenous enzymes are known to increase digestibility of feed and feed intake of poultry birds(Brener et al, 1993). Supplementation of the diets of monogastric animals (pig and poultry) with exogenous enzymes is increasingly being investigated as a means of enhancing and increasing the effectiveness of nutrient utilization (Acamovic, 2001). Enzymes help to digest fibre present in the feed of monogastrics and break the anti-nutritional factors present in feedstuffs (Bedford and Patridge, 2010). Enzymes also breakdown the phytate molecules that bind phosphorous and some other mineral  elements in plant based feedstuffs  (Mac Donald et al 2004; Fuller,2004).

Nutryzyme is a synthetic pharmaceutical multienzyme product designed to improve the digestibility of feed containing high amounts of fibre ingredients in monogastric animals. The enzyme is complex containing a range of carbohydrases, phytase, xylanase, glucanase, pectinase and hemicellulase.

1.2. Statement of the Problem

One of the major problems in Nigeria is the gross deficiency of protein intake, both in quality and quantity. The daily requirement of animal protein per adult is 65g and many developing countries have a per capita protein consumption that is far below 15g (FAO, 2002). This has been attributed to unavailability and high cost of animal protein. In Nigeria per capita protein intake is 15g/day (Federal Office of Statistics, 2004). This has grossly affected the social and economic well-being of the Nigerian people. Nigeria is struggling to keep its food production commensurate with its population growth and under-nutrition and malnutrition may even be increasing  (Ironkwe,  2007).  The  best  logical  solution  to  the  problem  of  animal  protein shortage is to increase the production and consumption of pigs, poultry and rabbit and make their products readily available at affordable cost. The high cost of monogastric livestock production in most developing countries of the world is as a result of high cost of feed ingredients  like  cereal  grains  and  protein  concentrates  (Esonu  et  al.,  2003;  Obih  and Ekenyem,  2001).  Alternative sources  of poultry  feed  ingredients  aimed  at  replacing  the conventional maize and soyabean which are becoming unaffordable such as cereal and industrial by-products need to be investigated for possible utilization in poultry ration formulation.

This study was therefore aimed at investigating the growth performance, carcass yield and blood profile of broiler birds fed high fibre diets containing varying levels of an exogenous enzyme (Nutrizyme).

1.3. Objectives

The specific objectives of the study were to determine:

i.           The effect of dietary inclusion of spent grain  on the growth performance of broiler birds.

ii.          The effect of dietary inclusion of nutrizyme on growth performance of broiler birds and

iii.        To evaluate the blood profile of birds fed with Nutrizyme at different levels of inclusion.

1.4. Justification of the Study

Poultry industry in Nigeria is fast growing and it is the fastest means of bridging the animal protein consumption gapprevailing in the country (FAO, 2009). The industry has been unable to tackle its challenges due to numerous constraints facing it, among which is high cost of

feed which accounts for over 70% of total cost of production (Madubuike, 2012). To address this problem, effort is geared towards supplementing feeds high in NSPs with exogenous enzymes. Improvement of poultry diets through the use of exogenous enzymes has been comprehensively reviewed by several researchers (Ani and Omeje, 2011, Ani, Osita and Alutu 2005). From their results it was reported that addition of exogenous enzymes to fibrous feeds  for monogastrics  (  poultry, fish  and  pigs)  reduced  viscosity  of the ingesta in  the intestine and showed marked improvement in animal performance indices (feed intake, body weight gain and feed conversion ratio). Bedford (1996) reported that exogenous enzyme supplementation resulted in overall improvements in nutrient digestion and reduction in endogenous amino acid losses.

However the use of feed enzymes in poultry diets in Nigeria is not widespread due to lack of data generated under local conditions. Nutrizyme is a synthetic pharmaceutical enzyme designed to improve the digestibility ofdiets containing high fibre ingredients in mongastric animals. The enzyme is a complex compound containing a range of carbohydrases which hydrolyze a broad spectrum of carbohydrate polymers such as hemicelluloses, pectin and glycan into low molecular weight fractions. It also contains phytase, xylanase, glucanase, pectinase and hemicellulase. All these enhance proper utilization of feed, proper weight gain, improved feed conversion ratio, and increased availability of protein, fats and carbohydrates. Alu et al. (2009) reported that although the use of commercial feed enzyme is gaining worldwide acceptability, its use in Nigeria is still not popular and recommended the use of exogenous enzyme to enhance the digestibility of feed ingredients.

The findings of this study would be of benefit to poultry farmers, feed manufacturers, and nutritionists by increasing feed efficiency of poultry birds thereby reducing their cost of production.

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