NUTRIENT INTAKE DIGESTION AND UTILIZATION BY RABBITS FED COWPEA HULL AND SOYBEAN HULL BASED DIETS

ABSTRACT

A study involving two experiments was conducted to investigate the growth performance  of  rabbits  fed  diets  containing  graded  levels  of  cowpea  hull (CPH) and soybean hull (SBH). Thirty-two weaner rabbits of about 6 weeks old were used for the study. In experiment1, sixteen 6-week old hybrid (Chinchilla x New Zealand white) weaner rabbits of both sexes with initial average weight of 730-790g were randomly divided into four groups of 4 rabbits each. The groups were randomly assigned to four treatment diets containing 0, 10, 20 and 30% levels of cowpea hulls. Each treatment group was replicated four times with a rabbit constituting a replicate placed in a four

–tier rabbit cages that had a total of 16 hutches per tier. In experiment two, 16 six-week old hybrid (Chinchilla x New Zealand white) weaner rabbits of both sexes with initial average weight of 730-790g were randomly divided into four groups of 4 rabbits each. The groups were randomly assigned to four treatment diets containing 0, 10, 20 and 30% levels of soybean hulls. Each treatment group was replicated four times with a rabbit constituting a replicate placed in a four –tier rabbit cages that had a total of 16 hutches per tier. The experiments lasted for 8 weeks during which the daily feed intake body weight gain, feed conversion ratio, protein efficiency ratio and feed cost per kg weight gain were determined. The haematological parameters, digestibility coefficients, carcass

and organ weights were also determined.  Results (experiment I) showed that while increasing levels of CPH in the diets had no significant effect (P>0.05) on the average daily feed intake, daily protein intake and protein efficiency ratio, they had significant effect (P<0.05) effect on average final body weight and average daily weight gain of rabbits. Differences between the treatments in nutrient digestibility coefficients were significant (P<0.05). Generally, digestibility coefficients decreased with increasing level of CPH in the diets. The inclusion of CPH in the rabbits’ diet resulted in the reduction of the cost of feed per kg gain. Dietary treatments did not have any adverse effect on such haematological values as the Hb, PCV, RBC, MCH, MCHC and MCV of rabbits. However, the WBC was observed to decrease at the 30% level of inclusion. While dietary treatments had  no significant effect (P>0.05) on organ weights of rabbits, they had significant (P<0.05) effect on live body weight, dressed carcass weight and dressing percentage. In experiment 2, dietary treatments  had  significant  effect  (P>0.05)  on  final  body  weight,  feed conversion ratio, and daily protein intake. However no significant (P>0.05) differences were observe among rabbits in daily feed intake and average daily weight gain. The effect of treatments on nutrient digestibility coefficients were significant (P<0.05). Both DM, CP, crude fibre, ether extract and nitrogen-free extract digestibility coefficients were significantly (P<0.05) decreased beyond 10% SBH inclusion level. The inclusion of SBH in the diets reduced significantly the cost of feed per kg weight gain. Inclusion levels of SBH did not have any adverse effect on such haematological values as the Hb, PCV, RBC,   MCH,   MCHC   and   MCV   of   rabbits.   However,   the   WBC   was significantly (P<0.05) decreased at the 30% SBH inclusion level. While dietary treatments had no significant effect (P>0.05) on organ weights of rabbits, they had significant (P<0.05) effect on live body weight, dressed carcass weight and dressing percentage. The results obtained in the present study show that up to 10%  cowpea  hull  and  30%  soybean  hull  can  be  included  in  rabbits’  diet without  any  deleterious  effect  on  growth  performance,  haematology  and internal organs of rabbits.

CHAPTER ONE

1.1 INTRODUCTION

Although Nigeria is the most populous black nation in the world with great potentials and brilliant experts in different fields of endeavour, her inability to break away from the class of the world’s poorest nation and from the shackles of poverty despite her rich natural and human endowment is a thing of pain (Olatunbosun, 2001). According to Nigerianet (2003), Nigeria is the largest geographical  unit  in  Africa  with  a  land  area  of  923,768  square  kilometer. Central  Bank  of  Nigeria  (2002)  reported  Nigeria’s  population  to  be  129.9 million in 2004 based on the projected annual growth rate of 2.8% of the revised 1991 census. At this given growth rate, the estimated population of Nigeria would be 141.1 million in 2007. In spite of Nigeria’s numerous natural resources which are sufficient to make her self-reliant in animal protein production and even become main exporter of all kinds of food items, there is an acute shortage of animal protein in Nigeria. The demand for animal protein is far higher than the supply. The high cost of animal protein has put it out of the reach of the average Nigerian (Ani and Adiegwu, 2005; Ugwuene 2003). Mbanasor (2000) estimated Nigeria’s livestock resource to consist of about 14 million cattle, 34 million goat, 22 million sheep, 100 million poultry and 1 million  horses.  In  a  similar  report,  Abubakar  et  al.  (2003)  estimated  the

livestock population of Nigeria to be about 14 million cattle, 22.1 million sheep, and  345  million  goats.  In  spite  of  Nigeria’s  high  population  of  domestic animals, animal protein supply is still far below the minimum level of 35g per day as recommended by FAO (1997). The fact that some developed countries with lesser natural resources can boast of self sufficiency and their ability to export animal protein calls for sober reflection among Nigerians. On this note, for quick increased supply of animal protein and products to be met, it is necessary that animals with short generation intervals be reared. One of the domestic animals with short generation interval to be considered in this study is the domestic rabbit (Oryctolagus cuniculus).

The domestic rabbit has the potential to become one of the world’s most important livestock specie (Daily Times, 1981). In terms of commercial production, the rabbit excels other livestock; cattle, sheep and goat and ranks close to broiler chicken in terms of growth rate, feed conversion efficiency and meat quantity, (Adegbola et al., 1986). Lebas and Metheron (1982) found that the production of 1 kg of rabbit meat requires only a quarter of the feed energy needed to produce the same amount of Pork. El Amin (1978) reported that it was theoretically possible to obtain 206kg of meat in a year from a doe (assuming 15kits per litter, 10 litters in a year at market weight of 2.5kg and 55% carcass yield on slaughter). Abe (1988) reported that about 20% of feed protein consumed by the rabbit is converted into edible meat. Nutritionally, rabbit has a higher protein (20-21%), low fat content (10-11%), when compared with meat from other species (Ajayi et al., 2007). Furthermore Janieri et al. (1987) had reported that rabbit meat has the cholesterol value of 169mg/100g (dry matter basis) when compared with beef (200mg), chicken (220mg), and low sodium content. Consequently, rabbit meat has been listed in United State Department   of   Agriculture   (USDA)   as   an   approved   meat   source   for hypertensive patients. The resurgence of interest in rabbit production in Nigeria calls for research into alternative sources of energy and protein yielding ingredients to replace or supplement the expensive conventional cereal grains and legumes. The prices of such conventional protein and energy feed ingredients such as maize, rice, sorghum, ground nut, soybean have escalated in recent times  that it is becoming uneconomical  to use them in  rabbit  feeds (Esonu  et  al.,  2001,  Esonu  et  al.,  2004;  Oduguwa  et  al.,  2004).  There  is therefore an urgent need to search for alternative cheap and available feed ingredients that do not attract competition between man and animal to formulate balanced rations for non ruminant animals like the domestic rabbit. Two of such alternative materials that meet the above criteria are soybean hull and cowpea hull.

Soybean hull is the by-product of soybean milling industry. Soybean hull has estimated feeding value of 74-80% as that of maize based diets (Esonu, 1998). It contains potentially digestible fibre (Van Soest, 1995) and replaces some or all grains in the diets of ruminants as well as the conventional requirement of fish meal in non-ruminant animal feed (Nworgu et al., 2000). Soybean hull contains 22.75% crude protein, 18-15% crude fibre, 14.6% ether extract, 8.0% ash and 20.90% nitrogen-free extract (Esonu, 1998; Esonu et al., 1997; Preston, 1989). Cowpea hull is an unexploited waste from bean cake processing with little information available for its use. Thus, Soybean and cowpea hull may therefore be potential sources of protein and energy in the diet of rabbits.

1.2          Objective of the study

The study aims at determining the nutrient intake, digestibility and utilization by rabbits fed cowpea hull and Soybean hull based diet.

The specific objectives of the study are as follows:

(1) To determine the dietary levels of cowpea hull and soybean hull on growth performance of rabbits.

(2) To determine the optimum levels of inclusion of cowpea and soybean hulls in the diets of growing rabbits.

(3) To determine the effects of graded levels of cowpea hull and soybean hull on haematology and organ characteristic of rabbits.

(4) To determine the cost implication of feeding graded levels of cowpea hull and soybean hull to rabbits

(5) To determine the gross pathological effects on and mortality of rabbits fed graded levels of cowpea hull and soybean hull.

1.3 Justification and Significance of Study

The  current  acute  shortage  of  animal  protein  in  Nigeria  and  the  increased demand for livestock products call for urgent solution. Increased rabbit production is one sure way of meeting the animal protein requirement of the Nigerian populace within the shortest possible time (Iyegbe – Erakpotobor et al., 2002). Rabbits do not compete with man for the scarce conventional feed ingredients. The inclusion of cowpea hull and soybean hull in the diets of growing rabbit will definitely reduce the cost of production and thus result in increased rabbit production thereby making the meat available to the Nigerian populace at reduced price.

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