ABSTRACT
Sixty “day old” broiler chickens were used to evaluate the growth performance, haematological parameters, organ characteristics and meat quality of broiler birds fed, pawpaw leaf meal (PLM). The birds were divided into four treatments with three replicates per treatment. Each replicate contained five birds. Broiler finisher rations were formulated in which PLM was incorporated at levels of 0%, 0.5%, 1.5%, and 2.0% in the control (T1), T2, T3 and T4 diets respectively. The diets were isocaloric and isonitrogenous containing 2850kcal ME/ Kg and 20% CP Daily feed intake in grams per bird per day (g/b/d) Daily Body Weight gain (g/b/d), Feed Conversion Ratio (FCR) and Feed cost per kilogram gain in Naira (N) were determined. Four birds were slaughtered at the end of the 10th week of birds’ age for meat strength and organoleptic determinations. All data were subjected to analysis of variance (ANOVA) for a Completely Randomized Design. Results showed that the effect of treatments on Average Daily Weight Gain (g) (ADWG), Average Final Body Weight (AFBW), Average Daily Feed Intake (ADFI) (g/b), and Feed Conversion Ratio (FCR) were significant (P < 0.05). There is a progressive increase in Daily Weight gain and Daily Feed intake as the dietary level of PLM increased. Haematological parameters of birds in all the treatments were within the normal haematological values of broiler birds within their age. There is an improved performance as level of PLM in diets increased from T1 toT4 in all the parameters evaluated. Similarly, there is an observed intense colour change of the shanks as the dietary level increased from 0.5% to 2.0%. The effect of feeding increasing dietary levels of PLM in Colour, Tenderness and General Acceptability of broiler meat were significantly (P<0.05) better than the control diet. The incorporation of PLM into finisher broiler diets had nutritional benefits which led to general improved performance in body weight changes, FCR, Feed cost/kg gain, Carcass and Organ Examinations, Haematologicals parameters, Organoleptic indices and Meat strength of broiler birds. It is concluded that 2% PLM can be included in the diets of finishing broilers without any adverse effect on performance.
CHAPTER ONE
1.0 INTRODUCTION
High cost of feed emanating from volatility in the macro environment and general unavailability of feed or high cost of feed ingredients, especially protein sources has resulted in declining productivity and profitability for intensive broiler production system. This Scenario has resulted in supply bottlenecks forcing an upsurge in the price of broiler products in Nigeria. Given the central importance that feeds play in intensive broiler system it becomes imperative to identify other feed ingredients of lower cost and sound biological values that can partly supplement the conventional protein sources in broiler diets.
The use of local, cheap and readily available materials particularly those that are not readily utilized by man has received particular attention as the only viable alternative to the use of conventional feedstuffs (Nwakpu et al., 2000; Ekenyem, 2006; Odunsi, 2003). This is as a result of the fact, that, the price of the conventional protein sources have soured so high in recent times, due to stiff competition between the Nigerian feed industry and man for the utilization of conventional ingredients such as groundnut, soyabean, fish meal etc. hence, call for investigation of this cheap, non conventional feed resources.
The protein from leaves may be recovered and fed to farm animals in form of leaf meal protein concentrates (Farinu et al., 1992). Leaf meal made from fodder shrubs is helping small – scale farmers in Tanzania to boast their income (WAC, 2006). Leaf meal does not only serve as protein source but also provide some necessary vitamins, minerals and also oxycarotenoids which cause yellow colour of broiler skin, shank and egg yolk (D’Mello et al., 1987; Opara, 1996).
Among tested leaf meals in poultry nutrition are Leucaena leucocephala, cassava leaf meal, Lablab purpureus, Tithonia diversifolia, Microdesmis puberula, Ipomoea asarifolia, Azadirachta indica, Tephrosia bracteolata among many others (Lopez et al., 1978; Lopez, 1986; Odunsi et al., 1996; Esonu et al., 2003; Odunsi, 2003; Ekenyem and Madubuike, 2006; Akande et al 2007). D’Mello (1995) recommended 5.0 and 10.0% dietary levels of leaf meals for broiler and laying hen respectively. Ademola and Farinu (2006) recommended dietary inclusions of Tithonia diversifolia in combination with either penicillin or streptomycin at 100 ppm in the diet of laying hens, while Odunsi (2003) recommended 100 and 150g/kg of Lablab purpureus leaf meal for laying hens.
However, D’Mello (1995) opined that major constraints of leaf meal utilization in non-ruminant animal nutrition are relatively high fibre, low energy, anti-nutritional factors and reduced feed intake.
Pawpaw (Carica papaya) is a plant native to Tropical America. It is known as “Okwuru bekee” in Igboland, “Gonda” in Hausa and “Ibepe” in Yoruba speaking areas of Nigeria. It is popular in the tropics and subtropics for its easy cultivation, rapid growth, quick economic returns, and adaptation to diverse soils and climates (Harkness, 1967; Campbell, 1984). Cultivated pawpaw is unbranched and usually dioecious plant, although hermaphroditic sex type occur (Harkness 1967; Seelig, 1970). However, pawpaw has been naturalized in many tropical and subtropical countries (Randall, 2002). Pawpaw tree is not considered to be a weed species (O.E.C.D., 2003). Pawpaw seedlings are among the most common seedlings to emerge from the forest floor. The fruit of papaw has a sweet taste and agreeable flavour and are high in vitamins (A, B, B2, C) and minerals (Ca, P, Fe), low in sodium, fat and contain practically no starch. Pawpaw leaf meal contains four identified proteolytic enzymes (Papain, Chymopapain A and B and Papaya Peptidase).
In the tropics, meat is often tenderized by wrapping in pawpaw leaves, the rate of reaction is slow at room temperature, increasing to maximum activity at 800C and rapidly inactivated at higher temperature. Hence, papain continues to tenderize the meat during the early stages of cooking (Health Watch, 2002).
There is scarcity of information in the literature on the effect of pawpaw leaf meal on finishing broilers. Thus, this study is designed to achieve the following objectives:
- To evaluate the growth performance of finishing broilers fed graded levels of pawpaw leaf meal.
- To investigate the haematological parameters of finishing broilers fed graded levels of pawpaw leaf meal.
- To determine the carcass and organoleptic characteristics of finishing broilers fed graded levels of pawpaw leaf meal.
- .To determine the effect of feeding pawpaw leaf meal on meat strength of the broilers.
1.3. JUSTIFICATION OF THE STUDY
The inadequate feeding of the right quantity and quality of feeds and the stiff competition between human and animals for the available feedstuff suggests that investigations should be directed to finding non-conventional, local, cheap and readily available protein and energy substitutes.
This will help sustain livestock production in Nigeria and solve the problem of protein deficit. It is evident, that there is significant increase in poultry consumption resulting from geometrical increase in population. This means that we will face a large gap in the availability of feed grains to sustain poultry meat production. However, the use of leaf meal which serves as protein sources in poultry diet will be the key to meeting the increased need for feed ingredients, if only they can be freed of their toxic substances commonly known as anti-nutritional factors or inhibitors (Scott, 1974). It is in this respect that the utilization of pawpaw leaf meal in broiler nutrition becomes relevant.
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