ABSTRACT
An experiment was conducted to investigate
the effects of using two different enzyme substrates on the performance of
broilers fed peeled cassava root meal (PCRM), in a 3 x 3 factorial arrangement
in a completely randomised design experiment. One hundred and eighty-nine
broiler chicks aged 14 days were assigned to nine experimental diets where PCRM
replaced maize at 0, 50 and 75 percent levels. The diets were formulated to be
roughly isonitrogenous and isoenergetic containing starter (15-36 days; 24% CP,
2800 Kcal/kg-1 ME) and finisher (37-58 days; 21% CP, 2800 Kcal/kg-1
ME) and 200ppm of enzyme (Nutrase xyla and Roxazyme G) were added to the diets.
Results indicated that Nutrase xyla and Roxazyme G supplementation increased
ADFI in the starter and finisher phases at all levels of PCRM inclusion
(P<0.05). The effect of nutrase xyla and roxazyme G supplementation on FCR
was positvely significant in the finisher phase (P<0.05). Roxazyme G
supplemented diet at 50% PCRM had the best least cost value in terms of feed
cost per kg weight gain. There was an increase in dressed weight percentage in
nutrase xyla and roxazyme G supplemented diets at 50% PCRM (P<0.05). Nutrase
xyla supplemented diet had increase significant effect (P<0.05) on dry
matter and metabolizable energy retention. Nutrase xyla and roxazyme G
supplemented diets had no significant effect (P>0.05) on edible organs
(heart and gizzard). It is concluded that enzyme supplementation on PCRM-based
diet had tremendous beneficial effect on production parameters.
CHAPTER
ONE
INTRODUCTION
A serious competition
exists between the feed industry and other channels in the food chain
(especially man) over conventional feed ingredients such as maize and soyabean.
This has resulted in the high cost and scarcity of these conventional
feedstuffs. Poultry feed producers are thus faced with the task of finding
alternative feedstuffs that will not compromise quality. The search for such
alternatives has exercised Animal Nutritionists in Nigeria for over a decade
(Onyimonyi and Okeke, 2002; Onyimonyi and
Onukwufor, 2003; Oke et al.,
2005; Onyimonyi and Okeke, 2005; Tuleun et al.,
2005).
Cassava, has been used
as an alternative energy source and its inclusion in diets for poultry has been
extensively studied (Tewe and Egbunike 1992, Eruvbetine 1995, Adegbola, 1977).
Nigerian cassava production is by far the largest in the world; a third more
than production in Brazil and almost double the production of Indonesia and
Thailand. The Food and Agriculture Organization of the United Nations estimated
2002 cassava production in Nigeria to be approximately 34 million tonnes(FAO,
2004). The trend of cassava production reported by the Central Bank of Nigeria
put the highest estimate of production at 37 million tonnes in 2000 (FMANR,
1997). The third series provided by (PCU, 2003) had the most conservative
estimate of production at 28 million tonnes in 2002. Nigeria’s production was
targeted at 40 million tonnes by 2005 and 60 million tonnes by 2020 (IITA,
2002).
Nigeria, being the
world’s largest producer of cassava should be able to utilize its vast
potential to provide enough of the tuber, not only for human consumption, but also for animal feed,
industrial use and export. In animal feed, it can be used as flour after being
peeled or chipped with the peels and ground before use. Studies have shown that
levels as high as 20% could be used in diets for layers (Tewe and Egbunike
1992) and 40% in broilers (Eruvbetine and Afolami, 1992) and 10% in replacement
pullets (Eruvbetine et al., 2002). Onyimonyi and Okeke (2005)
reported that 20 percent of the maize content of the diets of grower pigs can
be replaced by cassava peelmeal without any deleterious effect on the carcass,
organ characteristics and no pathological effects was observed.
The greatest limitation
to the use of cassava for livestock feeds is its content of cyanogenic
glucosides, linamarin and lotaustralin. Toxicity of cassava is caused by
hydrocyanic acid (HCN) which is liberated when the glucoside is hydrolysed by
the action of linamarase enzyme. The degree of toxicity depends upon the
variety, ecological conditions for growth of the plant., the form of the
product being fed and its processing technology (Coursey, 1973). The normal
range of HCN in fresh cassava root is 15-400ppm (Rogers, 1963). It has long
been established that the peel contains 5-10times the prussic acid content of
the pulp (Oyenuga and Amazigo, 1957). Maner (1974) observed that pigs can
tolerate 150-200ppm HCN on a fresh basis or 102 on a dry matter basis. Tewe and
Iyayi (1989) reported that hydrocyanic content of sundried pulp and oven-dried
pulp was 17.3-26.7ppm and 23.7-31.3ppm respectively. Where the HCN is below
100ppm, as in cassava flour or chips, cassava can be safely incorporated into
rations as is allowed in the EEC(Delange and Ahluwalia, 1983).......
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