ABSTRACT
A comparative study was conducted on some performance
characteristics with 225 each of Cobb 500 and Ross 308 broiler chickens fed
three rations in which PKOR replaced wheat bran at 0% (control), 10% and 20%
levels. There were 6 treatments (of 75 birds each) and 3 replicates (of 25
birds each), in a completely randomized designed 2x3 factorial experiment. The
trial used 3-week old broiler chicks over a 5 week period. The effects of
genotype, ration and their interactions on some growth parameters, carcass traits,
haematological and serological traits were assessed. The effects of genotype
and ration on most of the carcass, haematological and serological traits
evaluated were not significant (p>0.05). The growth traits evaluated were
also similar (p>0.05) for both Cobb 500 and Ross 308 birds. On the other
hand, there were significant (p<0 .05="" 10="" 20="" and="" birds="" compared="" control="" effects="" final="" for="" g="" growth="" had="" higher="" live="" major="" on="" p="" parameters.="" pkor="" ration="" rations="" significantly="" similar="" some="" the="" values="" weights="" were="" with="">0.05) for latter 2 groups. This
trend and significance levels were reflected in other growth parameters such as
weight gain and growth rate. Feed cost/kg weight gain declined from the control
(GH¢4.29) through to birds fed rations containing 20% of PKOR (GH¢3.59),
although differences were not significant (p>0.05). The effects of genotype
× ration interaction on all performance parameters assessed were not
significant (p>0.05); implying that farmers can raise either Cobb 500 or
Ross 308 on any of the three rations offered without any detrimental effects on
performance and would make savings/profit in feed cost/kg weight gain of
GH¢0.70 when PKOR is used in broiler ration up to 20% inclusion rate.
CHAPTER ONE
INTRODUCTION
Introduction
This chapter provides an
introduction to the research undertaken. Among the topics discussed in the
chapter are: background to the study, problem statement,
significance/justification, hypotheses, general and specific objectives of the
study.
Background to the Study
Growth performance in animals is
influenced by genotype as well as environmental factors, including nutrition
(Cameron, 1997; Falconer & Mackay, 1996). Thus, the expression of phenotypic
traits of broiler chickens is determined by both their genetic potential
(genotype) and the environment to which they are exposed; and sometimes, by an
interaction between genotype and environment (G × E).
The differential expression of
genotype over environment is reflected in the genotype x environment (G × E)
interaction phenomenon. The term genotype x environment interaction is most
commonly used to describe conditions where different genotypes (e.g. breeds,
lines, strains, progeny groups) respond differently to different environments
(e.g. diet/feed/nutrition, housing, location, season, production system,
medication, sanitation), according to Sheridan (1990). The differences of
various genotypes in their responses to different environments include changes
in mean performance in the measured traits of interest. The aspect of genotype
x environment interaction in broiler production which is best known to
influence phenotypic and economic performance is that of
genotype x nutrition/diet interaction (Razuki & Al–Rawi, 2007).
Consequently, Hoste (2007) reported that in terms of the future direction of
genetics linked to nutrition, costs of feed will remain a factor in the
economics of production, and therefore the optimization of feed utilization by
birds will remain a priority to geneticists in making economic decisions.
Over the last four decades, average
daily body weight gain in broiler chickens increased from about 22 g to more
than 50 g, yielding live market weights of more than 2500 g within a maximum
age of 50 days; concurrently, feed conversion ratio decreased from 4.1 to 1.7
(Arthur & Albers, 2003; Razuki & Al–Rawi, 2007). The role of breeding
in this tremendous increase in growth rate has been documented by Havenstein,
Ferket, Scheideler and Larson (1994) and McKay, Barton, Koerhuis and McAdam
(2000). Some of the broiler breeds or genotypes with faster growth rate
currently on the world market are the Cobb 500 and Ross 308. However, while the
genetic potential of the bird is improved, nutritional or dietary management
which influences most metric traits, including blood parameters (haemtological
and serological profile which assesses the health status of birds) also has to
adapt to these changing demands; there is therefore a need to formulate or
compound high quality and well balanced, but least cost diets, that will
enhance optimum growth. The general goal of poultry genetics for the immediate
future is to breed chickens with the ability to perform well within a wide range
of nutritional planes or dietary levels (Cavero, Icken, Schmutz &
Preisinger, 2011; Preisinger & Flock, 2000).
As indicated earlier, like
phenotypic performance, the economic performance of a broiler chicken
enterprise depends on both genotype (breed) and environment, most importantly
diet. Fortunately, many poultry breeding companies have been able to develop
fast-growing genotypes or breeds such as Cobb 500 and Ross 308 which can attain
a market weight of about 2.5kg within eight weeks (Arthur & Albers, 2003).
All broiler genotypes, irrespective of their genetic potential, will therefore
require the right nutrition from a well formulated or compounded diet. Diet
seems to be the most important variable input in commercial broiler chicken
production under intensive systems of management (Apantaku, Oluwalana &
Adepegba, 2006). Depending on the efficiency of feed utilization by broiler
genotypes and the ingredients used in formulating rations, diet forms about 70
to 80 percent of the total cost of broiler meat production (Flake &
Ashitey, 2008; Gyamera, 2010; Nyanu, 1999). This suggests that if the cost of
diet is lowered, the profit margin of broiler poultry farmers would likely
increase, and vice–versa. Additionally, lowered feed cost could also reduce the
price of broiler chickens, thereby increasing per capita consumption of animal
protein sources which is rated as low in Ghana, according to a report by Food
and Agriculture Organisation (FAO, 2004).
Generally, prices of conventional
feeds in Ghana such as maize, wheat bran and fish meal have been rising
steadily in recent years; this has resulted in unreliable supply and relatively
high prices of locally produced broiler chicken meat. This has led to the
closing down of many small and medium scale broiler poultry farms despite the
availability and affordability of fast-growing commercial broiler genotypes
(breeds) over the last decade (Flake & Ashitey, 2008; Yangtul, 2010).
Reducing and regulating feed costs are therefore critical to the sustainability
and profitability of the broiler industry, given that feed cost alone can
account for as high as 80 percent of the variable production costs (Flock,
Ameli & Glodek, 1991; Gyamera, 2010).
With the ever increasing prices of
some conventional feed ingredients and their associated erratic supply, there
is no doubt that, the use of other non– conventional feedstuffs, and
formulation of high quality balanced rations using the least cost ration
approach, will be an ideal avenue to reduce feed costs in broiler chicken
production (Nyanu, 1999). Hence, in recent times, many animal nutritionists
have focused on using crop residues and agro-industrial by-products, which are
low-cost vast feed resources very much under-utilized in Ghana, to solve the
problem of acute feed shortage and high feed cost. This assertion confirms
observations of Flake and Ashitey (2008) who reported that farmers and feed
manufacturers are switching to low-cost substitutes such as palm kernel cake
(PKC), palm kernel meal (PKM) and copra cake which are by-products of
agro-processing. Undeniably, palm kernel oil residue (PKOR; a variant of PKC/PKM)
which is a solid waste by-product of cottage industries that extract oil from
palm kernel, seems to have some potential as a low-cost non-traditional feed
ingredient for poultry, according to feeding trials on broiler birds undertaken
by Odoi, Adam, Awuma, Adu and Ayitey (2007) in Ghana.
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