ABSTRACT
Two experiments were conducted to evaluate the nutritive
value and enzyme supplementation of sorghum brewer‟s waste (SBW) in broiler
diets. In Experiment I, 225 one-week old broiler chickens with an average
initial live weight of 73g were fed diets containing graded levels of SBW.
There were five dietary treatments for both starter and finisher phases. The
treatments were replicated three times with fifteen birds per replicate and a
total of forty five birds per treatment in a completely randomized design.
Treatments 1, 2, 3, 4 and 5 contained 0, 10, 20, 30 and 40% SBW, respectively.
Results showed that at the starter phase, there were no significant differences
(P > 0.05) among the treatments up to 40% SBW while the finisher birds
performed better in terms of final weight and weight gain up to 30% level of
inclusion. Digestibility of crude protein and crude fibre were better up to 20%
and were similar to those fed 30% inclusion of SBW. Dietary treatments had
significant (P < 0.05) effect on live weight, dressing percentage, breast,
thigh, back, gizzard, liver, intestinal length and intestinal weight. At 40%
level of SBW, thigh, back, gizzard, liver, intestinal length and intestinal
weight were highest. In Experiment II, 225 one-week old broilers with an
average initial live weight of 80g were used to evaluate the effect of Rovabio®
enzyme supplementation at 0.01% on the performance, carcass characteristics and
digestibility of nutrients by broilers fed diets containing 0, 30, 35, 40 and
45% SBW in Treatments 1, 2, 3, 4 and 5, respectively. Design and management of
experimental birds were same as described in Experiment I. Results obtained at
the starter phase showed that Rovabio® enzyme supplementation
significantly (P < 0.05) affected feed intake and feed cost per kilogram gain.
Average feed intake was highest in birds fed 40% and similar to those fed 45%
SBW plus enzyme, respectively while Feed cost per kilogram gain was lowered in
birds fed 35 and 45% SBW. At the finisher phase, enzyme supplementation
significantly (P < 0.05) affected feed intake, feed conversion ratio and feed
cost per kilogram gain. Average feed intake was highest up to 30% and similar
to those fed 35% SBW. Feed conversion ratio was best with birds fed 40 and 45%
SBW and significantly (P < 0.05) lower than birds on the control diet. Dietary
treatments had no effect on the final weight, weight gain and mortality rate of
the birds. Birds on 35% SBW plus enzyme had highest digestibility in terms of
crude protein and crude fibre and similar to those on 40%. Digestibility of ash
was highest in birds fed the control diet and similar to those fed up to 40%.
Significant (P < 0.05) differences were observed on the carcass parameters
measured except for the live weight, dressing%, drumstick, heart, spleen,
intestinal weight and length. The results from these studies suggested that
Sorghum Brewer‟s Waste can be economically fed to broilers up to 33.33% as obtained
using a regression analysis with the feed cost/kg gain at the finisher phase as
the parameter used without inclusion of exogenous enzymes. However, the use of
Rovabio® enzyme enhanced the performance of birds up to 45%
inclusion level in terms of feed cost per kilogram gain.
CHAPTER ONE
1.0 INTRODUCTION
The present trend of inflation worldwide has become the
source of concern for livestock owners, as such inflationary trend often
imposes adverse effects on livestock feeds and hence, on costs of producing
livestock and livestock products (Nyannor et al., 2007). Consequently,
one of the greatest challenges facing the African continent is the provision of
sufficient food to the ever increasing population which is not matched with
similar increase in food production (Fasuyi, 2005).
The increasing demand for animal protein has aroused great
interest in the production of fast growing animals with short generation
intervals (Apantaku et al., 1998).Obinne and Okorie(2008) reported that
expansion of poultry industry in Nigeria holds the greatest promise for bridging
the animal protein requirement gap prevailing in the country within the
shortest possible time. Atteh (2004), reported that protein from poultry meat
and egg is of good quality and is used as a standard against which other
proteins are compared. Broiler chickens are fast growing species of poultry
that are commonly raised to provide tender meat for human consumption.The
availability of cheap and good quality protein sources remain the single most
important limiting factor in poultry production in Nigeria (Bawa et al.,
2003; Abeke et al., 2008).However, the rising cost of poultry feed has
continued to be a serious problem. This is because feed alone accounts for
about 70% of the total cost of production (Ogundipe et al., 2003).
Competition for conventional feedstuffs by man, industry and livestock has
contributed immensely to the high cost of these feedstuffs in the local
markets. This high cost coupled with inadequate knowledge of possible
alternative and cheap ingredients have been the most important factors
militating against the increase in commercial poultry production in Nigeria and
other developing countries (Olorede and Ajayi, 2005).
Babatunde (1986), suggested a drastic increase in the
production of ingredients commonly used in livestock feeds, such as maize,
soybeans, millet and others, so as to cater for the needs of both humans and
animals. Where this cannot be achieved, he emphasized that attempts should be
made to source for alternative feedstuffs for livestock. Therefore, the quest
for exploring the use of alternative feed ingredients that are cheaper and
locally available in dietary formulations to reduce production cost becomes
imperative (Okeke, 2000).A characteristic of such alternative feedstuff should
be its non competitive usage with man, brewery by- products fall into this
category (Dowling et al., 2003).Some non- brewery alternative feedstuffs
have been evaluated and found to be good replacements for the expensive
conventional feedstuffs which have direct use as human food. These alternative
feed sources have been utilized successfully by several animal nutritionists in
the formulation of feed which include the use of cassava peel meal in rabbits
(Adegbola and Oduozo, 1992), leucaena leaf in broiler diets (Dada et al.,
1998), cocoa pod husk meal in cockerel diets (Nworgu et al., 2003) etc.
According to Bello (1984), brewer‟s spent grains and
brewer‟s yeast are the most common by-products of the brewing industry in
Nigeria. Brewers‟ dried grain (BDG), a form of brewers‟ grain is a dried
extracted residue of barley malt alone or in mixture with other cereal grains,
resulting from the manufacture of beer (Adebowale and Ademosun, 1981).
Babatunde (1986) identified that brewers dried grains have relatively high
crude protein (23.62%) compared with maize (10.15%). They are rich sources of
essential fatty acids and vitamins especially B- complex vitamins and unidentified growth factors since they are
by-products of fermentation. A lot of work had been carried out on spent barley
grains (Almiral et al., 1995; Amin et al., 2011). However, works
on sorghum brewers‟ grains are very few. The production of sorghum brewers‟
waste (SBW) is derived from sorghum used solely or in combination with other
cereal grains like maize (maize-sorghum) in the production of burukutu
(Dogari, 1985; Ayodeji and Fasuyi, 2005). According to Udedibie and Emanalom
(1993) the striking features of the maize- sorghum based brewer‟s waste are its
relatively low fibre (12.42%) and very high crude protein (28.64%) contents,
deviating significantly from the crude fibre content of the conventional barley
based waste which ranges between 19-22% (Alawa et al., 1990; Maertens et
al., 1990).
Thousand tones of brewer‟s spent grains are turned out
annually from many small and large scale breweries in the country, with only a
small fraction being used by animals particularly monogastrics (Kingsell et
al., 1999). Udedibie and Emanalom (1993), Ayodeji and Fasuyi (2005) have
successfully incorporated 20% maize- sorghum beer residue in poultry diets.
Uchegbu et al. (2010) also reported the use of 30% maize-sorghum beer
residue in poultry diets without any deleterious effect on growth and
production performance. The production of beer from 100% sorghum is entirely a
new concept following the ban of the importation of barley in 1988 and the need
to conserve maize for human consumption. Sorghum brewer‟s waste is more
nutritious than the conventional barley-based by-product and would appear best
suited for feeding ruminant animals, taking advantage of its high fibre content
and fairly rich source of fermentable products (Maertens et al., 1990).
Abdulmalik (1997) reported that sorghum beer residue from the industry can be
included at a level of 15 and 20% in the diets of breeding and weanling does
respectively without adverse effects on performance. In a feeding trial, Tegbe et
al. (1995) fed graded levels of 0, 10, 20, 30% spent grains to weaned pigs and reported a
decrease in weight gain, feed intake, feed to gain and feed cost per kilogram
gain as the level of the spent grains increased in the diet. The best result on
the utilization of burukutu waste was obtained at 10% inclusion level. Tegbe
et al. (1995) also fed diets of 0, 12.5, 25 and 37.5% burukutu
waste to adult pigs and found that performance characteristics
related to feed intake, weight gain and feed to gain ratio were not affected by
the level of inclusion of the waste.
On the other hand, it is expedient to note that poultry
cannot fully utilize high fibre diets because they lack the digestive frame
work that can elaborately digest large amount of fibre. Many researchers have
proved that it is imperative to incorporate exogenous enzymes into their diets
in order to enhance the breakdown of the non-starch polysaccharides (NSPs)
present in fibre (Isikwenu and Bratte, 1999). Amin et al. (2011)
reported 15% Brewer‟s Dried Grain (BDG) on enzyme supplemented diet for
finishing broilers. Enzymes are known to increase the digestibility of fibrous
feed ingredients by disrupting the plant cell walls and by reducing the
viscosity of the gut contents, thereby enhancing nutrient absorption (Isikwenu
and Bratte, 1999). Almiral et al. (1995) reported that the inclusion of
ß- Glucanase enzyme in a diet based on barley increased the final body weight
of broilers. The enzyme considered in this study was Rovabio®.
Sorghum brewer‟s waste is
relatively cheap as large quantity is produced in local gin production (Awika et
al., 2001). It does not require much of additional processing such as
grinding before being incorporated into livestock diets and preserves the
ecosystem from further pollution resulting from its disposal.
The high cost of conventional feed ingredients such as
maize, millet, soybeans, groundnut and others arising from the competition
between man and animals has contributed immensely to the current high cost of
poultry feeds. Hence, the need to explore the use of underutilized,
non-conventional and cheap energy sources like sorghum brewer‟s waste as an
alternative energy source in poultry nutrition.
Poultry farmers will appreciate any ingredient that is cheap
and can be harnessed for production sustainability. Consequent of this,
brewer‟s spent grains which have high fibre contents are explored, thus, the
need to introduce exogenous enzymes in poultry diets because they lack
efficient digestive frame work to breakdown and utilize high fibre diets.
Supplementation of sorghum brewer‟s waste with Rovabio® enzyme in
broiler diets will enhance its effective utilization and there could be a
remarkable decrease in the cost of poultry feed to the advantage of the poultry
farmers in Nigeria.
1.2 Objectives
of the study
This study was
designed to:
1.
Evaluate the effects of using graded
levels of Sorghum Brewer‟s Waste (SBW) on performance and carcass
characteristics of broilers
2.
Evaluate the nutrient digestibility
of the diets of broiler birds fed graded levels of SBW.
3.
Evaluate the effect of enzyme
supplementation of SBW diets on performance, carcass characteristics and
digestibility of nutrients of broilers.
4.
Evaluate the cost: benefit of
utilizing SBW in the diets of broilers.
Ho; sorghum brewer‟s
waste with or without enzyme supplementation has no significant effect on
growth performance, carcass characteristics and nutrient digestibility of
broiler chickens.
Ha; sorghum brewer‟s waste with or without enzyme
supplementation has a significant effect on growth performance, carcass
characteristics and nutrient digestibility of broiler chickens.
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