ABSTRACT
The research was carried out in two phases/stages to evaluate the effect of graded levels of stone
grit with or without enzyme supplementation on the utilization of rice offal based diets by broiler
chickens. In the first phase, three hundred and sixty day old broiler chicks and two hundred and
seventy finishing broiler birds were used at the starter and finisher phases. The birds were reared
on deep litter, in an open sided wire mesh screened poultry house and fed on experimental diets
containing rice offal at 10% and 15% inclusion levels for the starter and finisher phases
respectively. Stone grit was added to this ration at graded levels of 0.0g, 2.0g, 4.0g, 6.0g, 8.0g
and 10.0 grams per bird per month. Each treatment was replicated three times with 20 birds per
replicate at the starter phase and 15 birds per replicate at the finisher phase in a completely
randomized design. Stone grit significantly improved (P<0.05) final body weight, feed intake,
feed conversion ratio and feed cost per kg gain thus indicating improvement in feed utilization.
Total protein (TP) improved with grit addition while packed cell volume (PCV) and
haemoglobin level (Hb) were not significantly affected (P>0.05). Crude protein, Crude fibre and
Nitrogen Free Extract significantly (P<0.05) improved with increasing grit levels. Similarly,
breast, back, thigh, shank, gizzard and dressing percentage improved with grit levels. It was
concluded that stone grit significantly (P<0.05) reduced feed wastage by improving feed
utilization as feed intake significantly (P<0.05) decreased with increasing levels of stone grit
while weight gain, feed to gain ratio, feed cost per kg gain, haematological parameters and
nutrient retention improved across the graded levels of stone grit. In the second phase, three
hundred and twenty four day old broiler chicks and two hundred and seventy finishing broiler
birds were used at the starter and finisher phases respectively. They were fed an experimental
diet that contained rice offal at 10% and 15% inclusion levels at both starter and finisher phases
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respectively however an Enzyme (maxigrain) was added to the diet at 0.01% across all dietary
treatments. Stone grit was also added to this ration at 0.0g, 2.0g, 4.0g, 6.0g, 8.0g and 10.0 grams
per bird per month thus making a total of six treatments. Each treatment was replicated three
times with 18 birds per replicate at the starter phase and 15 birds per replicate at the finisher
phase in a completely randomized design. Final body weight, feed intake, feed conversion ratio
and feed cost per kg gain improved (P<0.05) with increasing grit levels. No significant difference
(P>0.05) was observed for PVC, Hb and TP across the graded levels of stone grit. Live weight,
dressed weight, dressing percentage, back, thigh, wing and gizzard measurements significantly
(P<0.05) increased with graded levels of stone grit. Crude protein, Ether Extract and dry matter
significantly (P<0.05) improved with increasing grit levels. Birds fed diets containing stone grit
and enzyme supplementation (phase two) showed a higher final weight compared to birds fed
diets containing stone grit alone (phase one) hence the conclusion that feeding stone grit with
enzyme supplementation is encouraged to enhance higher final weight.
TABLE OF CONTENTS
Title page …………………………………………………………………………………………………………………….i
Declaration………………………………………………………………………………………………………………… ii
Certification ……………………………………………………………………………………………………………… iii
Dedication …………………………………………………………………………………………………………………. iv
Acknowledgement ………………………………………………………………………………………………………. v
Abstract ……………………………………………………………………………………………………………………. vi
Table of content …………………………………………………………………………………………………………. ix
List of Tables …………………………………………………………………………………………………………… xiv
CHAPTER ONE
1.0 Introduction ……………………………………………………………………………………………………… 1
1.1 Justification of the study …………………………………………………………………………………….. 3
1.2 Objectives of the study ………………………………………………………………………………………. 3
CHAPTER TWO
2.0 Literature review ………………………………………………………………………………………………. 5
2.1 Nutrient requirement of broiler chickens ……………………………………………………………….. 5
2.1.1 Water ……………………………………………………………………………………………………………… 5
2.1.2 Vitamins …………………………………………………………………………………………………………. 7
2.1.3 Minerals …………………………………………………………………………………………………………. 7
2.1.4 Protein ……………………………………………………………………………………………………………. 8
2.1.5 Energy ……………………………………………………………………………………………………………. 9
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2.1.6 Fat and fatty acids …………………………………………………………………………………………… 10
2.2 Factors affecting nutrient requirement of broiler birds ………………………………………….. 11
2.2.1 Sex ………………………………………………………………………………………………………………. 11
2.2.2 Housing system ……………………………………………………………………………………………… 11
2.2.3 Health status ………………………………………………………………………………………………….. 11
2.2.4 Production aims ……………………………………………………………………………………………… 11
2.2.5 Ambient temperature ………………………………………………………………………………………. 11
2.2.6 Reproductive state ………………………………………………………………………………………….. 12
2.2.7 Age ………………………………………………………………………………………………………………. 12
2.3 Non-traditional feedstuffs in poultry nutrition ……………………………………………………… 12
2.4 Factors limiting the use of non-traditional feed ingredients in poultry feed
formulation ……………………………………………………………………………………………………. 13
2.4.1 Nutritional aspects ………………………………………………………………………………………….. 13
2.4.2 Technical aspect …………………………………………………………………………………………….. 14
2.5 Strategies to improve the quality of non-traditional feedstuffs for
incorporation in poultry diet …………………………………………………………………………….. 14
2.5.1 Crop breeding ………………………………………………………………………………………………… 14
2.5.2 Feed processing ……………………………………………………………………………………………… 14
2.5.3 Nutrient Supplementation ………………………………………………………………………………… 15
2.6 Stone grit ………………………………………………………………………………………………………. 15
2.7 Rice offal as an alternative feed ingredient ………………………………………………………….. 17
2.8 The gizzard and its unique feature ……………………………………………………………………… 17
2.9 Enzyme ………………………………………………………………………………………………………… 18
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2.9.1 Source of enzymes ………………………………………………………………………………………….. 18
2.9.2 Benefit of feeding enzymes to poultry ………………………………………………………………… 19
2.9.3 Factors affecting the use of exogenous enzymes in broiler diet ………………………………. 20
CHAPTER THREE
3.0 Materials and Methods …………………………………………………………………………………….. 21
3.1 Experimental Site ……………………………………………………………………………………………. 21
3.2 Source of experimental birds …………………………………………………………………………….. 21
3.3 Source of stone grit and rice offal ………………………………………………………………………. 21
3.4 Laboratory analysis …………………………………………………………………………………………. 21
3.5 Phase 1 …………………………………………………………………………………………………………… 22
3.5.1 Performance of Broiler Birds Fed Rice Offal Based Diets wit Graded
Levels of Stone Grit (starter)……………………………………………………………………………… 22
3.5.2 Experimental diet ……………………………………………………………………………………………. 22
3.5.3 Management of birds ………………………………………………………………………………………. 22
3.6 Finisher phase …………………………………………………………………………………………………. 24
3.6.1 Performance of Broiler Birds Fed Rice Offal Based Diets with Graded
Levels of Stone Grit (finisher) …………………………………………………………………………… 24
3.6.2 Experimental diet ……………………………………………………………………………………………. 24
3.6.3 Management of birds ……………………………………………………………………………………….. 24
3.6.4 Evaluation of selected parameters post the finisher phase ……………………………………… 26
3.6.4.1 Haematological evaluation ………………………………………………………………………………. 26
3.6.4.2 Evaluation of carcass characteristics ………………………………………………………………… 26
3.6.4.3 Digestibility study ………………………………………………………………………………………… 26
3.7 Phase 2 ………………………………………………………………………………………………………….. 27
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3.7.1 Performance of Broiler Birds Fed Rice Offal Based Diets with Graded
Levels of Stone Grit and Enzyme Supplementation (1-4weeks) ………………………………. 27
3.7.2 Experimental diet ……………………………………………………………………………………………. 27
3.7.3 Management of birds ………………………………………………………………………………………. 29
3.8 Finisher phase ………………………………………………………………………………………………… 29
3.8.1 Performance of Broiler Birds Fed Rice Offal Based Diets with Graded
Levels of Stone Grit and Enzyme Supplementation (5-8weeks) ………………………………. 29
3.8.2 Experimental diet ……………………………………………………………………………………………. 29
3.8.3 Design and management of birds ………………………………………………………………………. 31
3.8.4 Evaluation of some selected parameters post the finisher phase ……………………………… 31
3.8.4.1 Haematological evaluation ……………………………………………………………………………….. 31
3.8.4.2 Evaluation of carcass characteristics ………………………………………………………………….. 31
3.8.4.3 Digestibility study ………………………………………………………………………………………….. 32
3.9 Statistical analysis ………………………………………………………………………………………….. 33
CHAPTER FOUR
2.9.3 Factors affecting the use of exogenous enzymes in broiler diet …………………………………………. 20
3.7.3 Management of birds ………………………………………………………………………………………. 29
3.8 Finisher phase ………………………………………………………………………………………………… 29
3.8.1 Performance of Broiler Birds Fed Rice Offal Based Diets with Graded
Levels of Stone Grit and Enzyme Supplementation (5-8weeks) ………………………………. 29
3.8.2 Experimental diet ……………………………………………………………………………………………. 29
3.8.3 Design and management of birds ………………………………………………………………………. 31
3.8.4 Evaluation of some selected parameters post the finisher phase ……………………………… 31
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3.8.4.1 Haematological evaluation ……………………………………………………………………………….. 31
3.8.4.2 Evaluation of carcass characteristics ………………………………………………………………….. 31
3.8.4.3 Digestibility study ………………………………………………………………………………………….. 32
3.9 Statistical analysis ………………………………………………………………………………………….. 33
CHAPTER FOUR
2.9.3 Factors affecting the use of exogenous enzymes in broiler diet …………………………………………. 20
3.5.3 Management of birds ………………………………………………………………………………………. 22
3.6 Finisher phase …………………………………………………………………………………………………. 24
3.6.1 Performance of Broiler Birds Fed Rice Offal Based Diets with Graded
Levels of Stone Grit (finisher) …………………………………………………………………………… 24
3.6.2 Experimental diet ……………………………………………………………………………………………. 24
3.6.3 Management of birds ……………………………………………………………………………………….. 24
3.6.4 Evaluation of selected parameters post the finisher phase ……………………………………… 26
3.6.4.1 Haematological evaluation ………………………………………………………………………………. 26
3.6.4.2 Evaluation of carcass characteristics ………………………………………………………………… 26
3.6.4.3 Digestibility study ………………………………………………………………………………………… 26
3.7 Phase 2 ………………………………………………………………………………………………………….. 27
3.7.1 Performance of Broiler Birds Fed Rice Offal Based Diets with Graded
Levels of Stone Grit and Enzyme Supplementation (1-4weeks) ………………………………. 27
3.7.2 Experimental diet ……………………………………………………………………………………………. 27
3.7.3 Management of birds ………………………………………………………………………………………. 29
3.8 Finisher phase ………………………………………………………………………………………………… 29
3.8.1 Performance of Broiler Birds Fed Rice Offal Based Diets with Graded
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Levels of Stone Grit and Enzyme Supplementation (5-8weeks) ………………………………. 29
3.8.2 Experimental diet ……………………………………………………………………………………………. 29
3.8.3 Design and management of birds ………………………………………………………………………. 31
3.8.4 Evaluation of some selected parameters post the finisher phase ……………………………… 31
3.8.4.1 Haematological evaluation ……………………………………………………………………………….. 31
3.8.4.2 Evaluation of carcass characteristics ………………………………………………………………….. 31
3.8.4.3 Digestibility study ………………………………………………………………………………………….. 32
3.9 Statistical analysis ………………………………………………………………………………………….. 33
CHAPTER FOUR
4.0 Results ………………………………………………………………………………………………………….. 34
4.1 Performance of Broiler Birds Fed Rice Offal Based Diets with Graded Levels
of Stone Grit (starter stage) ……………………………………………………………………………….. 34
4.2 Performance of Broiler Birds Fed Rice Offal Based Diets with Graded Levels
of Stone Grit (finisher stage) ………………………………………………………………………………. 36
4.3 Haematological Parameters of Finishing Broiler Birds Fed Rice Offal Based
Diets with Graded Levels of Stone Grit alone ……………………………………………………… 38
4.4 Nutrient Digestibility of Broiler Birds fed Rice Offal Based Diets with Graded
Levels of stone grit alone ………………………………………………………………………………… 40
4.5 Carcass Characteristics of Finishing Broiler Birds Fed Rice Offal Based Diets
with Graded Levels of Stone grit alone ………………………………………………………………. 42
4.6 Performance of Broiler Birds Fed Rice Offal Based Diets with Graded Levels
of Stone Grit and Enzyme Supplementation (starter phase) ……………………………………. 44
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4.7 Performance of Broiler Birds Fed Rice Offal Based Diet with Graded Levels
of Stone Grit and Enzyme Supplementation (finisher phase) …………………………………… 46
4.8 Haematological Parameters of Finishing Broiler Birds Fed Rice Offal Based
Diets with Graded Levels of Stone Grit and Enzyme Supplementation ……………………. 48
4.9 Digestibility of Nutrients by Broiler Birds fed Rice Offal Based Diet with
Graded Levels of Stone Grit and Enzyme Supplementation …………………………………… 50
4.10 Carcass Characteristics of Finishing Broiler Birds Fed Rice Offal Based
Diets with Graded Levels of Stone Grit and Enzyme Supplementation ……………………. 52
CHAPTER FIVE
5.0 Discussion …………………………………………………………………………………………………….. 54
5.1 Performance of Broiler Birds Fed Rice Offal Based Diets with Graded
Levels of Stone Grit alone (starter phase) ……………………………………………………………. 54
5.2 Performance of Broiler Birds Fed Rice Offal Based Diets with Graded
Levels of Stone Grit (finisher phase) …………………………………………………………………… 55
5.3 Haematological Parameters of Finishing Broiler Birds Fed Rice Offal Based
Diet with Graded Levels of Stone Grit ……………………………………………………………….. 56
5.4 Digestibility of Nutrients by Broiler Birds fed Rice Offal Based Diets with
Graded Levels of Stone Grit …………………………………………………………………………….. 56
5.5 Carcass Characteristics of Finishing Broiler Birds Fed Rice Offal Based Diets
with Graded Levels of Stone Grit ………………………………………………………………………. 57
5.6 Performance of Broiler Birds Fed Rice Offal Based Diets with Graded Levels
of Stone Grit and Enzyme Supplementation (1-4weeks)………………………………………… 58
5.7 Performance of Broiler Birds Fed Rice Offal Based Diets with Graded Levels
of Stone Grit and Enzyme Supplementation (5-8weeks)…………………………………………. 58
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5.8 Haematological Parameters of Finishing Broiler Birds Fed Rice Offal Based
Diets with Graded Levels of Stone Grit and Enzyme Supplementation ……………………. 60
5.9 Digestibility of Nutrients by Broiler Birds fed Rice Offal Based Diets with
Graded Levels of Stone Grit and Enzyme Supplementation …………………………………… 60
5.10 Carcass Characteristics of Finishing Broilers Fed Rice Offal Based Diets with
Graded Levels of Stone Grit and Enzyme Supplementation …………………………………… 61
CHAPTER SIX
6.0 Summary, conclusion and recommendation ………………………………………………………… 62
6.1 Summary ………………………………………………………………………………………………………. 62
6.2 Conclusion ……………………………………………………………………………………………………. 62
6.3 Recommendation ……………………………………………………………………………………………. 62
References …………………………………………………………………………………………………….. 63
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CHAPTER ONE
1.0 INTRODUCTION
Feed is the most important input in a poultry enterprise as it represents between 60-70% of the
total cost of production (Smith, 2001). The high cost of conventional feed ingredients coupled
with inadequate knowledge of alternative feedstuffs is among the factors militating against the
increase in commercial poultry production in Nigeria (Olorede and Ajayi, 2005). Consequently,
raising poultry birds will demand a greater monetary input from farmers with most of the cost
going into feeding. This has led to the search for alternative feed ingredients to reduce the cost
incurred in poultry production (Joseph et al., 2000; Emenalom, 2004 and Esonu et al., 2004).
One of such alternative feedstuffs that can be used in poultry production is rice offal (Abeke et
al., 2008). Amaefule et al. (2006) reported that in order to reduce feed cost and increase profit
margin in poultry production, producers should incorporate the use of low cost agro-industrial
waste such as rice offal.
Fagade (2000) reported that Nigeria has the potential to produce about 200,000 metric tons of
rice offal from the 500,000 metric tons of rice produced annually. However, in spite of the
abundance of rice offal in Nigeria, it has been neglected as feed for poultry because it contains
high level of fibre and low protein and energy (Ambashankar and Chandresekan, 1998; Oyawoye
and Nelson, 1999). Most non-conventional feedstuffs contain high amount of non-starch
polysaccharides (NSPs) that limit feed utilization by poultry birds. It was reported by Onyimonyi
(2005) that non-conventional feedstuffs when fed to non-ruminants could result into negative
responses such as reduction in nutrient utilization, metabolic dysfunction and depression in
growth rate. In order to enhance the utilization of non-conventional feedstuffs such as rice offal,
nutritionists have resorted to the use of feed additives such as stone grit (Atteh, 2003) and
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exogenous enzymes (Tuleun et al., 2009). Grits are bits of stone, sand and small particles used
by birds to enhance mechanical digestion by abrasion in the gizzard (Atteh, 2003). They are
hard, completely inert, neutral in pH and do not absorb water (Abeke et al., 2010). Grits are
classified into soluble and insoluble grit. The soluble grits are those that dissolve easily in the
gizzard and they include cattle bone, oyster shell, limestone etc. The insoluble grits are nondigestible
and are retained in the gizzard and they include silica, mica, granite etc. Though
arguments abound whether intensively reared birds under deep litter system have need for stone
grit in their gizzard, there is however a possibility that the presence of stone grit may result in
better digestion and utilization of ingested feed (Abeke et al., 2010).
According to Atteh (2003) addition of stone grit to the diet of poultry birds will lead to improved
feed utilization and efficiency resulting from mechanical abrasion that occurs in the gizzard
which is thought to increase the amount of nutrients that can be extracted from the feed. The
importance of stone grit in poultry nutrition stems from the fact that it provides additional
surface for grinding in the gizzard, helps to improve the digestibility of coarse and fibrous feed
particles and also helps to stimulate motility in the gizzard (Leeson and Summers, 2001). Jeff
(2010) reported that feeding poultry birds with grit is essential as it helps to improve gut health
by keeping the digestive tract moving thereby reducing the possibility of impaction and enteritis.
Another important way to circumvent the problem limiting the use of non-conventional feed
ingredients is by the use of exogenous enzymes. Acamovic (2001) reported that exogenous
enzymes increase the digestibility of feed ingredients and reduce the incidence of wet droppings
which may result from the presence of fibrous polysaccharides in the diets. Maxigrain is a potent
exogenous enzyme that can enhance the breakdown of the non-starch polysaccharide present in
rice offal thereby improving its utilization in poultry diets. The array of enzymes in maxigrain
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includes amylase, xylanase, Beta-glucanase, pectinase, protease, lipase, phytase and cellulase.
Maxigrain is widely used in poultry nutrition and it is readily available. Its potency stems from
the fact that it is: important in optimizing the use of non-conventional feedstuffs; it improves
weight gain in broiler birds, improves litter quality and dropping consistency, improves feed to
gain ratio, improves egg production and shell quality (Acamovic, 2001).
1.1 Justification of the Study
In recent times there has been an upward trend in the use of alternative feed resources in broiler
ration as a result of the high cost of conventional feed ingredients. However most of these nonconventional
feed resources are fibrous in nature and need to be improved upon for better
utilization. It was reported by Ensminger et al. (1990) that feed materials are usually not utilized
properly by broiler birds due to their rapid rate of feed intake, rapid rate of metabolism and
faecal output. Therefore it is expected that stone grit will help in mechanical grinding of feed
materials thus providing large surface area for endogenous and exogenous enzymes to optimize
performance and nutrient digestibility. Similarly, poultry birds instinctively pick up stones when
raised in an extensive system. Therefore, there is a need to simulate this natural phenomenon for
intensively raised birds.
1.2 Objectives of the Study
1. To assess the effect of stone grit at graded levels of 0.0g, 2.0g, 4.0g, 6.0g, 8.0g and 10.0
grams per bird per month on the performance, haematological, nutrient digestibility and
carcass characteristics of broiler birds fed rice offal based diets.
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2. To determine the effect of stone grit at graded levels of 0.0g, 2.0g, 4.0g, 6.0g, 8.0g and 10
grams per bird per month with enzyme supplementation on the performance,
haematological, nutrient digestibility and carcass characteristics of broiler birds fed rice
offal based diets
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