Abstract
The effect of seasons on aflatoxins loads of selected pig’s feedstuffs in the humid tropics was investigated, the feedstuffs sampled were cassava peels, bambara nut waste, palm kernel cake and brewer spent grains. The study lasted for thirty-two weeks. These feedstuffs were collected in two piggery farms in each of the six LGAs that make up Nsukka zone of Enugu State, in both dry and rainy seasons.The collected feedstuffsamples were analyzed in the laboratory for aflatoxins concentration levels using AOAC method of thin-layer chromatography (TLC)with some modifications. Data were collected from the aflatoxins laboratory analysis of these feedstuffs and with a structured questionnaire.The results of this study indicated the presence of aflatoxins in all the sampled feedstuffs, however the lowest concentration of aflatoxins which is 0.011ppb is obtained in cassava peels and bambara nut wastes while the highest concentration of aflatoxins obtained is 0.055ppb in brewer spent grains,these values are within the tolerance limit in Nigeria for total aflatoxins (B1+B2+G1+G2),which is 20ppb.The obtained aflatoxins levels are within range and poses less risk to pigs and pork consumers.The results also shows that there were no significant difference (P > 0.05) on the aflatoxins concentration levels of the feedstuffs at their sources, across the piggery farm locations, in the season and source of feeds interactions, season and the piggery farm locations interactions, as well as season and feedstuffs interactions. However the main effect of seasonon aflatoxins level which is 0.022ppb and 0.044ppb in the dry and rainy seasonrespectively were highly significant (P < 0.01).Also the main effect of aflatoxins of the feedstuffs were highly significant (P < 0.01) except in brewer spent grains were it is significant (P < 0.05). It follows that the aflatoxins levels according to season in the comparison between the source of feedstuffs and the piggery farm locations for the sampled feedstuffs were highly significant (P< 0.01) especially in the rainy season, except bambara nut wastewhich is highly significant (P< 0.01) in the dry season. There were higher values in the aflatoxins levels in all the feedstuffs sampled in the rainy season than in the dry season.It was therefore concluded that season has an effects on the aflatoxins level of pig’s feedstuffs with rainy season favouring toxigenic mould metabolism and growth in the feedstuffs which produces aflatoxins as their metabolites than in the dry season in this study, hence adequate preservative measures, proper feed handling and storage should be adopted. It is therefore recommended that piggery farmers should adopt adequate preventive measures and also apply the various preservative storage methods in order to reduce the aflatoxins levels infeedstuffs especially in the rainy season for better performance of the pigs and safety of pork consumers.
Table
of Contents
Title Page … … … … … … … … … …i
Certification … … … … … … … … … …ii
Dedication … … … … … … … …. … …iii
Acknowledgement … … … … … … …. … …iv
Abstract … … … … … … … … … …v
Table of Contentss … … … … … … … … …vi
List of Tables … … … … … … … … …xi
List of Figures … … … … … … … … … ….xii
Chapter One
1.0 Introduction
1.1 Background of the study … … … … …….1
1.2 Statement of Problem … … … … …….4
1.3 Objectives of the study … … … … …. ……5
1.4 Justification of the study … … … … ……6
Chapter Two
- Brief History of Aflatoxins …… … … … … ……7
2.2 Natural Occurrence of Aflatoxins … … … ……8
2.3 Mycotoxins and Its Effects…. … … … … … …..10
2.4 Chemical Reactions of Aflatoxins … … … ….12
2.4.1. Heat …. … … … … … … … … ….12
2.4.2 Alkalis … … … … … … … … ….12
2.4.3 Acids … … … … … … … … … ….14
2.4.4 Oxidizing Agents … … … … … ….14
2.4.5 Reduction … ….. …… … … … … …14
2.5 Chemical Structure of the Different Types of Aflatoxins 15
2.6 Aflatoxin B1 Pathways… … … … … …16
2.7 Metabolism of Aflatoxins … … … … …16
2.7.1 Bio-activation … … … … … … … …16
2.7.2 Conjugation… … … … … … … … …16
2.7.3 Deconjugation … … … … … … …17
2.7.4 Aflatoxins Units and its Conversion … … … …17
2.8 Factors that favours Mould Growth and Development 18
2.9 Clinical Signs/Symptoms of Aflatoxicosis in Pigs… …18
2.9.1 Acute Aflatoxicosis… … … … … …19
2.9.2 Chronic Aflatoxicosis … … … … … …19
2.10 The Effects of Aflatoxins in Pigs … … …20
2.11 Aflatoxins
Tolerance Levels and Action Limits in Animal Feeds …23
2.12 Aflatoxins and Climate Change… … … …27
2.13 Aflatoxins and its Economic Importance … …28
2.14 Aflatoxins Metabolism in Animals … … …29
2.15 Methods of Aflatoxins
Determination and Quantificationin Samples….
30
2.16 AflatoxinsPrevention and Control Strategies… ….32
2.17. Alternative Feedstuffs and their Uses in Pig Feeding …41
2.18 Cassava Peels Meal (CPM)…. … … … … …42
2.19.1 Nutritive Value of Cassava Roots/Peels … … …44
2.19.2 Utilization of Cassava Peels as feedstuffs … … ..… …45
2.19.3 Constraints to the Use of Cassava Meal/Peels as a feedstuff 47
2.20 Palm Kernel Cake (PKC)… … … … …48
2.20.1 Nutritive Value of Palm Kernel Cake as feedstuffs … …49
2.20.2 Utilization of Palm Kernel Cake … … …51
2.20.3 Constraints to the Use of Palm Kernel Cake … …52
2.21 Bambara Nut Waste (BNW)… … … … …53
2.21.1 Nutritive Value of Bambara Nut/Waste as feedstuff … …54
2.21.2 Utilization of Bambara Nut /Waste … … …56
2.22 Brewer’s Spent Grain (BSG)… … … …57
2.22.1 Nutritive Value of Brewer’s Spent Grains… … …58
2.22.2 Utilization of Brewer Spent Grains as feedstuff… … …61
2.22.3 Constraint to the Use of Brewer Spent Grains … …62
2.23 Brewer Yeast … … …. … … … … …63
2.23.1 Nutritive Value and utilization
of Brewer Yeast in Livestock feeds… …63
2.24 Effect of High Content of Fibre in Pigs Diets …65
2.25 Anti-nutritional factors in Non-conventional Feedstuffs 66
2.25.1 Classification of Anti-nutritional Factors (ANFs) …67
2.25.2 Factors
Interfering with the Digestion and Utilization of Dietary Proteins and Carbohydrates … … … … … …68
2.25.2.1 Tannins … … … … … … … …68
2.25.2.2 Saponins … … … … … … … …69
2.25.2.3 Trypsin
or Protease Inhibitors …. … … … … …69
2.25.2.4 Haemagglutinins… … …. … … …70
2.6 Factors that Interfers with availability of Minerals … …71
2.26.1 Phytates … … … … … … … …71
2.26.2 Oxalic Acid … … … … … … … …71
2.26.3 Glucosinolates… … … … … … … …71
2.26.4 Gossypol … … … … … … … …72
2.26.5 Phytoestrogens … … … … … … …72
2.26.6 Anti Vitamins … … … … … … … …72
2.26.7 Cynogens … … … … … … … …72
2.26.8 Lathyrogens … … … … … … … …73
2.26.9 Nitrates and Nitrite … … … … … …73
2.26.10 Flatulence Factors … … … … … …73
2.27 Pigs and its Characteristics … … … … …73
2.28 Humid Tropics and its Characteristics … … …74
Chapter
Three
3.0 Materials and Methods
3.1 Location of the Study… … … … … … … …76
3.2 Experimental Materials… … … … … … …76
3.3 Experimental Procedure… … … … … … … …77
3.4 Sample Preparation … … … … … … …77
3.5 Procedure
for Aflatoxins Determination and Quantification by (TLC)… …. …78
3.5.1 Apparatus… … … … … … … … …78
3.5.2 Reagents… … …. … … … … … …78
3.5.3 Procedure of AOAC Aflatoxins Analysis using TLC ….79
3.5.4 Method
of Determination of Aflatoxins Concentration in Feedstuffs Samples … …81
3.5.5 Safety Issues… … … … … … …81
3.6 Experimental Design… …. …. …. … … …82
3.7 Data Collection… … … … … … … …82
3.8 Statistical Analysis … … … … … … …83
Chapter Four
4.0 Results and Discussion
4.1
Results and Discussion of Aflatoxins Laboratory Analysis of Pigs
feedstuffs … …84
4.1.1: The results of the effect of source of feedstuffs on the aflatoxins levels of pig feedstuffs 84
4.1.2: The results of the
effect of farm location on the aflatoxin
levels of pig
feedstuffs … 85
4.1.3: The results of the effect of
season on the aflatoxins levels of pig feedstuffs ….
86
4.1.4: The results of the effect of feedtype on aflatoxins levels
of pig feedstuffs …. …. 86
4.1.5: The results of the effect of
season on aflatoxins levels
of pig feedstuffs …. …. 87
4.1.6: The results of the
effect of source and season on aflatoxins
levels of pig feedstuff …
88
4.1.7: The results of the
effect of feedstuff and season on aflatoxins levels of pig feedstuffs 89
4.1.8: The results of the
effect of season and farm location on
aflatoxins levels of feedstuffs 90
4.1.9: The results of the
effect of source and farm location on aflatoxins levels of feedstuffs 91
4.2 Pig Farmers Responses and Discussions … … 95
4.2.1 Marital status … … …. … 98
4.2.2 Educational Qualifications … … … … … 98
4.2.3 Gender … … … … … … … 98
4.2.4 Number of pigs reared in the farm …. …. … … 99
4.2.5 Frequency of sourcing pigs’ feedstuffs …. …. … …. 99
4.2.6 Quantity of feedstuffs purchased in kg/tons …… …. 100
4.2.7 How these feedstuffs are stored in the piggery farms … …. 100
4.2.8 Susceptibility of pig breeds to mould contaminated feedstuffs 100
4.2.9 Ingredients added to the feedstuffs to
improve its nutrient availability … ….
101
4.2.10 Mould incidence/infestation of feedstuffs fed to pigs . …. 101
4.2.11 Feedstuffs that develop moulds faster than others …. 101
4.2.12 How does these symptoms affect the pigs …. …. 102
4.2.13 Feedstuffs used by pig farmers to feed pigs in their farms 103
4.2.14 Main source of
feedstuffs from where the pig farmers procure feedstuffs …. …. 104
4.2.15 Signs and symptoms shown by pigs when fed
mould contaminated feeds …. ….
105
4.2.16 Preventive measures adopted to reduce mould
infestation of the feedstuffs …. ….
106
4.2.17 The season/ period of the year mould
infestation of feedstuffs are prevalent …. 107
Chapter Five
5.0 Summary,Conclusion and Recommendation
5.1 Summary
… … … … … … … … … …109
5.2 Conclusion… … … … … … … … … …110
5.3 Recommendations … … … … … …110
References
Appendices
List of Tables
Tables Pages
Table 2.1: The chemical formula and physical properties of different
types of aflatoxins 10
Table 2.2:
Tolerance limits and action levels for total aflatoxins in livestock feed 24
Table 2.3:
Dry matter of the fresh and air-dried cassava peels at 105oC for 24hrs 45
Table 2.4: Proximate composition of palm kernel cake 50
Table 2.5: The amino acid composition of palm kernel cake (g/16gN) 50
Table 2.6: Mineral content s of palm kernel cake 51
Table 2.7: Proximate composition of decorticated and undecorticated bambara nut 55
Table 2.8: Proximate composition of
toasted and raw bambara nut (%DM) 55
Table 2.9 : The essential amino acid content of bambara nut 56
Table 2.10: The amino acid composition of brewer spent grains as a
(%) of crude protein 59
Table 2.11: The digestibility of pigs (%) of brewer spent grains 59
Table 2.12:The dry matter (%) of brewer yeast 64
Table
2.13: The amino acid composition of brewer yeast as a (%) of crude protein 64
Table 4.1.1Effect of source of
feedstuff on the aflatoxins level of
the feedstuffs 84
Table
4.1.2: Effect of farmlocation on aflatoxins
levels of pig feedstuffs 85
Table 4.1.3:
Main effect of season on aflatoxins levels of pig feedstuffs 86
Table 4.1.4: Effect of feed type on aflatoxins levels of pig feedstuffs 86
Table 4.1.5: Effect of season on aflatoxins levels of pig feedstuffs 87
Table 4.1.6: Effect of source and season on aflatoxins levels pig feedstuffs 88
Table 4.1.7: Effect of feedstuff and season on the aflatoxins levels feedstuffs 89
Table 4.1.8: Effect of season and farm location on
the aflatoxins level of the feedstuffs 90
Table 4.1.9:
Effect of source and farm location on the aflatoxins levels of pig
feedstuffs 91
Table 4.1.10: The questionnaire responses of pig farmers 96
List of Figures
Figures Pages
Fig.1: Structure of Aflatoxin B1, B2, G1 and G2 13
Fig. 2: Structure of Aflatoxin M1, M2, B2A and G2A 14
Fig. 3: Aflatoxin B1 Metabolism Pathways 15
Fig. 4: Bar chart showing the various feedstuffs used by piggery farmers in feeding pigs in their farms 98
Fig 5: Bar chart showing the main source of feedstuffs from where the pig farmers procure feeds 98
Fig 6: Bar chart showing the signs/ symptoms shown by pigs when fed mould contaminated feeds 99
Fig 7: Bar chart showing the preventive measures adopted to reduce mould infestation of feedstuffs 99
Fig 8: Bar chart showing
the season/ period of the year mould infestation of
feedstuffs are prevalent 100
CHAPTER ONE
1.0 INTRODUCTION
1.1 Background of the Study
The
consumption of animal protein is very
essential for meeting the protein requirement of man for normal growth and healthy
development. The protein s
