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EFFECT OF SEASON ON AFLATOXINS LOAD OF SELECTED FEEDSTUFFS FOR PIGS IN THE HUMID TROPICS

Animal Science Project Topics & Materials

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

  • Literature Review

 

  • 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    Alatoxins 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 ofCassava 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 levelsfeedstuffs                    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 sources from animal origin are good sources of lysine and sulphur amino acids, which are lower in protein sources from plant origin (Omole, 1991). The shortage of protein, particularly animal protein is prevalent in most parts of Africa where it is estimated that on the average 10 grams of animal protein is consumed per day compared to the recommended daily intake of 35 grams (ILCA,1980; FAO, 1986). The level of animal protein consumption was estimated at 8 grams per caput per day, this is about  20 grams less than the National Research Council of  United States of America’s recommendation (Obioha, 1992; FAO, 1997). Ogini (2001) stated that Nigeria, despite its vast land area of 9,237,680km2 , the greater percentage of her citizens of  over 120 million are still battling with abject poverty and hunger. Atsu (2002) reported that there is inadequate intake of animal protein in Nigeria.

The high cost of feeds and feed ingredients, especially the conventional energy and protein feed sources such as maize, wheat, sorghum, soybean cake, groundnut cake and fish meal were as a result of the stiff competition between human consumers for food, for livestock feeds/feeding and industrial raw materials e.g. cereal grains for baby food formulas and biofuel production, especially maize (Agbede et al., 2002; Adegbola and Asaolu, 2008). Maize is a major source of energy in monogastric feeds, especially pigs, poultry and rabbits. In Nigeria, cereal grains are in high demand and its production has never been adequate to meet the needs of the increasing population; consequently there is little or no excess grains for livestock feeding. When available, it is always very expensive (Rhule,1999). The cost of conventional feedstuffs which are major sources of energy and protein in monogastrics diets has continued to increase (Onu and Madubuike, 2006; Defang et al., 2008) due to their short supply. In  2005 the price of  maize rose from about N30 to N70 per kilogram (Rhule,1999). As the competition between man, farm animals and industrial uses for grains continues to increase, substitutes for grains are being increasingly used in poultry and livestock feeding to reduce the high cost of feed (Babatunde and Hamzat, 2005). This continuous increase in the cost of conventional feed ingredients used in formulating poultry and livestock feeds has necessitated an intensive search for cheap alternative feed ingredients that will be able to replace a given portion, if not all of the conventional feed ingredients (Babatunde, 1985; Onyimonyi, 2002; Adesehinwa et al., 2011).

According to Ugwu et al. (2008), the main factors militating against the rapid expansion of animal production industry in Nigeria is the problem of inadequate supplies of feedstuffs at economic prices. The scarcity and  high cost of  conventional feedstuffs is largely responsible for the present high price of  finished animal products such as eggs, meat and milk (Rhule,1999; Adesehinwa et al., 2011).  Ijaiya et al. (2004) pointed out that feed cost is perhaps the most expensive input in intensively reared stocks and constitutes about 70 – 80% of the real cost of  animal production. Onyimonyi and Onukwufor (2003) had earlier reported that a major solution to the problem of  rising costs, scarcity of  energy and protein sources for monogastrics is to seek for new and non-conventional feed resources which are able to replace a certain percentage proportion of the known conventional feedstuffs without any deleterious effect on the animal performance. Esonu et al. (2001)  indicated that such substitute which have been successfully used to replace the conventional feedstuffs are brewer spent grains, stem/tuber residues and cereal by-products such as wheat offal, rice bran, maize bran as well as bambara nut waste and cassava or yam peels.

Fetuga et al. (1977), Iyayi et al. (2005)  and Onyimonyi and Ugwu (2007) had studied the feeding value of such non-conventional feed resources as palm kernel cake, bambara nut offal,  rice husk and cassava peels, and that they can be utilized in supplementing a given portion of the conventional feedstuffs. Onyimonyi and Ugwu (2007) further noted that these non-conventional feeding stuffs are commonly found in the South Eastern Nigeria. According to Babatunde and Hamzat (2005), these alternative feedstuffs have proved valuable in supporting the performance of  livestocks and poultry and that by utilizing them in ration formulation, it will go a long way in reducing the demand and cost of conventional feedstuffs, which greatly increases the total cost of  pork  production. Adegbola and Oduozo (1992) reported that some of the limiting factors associated with agro-industrial by-products and crop residues utilization as animal feeds include: procurement, storage, poor feed intake, high fibre content, toxic and anti-nutrients substances as well as being low in their digestibility which subsequently lowers the animal performance.

According to Serres (1992) pigs are known to be highly prolific and very efficient in converting feed nutrients into high quality animal protein. Adesehinwa (2008) stated that pigs are used to convert a variety of feeds into meat for human consumption. The supply of animal protein by pigs is limited by many factors among which are inadequate nutrition and feeding; poor breeding stocks, poor management practices and housing; disease prevention and control in pig production (Holness,1999).

Pitt and Miscamble (1995) defined mycotoxins as toxic secondary metabolites produced by micro-organisms of the fungus kingdom commonly known as moulds. Awan (2001) reported the ability of moulds to produce toxins potentially dangerous to man and animals are common and widespread. Odoemela and Osu, (2008) reported that toxigenic moulds have been found during growth, harvest and storage of diferent foods and feeds and other agricultural produce. Abarca et al.(2001) stated that there are five major agriculturally important fungal toxins of economic importance namely; aflatoxins, deoxynivalenol, ochratoxin, zearalenone and fumunism, which are produced by fungi invasion of agricultural produces and feed ingredients under favourable conditions of  temperature (25 – 30oc) and relative humidity of above 80% (Gilbert and Vargas, 2003). According to Farombi (2006), these moulds contaminate a large number of dietary staples and agricultural produce such as rice, corn, cassava, peanuts and spices, while noting that humans and animals are exposed to aflatoxins by consuming contaminated foods and feeds. These fungal metabolites which when ingested, inhaled or absorbed through the skin causes lowered performance, sickness or eventually death in both animals and humans (Kuilman et al.,1998; CAST, 2003).

Atanda et al.(2008) stated that several moulds and yeast species were isolated from grains with Fusarium verticilloides and Aspergillus flavus having the highest frequency of occurrence of 39.1% and 22.3%, respectively. Moulds have the potentials of forming aflatoxins and trichothecenes in grains, peanuts, cottonseed and other agricultural products (Atanda et al., 2008).

Adam (2000) reported that  Aspergillus spp produces aflatoxins. According to Sashidhare et al.(1992), the high incidence of mycotoxins contamination could be due to physical status of grains, the moisture content, temperature, oxygen and the amount of carbon (iv) oxide in the atmosphere. These factors are reported to influence the rate of infestation and proliferation of moulds in agricultural produce and grains, especially under storage condition.

1.2       Statement of the Problem

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