Abstract
The dairy sector in Kenya contributes to the daily diet of the population despite its being subsistence in nature. Quality control and assurance have been the most significant hurdle due to the loose of regulations enforcement. Therefore, the sector poses significant food safety risks to consumers. The fact that milk contributes significantly to the diet, especially for children, makes its safety paramount hence the need for quality checks at the farm level. The current study evaluated dairy practices that compromise milk quality and safety along the dairy supply chain. The main risk factor being antibiotics residue in raw milk consumed in Kiambu County. A cross-sectional survey was conducted using a structured questionnaire to determine the suitability of milk equipment, storage of milk, health management and animal treatment at farms, the level of knowledge of risks associated with antibiotics residue in milk, and farm management. Raw milk samples were also collected and analyzed to determine the levels of antibiotic residues. The results showed that small scale farmers keep 2 to 3 cows, which accounted for 98% of the respondents. The record management at the farm level was done by less than 40% of the respondents. Hygiene and poor storage highly contributed to milk rejection, as reported by 97% of the respondents. The buyers lacked testing gargets for determining contaminants such as antibiotics and preservatives. According to the present study, brokers who accounted for 14% of the respondents play a significant role in milk vending in the sub-urban centers in Thika town, Ruiru town, and Nairobi. The use of health records was not a priority among the farmers, coupled with irregular withdrawal periods ranging from 48 hours to 72 hours. Additionally, the present study found the presence of antibiotics in raw milk. Among the samples, 10 % tested beta-lactam positive on screening through the rapid test; namely: Gatei 11.7%, Gatundu 6%, and Kiganjo 12.1%. Consequently, eight derivatives were quantified and identified as follows: Ampicillin 0.007±0.0 µg/ml, Amoxicillin 0.02±0.022 µg/ml, and Penicillin G 0.016±0.017 µg/ml were above 0.004µg/ml recommended MRLs. However, Cloxacillin (0.008±0.004 µg/ml), Dicloxacillin (0.007±0.0 µg/ml), Nafcillin (0.010±0.004 µg/ml), Oxacillin (0.009±0.0.002 µg/ml), and Phenoxymethyl-penicillin (0.009±0.005 µg/ml) were below 0.030µg/ml recommended MRLs. The exposure assessment for the antibiotic residues, revealed that consumer under the study were safe, having ADI below the set standard by Codex. The levels of antibiotics residues quantified, including ampicillin, amoxicillin, and penicillin G were above the Codex standards maximum recommended levels, hence posing a food safety risk to the consumer. The study concluded that the prevalence of antibiotic residues in raw milk is 10%; this poses a high food safety risks to the milk consumers. Inappropriate dairy farming practices on food safety have heightened the situation. The creation of food safety awareness and improvement in dairy practices can mitigate the situation.
Table of Contents
DECLARATION I
DEDICATION IV
LIST OF TABLES IX
LIST OF FIGURES X
ABBREVIATIONS AND ACRONYMS XI
GENERAL ABSTRACT XIII
CHAPTER ONE: INTRODUCTION
1.1 Background information 1
1.2 Statement of the problem 3
1.3 : Justification of the study 3
1.4 Study aim 4
1.5 Study purpose 4
1.6 OBJECTIVES 4
1.6.1 Main objective 4
RESEARCH QUESTIONS 5
CHAPTER TWO: LITERATURE REVIEW
2.1 Kenya dairy sector and dairy farming practices 6
2.2 Dairy sector input in economy and nutrition 7
2.3 Challenges facing the dairy industry in Kenya 7
2.4 Preventive measures against livestock diseases 9
2.5 Commonly used antibiotics in livestock 10
2.6 Occurrence of antibiotics in milk and their control 12
2.7 Antibiotic residues in milk and human health 13
2.8 Common diseases in livestock 13
2.9 Antibiotics use in livestock health management 14
2.9.1 Commonly used antibiotics food production 15
2.9.3.0 ANTIBIOTICS DERIVATIVES 16
2.9.3.1 Tetracycline 16
2.9.3.1.1 Evolution of the tetracyclines 18
2.9.3.2 Beta-lactam antibiotics 18
2.9.3.3 SULFONAMIDES 20
2.9.4 ANTIBIOTICS CONTROL BY E.U. REGULATION 20
2.9.5 COMMON DISEASES IN LIVESTOCK 21
2.9.6 RISK ASSESSMENT 21
2.9.7 DETERMINATION OF ANTIBIOTICS 24
2.10 GAPS IN KNOWLEDGE 24
CHAPTER THREE: EFFECTS OF DAIRY FARMING PRACTICES ON RAW MILK CONSUMED IN KIAMBU COUNTY, KENYA
3.0 ABSTRACT 25
3.1 INTRODUCTION 26
3.2 STUDY DESIGN AND METHODOLOGY 29
3.2.1 Study area 29
3.2.2 METHODOLOGY 30
3.2.2.1 Study instrument 30
3.2.2.2 SAMPLE SIZE DETERMINATION 31
3.2.2.3 Data collection 31
3.2.2.4 Sampling procedure 32
3.2.2.5 Study ethics 32
3.2.2.6 Data analysis 32
3.3 RESULTS 32
3.5 DISCUSSION 38
3.5.1 Treatment and antibiotics use at the farm. 38
3.5.2 Farm management and records keeping at the farm 38
3.5 CONCLUSION 40
3.6 RECOMMENDATIONS 40
CHAPTER FOUR: PREVALENCE OF ANTIBIOTIC RESIDUES IN RAW MILK CONSUMED IN KIAMBU COUNTY, KENYA
4.1 ABSTRACT 41
4.2 INTRODUCTION 42
4.3 MATERIALS AND METHODS 43
4.3.1 Study area and study design 43
4.3.2 Sampling procedures 43
4.3.2 Qualitative analysis (samples preliminary screening) 44
4.3.3 Test procedures 45
4.3.1 LC-MS/MS Conditions 45
4.3.2 Analysis using Agilent bond elute 46
4.3.3 Data analysis 47
4.4 RESULTS 47
4.4.1 Antibiotic residues screening results 47
4.4.2 QUANTITATIVE LEVELS OF ANTIBIOTIC RESIDUES IN MILK SAMPLES 48
4.5 DISCUSSION 57
4.6 CONCLUSIONS 59
4.7 RECOMMENDATIONS 59
CHAPTER FIVE: QUANTITATIVE RISK ASSESSMENT OF PENICILLIN G. INTAKE THROUGH CONSUMPTION OF MILK IN KIAMBU, KENYA
5.1 ABSTRACT 60
5.2 INTRODUCTION 61
5.3 MATERIALS AND METHODS 63
5.3.1 SAMPLING, SAMPLE SIZE, AND SAMPLE COLLECTION 63
5.3.2 STUDY INSTRUMENT 63
5.3.3 RISK ASSESSMENT TOOL 63
5.3.4 DATA ANALYSIS 64
5.4 RESULTS 64
5.4.1 Exposure assessment 67
5.4.2 Risk Characterization 68
5.6 DISCUSSION 69
5.6 CONCLUSION 69
5.7 RECOMMENDATION 69
CHAPTER SIX: GENERAL CONCLUSIONS AND RECOMMENDATIONS
6.1 : Conclusions 70
6.2 RECOMMENDATIONS 71
REFERENCES 72
APPENDICES 80
TURNITIN REPORT 80
APPENDIX 1: CONSENT FORM 81
APPENDIX 2 QUESTIONNAIRE 81
FARMERS 82
Antibiotic 82
Handling and milk storage 82
Quality Controls at farm level 83
Experience and education 83
APPENDIX 3: UHPLC MS/MS DATA ON SAMPLES SPIKING (PPB) 83
APPENDIX 4: CONSUMPTION PATTERN FOR MILK QUESTIONNAIRE 92
APPENDIX 5: CONSUMPTION PATTERN OF MILK IN RUIRU TOWN 94
List of Tables
Table 3. 1: Equipment use and quality control at the farm level 33
Table 3. 2: Milk rejection and quality control at farm level 34
Table 3. 3: Antibiotic and treatment practices at the farm 34
Table 3. 4: Milk handling and selling to the co-operative society 35
Table 3. 5: Statitical output of dairy farming practices at farm level, confidence interval at 95% CI (p<0.05 level of significance) 36
Table 3. 6: Statistical output (ANOVA) of various dairy practices at farm level 37
Table 4. 1: Test interpretation on sample screening using bioeasy rapid kit 45
Table 4. 2: Mobile phase for water (A)% and CAN Acetonic 0.1 (B) % 46
Table 4. 3: Antibiotic residues screening results 47
Table 4. 4: statistical output of eight antibiotic residues from the analyzed samples (µg/ml) mean, at confidence interval at 95% and the p-value. 48
Table 4. 5 Level of antibiotics residue in morning and evening milk µg/ml 55
Table 4. 6 Correlations between antibiotics residue level and milking time. Confidence Interval (CI) 95% with Pearson Correlation 56
Table 5: 1 Group statistics on milk consumption between male and female 64
Table 5. 2: Statistical output of mean weight and milk consumption based on ml/kg BW 65
Table 5. 3: Results for distribution fitting and simulation used for quantitative risk assessment milk consumption 66
Table 5. 4: Estimated margins of dietary exposure to antibiotics through milk consumption 66
Table 5. 5: Summary of distribution fitting and simulation, mean intakes, mean output(90% CI), estimated dietary exposure to antibiotics at p95-95th percentile. 67
List of Figures
Figure 2. 1: Skeletal formula of tetracycline 18
Figure 2. 2: Skeletal formula of the beta-lactam ring 19
Figure 2. 3: Core structure of penicillin 19
Figure 2. 4: Sulfonamide chemical structure 20
Figure 2. 5: Steps in risk assessment process 23
Figure 3. 1: Farm management areas 29
Figure 3. 2: Map of Kiambu County in central Kenya 30
Figure 4 1: Sampling area and samples 43
Figure 4 2 : An incubator and µ dispenser 44
Abbreviations and acronyms
ATMs Automated machines
AVMA American Veterinary Medical Association
CAC Codex Alimentarius Commission
EU European Union
FDA Food and Drug Administration
GDP Gross Domestic Product
HPLC High-performance liquid chromatography
IARC International Agency Research of Cancer
ILRI International Livestock Research Institute
KCC Kenya Creameries Co-Operation
KDB Kenya Dairy Board
MRLs Maximum Residue Limits
RDCoDE Regional Dairy Centre of Excellence
SPSS Statistical Package for Social Science
USAID United States Agency for International Development
OIE Organization of Animal Health
PCPs Progressive Control Pathways
DEFINITION OF TERMS
Food safety- practices and conditions that preserves the quality of food against contamination and foodborne illness.
Antibiotics- are medication that slow down or destroy the growth of bacteria.
Antibiotic residue- are metabolites found in trace amounts in any portion of the animal product after administration of the antibiotics.
Traceability – ability to track any products through all stages of production.
Acceptable daily intakes (ADI)- is a measure of a specific substance e.g. veterinary drug residue in food or drinking water that can be ingested on daily basis over a life time without any health risk.
Dairy practices- ways through which dairy farming activities are coordinated to maximize production.
Maximum residue limits (MRLs) – is a maximum concentration of veterinary drug residue mg/kg likely to occur in food as result of the use of vet drugs in animal treatment.
Quality control - is a system through which standards are maintained against outlined specifications.
CHAPTER ONE
INTRODUCTION
1.1 Background information
The dairy sector in Kenya approximates 4.5 % of the Gross Domestic Product GDP (Kenya Dairy Master Plan 2010-2030). Agriculture accounts for 19 %, hence referred to as the backbone of Kenya's economy (National Livestock Policy, 2008). According to the Kenya Dairy Board (KDB, 2016), milk production has exceeded 4.6 million tonnes a year; of this, 1.5 million are from small scale holders, producing more than 80 % of milk. Officially the total herd size is about 3.5 million heads of dairy cattle (Muriuki et al., 2011). Today the actual herd is presumably bigger as reported by Kenya Dairy Board. (KDB, 2016) Rains patterns have changed due to global warming; seasons have changed; short and long rain seasons are at times delayed. These have brought acute shortage and oversupply hence fluctuating demand and supply, which affects the milk price. KDB has come on board with marketing tools to assist farmers though many benefits have not resulted.
In Africa, the Kenya dairy sector is one of the most developed. However, it expects to suffer a deficit of milk due to an increase in demand in Nairobi and other urban markets due to an ever- growing increase in the urban population. Dairy farming in Kenya is characterized by small scale farmers having 2-3 cows, which account for 70 % of dairy farming. According to Smallholder Dairy Research and Development Project (2010), 70 % of jobs in the dairy sector are in the informal sector. The informal sector is characterized by milk hawking, milk bars, and upcoming milk Automated machines (ATMs) (KDB 2013). The milk ATMs have taken a sizeable share of the market without considering the milk consumers' safety. Traceability of milk has been an issue due to the influx of unscrupulous traders. These have led to contamination of milk with additives such as water and preservatives. The milk sold in these places is unpasteurized, and in some instances, it is chilled, and at times it is not. This has led to milk preservation by the use of hydrogen peroxide; hence contamination and safety issues arise to the consumer of this product. (Mwangi et al., 2000).The Kenya Dairy Board recently championed milk safety and control of milk hawking countrywide. They have championed the use of milk for a healthy nation, especially in school feeding programs.
The informal sector dominates the dairy industry. Leading in milk processing are Brookside Dairy, New KCC, Githunguri Dairy, Sameer Agriculture and Livestock Company (Daima brand), and other small scale processors. Their mode of operation is characterized by collecting, chilling, bulking, and transporting to facilities where the processing occurs. The processed products are distributed for sale in various urban centers.
Antibiotic residues in milk have been an issue of great concern; it has been a challenge not only in developed countries but also in developing countries. Developing countries lack well-coordinated safety and quality management systems.Quality assurance channels hence a potential for public health risk (Aboge et al., 2000). Due to modernization and development in the dairy sector, production in line with antimicrobial usage will be estimated to increase to 67 % between 2010 and 2030, hence more significant concern in terms of risk factor (Van Boeckel et al., 2015). Small farmers characterize the dairy industry in Kenya. Due to its amorphous nature, the dairy sector lacks proper coordination; hence controls are not checked. Studies have shown the presence of antibiotics along the market chain (Aboge et al., 2000). The antibiotics can be found in contaminated feeds, which end up in milk. (Kangethe et al., 2005). Aboge et al. (2000) found that antibiotic residue in milk was three times higher in rural areas than in urban areas. Kangethe et al. (2005) found that the level of antibiotic residues at the consumer level was higher than at the market level, 9.4 %, and 5.7 %, respectively.
In Kenya, sulfonamides, beta-lactam, aminoglycosides, and tetracycline are mostly used to treat livestock (Aboge et al., 2000). Drug residue in Kenya has increased since market liberalization. In 1978 penicillin was found to be 1% of a milk sample; in the year 2000, the residue was found to be 16 % (Kangethe et al., 2005). In the year 2004, Shitandi studied farm practices related to veterinary drug usage. Only 22 % of small scale farmers documented drug usage. According to Orwa et al. (2017), tetracycline was the most used antibiotic drug (55 % of farmers) followed by sulfonamides (21 %) and beta-lactam (6 %).
1.2 Statement of the problem
Small-scale farmers who account for 70-80 % of milk production in Kenya lack equipment and tools such as strip cups for mastitis testing at milking sites. Due to harsh economic conditions, farmers only allow a one-day withdrawal period on lactating animals, posing a higher risk to the consumers by exposing them to antibiotic residues. Farmers have little or no knowledge of associated health risks of the residues of the administered drugs. Therefore risk factor becomes a matter of importance to food safety regulatory authority (Mitema et al., 2001; Hou et al., 2014).
Additionally, population growth and reduction in land size, have led to zero-grazing practices. Intensive dairy farming has led to poor hygiene controls at the farm level, consequently the emergence of diseases at the farm. The animals are fed from commercial feeds and grass. Due to economic constraints, most small-scale farmers end up feeding animals with grains and vegetable wastes, which compromise the health status of the dairy herd. Antibiotic and other microbial agents gain access to milk through the therapeutic and prophylactic treatment of animals, feed additives, or be added directly to the milk (Cabello, 2006, Jank et al., 2014). Loose dairy practices pose risks to the consumer in terms of the health hazard, which may result in bacterial resistance to medical treatment and allergic reactions due to drug residues or their metabolites. It also results in alteration and eventual destruction of gastrointestinal microflora leading to the growth of opportunistic microbes. There has been a concern of inhibition of culture hampering fermentation processes in the manufacturing industry, hence antibiotic residue in milk being a technological disadvantage to processors (Muriuki et al., 2011).
The dairy farming management for small scale farmers becomes more complicated due to the lack of record-keeping and follow-up in health management operations. At times, the farmers, due to the high cost of veterinary doctors, resort to self-treatment of their animals based on past treatments. Therefore they don't have proper administration of drugs and withdrawal periods are not followed to the letter (Omore et al., 2005)
1.3 : Justification of the study
It is essential to identify the critical control points during milk production, which introduces antibiotics. This will ensure the safety and quality of milk along the supply chain. Every household in Kenya consumes milk from a farm animal, milk vendors, milk bars, or packed milk from shops and supermarkets. Milk contributes a substantial portion of the diet to Kenya's population; hence its' hygiene and safety are of more significant concern. The safety and hygiene aspects become paramount across the food chain.
Consumption of contaminated products over a long time will harm the large population across the boundaries; hence intervention is warranted through a comprehensive survey of milk safety and hygiene. The primary milk producer being a small scale holder lacks proper coordination; therefore, management becomes a challenge, and safety assurance becomes a concern, which warrants an evaluation of milk product safety. The effective practices should not just be developed but also translated into working methods suitable for practical use. The intervention on quality and safety will save the population against possible immunological disorders. If critical control points are well-identified, this can save the government a lot of revenue in disease control and associated losses.
1.4 Study aim
This study aims at assessing dairy practices that compromise the safety of milk produced and consumed in Kiambu County, Kenya.
1.5 Study purpose
The study aims to identify factors that contribute to the presence of antibiotics, which compromise the safety of milk to the ultimate consumer.
1.6 Objectives
1.6.1 Main objective
To determine dairy farming practices, prevalence and intake of antibiotic residues in raw milk produced and consumed in Kiambu County, Kenya
1.6.2 Specific objectives
i. To establish dairy farming practices that compromise milk quality and safety in Kiambu County.
ii. To determine the prevalence of antibiotic residues in raw milk sold and consumed in Kiambu County, Kenya.
iii. To evaluate the quantitative risk assessment of penicillin intake through consumption of milk in Kiambu County, Kenya.
1.7 Research questions
i. What is the relationship between dairy practices and the presence of antibiotics?
ii. What is the prevalence of antibiotic residues in milk sold and consumed in Kiambu County, Kenya?
iii. Does consumption of milk contaminated with antibiotics residue pose any risk to the consumers?
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