Microbial content and quality of raw bovine milk from selected farmers in Namwala district of Zambia
Date
2019
Authors
Mweemba, Boyd
Journal Title
Journal ISSN
Volume Title
Publisher
The University of Zambia
Abstract
Contamination of milk by pathogenic microbes may be a hazard to human health. Worldwide,
pathogenic microbes contribute to numerous cases of diarrheal diseases and outbreaks. This
study set out to determine microbial content, nutrient quality and associated risk factors
regarding contamination of raw bovine milk in Namwala district of Zambia.
A cross sectional study was conducted in March, 2017 among small scale dairy farmers. Total
enumeration of three milk collection centres (MCCs) was carried out. A simple random sampling
method was employed to select study participants. Probability proportion to size was considered
in selecting the sample size per MCC. A total of seventy (70) farmers were included in the study.
Laboratory forms were used to collect data on the laboratory outcomes (microbial content and
milk quality) and questionnaire was used to collect data on the probable risk factors to
contamination. Observation checklist was also used to record hygiene practices during milking.
The microbial content and quality of raw milk was determined by comparing Total Bacteria
Count (TBC) and Total Coliforms Count (TCC) against the requirements by the Zambian Bureau
of Standards (ZABS) and the Food and Drugs Act (FDA). Bacterial speciation was determined
through isolation of microbes of public health importance such as E. coli and S. aureus while
milk compositional quality was determined by comparing the levels of added water in milk,
nutrients such as butter fat content, solid nonfat, density and protein. Data were analyzed using
STATA version 13.0. Multiple logistic regression was used after which Step wise regression
model (machine led) was adopted to establish association between the dependent and
independent variables adjusting for confounding factors.
A total of 70 farmers participated in the study out of which 16 (22.8%) were from Namwala
central, 24 (34.3%) from Nchole and 30 (42.9%) from Mungaila dairy farmers cooperatives.
Total bacterial count (TBC) of raw milk from 32 (45.7%) farms was above the maximum legally
accepted limits in Zambia. Total Coliforms Count (TCC) from 19 (27.1%) farms did not conform
to recommended Zambian standards. Nchole had the highest contamination of S. aureus (41.8%)
with Namwala central having the lowest (19%). The overall prevalence of pathogenic E.coli
(0157:H7) was at 21% with Namwala central having the highest (10%) contamination among the
MCCs in Namwala district. Milk samples from Namwala did not conform to only Zambian
standards but also to regional and international standards. Water adulteration was detected in
50% of the samples. About 56% and 47% samples were below standards for butter fat (BF) and
solid nonfat content, respectively. The milk density was below the recommended standards for
all samples. Microbial content as defined by Total Bacterial Count (TBC) was found to be an
average of 2.8 x 106± 9.8 x 105cfu at producer level. Total coliform count (TCC) values for
farmers in Namwala district averaged of 3.7 x 105± 6.3 x 105 cfu. Based on milk composition
quality, about 50% of farmers practiced water adulteration. Factors associated with
contamination of the milk in Namwala district included use of family members in milking 1.26
(p=0.50, 95% Cl 0.64-2.50) and age 1.47 (p=0.31, 95% Cl 0.69-3.09). About 83% (n=58) of the
farmers in Namwala district did not follow good hygienic practice of hand washing when
milking.The study found that milk in Namwala district was of poor quality with high water adulteration.
This suggests the need for a milk processing facility and active surveillance in the area to
improve hygienic practices to safeguard public health.
Keywords: Raw bovine milk, quality, microbial content, dairy farmers, risk factors,contamination.
Description
Thesis
Keywords
Raw bovine milk-- Quality, microbial content--Zambia , Dairy farmers-- Risk factors--Zambia , Pathogenic microbes--Zambia