Compositional and sanitary quality of raw milk produced by smallholder dairy farmers in Lusaka Province of Zambia

B Kunda, G S Pandey¹ and J B Muma¹

Zambia National Service Headquarters P.O. Box 32251, Lusaka, Zambia
¹ University of Zambia, School of Veterinary Medicine, Department of Disease Control, P.O. Box 32379, Lusaka, Zambia
pandeygs@gmail.com

Abstract

This study was conducted to evaluate the compositional and sanitary quality of raw milk produced by smallholder dairy farmers (SHDFs) in Lusaka province of Zambia. Compositional and sanitary quality of milk was determined by assessing the added water and milk components and Total Bacterial Count (TBC) and Total Coliforms Count (TCC), respectively. Altogether, 83 raw milk composite samples were collected from 83 SHDFs and analyzed at the University of Zambia, School of Veterinary Medicine Public Health Laboratory. Milk composition and added water were determined using a LactiCheck ^® Ultrasonic Milk Analyzer (Page & Pedersen International Ltd, USA). Total bacterial count (TBC) and TCC were determined by culturing the raw milk samples on Standard Plate Count Agar (SPC) and Violet Red Bile Glucose Agar (VRB), respectively.

Results showed that butter fat (BF) for raw milk from 23 out of 83 farms (27.7%) was below recommended standards and legal minimum limit of 3.2% fat. Solid Not Fat (SNF) for raw milk from 26 out of 83 farms (31.3%) was below recommended standards and legal minimum limit of 8.3%. Density of milk for 28 out of 83 farms (33.7%) was also below recommended standards (1.025g/cm³). It was also observed that 26 out of 83 farmers (31.3%) had added some quantity of water varying from 9.46 - 34.3 % to their raw milk. It is worth mentioning that all milk samples which were found to be adulterated with water had low density, low BF and low SNF content. Total Bacterial Count (TBC) ranged from 445 to 2.6 x 10⁶ cfu/ml and milk from 5 out of 83 farms (6.02%) had TBC above the recommended national standards and legal maximum required limit of 200,000 cfu/ml. Total coliforms count (TCC) ranged from 100 to 100,000 cfu/ml and milk from 4 out of 83 farmers (4.82%) had TCC above the maximum national recommended limit of 50,000 cfu/ml. The study concluded that sanitary quality of milk produced by SHDFs in Lusaka province of Zambia, as far as bacterial contamination is concerned was within acceptable standards as opposed to the findings in many other countries in the region including an earlier report from Zambia, where high bacterial contamination and poor quality of raw milk has been reported. The current good results in Zambia found in this study might be attributed to the recent emphasis and support towards clean hygienic production of milk and the higher price paid by milk processing companies for raw milk with low bacteria content and dry climatic conditions and absence of zero-grazing practice. Added water in some milk samples indicate that some SHDFs are engaged in fraudulent activities of milk adulteration and need to be regulated. It is therefore important that the compositional and sanitary quality of raw milk produced by SHDFs is monitored on a regular basis.

Key words: bacterial contamination, clean hygienic, milk adulteration, sanitary quality

Introduction

Milk is a major component of human diet all over the world (Gran et al 2002). It is an important source of nutrients required for growth in infants and for maintenance of health in adults. Raw cow milk is composed of approximately 87.2 % water, 3.7 % fats, 3.5% protein, 4.9% lactose 0.7% ash and has a pH 6.8 (Olatunji et al 2012). Due to its high moisture content, pH which is close to neutral and the diversity of nutrients, milk is a good growth medium for several types of microorganisms (Acuri et al 2006). Microorganisms can enter into milk during milking stage, storage or transportation to the market (Garedew et al 2012). These microorganisms can come from the environment, animals being milked, milkers or from equipment used in the milking parlour (Gran et al 2002). Once they enter into milk, microorganisms can multiply and cause changes to its quality and safety value. If pathogenic microorganisms are involved, they can cause harm to consumers by causing human illness and disease (Barros et al 2011).

Milk TBC is a major factor in determining its hygienic quality (Khan et al 2008). It indicates udder infection and the level of cleanliness of udders, milkers and milking equipment during milk production. It also indicates condition under which milk is stored and transported (Karikari et al 1998). Raw milk with high microbial load has poor keeping quality and products manufactured from it are of inferior quality and have a reduced shelf life (Hayes et al 2011).

Coliforms are almost always present in raw milk but with good methods of production their number can be kept low (Boor et al 1998). The presence of these microorganisms in milk and milk products is an indication of unsanitary production and improper handling of either milk or milk utensils and is generally associated with fecal contamination (Boor et al 1998). Kagkli et al (2006) showed that in addition to faecal contamination, other factors such as milking wet udders, inadequate cooling of milk and udder infection are the main sources of coliforms in milk. Escherichia coli (E. coli) is the most commonly isolated coliform from milk in the clinical laboratory (Ahmed and Salam 1991). In immune compromised individuals, for example HIV patients, some coliforms can cause a wide range of infections as opportunistic pathogens (Boor et al 1998).

Water is the most common adulterant in milk which is often added to milk by unscrupulous milk dealers who want to increase the volume in order to earn easy money (Ombui et al 1995). Addition of water to milk reduces its nutritive value and if the water added is contaminated, there is a health risk posed to consumers (Kandpal et al 2012). Such contaminated milk can be harmful to consumers if consumed raw and if it is processed, the products have reduced shelf life (Kandpal et al 2012).

The smallholder dairy farming industry in many African countries, including Zambia, is important because it plays a significant role in ensuring food security and alleviation of poverty. It provides households with the much required employment, income generation and nutritious food (Pandey, 2014). Smallholder Dairy Farmers (SHDFs) in Zambia have improved their milk production volumes as a result of assistance from government and Non Governmental Organizations (NGOs). Collection and transportation of milk which historically has been a serious problem for SHDFs is no longer a limiting factor in Zambia particularly in peri-urban areas (Yambayamba and Zulu 2011). Zambia’s domestic milk consumption is approximately 3.0 x 10⁸ litres per annum and it is estimated that half of this requirement is produced by SHDFs (Valeta 2004). This study was aimed at assessing the public health aspects of milk from SHDFs by evaluating the wholesomeness (water adulteration), safety (microbiological hazards) and compositional quality of milk produced by SHDFs.

Materials and methods

The study was done in Lusaka Province of Zambia during the months of January and February 2014 using a cross-sectional study design. Records at the milk collection centres (MCCs) and the Dairy Association of Zambia (DAZ) were used to create a sampling frame from which 83 SHDFs who participated in the study were randomly selected. Twenty six farmers belonged to Palabana dairy scheme MCC, 30 farmers to Mapepe dairy co-operative society MCC and 27 farmers to Lusaka west farming block. Farmers from these areas were selected to participate in the study because that is where the majority of SHDFs in Lusaka Province are found. Sampling units were individual smallholder dairy farms. From the bulk raw milk of each of the 83 selected farms, 50 ml was collected aseptically in sterile sample bottles as milk was being delivered to MCCs. The collected samples were stored in an ice packed cooler box and transported to University of Zambia, School of Veterinary Medicine Public Health laboratory and analyzed the same day.

Compositional quality

Composition of the 83 raw milk samples was analyzed using a LactiCheck^® Ultrasonic Milk Analyzer. Each milk sample was analyzed by getting 20 ml of the milk sample at room temperature, thoroughly mixing it in a test tube and then transferred into the sample cup. The sample cup was placed below the aspiration tube of the LactiCheck^® Ultrasonic Milk Analyzer connected to power and the start button was pressed to start the analysis. Analysis was done in about 85 seconds and the results of different parameters displayed on the screen of the LactiCheck^® Ultrasonic Milk Analyzer were noted. The parameters estimated were: added water, BF, SNF, protein and lactose in percentage, density in grams per cubic centimeters and freezing point in degree celsius.

Sanitary quality

Standard plate count (SPC) method was used to determine TBC in milk samples. Each of the 83 milk samples were aseptically diluted into three different dilutions of 1:10. 1:100 and 1:1,000 and plated in duplicates on standard plate count agar and incubated for 48 hours at 32°C. Then using a colony counter, bacteria (or clusters) that grew and became visible colonies were counted and expressed as number of colony forming units per milliliter (cfu/ml) of milk. To determine TCC, in the same way as for TBC, the 83 raw milk samples were diluted into three dilutions of 1:10. 1:100 and 1:1,000 and plated in duplicates on Violet Red Bile Glucose Agar, incubated at 32°C for 48 hours then similarly counted the colonies using a colony counter.

Statistical analysis

Data generated from testing the 83 samples of raw milk was entered into Microsoft excel then transferred to SPSS version 20 for analysis. Means and percentages of milk parameters were calculated. To determine association between added water and density and added water and SNF, correlation coefficient test was used.

Results

Compositional quality

Table 1 presents a summary of test results on milk composition. Butter Fat (BF) for milk from 23 out of 83 farms (27.7%) was below national recommended standards (3.2% fat) and SNF of milk from 26 out of 83 farms (31.3%) was below recommended standards (8.3%). Density of milk for 28 out of 83 farms (33.7%) was below recommended standards (1.025g/cm³) and milk from 26 out of 83 farms (31.3%) had added some quantity of water varying from 9.46 to 34.3% of the milk volume. The mean BF content of milk was 3.9%, SNF 9.3 %, protein 3.7 %, lactose 5.2% and water content 86.8%

Correlation coefficient tests, at a significance level of 0.01 (Table 2 and Figures 1 and 2) showed that there was a strong negative association (r = -.959; p=0.001) between added water and milk density. There was also a strong negative association between added water and SNF (r = -.916; p=0.001).

Figure 1. Correlation between added water and density	Figure 2. Correlation between added water and SNF

Bacteriological quality

Results on TBC (Table 3) showed that raw milk from 5 out of the 83 farms (6.02%) was above the maximum and legally accepted number in Zambia (200,000 cfu/ml of raw milk). Total Coliforms Count (TCC) of milk from 4 out of 83 farms (4.8%) did not conform to recommended standards (50,000 cfu/ ml of raw milk).

Discussion

Production of raw milk of good compositional and sanitary quality by farmers is important to milk processing companies, milk consumers and the farmers themselves. This is so because raw milk of poor compositional and sanitary quality has reduced processing properties and processed milk and milk products made from such raw milk have a reduced shelf life (Oliver et al 2005). For consumers, consumption of milk contaminated with pathogenic bacteria can lead to diseases. For SHDFs, producing milk of good quality is important because milk processing companies pay farmers in accordance with the compositional and sanitary quality of raw milk delivered to them (Yambayamba and Zulu 2011). Thus good quality means more income to the farmer.

On composition, the study found that Butter Fat (BF) for raw milk from 27.7% farms was below recommended standards and minimum legal limit of 3.2% fat. Solid Not Fat (SNF) at 31.3% farms was below recommended standards and minimum legal limit of 8.3%. Density for raw milk at 33.7% farms was below recommended standards of 1.025 g/cm³. On adulteration of milk with water, 31.3% farms had added some quantity of water varying from 9.46 - 34.3 % to their raw milk. It is worth to mention that all milk samples which were found to be adulterated with water had low density, low BF and low SNF content. It was therefore concluded that water adulteration was the most probable cause of low density, low BF and low SNF in some milk samples. This was supported by the results of correlation coefficient tests where a strong negative association between added water and density (r = -0.959; p=0.001) and between added water and SNF (r = -0.916; p=0.001) were found. In similar studies done in other countries, Donkor et al (2007) and Karimuribo et al (2005) found 18% farmers in Ghana and 5% farmers in Kilosa district, Tanzania respectively had added water to their milk. In Kenya, Mwangi et al (2000) found 13% of raw milk samples from Kiambu and Nairobi were adulterated with water. In comparison, these findings from other countries were lower than the 31.3% of water adulterated milk in Zambia as found by this study. When there is high demand for milk, unscrupulous milk dealers sometimes add water to milk in order to increase its volume so that they can earn easy money. Addition of water to milk should be avoided because it reduces the nutritive value of milk, and if contaminated, it poses a health risk to consumers (Kandpal et al 2012) and need stiffer penalty on milk adulteration. However the composite compositional value of milk was within the recommended standards.

For TBC and TCC, the study found that milk produced by 94% of the SHDFs conformed to the recommended standards. Milk from only 5 farmers (6.02%) had TBC above the recommended standards and maximum legal limit of 200,000 cfu/ml of raw milk while milk from 4 farmers (4.82%) had TCC above the maximum recommended limit of 50,000 cfu/ml of raw milk. Our microbiological findings are similar to the findings by Yambayamba and Zulu (2011) who reported TBC which ranged from 44,333 to 234,583 cfu/ml but contrary to the findings by Pandey et al (1996) who reported TBC ranging from log 7.66 - 9.15 cfu /ml and TCC ranging log 6.18 – 7.20 cfu /ml both studies from Zambia. In similar studies conducted in other countries in the region, very high bacterial counts were found in raw milk. In Malawi, Shitandi and Kihumbu (2004) found a high mean TBC of 3.4 x 10⁷ cfu/ml of raw milk. In Tanzania, Kivaria et al (2006) found a high TBC of 8.2 X 10⁶ cfu/ml of raw milk in the Dar es Salaam region while in Kilosa district Karimuribo et al (2005) found 13.4% of milk had TBC which did not conform to recommended standards of that country. In Mbarara, the major milk producing region in Uganda, Grimaud et al (2007), found a high bacterial load of 2 x 10⁶ cfu/ml of raw in a survey on milk quality done in 2004. Mwangi et al (2000) in Kiambu and Nairobi, Kenya found 82 % and 58 % of raw milk samples did not meet recommended standards for TBC and coliforms count respectively even when their (EAC) standards of TBC is extremely poor (2x10⁶ cfu/ml). They found TBC 1.49x10⁹ cfu/ml and coliforms count 1.49 x 10⁶ cfu/ml. In Swaziland Fakudze and Dlamini (2001) found high TBC (> 1 x 10⁷ cfu/ml of raw milk) and high coliforms count (> 7 x 10⁴ cfu/ml of raw milk). In the most recent study, Kanyeka (2014) in Tanzania found 85.7% of the raw milk samples had significantly higher TBC than recommended level of 2x10⁶ cfu/ml by EAC standards and concluded that quality of raw milk was very poor.

The positive results on TBC and TCC in our study might be attributed to the recent emphasis and massive support towards clean hygienic production of milk and the higher price paid by milk processing companies for raw milk with low bacterial count. Also the dry cold climatic conditions, clean housed milking and absence of zero-grazing might have also favoured low bacterial contamination. It was therefore concluded that the sanitary quality of milk produced by SHDFs in Lusaka province of Zambia, as far as bacteria content was concerned was within acceptable standards. There is need to extend this study to wider locations of milk producing areas in Zambia.

Conclusion and recommendations

• This study found that raw milk produced by SHDFs in Lusaka Province of Zambia generally conformed to recommended national standards and legal requirements on TBC and TCC.
  
  
• Added water found in the milk by small number of farmers indicated the need for extension education regarding public health concerns, fraudulent activities and also imposing stiffer penalty on repeated offenders.
  
  
• There is need to extend this study to wider locations of milk producing areas in Zambia.

Acknowledgments

The first author wishes to sincerely thank his sponsors The Zambia National Service Command, Production Branch and Training Branch for the financial and logistical support rendered towards his MSc study at The University of Zambia.

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Received 24 July 2015; Accepted 8 August 2015; Published 1 October 2015

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