Cite this asAdugna C, Eshetu M (2021) Hygienic practice, microbial quality and physco-chemical properties of milk collected from farmers and market chains in Eastern Wollega zone of Sibu Sire districts, Ethiopia. J Agric Sc Food Technol 7(1): 125-132. DOI: 10.17352/2455-815X.000099
Thirty samples of fresh cow milk was taken from farmers immediately after milking and 15 milk samples was taken from market chains and analyzed for quality. From the sample about 31.08% were coagulate on clot on boiling test and 55.55% samples were coagulated on alcohol tests. Overall mean total bacterial counts, coliform and yeast and mould count were 5.74±0.10.65, 3.14±0.72 and 3.71±0.83 cfu/ml respectively and significantly different b/n producers source and markets channel source at (P<0.05). The highest total colony count was 6.77±1.1cfu/ml was observed at retailers. From the samples about 66.7% of the sample was in a normal range for specific gravity and 33.3% of the sample was not in a range of normal specific gravity. The overall mean of fat, protein, solid not fat were 4.65±0.50%, 3.67±0.05%, 8.78±0.15% respectively. In general the result indicated that milk samples collected from producers and market chains, were subjected to microbial contamination and does not meet the international milk quality standard. Therefore, adequate sanitary measures should be taken at all stages from production to consumer level.
Milk is the most important and precious natural material which has been the basic component of human nutrition for long period of time . It is also an excellent medium for growth of microbes like bacteria which spoil and deteriorate milk quality which is not safe for human consumption . Milk can be spoiled due to different factors like health of animal, from milking environment, feed and mikers , diseased udder, storage temperature . Milking and storage equipment commonly used by households are believed to be inconvenient for hygienic cleaning and cause quality deterioration of milk and impose health risks on the consumers .
Milk must be free from pathogenic organism that causes milk borne diseases. Contamination of milk can leads milk to be spoiled which not suit for human consumption. Many milk-borne epidemics of human diseases are spread through milk contamination. Sources of microbial contamination in milk include primary microbial contamination from the infected or sick lactating animal. The secondary causes of microbial contamination occurs along the milk value chain which may include contamination during milking by milkers, milk handlers, unsanitary utensils and/or milking equipment’s and water supplies used in sanitary activities. Other secondary sources of microbial contamination occur during milk handling, transportation and storage of milk.
There is tertiary microbial contamination which occurs mainly due to re-contamination of milk after being processed due to unhygienic conditions and poor or improper handling and storage of milk during consumption (Parekh, 2008). The quality of milk is determined by its composition and overall hygiene. It is well known that the fresh milk contains some bacteria and somatic cells. These are the milk’s biological constituents. The numbers of these biological constituents change according to production conditions like the animal’s health and hygiene during milking, preserving and transporting the milk and the milk products. These microorganisms have an important role in the alteration and contamination of milk and milk products. Temperature control is essential to prevent milk alteration, because of the microbial growth. The number of microorganisms vary according to the temperature (season) indicating that the total number of coli forms and E. coli significantly differ in summer and winter. There is an increasing focus on milk quality and hygiene in the dairy industry. Producing high quality milk requires effective udder health programs at a herd level. The safety of milk is an important attribute for consumers of milk and dairy products. Milk and products derived from milk of dairy cows can harbour a variety of microorganisms and can be important sources of food borne pathogens. There is lack of information on hygienic practice, physco-chemical composition and microbiological quality of raw cow milk in the country in general and study area in particular. So, current study is conducted with the objective to assess hygienic practice, physco-chemical properties and microbiological quality of raw cow milk produced and marketed in study area.
Sibu Sire is one of the 18 districts of East Wellega zone, which is located in the eastern part of the zone. Sire is the capital town of the Woreda located on the way to Nekemte at a distance of 280 km from Addis Abeba and 50 kilometres far from the zonal capital of Nekemte. Sibu Sire district is contiguous with Gobu Seyo in the east, WayuTuka in the west, GudeyaBila in the north and Wama Hagalo to the south bordering also some part of WayuTuka in the south west. The total area of the district is about 1,054.40 km2 of land which occupies nearly7.45 percent of the zone’s total area having 19 farmers associations and 3 urban centres.
This district is divided in to three distinct geographical areas with different proportions; namely the highland 7.53 percent which is very small part of the district, midland 74.2 percent and the lowland 18.27 percent. The altitude ranges from 1300 to 3020 meters above sea level. The area is experienced with mean annual temperature between 240C and 25.50C and means annual rainfall of 1015 to 1050 mm per annum. Of the total population in the district, 83 percent live in the rural areas, where directly sustains their life from the agricultural and similar activities. The dominant livestock species in the study area were cattle, small ruminants, mule, horse and poultry (Figure 1).
The study involved both cross-sectional survey method to assess hygienic milk handling practices and laboratory test to determine microbiological quality of milk collected from farmer and different market channel. The district was stratified as highland, midland and lowland based on agro ecological zone and from each agro ecological zone two representative samples kebeles were selected using random sampling methods for collecting of information on hygienic milk handling practice during milking, storing and transporting.
From the three agro ecologies total of 45 samples of cow’s milk were collected. Thirty (30) samples were collected from farmer at morning time and 15 samples were collected from market chains like milk collectors, retailers, and hotels. Samples were collected aseptically from the different households following the procedure of Richardson  and then thoroughly mixed, labeled, coded and taken into sterile bottle of about 250mL. The samples were transported to Holleta dairy microbiology laboratory in an icebox and kept in refrigerator until the time of analysis. Each analysis was made in a duplicate. The analysis was performed within 36 hours after sampling (Alganesh et al,2007).
Microbial analysis: Total aerobic plate count. Appropriate decimal dilution was selected and samples were thoroughly mixed and serially diluted by adding 1mL of the test portion into 9 mL of 0.1% sterile peptone water. Dilutions were made so that plate counts range between 25 and 250 colonies were counted . Appropriate dilutions were placed on Petri dishes and pour plated with 10 to 15 mL molten plate count agar (about 45°C) and allowed to solidify for 15 minutes and incubated for 48 hours at 37°C. Finally, counts were made using a colony counter. The plate counts were calculated by multiplying the count on the dish by 10n in which n stands for the number of consecutive dilutions of the original sample .
Coli form count: After appropriate dilution was made by transfer 1 ml of each sample or a decimal dilution on to a sterile plate, and then added to each plate of 15 to 20 ml of VRBA tempered to 44 to 46 0 C. An agar control for each flask of medium used was poured. The number of samples to be planted in any one series was selected so that there was no more than a 20-minute time lapse between diluting the first sample and pouring the last plate in the series (Michael &Joseph, 2004).
Yeast and Mould Count (YMC): Sterile agar medium (250 ml portions in prescription bottles or flasks, autoclaved 15 min at 121°C) was prepared and then tempered to 45 ±1°C in water bath. Once medium has been tempered, it was held for 2-3 hr before use, provided water level of water bath was 2-3 cm above surface of agar in aliquot container. The potato dextrose agar was used as medium growth .
After counting and recording bacterial colonies in each Petri dish, the number of bacteria in milliliter milk was calculated by the following formula given by American Public Health Association .
N = Number of colonies per ml or g of product;
ΣC = Sum of all colonies on all plates counted;
n1 = Number of plates in first dilution counted;
n2 = Number of plates in second dilution counted;
d = Dilution from which the first counts were obtained.
When computing TBC, CC and YMC only the first two significant digits were recorded and the bacterial count was reported as colony forming unit per millitter of milk (CFU/ml).
The General Linear Model (GLM) procedure of SAS version 9.1 (2002) was used to analyze milk microbial quality and properties of raw milk. Microbial count data was first transformed to logarithmic values (log10) before subjected to statistical analysis in order to make the frequency distribution more symmetrical. Mean comparisons was done using the Least Significant Difference (LSD) technique when analysis of variance shows significant differences between means. Differences was considered statistically at p<0.05 level of significance.
The following model was used for the analysis of milk microbial quality of milk, physical and chemical properties of milk (Table 1).
Yij = μ + βi + eij
Where, Yij = individual observation for each test
μ = the overall mean
β = the ith milk source effect (i=1,2,3,4)
eij = the error term.
In all of the study area cows were hand milked and calves allowed to suckle dams prior to milking and suckling were used to stimulate milk letdown. In the study area milking practice was mainly carried out by woman and males were rarely involved in milking of the cows. About 37.5% of respondent in the midland wash their hands before milking while 62.2% of the respondent do not wash their hands. In the lowland parts of the study area only 5.5% of the respondent washes their hands before milking, and 94.5% of the respondents don’t wash their hands before milking and this was due to lack of awareness and scarcity water. Relatively midland (37.5%) respondents wash their hand before milking than lowland (5.5%) respondents. This result was in opposite with report of (Bekele,2015) who reported that 100% of the respondents in Dangila town of western Amhara region washes their hands before milking.
In all of the study area about 22.5% washes their hand before and after milking and 77.4% of the respondents don’t washes their hand before and after milking (Table 2). This was due to scarcity of water and lack awareness and this leads to poor quality milk. This finding was different from the report of  who reported that all of the interviewed respondents wash hands and milking vessels before milking cows in Bahir dar Zuria.
Washing and cleaning the udder of the cows before milking is the most important and the crucial thing for hygienic practices of milk production. The washing of the udder removes the dirty materials from the udder of the cows. This is because the udder of the cow has direct contact with dirty materials like urine, dung, and feed refusal . As observed in this study, 66.15% of the respondent washes the udder of the cow before milking and 33.85% did not wash and simply allowed their calves to suckle before milking which is considered as the calves removes the dirty of the teat and facilitate the letdown of milk. This figure is greater than the report of (Saba, 2015) about quality assessment of cattle milk in Adea Berga and Ejerie districts of West Shoa zone, Ethiopia.
Hygienic practice related to cleaning milk equipment and frequency of cleaning are among the major factors affecting the quality of milk and milk products. Milk get easily be contaminated by microorganism if not properly handled. Majority of the respondents interviewed uses plastic materials for milking and storing of the milk after milking except some of the respondents from lowland area (Table 3). According to  report similar result in Ezrha district of Gurage Zone where all of the respondents used plastic containers as milking materials. Milking and milk storage utensils should be properly cleaned and maintained if not it can spoil the milk and milk product easily since the milk is an easily perishable product. Therefore, cleaning, and draining of equipment after each milking is important for reduction of milk microbial contamination. Producers should pay particular attention for the type as well as cleanliness of milk equipment they use for milking. Most of the respondent from highland Agro-ecologies clean their equipment with cold water but in the midland and lowland of the study area some of them use hot(boiled) water for cleaning of milking materials. Hot water was better for cleaning of milking materials as it can reduce number bacterial multiplication.