Materials and Methods
Chapter 5 Discussion
In this study, condition of the milking area revealed that of using disinfectant were 100%, 80%, 70% and 60% in case of MFC, category A, category B and category C farm, respectively. Cleanliness of the floor is very important for clean milk production this is might be due to lower microbial load in the floor. Lower microbial load in floor readily decrease the contamination of milk after milking. Some other studies uttered in favour of the statement, Champak et al. (2017) stated that clean milk production depends mainly on health status of milch animals, condition of dairy animal housing, status of udder, hygiene of milkers, milking practices, milking containers, feed, fodder and feeding practices, grazing area and storage system for milk. Milk provides an ideal medium for growth of all kinds of microbes. For this, milk might be sometimes harmful for man especially if contaminated by various micro-organisms which may appear in milk directly, from the mammary gland (secretional contamination) or from the environment (post secretional contamination). Sinha (2000) described that potential sources of contamination of milk are dung, water, utensils, soil, feed, air, milking equipment, the animal and the milker her/himself. Contamination of milk can occur at the following levels: animal shed and environment, the animal, milker and milking routine, milking equipment, storage and transport. In the case of hand milking, the risk of contamination coming from the milker is higher as compared with machine milking. Nonga et al. (2015) described milk as a nutritious food, and is prone to microbial contamination and many milk-borne epidemics of human are spread through contaminated milk.
In this study, personal hygiene of the milk man were evaluated, personal hygiene is a very important parameters for clean milk production in dairy farm. Because in the dairy milk industry, the hands of milkers could be a potential source of microbial contamination. Lee et al. (2012) evaluated that the occurrence of Staph.
aureus isolates in milk and in the milking environment. 3.3% Staph. aureus were isolated from samples from milkers‟ hands. El-Gedawy et al. (2014) found that, in dairy workers hand swabs, the isolation rates of Staph. aureus, St. agalactia and Salmonellae were 10%, 2% and 8%. Pandey et al. (2014) explored that the potential source of contamination were milker hands, milking pails, udder of animals, milk
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cans and stored water used for washing of equipment. Tahoun et al. (2017) isolated 36.7%, 40.5% and 22.8% Listeria spp in raw milk, milking equipment, and hand swabs, respectively.
The present study shows cleaning of the milking utensils is one of the major parts of the clean milk production practices. Dry and hygienic utensils for milking purpose were practiced 100%, 80%, 80%, 60% and using separate utensils for milking of healthy and sick animal were practiced 100%, 70%, 60%, 60% by MFC, category A, category B and category C farm , respectively. Milking utensils may act as a source of contamination that is also proven by some other studies. Marchand et al. (2012) described that bacteria in milk have the ability to adhere and aggregate on stainless steel surfaces, resulting in biofilm formation in milk storage tanks and milk process lines. Growth of biofilms in milk processing environments leads to increased opportunity for microbial contamination of the processed dairy products. Suranindyah et al. (2015) investigated that improving sanitation significantly decreased milk acidity from 0.19% to 0.14% and number of bacteria in milk. Tegegne et al. (2017) found that the overall average total bacterial count (TBC) were 4.59 ± 0.118log10 (38,904.51 cfu/ml) and 4.77 ± 0.23log10 (58,884.37 cfu/ml) for milk samples collected directly from teat during milking and milking buckets at farm level, respectively. Accordingly, the count increased by 0.18 ± 0.23 log10 or 19,979.86 cfu/ml (51.36%) increase from teat to milking buckets. Abdalla et al. (2011) determined that the impact of application of some hygienic practices prior to milking on milk quality.
In this study, the average fat percentages of categorized farms were 4.34±0.251, 3.81±0.166, 3.84±0.196 & 3.81±0.166 in the MFC, category A, category B and category C farm, respectively. The highest amount of fat was recorded in MFC; this might be due to their proper feeding management of dairy cows. In the study of El- Leboudy et al. (2017) found milk fat 3.57%, which is closer to the findings of present study. Commercially, the fat of milk is unquestionably the most valuable constituent of milk. Milk having a fair amount of fat is more valuable as a food than milk which is poor in fat. The Food and Drug Administration (FDA) requires not less than 3.25%
milk fat for fluid whole milk. The U.S. Public Health Service (USPHS) Milk Ordinance and Code also recommended a minimum of 3.25% butterfat in farm milk
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(Graf, 1976).The BSTI (2002) requirement for fat content of pasteurized milk is a minimum of 3.5%.
Present study discovers average protein percentages of categorized farms were 3.78±0.208, 3.43±0.237, 3.49±0.272 & 3.43±0.167 in the MFC, category A, category B and category C farm, respectively. The highest amount of protein was recorded in MFC; this might be due to their proper nutrition of dairy cows. In the study of Hossain et al. (2013) the protein content of the raw milks varied from 3.07% to 3.57%. Lingathurai et al. (2009) reported slightly higher (3.77%) protein content.
These results support the findings of present study. This finding is also close to BSTI (2002) norms. In the study of El-Leboudy et al. (2017), found milk protein 3.8, this is slightly higher than the present study. This might be due to different breed of the cow.
In this study, the average specific gravity of categorized farms were 1.030±0.003, 1.025±0.006, 1.026±0.005 & 1.027±0.006 in the MFC, category A, category B and category C farm, respectively.
Generally the specific gravity of fresh milk is within the range of 1.027 to 1.035 having an average value of 1.031 (Eckles et al., 1971). Adulteration of milk by adding water decreased its specific gravity. In our experiment, the average specific gravity of milk samples was within the normal range but slightly below the average specific gravity of milk (1.031). This might be due to high fat and slightly low SNF content of milk. Eckles et al. (1951) stated that as milk fat is the lightest constituents of milk, the more that is present, lower the specific gravity will be and in a like manner, the greater the percentage of SNF the heavier the milk will be. Similar type of specific gravity was obtained by Biswas (1997) for BAU Dairy Farm milk.
Average specific gravity was within the normal range of specific gravity of milk.
Generally the specific gravity of fresh milk is within the range of 1.027 to 1.035 having an average value of 1.032 (Eckles et al, 1951). Adulteration of milk by adding water decreased its specific gravity. In our experiment, the average specific gravity of milk samples was within the normal range but slightly below the average specific gravity of milk (1.032). This might be due to high fat and slightly low SNF content of milk. Eckes et al. (1951) stated that as milk fat is the lightest constituents of milk, the more that is present, lower the specific gravity will be and in a like manner, the greater the percentage of SNF, the heavier the milk will be. Similar type of specific
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gravity was obtained by Biswas (1997) for BAU dairy farm milk. In the study of Rahman et al. (2018) specific gravity of milk samples was 1.030, which is also close to the present findings.
The average TVC of categorized farms were 13751000, 64064000, 638000000 &
774300000 in the MFC, category A, category B and category C farm, respectively.
Among the selected farms, MFC showed lower TVC, this might be due to their hygienic management of milking shed, milking utensils and milking personnels. The reason of high bacteria count in raw milk is well-known as good growth medium that supports the growth of several microorganisms because of its high water content, nearly neutral pH and variety of available essential nutrients that renders it as one of the best media for microbial growth and multiplication (Soomro et al., 2002). The total viable bacterial count is the number of bacteria in a sample that can grow and form countable colonies on Nutrient agar after being held at 37°C for 24 hours (Banik et al., 2014). The most frequent cause of high bacterial load is normally as a result of poor cleaning of the milking system. Bacterial count may be high due to milking dirty udders, maintaining an unclean milking and housing environment and failing to rapidly cool milk to less than 40°F. Aaku et al. (2004) and Arenas et al. (2004) have found 5.5×106 cfu/ml and 106 to 107cfu/ml of the total number of microorganisms in pooled raw milk, respectively, which were comparatively lower than this experiment.
Hossain et al. (2011) conducted an experiment in India and found that the bacterial count in raw milk ranged from 1.75×106 to 1.22×108 cfu/ml and Banik et al. (2014) found high bacterial load in raw milk sample which was ranged from 5.2×108 to 1.3×107 cfu/ml. Naidu (2000) found 42000 cfu/ml in raw milk.
The presence of coliform bacteria are nil (0%) in the milk samples of MFC, whereas 50% negative and 50% positive coliform bacteria are present in the milk samples of category A, category B and category C farm, respectively. The presence of nil percentage of coliform bacteria is excellent indication of clean milk production practice indices of MFC. Coliform count in milk is a good indicator of fecal contamination of milk. MFC showed lower coliform count that indicates proper sanitary management. Srairi et al. (2006) who found that the TCC (total coliform count) of raw milk was less than 30 to 2.08×107 cfu/ml. The higher coliform count indicates poor sanitary practices of dairy farm and processing unit. It may results from irregular bathing of animal, feeding system of animal in low land, muddy cow yard,
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unsanitary milking utensils, contamination of body surface by feces, poor personnel hygiene etc. (Khaton et al., 2014). Godefay and Molla (2000) and Uddin et al. (2011) found coliform counts above 1× 104 cfu/ml.
The average Somatic cell counts (SCC) of categorized farms were 238400±42626, 509800±172297, 538000±195494 and 520000±151796 in the MFC, category A, category B and category C farms, respectively. Somatic cell count (SCC) is widely used for evaluating milk quality. An increased SCC results either from an inflammatory process due to the presence of an intramammary infection or, under non-pathological conditions, from physiological processes such as estrus or advanced stage of lactation (Raynal-Ljutovac et al., 2007). An increase in SCC causes a decrease in milk yield and affects milk composition, which leads to reduced cheese making potential (Barbano et al., 1991).
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