complete comprehensive description of somatic cell count s.in milk

1. SOMATIC CELL COUNT ASSOCIATION WITH MILK
QUALITY AND METHODS TO REDUCE SCC IN MILK
SAMPLE
Introduction, SCC, Cause, Normal SCC, Factors that affect
and Methods to reduce.

2. Introduction:-
Mammary glands consist of large numbers of tissues and produce milk and secretions in healthy
conditions .These secretion are good for animal young ones as well as for the public use. Whenever
there is any infection in the udder or any trauma large no of organisms invade the mammary tissues
and cause large number of problems to animal as well as the people who drink such milk .As a
result of infection immune system is activated, causes infiltration of immune cells at the infected
area in order to combat pathogen .Somatic cell numbers are generally the number of immune cells
present in udder secretion. It is one of the best method to measure milk quality. In developed and
developing countries SCC is the standard to check milk quality.
What are Milk somatic cells?
These are normal body cells that are present in milk at very low level .Under normal conditions
majority of these include secretory tissues of udder ( epithelial cells), and in few amounts immune
cells of body specially leukocytes of white blood cells .Somatic cells are generally referred as
second line of defense against pathogens .Desquamation of mammary glands epithelium milk of
alveoli and ducts results in epithelial cells in milk .This is a normal physiological process for
regeneration of epithelium .Majority of cells are characterized as differentiated alveolar cells .
White blood cells are defense cells of body activated when pathogen invade the body tissues and
produce large number of cells, depends upon infection of body, These cells also help body in
repairing of damage tissues .Any kind of intramammary infections i.e. Mastitis results in increase
no of these cells in milk ,results in deterioration of milk.
Somatic cells count is the number of cells present per ml of milk .Large no of cells if there is severe
infection present in mammary glands .If there is trauma of teats results in microorganism
infiltration as a result SCC increases.
What causes SCC in milk?
Milk is the secretion of lactating animal mammary glands. Milk is produced by epithelial cells.
Blood vessels lined these epithelial cells, continuous supply of blood to milk results in provision
of large number of nutrients help in milk let down .When there is any damage to mammary glands.
Or any breech or barrier by invading pathogen, it causes damage and cause release of large no of
chemical compounds in milk. These results in limitation of infection, and mammary gland immune
system. Immune system activation provides immunity .Two types of immunity.
1) Cellular immunity (provide by defense cells i.e. leukocytes ( macrophages , neutrophils ,
lymphocytes , etc.) These cells are generally present in healthy udder of animal but
inactive.
2) Hummoral immunity( activation of immunoglobins IgA , IgE , antibodies , complement
proteins , antimicrobial peptides e.tc)
After milking opened teat sphincter is one of the main reason for entrance of pathogens. When
pathogen invades the teat, these send signals to immune system to activate body defense system.
These defensive cells i.e. macrophages start the process of phagocytosis to engulf the pathogen,
Inflammatory cells rush towards infection . Inflammatory process is started, the number of
defensive cells increased and these cells result in increased SCC. Milk SCCs are the measure of
any abnormality within mammary glands.

3. This is the diagrammatic representation of healthy and infected teats along with infiltration
of immune cells.
What are normal SCC?
In animal SCC counts up to 2 lac cells per ml of milk sample are considered healthy one. If these
are more than 2 lac per ml then there will be abnormality within the udder, chances of any
inflammatory condition (mastitis). Mastitis is one the main challenges to dairy sector of Pakistan.
Bufflo has generally less SCC than cow.

4. What are the factors which affect SCC?
1) Animal production
Animal production has direct relation with SCC. It has been estimated through different
experiments that the higher producing animals have stress of more production so they have weak
immune system leading to more no of cells in milk.
2) Lactation Stage
Stage of lactation has significant role in SCC. Animal lactation is generally divided into three
stages, Early, mid and late lactation. Usually in early lactation these cells are more in no then
gradually decrease, least numbers in mid lactation, again in late lactation it begins to increase
marginally.
3) No of lactation
Generally there is no difference or minute diff in SCC up to 4 lactation. After that it is noticed that
these increase.
4) Body condition score of animal
If animal is fatty there will be more SCC. It is one of the reason that first calver has less no of SCC
due to less BCS.
5) Season
High temperature and high humidity put stress on animal. These results in deficiency of some
nutrients to animals due to poor growth of fodder and this effect immunity of animal as result of
low immunity microorganisms increase in no.
6) Milking procedure
There are different milking procedures are performed according to farm status or facilities. It has
been recorded that manual milking has more SCC as compared to machine automatic milking .
Teat dipping with antimicrobial sol significantly reduce the no of cells in subsequent milking.
7) Physiological status of animal
Generally if animal is in stress more SCC than physiological healthy one.
8) Type of pathogens
SCC vary according to contagious or environmental infection.

5. 9) Breeds
High producing breeds have higher SCC than lower one.
Milk
constituents
Healthy Subclinical
mastitis
Clinical
mastitis
SCC (105
cells/ml)
<2 3-5 >5
Fat (%) 4.32 4.31 4.08
Protein (%) 3.30 3.34 3.70
SNF (%) 9.73 9.61 9.35
pH 6.61 6.63 6.80
Methods to count SCC in milk sample
These are measured by two methods
1) Direct microscopic count
This is one of the cheapest and easiest method to measure SCC. In this method we take 1ml of
milk sample and spread over 1cm2 area of glass slide ,air dry ,fix ,wash and stain with methyl blue
and count under microscope .In this method there may be the chances of false positive result.

6. 2) Electric Counter
One of the reliable method to count SCC in milk sample. It is the digital representation of SCC on
screen. Most developed farms have this facility and SCC measure is the routine practice.
Methods to reduce SCC in animals
It is the management that has significant effect on SCC. These can be reduced by wearing gloves
during milking, gentle and clean milking, post dipping, good bedding conditions e.tc. others
include;
1) Use of minerals in feed
Generally in summer fodder is deficient in nutrients needed by animal for normal physiological
procedures , deficiency put stress so in order to avoid stress it is recommended to add minerals or
micronutrients in feed to reduce SCC.
2) Use of vaccination
Proper vaccination at proper time is recommended to reduce SCC.
3) Use of natural melatonin
Through various procedure it has been recommended that use of melatonin decrease stress on
animal especially in first calvers as result decrease SCC.
4) Use of antioxidants
Selenium, Zinc, Vitamin E, Copper in animals significantly reduce the SCC.
5) Control flies
6) Milking equipment cleanliness
7) Regular testing