Somatic cells are mainly epithelial cells that has been shed from the epithelial lining of the gland and White blood cells (leukocyte) has entered the mammary gland in response to injury or infection.
2. WHAT ARE SOMATIC CELLS ??
Somatic cells are mainly epithelial cells that has
been shed from the epithelial lining of the gland and
White blood cells (leukocyte) has entered the
mammary gland in response to injury or infection.
Milk Somatic cells includes 75% leucocytes i.e
neutrophil, macrophages, lymphocytes. 25%
epithelial cells. Erythrocytes can be found at
concentration ranging from 0 to 1.51 X 106/ml
Normally in milk from healthy mammary gland, the
SCC is lower than 1 X 105 cells/ml while bacterial
infection led to increment.
3. WHY TO PERFORM SOMATIC CELL
COUNT??
Indicator of resistance and susceptibility of cows to
mastitis
Used to monitor the level of occurrence of sub
clinical mastitis in herds or individual cows
Predictor of Intramammary infections
Helps in assessment of aspects of milk quality
4. FACTORS AFFECTING SCC
Mammary gland infection level (mastitis)
Stage of lactation-
Increases with progressing lactation
regardless of whether the cow is affected or not
Age/ Breed-
SCC increases with increasing age due to
increased prevalence of infection in older cows.
High producing cattle breeds have higher
presence of SCC/ml of milk
Parity/Season/ Stress
5. Diurnal Variation-
SCC is lowest just before milking and increases
rapidly on stripping
2 consecutive milking from the same cow could
fluctuate SCC by 30%
Day to day milking also show 40% fluctuation
Milk Transportation and Management
6. METHOD FOR MEASURING SCC
Fossomatic™ FC , an electronic digitalized
machine is used
8. FOR MICROSCOPIC FACTOR
CALCULATION
=>Diameter of 1 microscopic field under oil immersion
is 0.16 mm
=> Radius will be 0.16/2 = 0.08mm
Thus area will be πr2
= 3.14 x (0.08)2 =
= 3.14 x 0.0064
= 0.02 mm2
9. Applying unitary method
We know,
= 0.02 mm2 area comprises 1 microscopic field
= For 1cm2 (100mm2) area will be 1/0.02 x 100 mm2
= 5000 mm2 / 0.01 ml of milk
Thus for per ml it will be 500000 mm2
Also while counting minimum we need to count 50
microscopic field.
So, Each field = 500000/ 50
= 10000 which is the WORKING FACTOR
10. Now,
Let the number of cells counted in total of 50
microscopic field be y
Therefore Somatic cell count will be y X
WORKING FACTOR number of cells per ml
NOTE- The working factor will differ according to the
number microscopic field taken during counting
11. PREPARATION OF SMEAR OF FILM
0.01 ml of milk is transferred to the marked area
with the help of platinum loop
Gently the milk is spread with the loop itself so as
to cover the whole 1 cm2 area on the glass slide
The slide is allowed to dried
After the smear is thoroughly dried it is ready to be
stained
12. STAINING OF SMEAR
Different staining procedure by different scientist
has been given.
Among which the stain followed includes-
1. Broadhurst Stain
2. Loeffler’s Modified Methylene Blue Stain
3. Modified Newman Lampert Stain
13. READING
100,000 cells/ml is often considered to be ‘normal’,
reflecting a healthy mammary gland
SCC of >200,000 cells/ml is suggestive of bacterial
infection.
Cows infected with significant pathogens have an
SCC of 300,000 or greater.
Milk with an SCC of more than 400,000 is deemed
unfit for human consumption
NOTE- A reading less than 250,000 cells/ml is
considered insignificant for mastitis
14. CONCLUSION
SCC is a useful predictor of Intramammary
Infections and therefore, an important component of
milk in assessment of aspects of quality , hygiene
and mastitis control.
