Somatic cell count

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.

1. SOMATIC CELL COUNT BY- CHANDRANI GOSWAMI DEPT. OF VETERINARY PUBLIC HEALTH

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 10 6 /ml Normally in milk from healthy mammary gland, the SCC is lower than 1 X 10 5 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

7. CONVENTIONAL METHOD MICROSCOPIC METHOD PROCEDURE Microscopic slide is marked with 1 cm 2 area i.e. 1 cm x 1 cm

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 π r 2 = 3.14 x (0.08)2 = = 3.14 x 0.0064 = 0.02 mm2

9. Applying unitary method We know, = 0.02 mm 2 area comprises 1 microscopic field = For 1cm 2 (100mm 2 ) area will be 1/0.02 x 100 mm 2 = 5000 mm 2 / 0.01 ml of milk Thus for per ml it will be 500000 mm 2 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 cm 2 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- Broadhurst Stain Loeffler’s Modified Methylene Blue Stain 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.

15. THE END THANKS