veterinary laboratory and diagnostics milk analysis

1. Milk sample examination
Submitted by :
Hanumant Irappa Pujeri
HVK -1921

2. INTRODUCTION
 Examination of the milk sample is done to check for the presence of the bacteria , virus,
somatic cells or blood cells
 It is also done for the diagnosis of the different disease conditions in case of the cattle
and also for the routine examination of the udder health
 Most of the time examination of the milk sample is done for the diagnosis of the
subclinical mastitis in high producing dairy cattles

3. Methods of milk sample examination
1.Physical examination
A] Colour : Normally is White in buffalo and whitish yellow in cow
 Physiological Discoloration
 Yellow: ration contain high carotene
 Blood stained: high producing animal.
 Pathological Discoloration
 Red: Leptospirosis, Staphylococcosis
 Green: Corynebacterium
 Yellow: Most of bacterial Mastitis.

4. b) Odor Normally milky odor
 Abnormally
o Fetid (Putrefied) odor: Gangrenous Mastitis, Dry cow Mastitis .
o Fecal odor: Coliform Mastitis.
o Acetone odor: Ketosis .
o Rancid odor: Milking in bad ventilated place or leaving milk for 2 days in environment
after milking .
o Antiseptic odor: excessive dipping of teat.

5. c) Consistency: Normally Milky consistency
 Abnormally:
o Watery milk (decrease consistency) >Streptococcal mastitis .
o Increase consistency > corynebacterial mastitis.
d) pH:
o Normally 6.4 – 6.8 (average 6.6)
o during mastitis become alkaline due to high sodium, chloride and
bicarbonate and low casein, lactose and fat
o Buffalo’s milk - from 6.6 to 6.9.

6. e) Electrical Conductivity (EC) Test
 Elevation in levels of ions such as sodium, potassium, calcium,
magnesium and chloride during inflammation.
 Can be detected by Hand held mastitis detector, as well as by EC-
meter.
 Milk samples with EC ≥ 300 are considered to be from healthy and
uninfected quarters, whereas, those with EC ≤ 250 are considered to
be from SCM suspected quarters.

7. Strip cup test
o Mastitis produce clots of varying sizes in milk which
can be detected by proper use of strip cup
o Carefully observed for the presence of clots or
abnormal consistencies such as watery appearance

8. California Mastitis Test (CMT)
 The CMT is performed to detect the presence of subclinical infections at the beginning of or
during lactation as part of an udder health management program.
 Principle
CMT reagent (sodium lauryl sulphate) reacts and rupture leukocytes (WBCs) and thus
deoxyribonucleic acid (DNA) is released from their nuclei which result in gel formation. Thickness
of gel indicates the severity of inflammation
 The degree of gelling indicates the presence and severity of mastitis. The change in colour
indicates the pH variation of the milk and therefore, the level of inflammation
 CMT reagent (3% sodium lauryl sulphate containing 1:10000 bromocresol purple pH 7.0 to
7.5)

9.  Step 1: Take about 2-3 ml milk from each quarter in each paddle compartment , after foremilk
is removed.
 Step 2: Add CMT solution to each cup in the paddle. CMT reagent is added to each
compartment in volume equal to the milk quantity. The milk reagent mixture is swirled in a
circular motion with presence of gel or slime being recorded for each quarter
 Step 3: Rotate the CMT Paddle in a circular motion to thoroughly mix the contents. Do not mix
more than 10 seconds.
 Step 4: Read the test quickly. Visible reaction disintegrates after about 20 seconds. The
reaction is scored visually. The more gel formation, the higherthe score

11. Surf Field Mastitis Test
 It is the gold standard of mastitis diagnosis
 Availability of the required reagent, i.e. Surf Excel Powder in almost every village
 User friendly nature of the test.

12. White side test for milk
 This test is roughly corelated with the leukocyte content of the milk
 Procedure
 In this test 5 drops of milk are placed upon a glass plate , one drop of 4% NaOH solution is added
by the means of medium dropper
 The mixture is stirred for about 20 seconds with small tooth pick
 Clumps of varying sizes indicate subclinical maastis ,where normal cow milk gives homogenous
mixture

13. Somatic cell count method
 Methods of SC Counting
A. Direct Method: Direct Microscopic Counting – Direct Somatic Cell Counter
B. Indirect Method: Using Chemical Reaction:
 Permissible limit: less than 200,000 cells/ml milk
 The proportion of neutrophils in the SCC is very low « 11 %) in healthy quarters but is
markedly increased in quarters with intramammary infection (to > 90%) .
 Accordingly, the percentage of neutrophils in the SCC may provide a useful indication of
intramammary infection.

14.  This test done check for the antibiotic sensitivity of
animal for the different antibiotics for purpose of the
treatement in different disease conditions
Antibiotic sensitivity test

15. Methylene blue reduction test
 Procedure :
 Take tube add 10 ml of milk samole
 Add drops of methylene blue dye
 Incubate for 15 min ( 37° C )
 absorb colour of the test tubes with respect to
time

16.  Interpretation : Time taken for colour to disappear Quality of the ilk
30 min Very bad (poor)
1 hour Bad
6hour Fair
8hour Good
24 hour excellent