Milk Tests for Mastitis Diagnosis in Animals

Milk Tests for Mastitis Diagnosis in Animals

1.      California Mastitis Test

This is rapid mastitis test.
Take 5 ml milk in shallow and take equal amount of NaOH.
NaOH is California mastitis test (CMT) reagent.
Rotate and mix plate.
Any thickening, gel formation, or change in pH of milk.
Gel formation is due to this material react with bacteria.
1mg indicator in the regent bromcresol purple indicates the pH of the milk by changing the color of milk.

2.      NAGase Test

This based on the measurement of cell associated enzymes Sodium Acetyl beta D- glucosaminidase in milk.  
This enzyme in milk actually come from neutrophils and damage epithelial cells.
Highly active this enzyme high level of somatic cells and this indicate high level of mastitis because somatic cell count (SCC) increase in mastitis by inflammation of udder.

3.      Pour Plate Method

Principle:
In this method we will be able to understand the pour plate method in which the bacteria are mixed evenly distributed and separated evenly in the throughout the liquid.
The method agar is then poured into an empty palate and allowed to solidify
Material:

·         Nutrient agar liquefied

·         Sterile petri dish

·         Test tubes

·         Microscope

Procedure:
Take a test tube in which milk sample and molten broth is present.
Place that sample on petri dish.
Swirl the petri dish in this way both sample and nutrient agar mix up.
Agar at that temp would killed the bacteria when are introduced so the agar is cooled to 60C and held in the water bath to maintain temp.
Inoculate the plate at 37C for 24hrs to 48 hrs.
After 48hr examine the petri dish and count the CFU
Result:
Colonies were obtained from surface of petri dish.

4.      Somatic Cell Count

It is number of somatic cells in milk.
Poor quality milk has a high number of SC.
Most herd milk contain b/w 200000-500000 SC/ml of milk.
This test is used to evaluate the udder health of all individual cows in herd.
To determine the level of mastitis in herd.
To tell us the quality of milk.
SC count increase with the severity of udder infection. However the corresponding milk loss does not increase at the same rate.
In healthy cows SCC up to 100000 / ml.
SC also depends on lactation number:
*1st Lactation cow have up to 35000 /ml
*2nd Lactation cow have up to 50000 /ml
*3rd Lactation cow have up to 60000 /ml
If SCC/ml < 200000 than no mastitis. Test is negative. Mixture remains liquid with no evidence of thickening or formation of precipitate. Test score negative.
If SCC/ml 150000-500000 than animal is suspicious. Than test is Trace. Slightly thickness. Tests score 0.
If SCC/ml 400000-1500000 than weak mastitis present. Tests score 1. Distinct thickening. But no gel formation. Thickening may disappear after prolonged rotation of paddle.
If SCC/ml 800000-5000000 than distinct mastitis present. Its score 2. Mixture thicken immediately. If paddle the milk thick material move in center.
If SCC/ml > 5000000 than sever mastitis present. Distinct mass. Abrupt thickness and also gel form.

5.      Standard Plate Count

Standard plate count is a common microbial test to check the quality of milk.
SPC indicate the number of bacterial colonies growing on a non-specific solid nutrient agar (medium) after a given period of incubation.
Materials:

·         Milk sample

·         Test tube

·         Sterile petri plate

·         Microscope

·         Nutrient agar

·         Register

Procedure:
Setup a dilution scheme and raw milk is normally diluted to 1:10, 1: 100, 1: 1000 , 1: 10000 , 1: 100000.
Before starting the dilution procedure, shake the milk sample 25 times in the customary manner.
After dilution we pour the samples on petri dishes in which already solidify nutrient agar is present.
Incubate the plate at 35C for 24hrs then count the colonies on plate that has been between 30 and 300 colonies.
Calculation:
Numbre of colonies on plate × Reciprocal of dilution of sample = Number of bacteria/ml
e.g. 32 × 10000 = 320000 /ml.

6.      Strip Cup Test

Use for the physical examination of the milk.
This test is only use for clinical mastitis.
Shiny black plate with 4 shallow should be used.
Take milk sample its 1st 2, 3 stream.
Take 5-10 ml of milk sample from every teat.
Check for any discoloration, clot, or flakes formation or any purulent material.
Discoloration may be blood stain or any watery appearance shows positive case of mastitis.

7.      Surf Field Mastitis Test

Quick method for diagnosis of sub-clinical mastitis.
These all test directly related to somatic cell count.
Take a black plate and make 3% solution of surf.  
Take milk 5ml from 4teat&take in 4 shallow and mix in each 5ml surf solution and mix for 1 mint.
After that we examine the mixture for any thicking or clot or flake or color or any abnormality.
Quality of thickness indicate the condition of mastitis
Surf contains Sodium alkyl aryl sulphate which break down the cell wall of bacteria and react with their DNA.

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