MILK PRESERVATIVES

DAIRY HERD IMPROVEMENT
1985

DUNHAM, J.R., & KROGER, M.
VOLUME: NCDHIP HANDBOOK

Preservatives for Dairy Herd Improvement (DHI) milk samples are
required in most states because often refrigeration is not
practical. Few preservatives have been developed that meet the
minimum requirement of DHI milk samples to be preserved for
reliable component testing up to 1 week under varied environmental
conditions. DHI milk sample preservatives should have the following
characteristics:

-  easily dispersed in milk

-  adds color to indicate presence of preservative

-  stable during storage

-  nontoxic

-  disposable without pollution

-  low cost

    Advantages and Disadvantages of Milk Sample Preservatives.

                                  Advantages

    Potassium Dichromate     Low cost; color to indicate presence
                             of preservative; easily dispersed
                             in milk.
    Bronopol                 Low cost; easily dispersed in milk;
                             low toxicity.

    Formaldehyde             Low cost; easily dispersed in milk.


    Hydrogen Peroxide        Low cost; easily dispersed in milk;
                             low toxicity.

                                  Disadvantages

    Potassium Dichromate     Toxicant*; fat tests deteriorate
                             with time; pollutes sewer systems.

    Bronopol                 Must be stored under dry conditions;
                             does not prevent yeast growth in
                             unrefrigerated samples.
    Formaldehyde             Not suitable---interferes with
                             fat tests in electronic equipment;
                             liquid state.
    Hydrogen Peroxide        Low stability; no color; short
    preservation time; liquid state.


* Due to the toxic properties of dichromate, those employees
handling potassium dichromate are urged to become familiar with
recommended precautions in the handling and use of this substance.
A safety data sheet, available from a chemical supplier will
provide information relating to the use, handling, precautions and
proper disposal of any chemical.

Potassium dichromate is the prevalent preservative used in DHI
samples even with its toxic nature and pollution problems. Bronopol
has been a very satisfactory preservative in labs counting somatic
cells by the microscope method.
i



תתתתתתתתתתתתתתתתתתתתThe National Dairy Database (1992)תתתתתתתתתתתתתתתתתתתת
תתתתתתתתתתתתתתתתתתתתתתת\NDB\DAIRY\TEXT\DA104200.TXTתתתתתתתתתתתתתתתתתתתתתתת


%f TITLE;MILK PRESERVATIVES
%f COLLECTION;DAIRY HERD IMPROVEMENT
%f ORIGIN;Kansas
%f DATE_INCLUDED;June 1992