Endogenous ways

1. Diseased Animal (when the animal is affected by some infections disease as T.B, Anthrax … etc.

2. Lowered natural resistance due to stress → microorganisms (m.os) invade the intestinal mucosa and distribution by blood and lymph to different organs and tissues as E. coli and as well as anaerobic m.os → bone taint deep muscular putrefaction and ham taint in pig.

Exogenous ways

1. From exterior (soil and hide)

The skin is the main sources of the contamination of meat

2. During carcasses preparation & evisceration

Should close the rectum and esophagus

Fasting of the animals help in decreasing contaminations

3. Equipment and tools

Tools, knives and other equipment used during skinning, preparation and processing of meat (must be dipped for 5 sec in a bucket with boiling water and water is thoroughly changed and boiled).

4. Hands and cloths

5. Flies, rodents and stray dogs

6. Transport and storage