The various ways in which a disease may affect the productive value of animals in a herd or flock

1. On digestion

1.1. Altered feed intake

1.1.1. Available feed not fully utilized by animals-consumed by decomposers

1.2. Altered feed digestibility

1.2.1. Nutritive value of feed not fully used, remainder excreted

2. Metabolism

2.1. Altered natural utilization Protein - Energy - Minerals and other nutrients

2.2. Altered respiratory efficiency

2.3. Body material excreted in faeces and urine to abnormal extent

2.3.1. Consumed by decomposers or used for duel

3. Consequential production effects in affected animals

3.1. Premature death

3.2. Changed value of animals

3.3. Reduced body weight

3.4. Reduced yield and/or quality of milk, eggs, wool, etc.

3.5. Reduced capacity for work

3.6. Altered production of dung (used for fuel)

3.7. Body material diverted for use of disease agent

3.7.1. Increased yield of disease agent

4. Herd production effects

4.1. Reduced productive life of animals

4.2. Reduced fertility and fecundity

4.3. Lower precision in recognition of animals of superior genetic merit

5. Effects on herd maintenance and improvement

5.1. Altered replacement pattern and reduced capacity for genetic improvement