The investigation of nutritional disorders.

The following list is presented as a summary of guidelines that may be helpful in the investigation of a nutritional disorder. 1. Identify the perceived herd or flock problem. The client's complaint usually reflects an appearance of clinical signs or a depression in production parameters. The practitioner should also identify subclinical manifestations and other concurrent problems. 2. Identify the affected population or subpopulation. Groups should be identified according to breed, sex, age, reproductive status, growth phase, and lactation status. It is critical to identify the affected population, as a diet can be adequate for one population and deficient or excessive for another. For example, 24-month-old Angus heifers in the first 60 days of lactation would have greater risk of protein-energy malnutrition than would 5-year-old Angus cows in their second trimester of gestation if both were fed a marginal hay ration. 3. Identify the nutritional requirements for the affected population. The National Research Council publications serve as a guideline in determining nutrient requirements. 4. Identify factors that influence nutrient requirements and feed intake. Environmental factors, such as ambient temperature, can affect both nutrient requirements and feed intake of the population. Housing conditions, such as muddy lots, can increase maintenance requirements. 5. Sample and evaluate the feedstuffs. Nutrient(s) must be bioavailable--that is, they must be in a form that can be ingested, digested, and absorbed by the animal. 6. Sample and evaluate water sources for quantity and quality. 7. Evaluate feed bunk management practices. 8. Examine the herd. Both affected and normal populations should be examined. 9. Evaluate and submit to a laboratory any animal samples that may relate to the disorder. 10. Assemble the data and develop a hypothesis to support a diagnosis. 11. Provide a written account of all recommendations for the producer.