FDA recommends that sponsors expressly communicate with subordinate and contract personnel the type and quantity of food that will be offered, and also to pre-specify that cage sizes, and the location and quantity of food receptacles should be ample in pen housed situations. You should also consider following other research standards that more specifically prescribe housing limitations.
The FDA finds weight loss challenging to interpret, making it difficult to attribute whether weight loss is or is not device related. As such, you should ensure that individuals monitor animals to document specifics regarding appetite, food and water intake, and micturition and bowel movements, particularly when animals are pen-housed. Bullying and resource coveting are commonly associated with weight loss due to inadvertent reduced caloric or fluid intake.
Animals (i.e. small ruminants) enrolled in chronic studies are often transferred to a more typical agricultural setting where animals are allowed to graze on open pasture and/or are fed hay as a component of their diet. The sponsor/test facility should ensure that the pasture is free of potentially poisonous plants, parasite ova and other potential contaminants, and that the condition (soil, grass) of the pasture meets the animal’s nutritional requirements, including minerals. Some species may be sensitive to imbalances in organic metals in the soil (e.g. sheep are sensitive to copper and molybdenum imbalances) which may inadvertently lead to toxicities (copper toxicity in sheep). Growth-enhancing additives, such as monensin, are another common source of inadvertent toxicity due to errors in ration preparation or feeding a ration for one species to another. Feed and water used for the animals must be analyzed periodically to ensure that contaminants known to be capable of interfering with the study and reasonably expected to be present in such feed or water are not present at levels above those specified in the protocol (21 CFR 58.90(g)). The sponsor/test facility should be cognizant of these potential problems and judicious in writing standard operating procedures that address periodic tests of water and feed for potential contaminants, the pasture soil and crop for nutritional balance, training employees on the importance of reading ration labels, feeding species-specific rations, etc. Local farm extension services provide invaluable assistance for this purpose.