Effect of drying conditions on the nutritive value of a processed stock diet for animals

Tests carried out with weanling rats showed that a diet containing fish, whalemeat, meat and liver meal, biscuit waste and propyl gallate, dried in air at temperatures below 140°, supported good growth, whereas the same diet dried at 140–160° produced successively inferior growth. Rats given the diet dried at 160° were thin, lethargic and incapable of reproduction, resembling rats maintained on a diet deficient in protein or in amino‐acids rather than in vitamins. Chromatographic analysis did not indicate any destruction of essential amino‐acids, but the diet dried at 160° was more resistant to peptic digestion. It is suggested, and is supported by the findings of other workers, that the poor nutritional value of the diet dried at 140° and above was due to failure to digest the protein which had been ‘damaged’ at this relatively low temperature by the formation of N ‐glycosides in the presence of reducing sugars.