Observations on autoclaved, fumigated and irradiated diets for breeding mice

Abstract

How to provide an adequate diet free from common murine pathogens is a problem facing the curators of all pathogen-free animal units. The commercial production of diets suitable for such units has not always been a complete success. There is the difficulty of obtaining complete sterility of the diet and the almost insurmountable obstacle of preventing contamination of the diet from the time it leaves the factory until it is placed before the animal. E X P E R I M E N T A L DietsFor the tests we used the following commercially produced diets for rats and mice: No.

Influence of diet pellet hardness and particle size on food utilization by mice, rats and hamsters

“…It has been stated that hardness of pellets is not identical with their resistance to abrasion (Porter & Lane-Petter, 1965;Sebestyen, 1973) but the results obtained here suggested that over a limited range the 2 are very closely related. However the very hard diet, H, did suggest that this relationship may not be linear over a wider range, giving a hardness with the tablet tester of 30·2 kg and the coffee grinder of 61 %, values which fall below an extrapolation of the line in Fig.…”

“…In addition, the effect of the raw material particle size before pelleting was studied. A growth study was also carried out, since Porter & Lane-Petter (1965) and Schmidt (1965) have suggested that increasing pellet hardness ultimately reduces food intake, so affecting growth and hence food utilization and conversion. Efficiency of animal production can only be achieved by the use of diets for which wastage is low and digestion and utilization are high.…”

Effect of autoclaving and physical structure of diets on their utilization by mice

“…While the form or treatment during production of the expanded diets could have improved the way in which the nutrients were metabolised, for example by increasing digestibility, this difference could also be attributed to the composition of the diets. Little effect of autoclaving could be found on production or growth, suggesting that nutrient losses which may have occurred (Zimmerman & Wostmann 1963;Porter & Lane-Petter, 1965;Udes Hiller & Juhr, 1971;Ford, 1976) were insufficient to reduce those nutrients below an optimal requirement. Indeed autoclaving had a positive effect in the case of Diet 1, reducing food wastage and hence apparent food consumption and improving food utilization efficiency of the growing animals, although this was not apparent in the breeding group.…”

“…Within the limits of present knowledge, modern commercial diets are formulated to supply all nutrients in adequate proportions and in theory should all support maximum production providing sufficient is eaten. However, differences have been recorded due to the use of different formulations and qualities of raw materials (Porter & Lane-Petter, 1965) and variable performance by different inbred strains on individual diets has also been reported (Hoag & Dickie, 1960, 1962.…”

“…Sterilization of diets may also produce variable effects depending upon the form and severity of sterilization used, and the dietary formulation (Porter & Festing, 1970;Porter & Lane-Petter, 1965). …”