The effects of reduced dietary intake upon the body and organ weights, and some clinical chemistry and haematological variates of the young Wistar rat.

Two groups, one of each sex, of 5-week-old Wistar rats were fed ab lib for 5 weeks with a commercial diet (LAD 2). Four other groups of each sex, were given the same diet daily; each male received 21, 19, 17 or 15 g and each female 17, 16, 15 or 13 g. In a second experiment, in addition to the groups fed ad lib, each day for 5 weeks males were given 30 ('daily ad lib' group), 23, 22 or 21 g and females 25 ('daily ad lib' group), 19, 18 or 17 g. Rats, particularly males, fed ad lib showed differences, e.g. in body weight, with rats fed 'daily ad lib' even though food consumption was similar. Rats fed reduced amounts of diet had smaller livers, increased haemoglobin concentration, erythrocyte count, haematocrit, and plasma chloride. These rats excreted an increased volume of more alkaline urine of lower specific gravity with more precipitated triple phosphate than rats fed ad lib. In the comparisons of the modestly reduced food intake groups with the ad lib groups the significant decreases found in plasma protein, urea and alkaline phosphatase activity probably arose mainly from differences in post-prandial intervals. In groups where the reduction in food intake was greater, the decreases observed were not wholly dependent upon the post-prandial interval.