A system of restricted feeding in which feed is entirely withheld for intervals of 24, 48 or 72 hr. following a 24-hr. period of ad libitum feeding in continuous sequence throughout the finishing period depresses weight gain and efficiency of feed utilization in direct relation to duration of the fasting period and has marked associated effects on carcass measurements, gland and organ weights and a small effect on fatty acid composition of the back fat (Veum et al., 1970). Cohn (1963) and Leveille and Hanson (1965, 1966) have shown marked changes in metabolism of nutrients and in body composition associated with frequency of meal intake in laboratory animals. The work reported herein was included as a part of the experiment of Veum et al. (1970). The purpose was to determine the effects of feeding-fasting interval of finishing pigs on several blood parameters in terms of postprandial and long-term changes in concentrations associated with feeding sequence.

The effects of undernutrition on ketone metabolism and its relation to brain growth in developing rats were studied. In the first series of experiments, undernutrition was induced by increasing the litterr size from 4 to 16 pups. Body weight of pups was inversely related to litter size. Increasing the litter size lowered brain weight by 6-16% and liver weight by 20-46%. The ratio of brain weight:body weight was greater by 16 to 39% in the larger litters. Increasing the litter size did not alter concentration of brain lipid. liver glycogen or plasma ketone bodies. In the second series of experiments, undernutrition was induced by restricting maternal dietary intake to 40% of that of the control dam. This undernutrition caused a more pronounced growth retardation than that resulting from increasing litte size. At 14 days of age, the mean body weight of the undernourished group was 44% lower than the control value. The dietary restriction lowered brain weight by 19%, liver weight by 38%, liver glycogen by 47%, brain lipid by 11%, plasma ketone bodies by 30%, glucose by 37% and the rate of hepatic ketogenesis by 28%. The results suggest that brain-growth retardation is related to low brain lipids and impaired ketone metabolism.

The effects of feeding diets containing no fat, 3% hydrogenated coconut oil (HCO) or graded levels (0.1, 0.5, 1.0 or 3%) of safflower oil (SO) on serum cholesterol, lipids and protein level; on total heart and liver cholesterol and lipid level and on growth rate and skin condition were studied in weanling Yorkshire and Yorkshire x Hampshire pigs. Pigs fed the fat-free diet for 21 weeks developed severe skin lesions not observed in pigs fed HCO diets. Highly significant elevation of serum, liver and heart lipid and liver cholesterol, and a highly significant depression of total serum protein were observed with the feeding of HCO or fat-free diets. Serum cholestrol was significantly increased by HCO as compared with the fat-free diet or diets containing SO during the repletion period. Total heart cholesterol, growth rate and erythrocyte fragility were unaffected by diets. It is concluded that growth rate is not adversely affected in the pig by fat-free diets and that HCO does not produce skin lesions in the pig characteristic of fatty acid deficiency. Of all the correlation coefficients analyzed, only the serum cholesterol and total serum lipids were consistently highly significantly correlated, while serum protein was significantly inversely related to the total liver lipid.