Howard D. Stowe

Diet restriction and ageing in the dog: major observations over two decades

This report reviews decade two of the lifetime diet restriction study of the dog. Labrador retrievers (n 48) were paired at age 6 weeks by sex and weight within each of seven litters, and assigned randomly within the pair to control-feeding (CF) or 25 % diet restriction (DR). Feeding began at age 8 weeks. The same diet was fed to all dogs; only the quantity differed. Major lifetime observations included 1.8 years longer median lifespan among diet-restricted dogs, with delayed onset of late life diseases, especially osteoarthritis. Long-term DR did not negatively affect skeletal maturation, structure or metabolism. Among all dogs, high static fat mass and declining lean body mass predicted death, most strongly at 1 year prior. Fat mass above 25 % was associated with increasing insulin resistance, which independently predicted lifespan and chronic diseases. Metabolizable energy requirement/lean body mass most accurately explained energy metabolism due to diet restriction; diet-restricted dogs required 17 % less energy to maintain each lean kilogram. Metabonomics-based urine metabolite trajectories reflected DR-related differences, suggesting that signals from gut microbiota may be involved in the DR longevity and health responses. Independent of feeding group, increased hazard of earlier death was associated with lower lymphoproliferative responses to phytohaemagglutinin, concanavalin A, and pokeweed mitogen; lower total lymphocytes, T-cells, CD4 and CD8 cells; lower CD8 percentages and higher B-cell percentages. When diet group was taken into account, PWM responses and cell counts and percentages remained predictive of earlier death.

Fat-soluble vitamin nutrition for dairy cattle.

The need for supplementation of dairy cow diets with fat-soluble vitamins depends on the amount of vitamins naturally present in the diet, the availability of dietary vitamins, and the vitamin utilization rate of the animal. Fresh forage contains ample amounts of the vitamin A precursor beta-carotene as well as vitamin E. Irrespective of the dietary amount, however, the availability of vitamins A, D, and E, as well as beta-carotene, can be adversely influenced by poor fat digestion, as commonly occurs due to enteric disease in young calves. In addition, high-grain diets appear to increase the amount of ruminal vitamin destruction and may thus increase vitamin requirements. The vitamin utilization rate may be increased by inflammation as well as dietary and environmental factors. The factors influencing vitamin availability and utilization rate should be considered when formulating rations. Because the vitamin requirement is variable, blood concentrations of vitamins should be monitored when conditions such as poor fertility, weak calves, and poor immune response are present.

Separation of β- and γ-tocopherol

Abstract β- and γ-Tocopherols were effectively separated with one-dimensional ascending thin-layer chromatography. Kieselgel G according to Stahl was the stationary phase, and the mobile phase consisted of light petroleum (60–80 °), isopropyl ether, acetone, ethyl ether, and glacial acetic acid 85:12:4:1:1. Development was completed in unlined glass tanks in 70 min. at room temperature.

Influence of lifetime food restriction on physiological variables in Labrador retriever dogs.

Effects of lifetime food restriction on erythrocytes and numerous clinical chemistry, thyroid, parathyroid, and acid-base variables are reported from a paired-feeding study of 25% diet restriction in dogs. The 48 dogs were paired by gender and weaning weight within litter, and 1 dog in each pair was fed 25% less than its pair mate, from age 8 weeks until death. Erythrocyte and serum biochemistry profiles were evaluated by annual sampling intervals and longitudinally. Erythrocyte variables were slightly higher among control-fed dogs, a possible reflection of the need to support both higher body fat mass and lean mass that uses energy less efficiently. Among serum biochemistry variables, glucose and triglyceride were lower among diet-restricted dogs, while creatinine was slightly higher in the absence of renal disease or failure, over the life spans of the dogs. Glucose outcomes reflect improved glucose tolerance that has been demonstrated with diet restriction protocols in several species, while triglyceride data may reflect the difference in total body fat cells between feeding groups. Creatinine outcomes may reflect lean mass responses to diet restriction or more efficient function of the intracellular proteasome. Serum triiodothyronine levels were lower among diet-restricted dogs. Other clinical chemistry and thyroid variables, parathyroid variables, and acid-base variables were not strongly influenced by diet restriction but revealed age-related effects.