Changing perspectives on aging and energy requirements: Aging and digestive function in humans, dogs and cats

When considering the question of energy balance, it is important to take in to account energy provision and the ability of aging animals to digest macr onutrients and thus obtain their maintenance energy requirement. A large nu mber of studies have been conducted in humans in an effort to establish whe ther aging of the gastrointestinal tract has a significant effect on availa bility of dietary energy. The results of these studies have been conflictin g, with indications that some aspects of gut functionality do decline with age, but little evidence overall to suggest that aging humans are at risk o f energy deficit due to compromised digestive efficiency. A number of diges tibility studies carried out with dogs confirm that there is no evidence of an age-related decline in digestive efficiency. This knowledge makes the d etermination of energy provision to senior dogs relatively straightforward to calculate. Many senior cats appear to exhibit quite a marked reduction i n their ability to digest macronutrients, particularly fat, efficiently. Be cause this reduces the overall capacity to obtain energy from the diet, it is recommended that old cats should not routinely be offered reduced energy diets. For senior cats, the feeding regimen in later life should be to off er highly digestible diets that provide as much energy as adult maintenance rations.