Changes in the nutrient composition of the diet (the proportion of lipids, proteins and carbohydrates) may occur during development (e.g. weaning) or with seasonal changes in the abundance of different food types. These diet changes can elicit plasticity in the activity of particular digestive enzymes on the brush border of the small intestine. For example, in the first few days after hatching, nestling house sparrows (Passer domesticus) transition from an insect diet, high in protein and lipids, to a seed based diet that contains mostly carbohydrates; this diet change is accompanied by two-fold increase in the activity of the enzyme maltase, which digests carbohydrates. Acclimatiing animals to high protein diets can increase the activity of aminopeptidase-N, which digests proteins.
Poor quality diets (those that contain a large amount of non-digestible material) have lower concentrations of nutrients, so animals must process a greater total volume of poor-quality food to extract the same amount of energy as they would from a high-quality diet. Many species respond to poor quality diets by increasing their food intake, enlarging digestive organs, and increasing the capacity of the digestive tract (e.g. prairie voles, Mongolian gerbils, Japanese quail, wood ducks, mallards). Poor quality diets also result in lower concentrations of nutrients in the lumen of the intestine, which can cause a decrease in the activity of several digestive enzymes.
Animals often consume more food during periods of high energy demand (e.g. lactation or cold exposure in endotherms), this is facilitated by an increase in digestive organ size and capacity, which is similar to the phenotype produced by poor quality diets. During lactation degus (Octodon degus) increase the mass of their liver, small intestine, large intestine and cecum by 15-35%. Increases in food intake do not cause changes in the activity of digestive enzymes because nutrient concentrations in the intestinal lumen are determined by food quality and remain unaffected. Intermittent feeding also represents a temporal increase in food intake and can induce dramatic changes in the size of the gut; the Burmese python (Python molurus bivittatus) can triple the size of its small intestine just a few days after feeding.
Other articles related to "diet, diets":
... The diet of eastern cottontails is varied and largely dependent on availability ... many as 70 to 145 plant species in local diets ...
... Diet Pepsi was originally created in the U.S ... habits and preferences among the Baby Boom Generation at the time, the drink was re-branded as Diet Pepsi the following year ... It became the first diet cola to be distributed on a national scale in the United States ...
... See also Diet Pepsi variations Additional variations of Diet Pepsi have been introduced over the years, wherein other flavors (such as wild cherry, vanilla, lemon, and lime) have been ... A caffeine-free version of Diet Pepsi is also produced ... availability and brand identification of Diet Pepsi flavor variants varies by country ...
... The diet of barbets is mixed, with fruit being the dominant part of the diet ... Barbets are capable of shifting their diet quickly in the face of changes in food availability Numerous species of fruiting tree and bush are visited ...
... that it was any more effective than a "balanced" diet ... The Hay diet is one type of food combining diet ...
Famous quotes containing the word diet:
“Literary tradition is full of lies about povertythe jolly beggar, the poor but happy milkmaid, the wholesome diet of porridge, etc.”
—Mason Cooley (b. 1927)
“Television programming for children need not be saccharine or insipid in order to give to violence its proper balance in the scheme of things.... But as an endless diet for the sake of excitement and sensation in stories whose plots are vehicles for killing and torture and little more, it is not healthy for young children. Unfamiliar as yet with the full story of human response, they are being misled when they are offered perversion before they have fully learned what is sound.”
—Dorothy H. Cohen (20th century)
“Newsmen believe that news is a tacitly acknowledged fourth branch of the federal system. This is why most news about government sounds as if it were federally mandatedserious, bulky and blandly worthwhile, like a high-fiber diet set in type.”
—P.J. (Patrick Jake)