Compensatory growth (organism)
Encyclopedia
Compensatory growth, also known as catch-up growth and compensatory gain, is an accelerated growth of an organism following a period of slowed growth, particularly as a result of nutrient
Nutrient
A nutrient is a chemical that an organism needs to live and grow or a substance used in an organism's metabolism which must be taken in from its environment. They are used to build and repair tissues, regulate body processes and are converted to and used as energy...

 deprivation. Oftentimes, the body weights of animals who experience nutritional restriction will over time become similar to those of animals who did not experienced such stress. It is possible for high compensatory growth rates to result in overcompensation, where the organism exceeds normal weight and often has excessive fat deposition.

An organism can recover to normal weight without additional time. Sometimes when the nutrient restriction is severe, the growth period is extended to reach the normal weight. If the nutrient restriction is severe enough, the organism may have permanent stunted growth
Stunted growth
Stunted growth is a reduced growth rate in human development. It is a primary manifestation of malnutrition in early childhood, including malnutrition during fetal development brought on by the malnourished mother. In developing countries, stunted growth is a common problem affecting a large...

 where it does not ever reach normal weight. Usually in animals, complete recovery from carbohydrate
Carbohydrate
A carbohydrate is an organic compound with the empirical formula ; that is, consists only of carbon, hydrogen, and oxygen, with a hydrogen:oxygen atom ratio of 2:1 . However, there are exceptions to this. One common example would be deoxyribose, a component of DNA, which has the empirical...

 and protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 restriction occurs.

Compensatory growth has been observed in a number of organisms including species of mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...

s, bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

s, reptile
Reptile
Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...

s, fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

, plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...

s (especially grass
Grass
Grasses, or more technically graminoids, are monocotyledonous, usually herbaceous plants with narrow leaves growing from the base. They include the "true grasses", of the Poaceae family, as well as the sedges and the rushes . The true grasses include cereals, bamboo and the grasses of lawns ...

es and young tree seedling
Seedling
thumb|Monocot and dicot seedlingsA seedling is a young plant sporophyte developing out of a plant embryo from a seed. Seedling development starts with germination of the seed. A typical young seedling consists of three main parts: the radicle , the hypocotyl , and the cotyledons...

s and saplings), fungi, microbes, and damselflies
Eastern Forktail
Eastern Forktail is a member of the damselfly family Coenagrionidae.The males are yellow-green with blue on the top of the eighth and ninth abdominal segments.The females may be orange, or less commonly yellow-green like the male....

.

History

In 1911, Hans Aron performed the earliest study of growth after periods of undernourishment. He underfed a dog and found that it still had the capacity to rapidly gain weight, though it did not reach the final weight of a dog that was fed normally. In 1915, Osborne and Mendel were the first to demonstrate that rats fed after growth restriction had an accelerated growth rate. In 1945, Brody developed the idea of “homoestasis of growth” in the book Bioenergetics and Growth. In 1955, Verle Bohman was the first to use the term “compensatory growth” in an article pertaining to beef cattle
Beef cattle
Beef cattle are cattle raised for meat production . The meat of cattle is known as beef. When raised in a feedlot cattle are known as feeder cattle. Many such feeder cattle are born in cow-calf operations specifically designed to produce beef calves...

.

Mechanism

In animals, homeostatic
Homeostasis
Homeostasis is the property of a system that regulates its internal environment and tends to maintain a stable, constant condition of properties like temperature or pH...

 and homeorhetic
Homeorhesis
Homeorhesis, derived from the Greek for "similar flow", is a concept encompassing dynamical systems which return to a trajectory, as opposed to systems which return to a particular state, which is termed homeostasis.-Biology:...

 processes are involved in the abnormally high growth rates. Homeostatic processes usually affect compensatory growth in the short term, whereas homeorhetic processes usually have a long term effect.

The exact biological mechanisms for compensatory growth are poorly understood, though it is clear that in some animals the endocrine system
Endocrine system
In physiology, the endocrine system is a system of glands, each of which secretes a type of hormone directly into the bloodstream to regulate the body. The endocrine system is in contrast to the exocrine system, which secretes its chemicals using ducts. It derives from the Greek words "endo"...

 is involved in the metabolism
Metabolism
Metabolism is the set of chemical reactions that happen in the cells of living organisms to sustain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories...

 and nutrient partitioning in the tissues.
First, during nutrient starvation, a reduction of basal metabolism takes place. The gut tissues are the first tissues to be reduced in weight and activity. Then, during the realimentation (re-feeding) phase, an increase in feeding enables more dietary protein and energy to be contributed for tissue growth instead of basal metabolism. The gut tissues are the first to increase in weight, followed by muscle tissue and finally adipose tissue.

Factors affecting compensatory growth

In 1960, Wilson and Osborne outlined six factors that could affect compensatory growth in a review article. The importance of each, some, or all of these factors is not well-understood. These factors are as follows:
  • The nature of the restricted diet
  • The degree of severity of undernutrition
  • The duration of the period of undernutrition
  • The stage of development at the commencement of undernutrition
  • The relative rate of maturity of the species
  • The pattern of re-alimenation


Animal factors that can affect compensatory growth may include the maturity level and fat proportion of the animal at the time of nutrient deprivation, the genotype, the gender, and the metabolic changes. The stage of development of the animal when the nutrient restriction occurs greatly affects its body composition.
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