 |
Quick Find |
 |
|
| 0 items |
|
|
|
Information |
|
|
|
|
|
Tell A Friend |
|
|
|
| Metabolic Responses to Food Deprivation in Fish pp. 303-346 |
$100.00 |
|
Authors: (Amalia Pérez-Jiménez, Cristina E. Trenzado Romero, Gabriel Cardenete Hernández, Dpt. Animal Biology, Faculty of Sciencies, University of Granada, Campus Fuentenueva, 18071, Granada, Spain)
|
Abstract:
Fish, in general, manifest a high capacity to face short or long starvation periods in natural environment conditions: fluctuations in press availability, reproductive processes, migrations, etc. By other hand, farmed fish also undergo fasting periods derived from practices associated to aquaculture conditions. Food deprivation, whether under natural or artificial conditions, entails a mobilization of energy stores, and in some cases of body tissues, by physiological and metabolic adjustment to cover survival energy requirements. In this sense, decreased weight values and changes in tissues composition are common responses in fish under this adverse condition. The mobilization of reserves is mediated by the endocrine system through complex process involving several hormonal factors. Nevertheless, there are intra and interspecific factors that affect the metabolic response to starvation. In most fish species, food deprivation leads to hypoglycemia. Moreover, in the first stages of starvation an activation of hepatic glycogenolytic pathway is manifested in order to maintain plasma glucose levels and cover energy expenditure. Glycogen in muscle can be decreased or otherwise maintained at expense of hepatic glucose release. Hypoglucemic status can induce a lower glucose cellular caption by a decreases activity of enzymes related to this substrate catabolism. Under this condition an activation of gluconeogenic pathways occurs in response to decreased glucose levels. In parallel with glycogen exhaustion, activation of lipid reserves catabolism plays an important role covering energy demands. The evaluation of different lipid body reserves in fish under a starvation condition manifested a first mobilization of perivisceral fat followed consecutively by hepatic and muscle stores. It is remarkable that this response can be different according to fish species. Finally, if starvation is prolonged in time, proteins from muscle would be mobilized as gluconeogenic substrate and also with energy purposes, being manifested an increased activity of enzymes that supplies amino acids. Depending of starvation conditions, fish refeeding would lead to a total, partial or ineffective recovery response if irreversible fish deterioration is produced. However, fish damages are not usually dramatic, so they can restore physiological parameters previous to starvation. In this sense, a fast weight recovery is usually linked to an increased grow rate that indeed exceeds original values previous to food deprivation. This response is called "compensatory growth" and it is of great interest for fish production practices since an adequate management by alternating fasting and refeeding cycles would increase production of a determined fish species derived from an improved growth rate and conversion index. |
|
|
| |
|
|
|
|
|
|
|
|
|
|
|
Special Focus Titles |
|
|
