The acute effect of cortisol implant on self‐feeding activity of rainbow trout Oncorhynchus mykiss (Walbaum)
About: This article is published in Aquaculture Research.The article was published on 2001-06-01. It has received 6 citations till now. The article focuses on the topics: Rainbow trout.
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TL;DR: While CRF and UI appear to participate in the stress-induced changes in feeding behaviour in fish, the role of other know components of the CRF system is not known and the extent to which the anorexigenic effects of CRF-related peptides are mediated through the hypothalamic feeding center, the HPI axis and cortisol, or via actions on descending autonomic pathways remains to be investigated.
177 citations
Journal Article•
TL;DR: It could be recommended that submerged macrophytes, used as fish refuges from predators or for periphyton production, should be at low or moderate density, however, dense vegetation reduces significantly fish growth and feed utilization.
Abstract: A growth response study was carried out to evaluate the influence of artificially submerged macrophytes on growth performance and supplemental feed utilization of Nile tilapia, Oreochromis niloticus (L.) fry under aquarium conditions. In glass aquarium (80 x 50 x 50 cm) filled with 140 litres of well-aerated tap water (25 to 28 o C), leafless stems of phragmites plant (0.7 m long and 0.5 cm diameter) were used at densities of 0, 25, 50, 75, 100 and 125 stems/m 2 . The final fish weight, weight gain and specific growth rate (SGR) decreased significantly with the increase in plant density (P 0.05). The total lipid content was only decreased, while ash content increased significantly at plant density of 125 stems/m 2 . It could be recommended that submerged macrophytes, used as fish refuges from predators or for periphyton production, should be at low or moderate density, however, dense vegetation reduces significantly fish growth and feed utilization.
7 citations
Cites background from "The acute effect of cortisol implan..."
...In this regard, Gregory and Wood (1999), and Lyytikainen and Ruohonen (2001) found that the elevation of plasma cortisol has been shown to suppress feed intake....
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Dissertation•
01 Oct 2006
TL;DR: This research thesis was supported by Nutreco Aquaculture Research centre / Marine Harvest and the University of Stirling, as well as the Fisheries Society of the British Isles for providing a small research grant towards the cost of the hormone analysis.
Abstract: This research thesis was supported by Nutreco Aquaculture Research centre / Marine Harvest (Stavenger, Norway) and the University of Stirling, as well as the Fisheries Society of the British Isles for providing a small research grant towards the cost of the hormone analysis.
by Nutreco Aquaculture Research Centre / Marine Harvest and University of Stirling
4 citations
Cites background from "The acute effect of cortisol implan..."
...Cortisol implants for example, have been found to either result in a negative impact on appetite, growth and condition (Gregory and Wood, 1999) or lead to a higher feeding activity (Lyytikäinen and Ruohonen, 2001)....
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TL;DR: It is suggested that any model of appetite should create output that is deterministic, non-stationary, low-dimensional and having nonlinear dynamics.
4 citations
TL;DR: In this article , a stress trial was conducted with koi carp, aiming at identifying typical effects of stress on regulation of appetite genes, and the results showed that, apart from the typical appetite regulation in the hypothalamus, the different brain regions also display pronounced responses of appetite gene to the different stressors.
Abstract: Our understanding of the timing of stress responses and specific roles of different regulatory pathways that drive stress responses is incomplete. In particular, the regulation of appetite genes as a consequence of exposure to different stressors has not been studied in sufficient detail in fish. Therefore, a stress trial was conducted with koi carp, aiming at identifying typical effects of stress on regulation of appetite genes. The stressors tank manipulation, air exposure and feed rewarding were chosen. The responses to these stressors were evaluated 10, 30 and 60 min after the stressors were applied. Orexigenic and anorexigenic genes were investigated in four different brain regions (telencephalon, hypothalamus, optic tectum and rhombencephalon). The results show that, apart from the typical appetite regulation in the hypothalamus, the different brain regions also display pronounced responses of appetite genes to the different stressors. In addition, several genes in the serotonergic, dopaminergic and gaba-related pathways were investigated. These genes revealed that rearing in pairs of two and opening of the tank lid affected anorexigenic genes, such as cart and cck, which were not changed by air exposure or feed rewarding. Moreover, distress and eustress led to limited, but distinguishable gene expression pattern changes in the investigated brain regions.
1 citations
References
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TL;DR: A minimum of 2 weeks was required for complete recovery and a return to normality in the response of the brown trout to a single, short incidence of handling stress.
Abstract: The response of the brown trout to a single, short (c. 1 min) incidence of handling stress was monitored for a period of 1 month post-stress. Significant changes were found in feeding behaviour, in the levels of plasma cortisol, glucose and lactate, in the concentration of circulating lymphocytes and in the degree of epidermal mucification. No changes were detected in the growth rate and coefficient of condition, in the levels of plasma thyroxine, in the concentrations of circulating erythrocytes, neutrophils and thrombocytes or in the thickness of the epidermis. The time-course for recovery of each parameter was examined and from this it was concluded that a minimum of 2 weeks was required for complete recovery and a return to normality.
456 citations
TL;DR: The results suggest that the structure of the feeding hierarchy may not be determined solely by competitive ability but may also be greatly influenced by differences in the feeding behaviour of unstressed fish versus stressed fish caused by cortisol elevation in the latter.
Abstract: Plasma cortisol elevation, a common consequence of stress, occurs in salmonids of subordinate rank; these fish acquire a smaller share of available food and grow more slowly. This study examined the role of cortisol itself in these phenomena. Cortisol implants, with parallel sham and control treatments, were used to create a chronic threefold elevation in plasma cortisol levels in juvenile rainbow trout, and the individual feeding patterns of the fish were evaluated using X‐ray radiography. The three treatment groups were (1) held alone and fed to satiation, thereby providing a measure of voluntary appetite, or mixed together in equal proportions and fed to either (2) satiation or (3) half‐satiation, thereby allowing assessment of the additional effects of competitive interaction and food limitation. Chronic plasma cortisol elevation had significant negative effects on individual appetite, growth rate, condition factor, and food conversion efficiency, independent of whether the fish were held und...
265 citations
TL;DR: The results of this study suggest that during SW transfer in juvenile salmonids, increases in cortisol may act as both a mineralocorticoid and a glucoc Corticoid, depending on the developmental state of the fish (e.g., smolt versus parr).
Abstract: The influence of cortisol on oxygen consumption and osmoregulatory variables was examined in coastal cutthroat trout (Oncorhynchus clarki clarki) parr kept in fresh water (FW) and transferred to seawater (SW). Intraperitoneal implants containing cortisol (50 μg g−1) in vegetable oil resulted in elevated plasma cortisol titres similar to those observed in fish following a 24h SW exposure. Cortisol treatment significantly increased the oxygen consumption and plasma glucose levels of trout in FW, consistent with the glucocorticoid role of cortisol. Cortisol treatment did not cause any changes in plasma ion concentrations or gill Na+,K+-ATPase activity in FW after 10 days. Cortisol-implanted fish exposed to SW for 24h showed slightly improved ion regulatory ability compare to non-implanted controls. The results of this study suggest that during SW transfer in juvenile salmonids, increases in cortisol may act as both a mineralocorticoid and a glucocorticoid, depending on the developmental state of the fish (e.g., smolt versus parr). Furthermore, the relative energetic costs of osmoregulation and that of the stress associated SW transfer cannot be discerned using whole-animal oxygen consumption rates.
116 citations
TL;DR: Some preliminary results obtained with rainbow trout, Oncorhynchus mykiss, are presented in order to illustrate the uses of this modular eater meter for fish.
72 citations
TL;DR: These implants might be useful in allowing culturists to move salmon to sea cages at times outside the typical smolt window by increasing the fluid uptake rate of the non-everted posterior intestinal sac after 1 month and increased the gill Na + K + - ATPase activity after 1 week.
51 citations