Techniques for Measuring Feed Intake

Jobling, Malcolm; Covès, Denis; Damsgård, Børge; Kristiansen, H. R.; Koskela, Juha; Petursdottir, Thuridur E.; Kadri, Sunil; Guðmundsson, Ólafur

doi:10.1002/9780470999516.ch3

Cited by 67 publications

(64 citation statements)

References 172 publications

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“…Lysis of erythrocytes occurs through (1) a metalloprotease secreated by the parasite (Zuo & Woo 1997, and/or (2) the formation of immune complexes on erythrocytes activating complement-mediated hemolysis (Thomas & Woo 1988. Anemia is most evident during the acute stage of the disease (high parasitemia) and it is at this time that fish are more susceptible to environmental hypoxia (Wehnert & Woo 1986), which is known to contribute to anorexia in fish (Kramer 1987, Jobling 1994. Acute disease incurs significantly higher bioenergetic costs (Beamish et al 1996) and reduces the maximum scope aerobic activity (Kumaraguru et al 1995).…”

Section: Discussionmentioning

confidence: 99%

“…The role of CRF-related peptides in mediating anorexia in C. salmositica infection or in the physiological regulation of gastric evacuation needs to be investigated. MSM and CV can be used to assess social hierarchy in fish, with a negative correlation indicating a strong hierarchy (Jobling et al 2000). McCarthy et al (1992) found the correlation became stronger when food was given at lower rations and that larger fish were generally dominant (Sloman & Armstrong 2002).…”

Section: Discussionmentioning

confidence: 99%

“…The fish were anesthetized 1 h after feeding with 2-phenoxyethanol, and x-rayed using an acu-ray HFJ series, universal portable X-ray (Sterne Equipment) at 50 kV, 1.05 mA s at 83 cm. The food intake of each fish was quantified by relating the number of beads found in its stomach to a standard curve (r 2 = 0.99, n = 16) (Jobling et al 2000). Fish were again x-rayed 48 h later, and the remaining beads counted to estimate the amount of food cleared.…”

Section: Methodsmentioning

confidence: 99%

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Effect of Cryptobia salmositica-induced anorexia on feeding behavior and immune response in juvenile rainbow trout Oncorhynchus mykiss

Chin¹,

Guo²,

Bernier³

et al. 2004

Dis. Aquat. Org.

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At 10°C, rainbow trout Oncorhynchus mykiss (n = 13 per group) infected with Cryptobia salmositica Katz, 1951 became anorexic at 3 wk post-infection (w.p.i.), with feed-intake decreasing significantly from 1.33 to 0.94% body weight (b.w.). Anorexia was most severe at 4 w.p.i. (0.80% b.w.), coinciding with peak parasitemia (9.2 × 10 6 parasites ml blood -1) and anemia. At 8 w.p.i., fish had recovered their appetite although they still had contained detectable parasites (6.8 × 10 5 parasites ml ) and low PCV (10.8%). Fish at 5°C had lower gastric evacuation (GE) rates (GE 48h ) than 10°C fish, however there were no differences between infected and naïve fish at both temperatures. Before anorexia, there was no significant correlation between mean share of meal (MSM, a measure of how food was partitioned within a group) and coefficient of variation in feeding but this became significant during anorexia (p = 0.02 and p = 0.0002 at 10 and 5°C respectively). Significant correlations were detected between b.w. and MSM before onset of anorexia at 10°C (p = 0.005) and 5°C (p = 0.02); this was maintained at 10°C (p = 0.001) but not at 5°C (p = 0.98). Fish on an anorexic diet (0.93% b.w.) responded well at 10°C to a live C. salmositica vaccine; this could partly be due to constant antigenic stimulation by the live vaccine.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Effect of Cryptobia salmositica-induced anorexia on feeding behavior and immune response in juvenile rainbow trout Oncorhynchus mykiss

Chin¹,

Guo²,

Bernier³

et al. 2004

Dis. Aquat. Org.

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“…Using X-radiography (Jobling et al, 2001), food intake was assessed twice from each individual fish over the course of this study: 7 days prior to the start of the ammonia exposures (control food intake) and immediately after the ammonia exposures. In brief, the commercial trout food was grounded and re-pelleted with 450·µm steel beads (Draiswerke, Mahwah, NJ, USA) at a ratio of 5% by mass of dry powdered food.…”

Section: Assessment Of Food Intakementioning

confidence: 99%

Appetite-suppressing effects of ammonia exposure in rainbow trout associated with regional and temporal activation of brain monoaminergic and CRF systems

Ortega

Renner

Bernier

2005

Journal of Experimental Biology

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SUMMARY To assess whether the brain's monoaminergic and/or corticotropin-releasing factor (CRF) systems may be involved in mediating the appetite-suppressing effects of high environmental ammonia levels, we exposed rainbow trout to one of four NH4Cl treatments (0, 500, 750 1000 μmol l-1)for 24 or 96 h and monitored changes in food intake, brain serotonin (5-HT)and dopamine (DA) activity, CRF and urotensin I (UI) mRNA levels, and plasma cortisol levels. Food intake decreased in a dose-dependent manner after 24 h of ammonia exposure and partially recovered in all groups after 96 h. Ammonia also elicited dose-dependent increases in serotonergic activity in the hypothalamus (HYP), telencephalon (TEL) and posterior brain (PB). Whereas the increase in serotonergic activity was timed with the 24 h food intake inhibition, TEL and PB serotonergic activity increased after 96 h. In the PB,exogenous ammonia also elicited dose-dependent increases in dopaminergic activity after both 24 and 96 h of exposure. Transient increases in TEL CRF and UI mRNA levels, HYP UI mRNA levels, and plasma cortisol concentrations were evidence that the hypothalamic-pituitary-interrenal (HPI) stress axis was primarily stimulated in the first 24 h of ammonia exposure when food intake was depressed. Overall, the transient nature of the appetite suppression during chronic ammonia exposure, and the time-dependent changes in brain monoaminergic and CRF systems, implicate 5-HT, DA, CRF and UI as potential mediators of the appetite-suppressing effects of ammonia. Among these anorexigenic signals, our results specifically identify hypothalamic 5-HT as a potentially key neurobiological substrate for the regulation of food intake during exposure to high external ammonia concentrations.

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“…I quantified content of each prey category for all fish sampled using frequency of occurrence and mean estimated volume of contents (Bowen 1996, Jobling et al 2001.…”

Section: Diet Analysismentioning

confidence: 99%

The Role of Teleost Grazers in a Relatively Pristine Seagrass Ecosystem

Bessey

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All rights reserved.iv ACKNOWLEDGMENTS I would like to thank the numerous professors, assistants, colleagues, collaborators, businesses, and agencies in both the United States and Australia that have provided support, guidance, opportunities, and stimulating scientific discussions. It would be desirable to acknowledge each and every one by name, but to do so may lead to omissions that I would regret. However, I would like to specifically thank my major professor, Dr. Michael R. Heithaus. He provided me with not only the opportunity to accomplish a goal that I had pondered for over a decade, but also the support, guidance and funding to successfully complete that goal. The professional and personal outcomes Trophic downgrading of ecosystems necessitates a functional understanding of trophic cascades. Identifying the presence of cascades, and the mechanisms through which they occur, is particularly important for seagrass meadows, which are among the most threatened ecosystems on Earth. Shark Bay, Western Australia provides a model system to investigate the potential importance of top-down effects in a relatively pristine seagrass ecosystem. The role of megagrazers in the Shark Bay system has been previously investigated, but the role of macrograzers (i.e., teleosts), and their importance relative to megagrazers, remains unknown. The objective of my dissertation was to elucidate the importance of teleost macrograzers in transmitting top-down effects in seagrass ecosystems. Seagrasses and macroalgae were the main food of the abundant teleost Pelates octolineatus, but stable isotopic values suggested that algae may contribute a larger portion of assimilated food than suggested by gut contents. Pelates octolineatus is at risk from numerous predators, with pied cormorants (Phalacrocorax varius) taking the majority of tethered P. octolineatus. Using a combination of fish trapping and unbaited underwater video surveillance, I found that the relative abundance of P. octolineatus was vi greater in interior areas of seagrass banks during the cold season, and that the mean length of P. octolineatus was greater in these areas compared to along edges of banks.Finally, I used seagrass transplants and exclosure experiments to determine the relative effect of megagrazers and macrograzers on the establishment and persistence of three species of seagrasses in interior microhabitats. Teleost grazing had the largest impact on seagrass species with the highest nutrient content, and these impacts were primarily observed during the warm season. My findings are consistent with predictions of a behaviorally-mediated trophic cascade initiated by tiger sharks (Galeocerdo cuvier) and transmitted through herbivorous fishes and their predators. bed, where each site contains megagrazer treatment plots that A) are full controls; no exclusions, B) megagrazers no excluded, and C) megagrazers excluded. Each plot was 2.6 x 3.0m, which consisted of nine 30cm x 30cm macrograzer treatment subplots, spaced 50cm apart. Macrograzers exclusion cage (ME) ...

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Techniques for Measuring Feed Intake

Cited by 67 publications

References 172 publications

Effect of Cryptobia salmositica-induced anorexia on feeding behavior and immune response in juvenile rainbow trout Oncorhynchus mykiss

Effect of Cryptobia salmositica-induced anorexia on feeding behavior and immune response in juvenile rainbow trout Oncorhynchus mykiss

Appetite-suppressing effects of ammonia exposure in rainbow trout associated with regional and temporal activation of brain monoaminergic and CRF systems

The Role of Teleost Grazers in a Relatively Pristine Seagrass Ecosystem

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