摘要:

AbstractThere are three main methods used in the study of feeding behaviour and food consumption in captive populations of fish. These are direct observation, the recording of feeding activity using‘on‐demand’feeders, and the quantitative determination of gastrointestinal content using a non‐invasive‘labelled feed’technique. Observational techniques have been widely used in studies of foraging behaviour and feeding responses, but these methods are usually confined to the study of fish held in small groups.‘Labelled feed’techniques are well suited to the monitoring of feed intake of individual fish held in large groups, but cannot be used for the continuous monitoring of feeding behaviour. They are, therefore, not particularly suitable for the collection of information about short‐term changes in feeding rhythms, or possible diel changes in feeding activity. Studies of feeding activity may best be carried out using computer‐operated‘on‐demand’feeding systems, but the data collected using these systems give no information about individual feed consumption. Examples are presented showing how data collected using the three methods can be used to provide insights into how various abiotic and biotic facto

ISSN:1353-5773    

DOI:10.1111/j.1365-2095.1995.tb00037.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractA method for identifying and confirming the efficacy of feeding stimulants and deterrents is described. Feeding studies carried out using Atlantic salmon,Salmo salar L., have shown that the addition of squid extract as a stimulant to feeds may lead to modification of feed intake, and may ameliorate the negative effects of unpalatability when fish are presented with medicated diets.

ISSN:1353-5773    

DOI:10.1111/j.1365-2095.1995.tb00038.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe aim of the study was evaluation of whole oat meal as an ingredient in salmon diets. Atlantic salmon (145 g) were fed diets with 0, 100, 150, 200, 250 or 300 g kg1of oats (oat series), or diets containing 300 g kg−1of mixes of oats and maize (oat maize series). The mixes of oats/maize were 0/300, 60/240, 120/180, 180/120, 240/60 and 300/0 g kg−1. Net pens in sea water were used. The growth trial lasted 72 days and was followed by a digestibility trial. Oat starch, which had not been subjected to any form of heat treatment, was found to be well digested at low dietary incorporation levels. In the oat series, starch digestibility decreased with increasing starch level and lipid digestibility improved, whereas no changes were observed in protein digestibilities. The fish absorbed significantly more starch from the diet with oat/maize mix 180/120 g kg−1than from the diet with only oats or maize. A significant growth reduction was observed in the oat series as oat inclusion increased. Absorbed starch (calculated value) was not significantly correlated to plasma glucose or insulin level, but was found to be positively correlated to liver glycogen in the maize oat s

ISSN:1353-5773    

DOI:10.1111/j.1365-2095.1995.tb00039.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractEmulsions with different content of (n‐3) PUFA and vitamin A were used to enrichArtemiaand examine the effect of these nutrients on pigmentation success in turbot,Scophthalmus maximus(L.). The best pigmentation rates were obtained using an overdose of vitamin A (500 000 IU L−1), but coincided with a high incidence of skeletal deformations. Higher growth and pigmentation rates were achieved by increasing the quantity of (n‐3) PUFA oil in the emulsion. The use of (n‐3) PUFA‐deficient diet caused the highest occurrence of albinism as well as a cessation of meta

ISSN:1353-5773    

DOI:10.1111/j.1365-2095.1995.tb00040.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractPress cake meals were prepared from previously frozen herring immediately following thawing and after storage for 8 or 12 days at 2‐5°C. Each of the raw sources of herring was subjected to two processing temperatures, 75°C and 100°C, during meal preparation. Also, protein hydrolysates were prepared using ocean perch when fresh or after storage at 2‐5°C for 4 or 8 days. Subsequently, each of the three hydrolysates was dried at 85°C or 93°C.In two separate experiments, each of the herring press cake meals and dried perch protein hydrolysates was blended with a reference diet in a 30:70 ratio (test protein source: reference diet). All diets contained 5 g kg−1chromic oxide as an indigestible marker. The reference diet and all test diets were provided to satiation to chinook salmon in salt water and rainbow trout in fresh water, with digestibility of organic matter, protein and energy measured by difference. Digestibility of protein was also measured by the pH‐stat and dilute pepsin solubilityin vitrotechniques.The results indicated that variation in processing temperature to a maximum of 100°C had little effect on digestibility of marine fish protein sources. By contrast, raw material storage for 8 days or more at 2‐5°C prior to processing was found to reduce organic matter digestibility and sometimes nitrogen digestibility in salmonids.In vitromeasures of digestibility were of little help in predicting the nutritive value of the test protein sources. Cadaverine level in herring press cake meal was shown to be a good indicator of spoilage in

ISSN:1353-5773    

DOI:10.1111/j.1365-2095.1995.tb00041.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe total energy budget of 65 ± 8.0 g common carp,Cyprinus carpio L., was studied in the laboratory. The pattern of energy allocation varied with dietary protein content and ration levels. The energy lost as heat of metabolism, R, was found to increase with dietary protein level and total ration. Energy lost as faeces, F, varied from 19% to 24% of consumption, C, but did not appear to be related to either protein content or ration levels. The energy equivalent of nitrogenous excretion, U, as a proportion of C increased with an increase in dietary protein but decreased with an increase of ration level. Regression equations were developed from the data to allow prediction of respiratory energy losses, faecal losses and excretory losses. The balance of energy budgets compiled from experiments conducted over an 18‐day period was between 66% and 82%. Observed growth was always less than predicted growth, so the predictive models overestimated growth. The data presented form the basis for the first reported study of total energy budgets inCyprinus carp

ISSN:1353-5773    

DOI:10.1111/j.1365-2095.1995.tb00042.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractAtlantic salmon fry hatched from pigment‐free eggs and from eggs containing the pigment astaxanthin were fed eleven casein/gelatine‐based purified diets with varying levels of astaxanthin, ranging from 0 to 317 mg kg−1, to determine the optimum dietary astaxanthin level for satisfactory growth and survival during the start‐feeding period. The fish were fed the experimental diets for a period of 11 weeks.No difference in performance was found between the two types of fry originating from the pigment‐free eggs and those containing pigment. However, the dietary astaxanthin concentration was found to have a significant effect on both the growth and the survival of fry. Fish fed diets with astaxanthin concentrations below 5.3 mg kg−1were found to have marginal growth. In addition, mortality was high in the groups fed diets with astaxanthin concentrations below 1.0 mg kg−1. The specific growth rate (SGR) was also affected by the dietary treatment. The lipid content was higher and the moisture content was lower in the fish fed the diets containing astaxanthin concentrations above 5.3 mg kg−1. The vitamin A and astaxanthin concentrations in whole‐body samples of the fry were significantly affected by the dietary level of astaxanthin. A plateau level in whole‐body vitamin A concentration was observed at dietary levels of approximately 80 mg astaxanthin kg−1and higher, while no maximum astaxanthin concentration in whole‐body samples was observed within the dietary levels used.The results suggest the need for a minimum dietary astaxanthin concentration of 5.1 mg kg−1to achieve maximum growth and survival during the start‐feeding period. The results indicate a low bioavailability of vitamin A palmitate and acetate and the results also suggest a provitamin A function for astaxan

ISSN:1353-5773    

DOI:10.1111/j.1365-2095.1995.tb00043.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY