Cg Carter

Fish meal replacement by plant meals in extruded feeds for Atlantic salmon, Salmo salar L.

The replacement of fish meal protein with soybean meal (SB) or protein concentrates made from narrow-leafed lupin (LP) or field peas (PP) was investigated in extruded feeds for Atlantic salmon. Salmon (47 g) were fed for 63 days on extruded feeds containing each of the plant meals to replace 25% and 33% of the fish meal protein and performance compared against a nutritionally balanced control and a commercial salmon feed formulation (extruded under the same conditions). There were no significant differences in weight gain between the control and feeds containing the plant proteins. The commercial feed produced significantly higher weight gain than the control feed and LP at both replacement levels. Feed consumption was significantly higher for LP at 33%, but there were no other significant differences between the other feeds. Feed efficiency ratio (FER) and productive protein value (PPV) were highest for PP and SB and not affected by inclusion level, whereas they were significantly lower for LP at 33% inclusion. The weight gain and feed efficiency ratio data showed that soybean meal and pea protein concentrate had the best potential for replacing at least 33% of the fish meal protein in extruded salmon feeds and that lupin protein concentrate was less well utilised at the higher inclusion level. These results support the use of processed plant meals as important replacement protein sources for fish meal in extruded feeds for Atlantic salmon.

Replacement of fish oil with sunflower oil in feeds for Atlantic salmon (Salmo salar L.): effect on growth performance, tissue fatty acid composition and disease resistance.

Dietary sunflower oil (SFO) was used to gradually replace fish oil (FO) in six diets (which also contained fish meal) for Atlantic salmon parr (initial mass: 21.7 g). The effect on growth performance, tissue fatty acid profiles and disease resistance was monitored after 63 days. At the conclusion of the trial, no significant differences were detected in growth between any of the feeds. Fatty acid composition of whole carcass, dorsal muscle and liver generally reflected that of the diets. Forty percent of the FO could be replaced by SFO before tissue 22:6n-3 was significantly reduced, although other essential and non-essential fatty acids were more susceptible to change. Significant differences were detected in cumulative mortality of Atlantic salmon challenged with Vibrio anguillarum at the trials conclusion, although this was not correlated to the inclusion level of SFO. Despite the changes observed to the tissue fatty acid profile, there was no significant effect on growth suggesting that SFO is a suitable alternative to FO in diets for Atlantic salmon parr when fish meal is also included.

So!apbox: editorial essays: Strategy as practice?:

Strategy is supposed to lead an organization through changes and shifts to secure its future growth and sustainable success, and it has become the master concept with which to address CEOs of contemporary organizations and their senior managers. Its talismanic importance can hardly be overstated. Thus, strategic management is increasingly understood as the task of the top management team. While seminal works on strategy bear the imprint of modernist rationality (Ansoff, 1965; Porter, 1980), there have been numerous contributions to the strategy literature that can be characterized as more reflexive and critical (e.g. Clegg et al., 2004). More expressly sociological in nature, they have placed emphasis on, inter alia, how power and politics shape the strategies that emerge (Mintzberg, 1987; Pettigrew, 1985); the strategic choices made (Child, 1972); the language games that constitute strategy (Barry and Elmes, 1997); as well as how strategy is best understood through interpretative approaches (Schwenk, 1989), structuration theory (Whittington, 1992) or epistemology (Knights and Morgan, 1991). Such works set out an alternative to the neat assumptions of ubiquitous rationality underpinning orthodox strategy. Most recently, the so-called strategy as practice approach has claimed to integrate earlier epistemologically and ontologically more reflexive positions into a new orthodoxy. The new approach is one that is very much couched in European characters ( Jarzabkowski, 2003, 2004; Samra-Fredericks, 2003; Whittington, 1996, 2002, 2003, 2004), and is clearly to be understood as a systematic critique of orthodox, hegemonic, and mainly North American, or North American-inspired, strategy research. In this essay, we seek to advance the current debate in the field of strategy in several respects: first, we discuss the intellectual genesis of the strategy as practice STRATEGIC ORGANIZATION Vol 6(1): 83–99 DOI: 10.1177/1476127007087154 Copyright ©2008 Sage Publications (Los Angeles, London, New Delhi and Singapore) http://so.sagepub.com

n-3 Oil sources for use in aquaculture--alternatives to the unsustainable harvest of wild fish.

The present review examines renewable sources of oils with n-3 long-chain (> or = C20) PUFA (n-3 LC-PUFA) as alternatives to oil from wild-caught fish in aquafeeds. Due to the increased demand for and price of wild-caught marine sources of n-3 LC-PUFA-rich oil, their effective and sustainable replacement in aquafeeds is an industry priority, especially because dietary n-3 LC-PUFA from eating fish are known to have health benefits in human beings. The benefits and challenges involved in changing dietary oil in aquaculture are highlighted and four major potential sources of n-3 LC-PUFA for aquafeeds, other than fish oil, are compared. These sources of oil, which contain n-3 LC-PUFA, specifically EPA (20:5n-3) and DHA (22:6n-3) or precursors to these key essential fatty acids, are: (1) other marine sources of oil; (2) vegetable oils that contain biosynthetic precursors, such as stearidonic acid, which may be used by fish to produce n-3 LC-PUFA; (3) single-cell oil sources of n-3 LC-PUFA; (4) vegetable oils derived from oil-seed crops that have undergone genetic modification to contain n-3 LC-PUFA. The review focuses on Atlantic salmon (Salmo salar L.), because it is the main intensively cultured finfish species and it both uses and stores large amounts of oil, in particular n-3 LC-PUFA, in the flesh.

Variation in individual food consumption rates of fish and its implications for the study of fish nutrition and physiology

The aim of the present paper is to review recent information on food consumption rates of individual fish and to explore the ways in which values for individual food consumption can be used in studies of fish behaviour, nutrition and physiology. There are two main ways of carrying out nutritional studies in fish in which the aim is to investigate how the amount or the composition of the diet influences growth rate. One involves feeding tanks of animals and measuring the growth rates of the groups. This method stresses the importance of the group response to dietary manipulation and the ground rules for carrying out such studies have recently been clearly expounded (Cho, 1992; Cowey, 1992). An alternative method is to measure the food consumption of the individual fish and to construct from the data on individual animals food consumptiongrowth rate relationships for the species. In some species of fish which can be held and fed individually, e.g. cod (Gadus morhua L.; Houlihan et al. 1989) or minnow (Phoxinus phoxinus L.; Cui & Wootton, 1989), there is not a problem in determining food consumption and growth rate relationships. However, in fish feeding in groups a major problem has been to develop a reliable method to make repeated measurements of an individual’s food consumption. Early attempts involved direct observations of feeding activity or the examination of gut contents in order to estimate consumption. These techniques have proved unsatisfactory, as the methodologies involved are timeconsuming, stressful or invasive and periods of preor postprandial starvation were necessary (for review, see Talbot, 1985). In the 1980s, two non-invasive methods were developed to measure consumption rates of individual fish, held in groups, which employed either feed labelled with the radioisotope I3lI (Storebakken et al. 1981) or with an X-ray opaque particulate marker (Talbot & Higgins, 1983). These techniques permitted repeated measurements of food consumption rates of fish held in groups without any alteration to the feeding regimen. However, for health and safety reasons X-radiography has been the preferred technique (for review, see Talbot, 1985).

INDIVIDUAL VARIATION IN PROTEIN TURNOVER AND GROWTH EFFICIENCY IN RAINBOW TROUT, ONCORHYNCHUS MYKISS (WALBAUM)

The aims of this study were to examine the relation between consumption, growth and protein synthesis for individual rainbow trout held in groups, and to examine how differences in protein turnover may help to explain the observed differences in protein growth rate between rainbow trout with similar protein consumption rates. Therefore four measurements of consumption were made for 37 individual fish over a 73 day period by using radiography. At the end of the experiment, fractional rates of protein synthesis were measured by using a single flooding dose injection of [3H]phenylalanine. The results showed that fractional rates of protein growth and synthesis increased with consumption rate. However, degradation rates were independent of consumption. Fish consuming similar amounts of food exhibited two- to threefold differences in fractional protein growth rates, and twofold differences in fractional rates of protein synthesis. Nine pairs of fish with similar protein consumption rates but different rates of protein growth were selected to examine if differences in protein metabolism, digestive efficiency or RNA concentration or activity could explain these observed differences in protein growth efficiency. More efficient fish were found to have reduced degradation rates; this was the only significant result obtained. The results support the hypothesis that individual differences in protein turnover are important determinants of growth efficiency in fish.

Growth of juvenile southern rock lobsters, Jasus edwardsii, is influenced by diet and temperature, whilst survival is influenced by diet and tank environment

Abstract The growth and survival of juvenile (2–15 g) southern rock lobsters (Jasus edwardsii) were examined under various culture regimes. In Experiment 1, lobsters held at ambient (13–18°C) or 18°C were fed either fresh mussels, a commercial prawn diet or a moist diet. Growth (specific growth rate (SGR)=1.2–1.32% BW day−1), survival (98%) and food conversion ratios (FCR=1.26–1.29) were significantly better (P 0.05), when the lobsters were fed mussels. There was a significant interaction (P 0.05). The high acceptance and good consumption rate of formulated diets is a positive first step in the development of commercial diets for southern rock lobsters. In Experiment 2, lobsters held at ambient (13–18°C) or 18°C were maintained in tanks containing hides, substrates or neither. Hides increased survival (98%, cf. 60–75%) (P>0.05), although they did not increase growth (P>0.05) compared to tanks without hides. The provision of a substrate to aid the lobsters in the moulting process did not prevent cannibalism. Lobsters grew significantly faster (P

Optimal dietary protein level for juvenile southern rock lobster, Jasus edwardsii, at two lipid levels

This study determined the effect on growth efficiency, nutrient retention and apparent digestibility of varying dietary protein concentration and protein/energy ratio for juvenile southern rock lobster, Jasus edwardsii. Isoenergetic diets were formulated at six crude protein levels (5% increments between 24% and 50%) and at each of two lipid levels (5% and 9%). Duplicate groups of 10 lobsters (initial weight mean 3.58 SE 0.86 g) were held in 50-l tanks, in a recirculating seawater system at 18 degrees Celsius and fed to 95% satiation over a 12-week growth trial. There were significant ( P < 0.05) differences in apparent crude protein digestibility (76.4-83.2%), but no difference in dry matter (mean 59.1 SE 0.8%) or energy digestibility (mean 77.7 SE 0.8%). Survival, feed intake, digestive gland index, protein efficiency ratio, energy efficiency ratio and whole-body composition were not significantly affected by dietary treatment. The relationship between nutrient intake and weight gain indicated optimal dietary digestible crude protein (DCP) levels of 29% and 31% when lobsters were fed diets containing 5% and 9% lipid, respectively. For the two lipid levels studied, the optimal dietary protein/energy requirement was similar for maximum weight gain (29 gDCP/ MJ DE) and feed conversion ratio (FCR, 30 gDCP/MJ DE).

Feed availability and its relationship to survival, growth, dominance and the agonistic behaviour of the southern rock lobster, Jasus edwardsii in captivity.

Abstract The effect of feed availability (ration level and feeding frequency) on the culture performance of the juvenile (5–22 g) southern rock lobster Jasus edwardsii was examined to determine whether multiple daily feeding of a formulated feed would stimulate growth. Furthermore, the relationships between feed availability, agonistic behaviour, dominance, growth and survival were examined. A total of 252 lobsters (mean weight 5.26 g) were stocked into 28 black 52-l tanks at a density of nine lobsters per tank (42 m −2 ) and maintained at a temperature of 18.8 °C in a recirculating seawater system for 119 days. Lobsters were fed with high (4% BW day −1 ) or low (0.5% BW day −1 ) rations divided between one, two or four meals per day. These regimes were compared to a regime of fresh mussels ( Mytilus edulis ) fed to excess once per day. Feeding lobsters with a high-ration level, 4 day −1 , made no significant ( P >0.05) improvements in specific growth rate (SGR) (0.77–0.82% BW day −1 ), survival (75–84%) or biomass yields (96–102 g) compared to feeding 1 or 2 day −1 . Low-ration-fed lobsters had a higher final mean weight (17.5–20.9 g) compared to high-ration lobsters (13.4–14.3 g), however, survival of lobsters that were fed with low ration of 4 day −1 (41%) was significantly ( P P Lobsters were size-ranked (g) to determine the effects of feed competition on the growth and survival of individuals of different rank. The ability and/or motivation of the largest lobsters to maintain their size status increased as feed availability decreased, suggesting that feed restrictions increased the strength of dominance. Size-ranking also demonstrated that small lobsters were more vulnerable to being cannibalised, especially when the feed-ration level was low. Feed competition was consistent with the concept of economic defensibility, predicting that levels of agonistic behaviour are highest when a low ration was patterned into smaller, more easily defended meals (low-ration fed, 4 day −1 ). In contrast, feed competition and agonistic behaviour were rarely observed when feed was freely available (high-ration fed, 4 day −1 ). The high levels of cannibalism of small size-ranked lobsters meant that assessing growth depensation was not a useful approach to the evaluation of the relationships between competition and growth in groups. The implications for J. edwardsii culture are that feeding high-ration levels of formulated feeds, more than once daily, reduces feed competition and incidence of agonistic behaviour. However, there appear to have few benefits in terms of growth or survival. The recommendation from this study is to feed lobsters once daily to excess after dusk.

Potential of Thraustochytrids to Partially Replace Fish Oil in Atlantic Salmon Feeds

AbstractThe replacement of fish oil with a dried product made from thraustochytrid culture, a marine microorganism, in canola-oil-based diets for Atlantic salmon was investigated. Salmon (37 g) were fed for 51 days on diets containing only canola oil, canola oil and fish oil, or canola oil and the thraustochytrid. There were no significant differences in final weight (106.1 ± 1.1 g), weight gain (69.6 ± 1.1 g), feed consumption (16.5 ± 0.2 mg dry matter g-1 d-1), feed efficiency ratio (1.15 ± 0.03 g g-1), or productive protein value (51.2% ± 1.7%) between the diets. Nor were there any significant differences in whole-body chemical composition, organ somatic indices, or measures of immune function. However, following transfer to seawater and 2 challenges with Vibrio anguillarum, cumulative mortality was significantly lower in fish fed some fish oil than in those fed the 2 diets containing no fish oil. In conclusion, the thraustochytrid had no detrimental effects on the performance of salmon but, at the current inclusion of 10%, failed to confer the same effect as fish oil under challenging conditions.