Apparent absorption efficiencies of amino acids in rainbow trout, Oncorhynchus mykiss (Walbaum), fed diets containing bacterial single-cell protein

The aim of the present study was to compare the apparent absorption efficiency of individual indispensable and dispensable amino acids in diets containing varying proportions of bacterial single cell protein (BSCP) and fishmeal when fed to rainbow trout, Oncorhynchus mykiss (Walbaum). Four diets were formulated to contain a total of 45.8% crude protein, of which 0% was from BSCP in diet 1 (BSCP-0), 25% in diet 2 (BSCP-25), 62.5% in diet 3 (BSCP-62.5) and 100% in diet 4 (BSCP-100); the remainder of the protein was from fishmeal. The four diets were isonitrogenous and had similar amino acid compositions. Duplicate groups of 25 fish were fed one of the four experimental diets at the rate of 20 g kg^?1 body weight per day for 132 days. Apparent absorption efficiency was measured over a 45-day period during the growth trial. Results from two methods of faeces collection and two indicators of absorption efficiency were compared. The amino acid absorption efficiency of BSCP-100 was significantly lower (P < 0.05) when compared to the other three diets and absorption of some of indispensable amino acids was below the requirement level. The variation seen in individual amino acids absorption efficiencies between diets suggests that this parameter may be important in fish nutritional investigations.     

Growth and feed utilization efficiencies of seawater Atlantic salmon, Salmo salar L., fed a diet containing supplementary enzymes

Abstract. Supplementary enzymes were added to a diet in order to increase its digestibility and improve the growth achieved by seawater Atlantic salmon, Salmo salar L. The supplementary enzymes were selected to hydrolyse proteins and carbohydrates. Three diets, with fishmeal as the only source of protein (C1), with fishmeal and soybean meal (C2) and diet C2 with supplementary enzymes (C3) were fed to seawater salmon (100g) for 12 weeks at nominal tank rations equivalent to 2·5% body weight per day. Consumption rates of individual fish were measured by radiography. The salmon fed C3 had higher rates of food consumption, significantly higher final weights and rates of growth and lower food conversion efficiencies and maintenance ration than those fed C2. Salmon fed C1 had similar food conversion efficiencies to the C3 fed fish. These results indicate that the addition of supplementary enzymes to diets containing soybean meal improves the growth and food conversion efficiency of salmon.     

Global climate change and ocean upwelling

The influence of global greenhouse warming on the ocean's biological productivity may be more complicated and weaker than that proposed by Bakun (1990). A doubled carbon dioxide simulation made with the Canadian Climate Centre atmospheric general circulation model coupled to a simplified mixed layer ocean model suggests that the midlatitude continents do not all follow the Bakun scenario in developing anomalous low pressure in summer and enhancing coastal winds favorable to upwelling. In the open ocean the equatorial and subpolar zonal upwelling bands and the subtropical downwelling bands generally weaken as winds diminish owing to the weakening of the equator-to-pole temperature gradient in the lower troposphere under global warming. With a weakening of open ocean upwelling and an absence of enhanced coastal upwelling, the overall effect of global warming could be to decrease the global biological productivity.     

Income Inequality Across Regions Over Time

ABSTRACT This paper provides a profile of regional income inequality using a distributional criterion whereby a state's share of total income equals its share of total population. The results for 1929 to 1990 show that inequality persisted among regions with a substantial declining trend up to 1979 and a slight rise thereafter. On the other hand, equality among states within their regions is found to have been the condition since 1929.