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Average Initial Weight (average + initial_weight)
Selected AbstractsInvestigation of the Effects of Salinity and Dietary Protein Level on Growth and Survival of Pacific White Shrimp, Litopenaeus vannameiJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 4 2007Martin Perez-Velazquez It is presumed that in hypo- and hypersaline environments, shrimp's requirements for some specific nutrients, such as protein, may differ from those known in the marine habitat; however, few investigations have been conducted in this area of study. In the present investigation, the effects of salinity and dietary protein level on the biological performance, tissue protein, and water content of Pacific white shrimp, Litopenaeus vannamei, were evaluated. In a 3 × 4 factorial experiment, juvenile shrimp with an average initial weight of 0.36 ± 0.02 g were exposed for 32 d to salinities of 2, 35, and 50 ppt and fed experimental diets with crude protein contents of 25, 30, 35, and 40%. A significant effect of salinity on growth of shrimp was detected, with the growth responses (final weight, weight gain) ranked in the order 2 ppt (3.87, 3.50 g) > 35 ppt (3.40, 3.04 g) > 50 ppt (2.84, 2.47 g). No effects of dietary protein level or an interaction between salinity and protein on growth of shrimp were observed under the experimental conditions of this study. Percent survival of shrimp fed the highest protein content (40%, survival of 74%) was, however, significantly lower than those of shrimp fed the other feeds (25, 30 and 35% protein, survival of 99, 91, and 94%, respectively), a result likely associated with the concentration of total ammonia nitrogen, which increased significantly at increasing protein levels. Final water content of whole shrimp was significantly lower in animals exposed to 50 ppt (70.8%) than in shrimp held at 2 (73.7%) and 35 ppt (72.3%). No effect of salinity, protein, or their interaction was observed on the protein content of whole shrimp. The results of the present study are in agreement with reports of superior and inferior growth of L. vannamei reared in hypo- and hypersaline environments, respectively, as compared to what is generally observed in seawater. [source] Effect of Dietary Protein Concentration and Stocking Density on Production Characteristics of Pond-Raised Channel Catfish Ictalurus punctatusJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 2 2003Menghe H. Li Diets containing 28% and 32% crude protein were compared for pond-raised channel catfish Ictalurus punctatus stocked at densities of 14,820, 29,640, or 44,460 fish/ha. Fingerling channel catfish with average initial weight of 48.5 g/fish were stocked into 30 0.04-ha ponds. Five ponds were randomly allotted for each dietary protein ± stocking density combination. Fish were fed once daily to satiation for two growing seasons. There were no interactions between dietary protein concentration and stocking density for any variables. Dietary protein concentrations (28% or 32%) did not affect net production, feed consumption and weight gain per fish, feed conversion ratio, survival, processing yields, fillet moisture, protein and ash concentrations, or pond water ammonia and nitrite concentrations. Fish fed the 32% protein diet had slightly but significantly lower levels of visceral and fillet fat than fish fed the 28% protein diet. As stocking density increased, net production increased, while weight gain of individual fish, feed efficiency, and survival decreased. Stocking densities did not affect processing yield and fillet composition of the fish. Although highly variable among different ponds and weekly measurements, ponds stocked at the highest density exhibited higher average levels of total ammonia-nitrogen (TAN) and nitrite-nitrogen (NO2 -N) than ponds stocked at lower densities. However, stocking density had no significant effect on un-ionized ammonia-nitrogen (NH3 -N) concentrations, calculated based on water temperature, pH, and TAN. By comparing to the reported critical concentration, a threshold below which is considered not harmful to the fish, these potentially toxic nitrogenous compounds in the pond water were generally in the range acceptable for channel catfish. It appears that a 28% protein diet can provide equivalent net production, feed efficiency, and processing yields as a 32% protein diet for channel catfish raised in ponds from advanced fingerlings to marketable size at densities varying from 14,820 to 44,460 fish/ha under single-batch cropping systems. Optimum dietary protein concentration for pond-raised channel catfish does not appear to be affected by stocking density. [source] Response of rainbow trout (Oncorhynchus mykiss) to varying dietary astaxanthin/canthaxanthin ratio: colour and carotenoid retention of the muscleAQUACULTURE NUTRITION, Issue 5 2010G. CHOUBERT Abstract Rainbow trout with an average initial weight of 160 g were fed during 42 days diets containing varied keto-carotenoids astaxanthin (Ax)/canthaxanthin (Cx) ratio, as follows: Ax 100% : Cx 0%; Ax 75% : Cx 25%; Ax 50% : Cx 50%; Ax 25% : Cx 75% and Ax 0% : Cx 100%. Muscle colour and carotenoid muscle retention were studied. Colour parameter values for mixed astaxanthin,canthaxanthin-fed fish were intermediate between those obtained for Ax 0% : Cx 100% fed fish group and for Ax 100% : Cx 0% fed fish group. Concerning muscle carotenoid retention, it has been observed that as the level of canthaxanthin in diet increased, the muscle total carotenoid retention decreased. In the mean time, as the level of canthaxanthin in diet increased, the muscle astaxanthin retention decreased while that of canthaxanthin increased. The results reported here provide further evidence of non-beneficial effects in terms of muscle colour and muscle carotenoid retention of the use of varying dietary astaxanthin/canthaxanthin ratio for feeding rainbow trout compared to values obtained for astaxanthin-only feed. [source] Dietary pyridoxine requirement of juvenile Jian carp (Cyprinus carpio var. Jian)AQUACULTURE NUTRITION, Issue 4 2009W. HE Abstract In a 80-day feeding trial, a total of 1050 juvenile Jian carp (Cyprinus carpio var. Jian) with an average initial weight of 10.71 ± 0.05 g were fed semi-purified diets containing seven graded levels of pyridoxine (0.20, 1.71, 3.23, 4.96, 6.32, 8.58 and 12.39 mg pyridoxine kg,1 diet). Results indicated that with increasing dietary pyridoxine levels up to 4.96 mg kg,1 diet, percent weight gain (PWG) and specific growth rate (SGR) were improved, and no differences were found with further increase of pyridoxine levels. Feed intake also followed the similar pattern to that observed with PWG and SGR when dietary pyridoxine levels were ,6.32 mg kg,1 diet. But feed efficiency and protein efficiency ratio were not affected by pyridoxine levels. Crude protein of carcass, productive protein value and plasma ammonia concentration were improved with increasing dietary pyridoxine levels up to 4.96 mg kg,1 diet. Amylase activities in the intestine were improved with increasing dietary pyridoxine levels up to 4.96 mg kg,1 diet, but protease and lipase activities in the intestine were not affected by pyridoxine levels. Na+, K+ -ATPase and Gamma-glutamyl transpeptidase activities in proximal intestine, mid intestine (MI) and distal intestine (DI) were lowest when fed the diet containing 1.71 mg pyridoxine kg,1 diet. The alkaline phosphatase activities in MI and DI followed the same pattern. The dietary pyridoxine requirement of juvenile Jian carp based on PWG estimated by broken line model was 6.07 mg pyridoxine kg,1 diet. [source] Influence of several non-nutrient additives on nonspecific immunity and growth of juvenile turbot, Scophthalmus maximus L.AQUACULTURE NUTRITION, Issue 5 2008Y. LI Abstract The effects of three non-nutrient additives on nonspecific immunity and growth of juvenile turbot (Scophthalmus maximus L.) were studied in this feeding experiment. The five treatments are basal diet alone, basal diets containing three different additives [0.4 g kg,1 of xylo-oligosaccharides (XOS), 1.3 g kg ,1 of yeast cell wall and 0.8 g kg ,1 of bile acids] individually or in combination. Two hundred and twenty-five turbots (average initial weight 151.3 ± 11.3 g) were randomly allotted in five treatments with three replicates within each treatment in a 72-day period. Comparing with basal diet group, activities of C3, C4, phagocyte, lysozyme, specific growth rate and feed conversion rate in yeast cell wall, XOS and the combined groups was enhanced significantly (P < 0.05); however, these parameters in bile acid groups were increased slightly (P > 0.05) except for phagocyte (P < 0.05); superoxide dismutase activity in additive groups was not significantly increased (P > 0.05) except for the combined group (P < 0.05). In conclusion, supplementation of yeast cell wall and XOS enhanced the nonspecific immunity of juvenile turbot. Synergistic or additive effect of the three additives was not observed. [source] | ||||||||||