Voluntary feed intake and energy partitioning in tilapia, (Oreochromis niloticus) fed diets with different protein/energy levels
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In order to investigate the effect of different protein/energy levels of diets (two commercial and one laboratory) on voluntary feed intake and energy partitioning in tilapia (O. niloticus), 15 fishes with an initial body mass of 33 g were reared individually in respirometric chambers for 42 days and offered 3 diets ad libitum. The protein contents of the diets were 36.1, 33.8 and 36.8% (dry matter base); the energy content 18.9, 18.4 and 19.2 kJ GE/g and 11.7, 10.5 and 15.4 kJ ME/g. The initial body composition and energy content was estimated from a control group. Feed consumption was recorded for each individual fish. Body mass development was monitored weekly. At the end of the experiment, the fishes were sacrificed and their chemical composition (protein as N.6.25, lipid, ash) and gross energy content were determined. To establish energy budgets, ingestion (I) was calculated from feed intake, retention (P) from accretion in the carcass, heat production (R) from oxygen consumption (indirect calorimetry) and apparently non-utilized energy (faecal and non-faecal losses, U) by difference from energy ingestion. In the beginning, food consumption amounted to ~5% body mass equivalent (BME) per day for all groups and gradually decreased to 2.5, 2.8 and 1.6% BME by the end of the experiment. While the food consumption was significantly different between the treatments, there were no significant differences in the body mass development. Average final body mass was 98.6, 93.8 and 103.7 g. Energy retention was 29.7, 29.2 and 44.4% of GE ingested; heat dissipation 32.1, 27.9 and 36.0%; faecal and non-faecal losses 38.2, 43.2 and 19.6%. For all energy budget parameters, values for the laboratory diet were significantly different from those of commercial feeds 1 and 2. Calculation of metabolizable energy from ingested feed revealed no significant differences in the energy uptake, suggesting that the voluntary feed uptake was controlled by the demand for metabolizable energy. The fishes were able to completely compensate for the lower ME content of the commercial feeds by increasing voluntary feed intake.
In: Chwalibog, A., Jakobsen, K. (Eds.). Energy Metabolism in Animals. Proceedings of the 15th Symposium on Energy Metabolism in Animals, 11-16 September 2000, Snekkersten, Denmark. EAAP Publication No. 103. pp. 181-184
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Growth response and carcass composition of red tilapia fry fed diets with varying protein levels and protein to energy ratios CB Santiago & MA Laron - In SS De Silva (Ed.), Fish Nutrition Research in Asia. Proceedings of the Fourth Asian Fish Nutrition Workshop, 3-8 September 1990, Vijayawada, Andhra Pradesh, India, 1991 - Asian Fisheries SocietyAn 8-week feeding experiment was conducted with red tilapia (Oreochromis ) fry of 0.160 plus or minus 0.035 g initial weight. Twelve diets of 4 protein levels (25, 30, 35 and 40%) and 3 protein to energy (P/E) ratios (111, 100 and 80 mg protein/kcal) at each protein level were used. The highest growth was attained by fry fed a 40% protein diet with a P/E ratio of 111 mg/kcal. A lower but not a significantly different growth response was attained by fry on a 35% protein diet with a P/E ratio of 111 mg/kcal and a 30% protein diet with a P/E ratio of 100. Protein efficiency ratio was affected by the dietary protein level. Feed conversion ratio was not significantly influenced by the dietary protein level nor the P/E ratio. Carcass moisture content (%) was affected only by the P/E ratio. Carcass moisture content was directly related to the P/E ratio of the diets and was inversely related to the digestible energy (DE) level. Both protein level and P/E ratio significantly influenced carcass lipid content (%) on a dry matter basis but not the ash content. Carcass lipid (5) increased with increasing dietary protein and increasing DE levels of the diet, but decreased with increasing P/E ratio. Carcass protein content decreased significantly with the decrease of P/E ratio and increase of DE level of the diet.
Effect of dietary protein and lipid levels and protein to energy ratios on growth, survival and body composition of the mangrove red snapper, Lutjanus argentimaculatus (Forsskal 1775) The approximate levels of dietary protein and energy that would sustain good growth and survival of the mangrove red snapper Lutjanus argentimaculatus (Forsskal) were determined in two feeding experiments. In the preliminary experiment, six fish meal-based diets were formulated to contain three protein levels (35%, 42.5% and 50%) and two lipid levels (6% and 12%) for each protein, with dietary energy ranging from 14.6 MJ kg−1 to 20.5 MJ kg−1. The protein to energy (P/E) ratios of diets ranged from 20.6 mg protein kJ−1 to 27.5 mg protein kJ−1. Diets were fed for 100 days to triplicate groups of snappers with an average initial weight of 24.8 ± 0.4 g. No significant interaction between different levels of protein and lipid was observed. Survival rates (93.8% to 100%), feed conversion ratios (FCR) (2.61–3.06) and condition factors (K) were not affected by different dietary treatments. Regardless of lipid level, fish fed 50% protein diets had a significantly higher specific growth rate (SGR) than fish fed the 35% protein diets, but not compared with the 42.5% diets (P < 0.05). Increasing lipid to 12% in all protein levels resulted in no improvement in growth over the 6% level. Fish body moisture did not vary while lipid levels based on dry matter were high (27.9% to 33.7%). Snapper appear to require more than 40% dietary protein and a high dietary energy level for good growth. In the second experiment, fish (21.1 ± 0.1 g) in four replicate groups were fed for 94 days with three diets (39%, 44% and 49% protein with P/E ratios of 21.1, 23.3 and 25.5 mg protein kJ−1 respectively) containing similar dietary energy levels of about 19 MJ kg−1. Average final weight, SGR and FCR were significantly higher in diets containing 44% and 49% protein diets (P > 0.05). There were no differences in survival rates, protein efficiency ratio (PER) and nutrient composition of snapper flesh. All fish had fatty livers. Results indicated that the diet containing 44% protein with a P/E ratio of 23.3 mg protein kJ−1 was optimum for snapper growth under the experimental conditions used in the study.
Effect of dietary protein and energy level on growth, protein utilization and carcass composition of rabbitfish, Siganus guttatus MM Parazo -
Aquaculture, 1990 - ElsevierSix semipurified diets comprising three levels of protein (25, 35, 45% of dry matter) each at two levels of estimated energy (3161, 3832 kcal/kg) were fed to fry for 8 weeks in 250-l tanks at a stocking density of 80 fish/tank. Growth increased with increasing dietary protein (P<0.01) and energy (P<0.05). Within isocaloric diets, a positive correlation was found between growth and dietary protein-to-energy (P⁄E) ratio (P<0.05). Protein productive value (PPV) and protein efficiency ratio (PER) were negatively correlated with dietary P⁄E ratio. The equations describing this trend were: PPV=50.16−0.19X and PER=2.83−0.12X, where X is P⁄E. Based on responses for growth rate and efficiency of protein utilization, a diet with 35% protein and 3832 kcal/kg energy was found to be best for rabbitfish fry. Carcass fat levels increased in those fish fed diets with 3832 kcal/kg energy. Carcass protein and ash percentages remained essentially constant and independent of dietary treatment.