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Broken-line Model (broken-line + model)
Selected AbstractsDietary digestible lysine requirement and essential amino acid to lysine ratio for pacu Piaractus mesopotamicusAQUACULTURE NUTRITION, Issue 4 2010E.G. ABIMORAD Abstract To determine the digestible lysine requirement for pacu juveniles, a dose,response feeding trial was carried out. The fish (8.66 ± 1.13 g) were fed six diets containing the digestible lysine levels: 6.8, 9.1, 11.4, 13.2, 16.1 and 19.6 g kg,1 dry diet. The gradual increase of dietary digestible lysine levels from 6.8 to 13.2 g kg,1 did not influence the average values of the parameters evaluated (P > 0.05). The increase of dietary digestible lysine level to 16.1 g kg,1 significantly improved weight gain (WG), specific growth rate (SGR), protein productive value (PPV), protein efficiency rate (PER), and apparent feed conversion rate (FCR), but was not different from fish fed diets containing 19.6 g kg,1 lysine. Fish fed diets containing 16.1 and 19.6 g kg,1 digestible lysine showed lower body lipid contents than fish in the other treatments. The digestible lysine requirement as determined by the broken-line model, based on average WG values, was 16.4 g kg,1. The other essential amino acid requirements were estimated based on the ideal protein concept and the value determined for lysine. [source] Re-evaluation of total sulphur amino acid requirement and determination of replacement value of cystine for methionine in semi-purified diets of juvenile Nile tilapia, Oreochromis niloticusAQUACULTURE NUTRITION, Issue 3 2009T.N. NGUYEN Abstract Two feeding experiments were conducted to re-evaluate the total sulphur amino acid (TSAA; methionine and cystine) requirement and determine the replacement value of cystine for methionine of juvenile Nile tilapia (Oreochromis niloticus). Semi-purified diets used in both experiments contained 3510 kcal gross energy and 280 g of protein per kilogram diet from casein, gelatin and crystalline amino acids. The basal diet of the first experiment contained 3.1 g methionine and 0.4 g cystine per kilogram. l -methionine was added to the seven remaining diets at 1.0 g kg,1 increment to produce methionine levels ranging from 3.1 to 10.1 g kg,1 diet. Each diet was fed to four replicate groups of juvenile Nile tilapia (1.28 g mean weight) in a recirculation system for 8 weeks. Broken-line regression analysis of weight gain data indicated that the TSAA requirement of juvenile Nile tilapia was 8.5 g kg,1 of the diet or 30.4 g kg,1 of dietary protein. In the second experiment, TSAA level was set at 95% of the requirement value determined in the first experiment. Seven diets were made with different ratios of l -methionine and l -cystine (20 : 80, 30 : 70, 40 : 60, 50 : 50, 60 : 40, 70 : 30 and 80 : 20, based on an equimolar sulphur basis). Each diet was also fed to four replicate groups of juvenile Nile tilapia (4.14 g mean weight) in a recirculation system for 8 weeks. Regression analysis of weight gain data using broken-line model indicated that cystine (on a molar sulphur basis) could replace up to 49% of methionine requirement in semi-purified diets for juvenile Nile tilapia. [source] Effect of dietary lipid level on the growth performance, feed utilization, body composition and blood chemistry of juvenile starry flounder (Platichthys stellatus)AQUACULTURE RESEARCH, Issue 10 2010Liyun Ding Abstract A study was conducted to determine the effect of dietary lipid level on the growth performance, feed utilization, body composition and blood chemistry of juvenile starry flounder. Five isonitrogenous diets with increasing dietary lipid levels (6%, 10%, 14%, 18% and 22% dry material) were each fed to triplicate groups of starry flounder (29.9 g) for 8 weeks. Weight gain (WG) and specific growth rate of fish fed the 6% lipid diet were significantly lower than the other groups, while there was no significant difference in fish fed the 10%, 14%, 18% and 22% lipid diets. Body lipid content increased with increasing dietary lipid levels. The moisture content of the whole body was negatively correlated to the dietary lipid level. The dietary lipid level also affected the lipid content of the dorsal muscle positively. Liver lipid content increased as the dietary lipid level increased from 6% to 14% and then decreased. With increasing dietary lipid level, the nitrogen retention achieved the highest value when the fish were fed the 14% lipid diet, but there were no significant differences with the 10% and 22% groups. The plasma total protein content first showed an increasing and then a decreasing trend with increasing dietary lipid level, and it was significantly higher in the 14% lipid group than other groups. Based on the WG response using the broken-line model, the optimum dietary lipid level for juvenile starry flounder was estimated to be 10.62% in the experiment. [source] Effects of dietary protein levels on the growth performance, digestive capacity and amino acid metabolism of juvenile Jian carp (Cyprinus carpio var. Jian)AQUACULTURE RESEARCH, Issue 9 2009Yong Liu Abstract This experiment was conducted to evaluate the effects of protein levels on the growth performance, digestive capacity and amino acid metabolism of juvenile Jian carp. Brown fish meal was used as the sole protein source in the present study. Six isoenergetic experimental diets containing 14.4 MJ kg,1 of digestible energy and 220,495 g crude protein kg,1 diets were fed to triplicate groups of 50 fish with a mean initial weight of 16.67 ± 0.01 g for 45 days. Per cent weight gain (PWG) and feed efficiency ratio (FER) improved with an increase in the dietary protein levels up to 330 g kg,1 diet. The condition factor, relative gut length, intestinal folds height, hepatopancreas and intestine protein content improved with an increase in the protein levels up to 330,385 g kg,1 diet. Trypsin, creatinkinase, Na+, K+ -ATPase and alkaline phosphatase activities generally followed the same tendency as that of growth parameters. Amylase and ,-glutamyl transpeptidase (,-GT) activities were negatively correlated with increasing protein levels from 220 to 330 g kg,1 diet, and no differences were found thereafter. Lipase activity was unaffected by protein levels. Lactobacillus amount was increased with protein levels up to 275 g kg,1 diet, while Aeromonas amount followed the opposite pattern. Escherichia coli amount was not influenced by dietary protein levels. Glutamate,oxaloacetate transaminase (GOT) activities in the hepatopancreas and plasma ammonia concentration (PAC) were not influenced by protein levels between 220 and 275 g kg,1 diet, but significantly increased with increasing protein levels from 275 to 440 g kg,1 diet, and remained similar thereafter. Glutamate,pyruvate transaminase (GPT) activities significantly increased with protein levels >275 g kg,1 diet. Based on the broken-line model, the dietary protein requirement for PWG of Jian carp (16.7,55.0 g) was estimated to be 341 g kg,1 diet with a digestible energy of 14.4 MJ kg,1 diet. [source] Growth and haematology of pacu, Piaractus mesopotamicus, fed diets with varying protein to energy ratioAQUACULTURE RESEARCH, Issue 4 2009Álvaro José De Almeida Bicudo Abstract Haematopoiesis and blood cells' functions can be influenced by dietary concentration of nutrients. This paper studied the effects of dietary protein:energy ratio on the growth and haematology of pacu, Piaractus mesopotamicus. Fingerling pacu (15.5±0.4 g) were fed twice a day for 10 weeks until apparent saciety with diets containing 220, 260, 300, 340 or 380 g kg,1 crude protein (CP) and 10.88, 11.72, 12.55, 13.39, 14.22 MJ kg,1 digestible energy (DE) in a totally randomized experimental design, 5 × 5 factorial scheme (n=3). Weight gain and specific growth rate were affected (P<0.05) by protein level only. Protein efficiency ratio decreased (P<0.05) with increasing dietary protein at all levels of dietary energy. Daily feed intake decreased (P<0.05) with increasing dietary energy. Mean corpuscular haemoglobin concentration was affected (P<0.05) by DE and interaction between dietary CP and DE. Total plasma protein increased (P<0.05) with dietary protein and energy levels. Plasma glucose decreased (P<0.05) with increasing dietary protein. The CP requirement and optimum protein:energy ratio for weight gain of pacu fingerlings, determined using broken-line model, were 271 g kg,1 and 22.18 g CP MJ,1 DE respectively. All dietary CP and DE levels studied did not pose damages to fish health. [source] | ||||||||||