Increase Of Dietary Lipid Level Research Articles

Growth and hepatic acetyl coenzyme-A carboxylase activity are affected by dietary protein level in European seabass ( Dicentrarchus labrax)

Two trials were undertaken with European seabass ( Dicentrarchus labrax) to estimate the protein requirements for maintenance and growth as well as the effect of dietary protein level on the activity of hepatic acetyl coenzyme-A carboxylase (ACoAC). Six diets were formulated to contain graded levels of protein (from 5 to 55% crude protein (CP)) at a constant (12%) lipid level. Three other diets were also formulated to contain 35, 45 and 55% CP, but with a higher lipid level (19%). Groups of 10 individually marked fish (IBW: 100 g) and groups of 8 fish (IBW: 160 g) were used in trial I and II, respectively. Fish were fed to visual satiety and intake was recorded. At the end of both studies, whole body, liver and plasma samples were withdrawn for analyses. Growth rate was improved with increasing dietary CP level. Despite not being the object of a statistical analysis, feed efficiency tended to be enhanced at higher dietary CP level and protein efficiency ratio tended to decrease with increased protein intake. The reduction of the dietary protein/energy ratio, due to the increase of dietary lipids further improved growth and feed utilisation. Data from both experiments indicate 4.5±0.5 g kg −1 d −1 as the daily protein intake for maximum N gain and 520±50 mg kg −1 d −1 as the maintenance needs for nitrogen balance. An increase of dietary CP level, up to 25%, increased ACoAC activity. A further increase in dietary CP level (35 to 55%) did not affect liver ACoAC activity. The increase in dietary lipid level depressed significantly liver ACoAC specific activity.

사료 지질 및 한방제 첨가가 돌돔의 성장에 미치는 영향

A feeding trial was carried out to Investigate the effect of lipid level and herb mixture in the diets on growth of juvenile parrot fish, Oplegnathus fasciatus. Two plicate groups of fish averaging 4.5 g were fed four experimental diets containing herb mixture (0 and 5 g/kg diet) at each of two lipid levels <TEX>$(8\%\;and\;16\%)$</TEX> for 8 months from summer to spring (water temperature, <TEX>$7.2-25.4^{\circ}C)$</TEX>. Weight gain improved with increasing dietary lipid level or supplementation of herb mixture during the first 4 months feeding period. Weight gain of fish fed the diet containing <TEX>$16\%$</TEX> lipid level was significantly higher (P<0.05) than that of fish fed the diet containing <TEX>$8\%$</TEX> lipid level. Weight gain of fish fed the diet with herb mixture was significantly higher (P<0.05) than that of fish fed the diet without herb at the <TEX>$16\%$</TEX> lipid level. Feed efficiency was influenced by dietary lipid level or herb mixture during the first 4 months. On the other hand, weight gain and feed efficiency were not affected by dietary lipid level and herb mixture after 4 months until end of feeing period. Survival of fish fed the diet containing <TEX>$8\%$</TEX> lipid without supplementation of herb mixture was the lowest among the groups (P<0.05). Lipid contents of liver and viscera tended to increase with increasing dietary lipid level during the first 4 months feeding period, however muscle lipid content was not influenced by dietary lipid and herb. Total cholesterol of serum was influenced by dietary lipid level during the first 4 months feeding period. These results indicate that an increase of dietary lipid level from <TEX>$8\%\;to\;16\%$</TEX> and supplementation of herb mixture can improve growth performance of juvenile parrot fish when water temperature is optimum for growth such as the summer season in Korea.

Effects of digestible protein and lipid levels in practical diets on growth, protein utilization and body composition of juvenile rockfish ( Sebastes schlegeli)

A feeding trial of three dietary digestible protein (DP) levels (37%, 42% and 47%) and two dietary digestible lipid (DL) levels (7% and 14%) factorial design with three replications was conducted to investigate the proper dietary protein and lipid (energy) levels for the growth of juvenile rockfish. Fish, average initial weight 21.9 g, were fed the experimental diets for 20 weeks. Weight gain improved with increasing dietary DP and DL levels. Weight gain of fish fed the diet containing 47% DP was significantly higher ( P<0.05) than that of fish fed the diet containing 37% DP, and was not different from that of fish fed the diet containing 42% DP at the 14% DL level. However, weight gain was not significantly affected by dietary DP level at the 7% DL level. Feed efficiency ratio of fish was improved as dietary DP and DL levels increased, whereas there was no significant difference between those of fish fed the diets containing 42% or 47% DP at the same dietary DL level. Feed efficiency ratio of fish fed the 14% DL diets was significantly higher ( P<0.05) than that of fish fed the 7% DL diets at the same DP level. Hepatosomatic index (HSI), visceralsomatic index (VSI), protein efficiency ratio, and protein retention were significantly influenced by dietary DL level, but not by dietary DP level. Daily feed intake tended to decrease with increasing DP and DL levels. Lipid contents of whole body, liver and viscera increased with increasing DP and DL levels, whereas dorsal muscle lipid was not affected by dietary DP and DL levels. The apparent digestibility coefficients (ADC) of protein and nitrogen-free extract (NFE) were not significantly affected by dietary DP and DL, while ADC of dry matter, lipid and energy increased with dietary DP and DL. The results of this study indicate that an increase of dietary lipid level has protein-sparing effect, and the diet containing 42% DP and 14% DL (4.2 kcal DE/g diet) is optimal for growth and effective protein utilization of juvenile rockfish.

Dietary lipid level affects fatty acid composition and hydrolase activities of intestinal brush border membrane in seabass.

Triplicate groups of juvenile seabass (initial weight of 241 g) were fed during 13 weeks three isonitrogenous experimental diets containing different lipid levels, 12% (LL group), 21% (ML group) and 30% (HL group). At the end of the experiment, fish weight gain was similar among the 3 dietary groups. Intestinal brush border membranes were purified for each dietary group; one part of the brush border fraction was dedicated to enzyme assays, the remaining fraction being used for lipid extraction followed by fatty acid analysis. The fatty acid composition of the brush border membrane differed among the 3 groups, although the 3 experimental diets had the same fatty acid composition. The increase in dietary lipid level resulted in a lowering in (n-3) polyunsaturated fatty acid (PUFA) paralleled with an increase in monounsaturated fatty acid. A significant reduction in the brush border enzyme activities, namely alkaline phosphatase, aminopeptidase N, gamma-glutamyl transpeptidase and maltase, was also observed with the elevation of the dietary lipid level. The change in activity of intestinal digestive enzymes, which are membrane-bound proteins, could be attributed to the modification of fatty acid composition and fluidity of the brush border membranes (BBM). Such lowering in PUFA and increase in monounsaturated fatty acid in BBM, concomitant with a decline in membrane enzymatic activity, has been described as a malnutrition indicator in mammals. It raises the question of possible disorders of gut functions in fish fed increasing lipid levels.

Effect of dietary lipid level on growth performance and feed utilization by European sea bass juveniles ( Dicentrarchus labrax)

A study was undertaken to determine the effect of the dietary lipid level on growth and feed efficiency of European sea bass juveniles. Four isonitrogenous diets (48% crude protein) with increasing dietary lipid levels (12, 18, 24 and 30% DM) were fed to satiety to triplicate groups of 25 fish (IBW=7 g) for 8 weeks. Final body weight of fish fed the 24% lipid diet was significantly higher than that of fish fed the 12 and 30% lipid diets, although no significant differences in SGR were observed among groups. Feed efficiency values for the 30% lipid diet were significantly lower than those for the other diets. Feed intake of the 12, 18 and 24% lipid diets seemed to be regulated more by protein intake rather than by energy intake. With the 30% lipid diet, both protein and energy intake (g kg −1 day −1) were significantly higher than with the other diets. At the end of growth trial, protein content was significantly higher in fish fed the 12% lipid diet, and lipid and energy content were significantly lower in fish fed the 12 and 18% lipid diets than in the other groups. Liver lipid content was significantly higher in fish fed the 24% lipid diet than in the other groups. Muscle lipid content was unaffected by dietary lipid level. Nitrogen and energy retention (percentage intake) values were significantly lower in fish fed the 30% lipid diet than in the other groups. Energy retention (percentage intake) increased as dietary lipid level increased from 12 to 24%. Lipid retention (percentage intake) decreased as dietary lipid level increased. The apparent digestibility coefficients (ADC) of dry matter and protein were not affected by diet composition, while ADC of lipid and energy were significantly higher in the 24 and 30% lipid diets. The results of this trial indicate that an increase of dietary lipid level from 12 to 24% did not improve growth performance and feed efficiency of sea bass juveniles. The increase of dietary lipid level had no protein sparing effect. Although, the inclusion of 30% of dietary lipid did not depress growth rate, it significantly reduced protein and energy retention efficiencies. It may be concluded that, under the experimental conditions, the increase of dietary lipid level beyond 12% had no beneficial effects.

A preliminary model for dynamic simulation of growth in fish larvae: application to the African catfish ( Clarias gariepinus) and turbot ( Scophthalmus maximus)

The present study describes an explanatory model that simulates growth and body composition of fish larvae. Its objective is to improve the understanding of the growth process in larval fish, and by doing so, to enable the optimisation of the feeding strategies in larviculture. The model is driven by nutrient intake, with the absorbed dietary nutrients being used for energy production or for biosynthetic processes, and it is based on the stoichiometry of intermediary metabolism. The model was parameterised using literature data and validated for the African catfish and turbot. According to the model, high unavoidable losses of amino acids due to imbalances between the dietary and the larval amino acid profiles lead to an increase in lipid deposition in periods of high food intake. In catfish, this occurs with the contribution of gluconeogenesis. Model simulations indicate that an increase in the dietary protein level of currently used diets would stimulate growth and lead to a reduction in lipid deposition, providing the dietary AA profile is well balanced. An increase of 25% in the dietary protein level may stimulate growth (dry matter) by 15% for the African catfish, and 140% for turbot. Model simulations also show that a 25% increase in dietary lipid level may lead to a small protein-sparing effect, and to an increase of 46 and 36% in larval lipid content for African catfish and turbot, respectively. Due to its mechanistic nature, the present model can be used for other fish species, and in particular in the development of tentative feeding strategies when new species are brought into cultivation.

Effects of dietary energy: protein ratio on growth characteristics and body composition of hybrid striped bass, Morone chrysops ♀ X M. saxatilis ♂

Six semipurified diets with energy: protein (E: P) ratios of 6, 7, 8, 9, 10 and 11 kcal available energy/g protein were fed in triplicate to groups of juvenile hybrid striped bass (initial weight approximately 9.0 g/fish) for a period of 8 weeks in flow-through aquaria receiving fresh well water. The greatest weight gain and protein efficiency ratio values were associated with fish fed diets with E: P ratios ranging from 6 to 9 kcal/g protein. Weight gain was reduced ( P < 0.05) and intraperitoneal fat (IPF) ratio (IFF weight × 100/body weight) was increased ( P < 0.05) as dietary lipid level and E: P ratio increased. Moreover, an increase in dietary lipid level and E:P ratio resulted in higher ( P < 0.05) hepatosomatic index (liver weight × 100/body weight) and lower ( P < 0.05) muscle ratio (whole muscle weight × 100/body weight) values. Proximate composition of muscle was not significantly affected by dietary E: P ratio. However, whole-body protein content decreased ( P < 0.05) and lipid content increased ( P < 0.05) at higher E: P ratios. Liver dry matter and glycogen increased ( P < 0.05), while protein and lipid levels decreased ( P < 0.05) as E:P ratio increased. The optimum E: P ratio for hybrid striped bass was determined to be 8 kcal/g protein, based on high weight gain and protein efficiency ratio values, as well as lower lipid deposition in the abdominal cavity.