Influence Of Dietary Protein Levels Research Articles

The Requirement and Protective Effects of Dietary Protein against Chronic Ammonia Exposure in Juvenile Genetically Improved Farmed Tilapia (Oreochromis niloticus).

Ammonia is a key risk factor in intensive aquaculture systems. This experiment is aimed at investigating the influence of dietary protein levels on genetically improved farmed tilapia (GIFT, Oreochromis niloticus) under chronic ammonia stress. GIFT juveniles of 4.00 ± 0.55 g were exposed to high ammonia level at 0.88 mg/L and fed with six diets comprising graded protein levels at 22.64%, 27.26%, 31.04%, 35.63%, 38.47%, and 42.66% for 8 weeks. The fish in negative control was fed the diet with 31.04% protein in normal water (0.02 mg ammonia/L water). Our results showed that high ammonia exposure (0.88 mg/L) caused significant decrease in fish growth performance, hematological parameters, liver antioxidant enzymes (catalase and glutathione peroxidase), and gill Na+- and K+-dependent adenosine triphosphatase (Na+/K+-ATP) activity. When fish were under high ammonia exposure, the weight gain rate, special growth rate, feed efficiency, and survival rate elevated significantly with dietary protein supplementation increase to 35.63%, whereas protein efficiency ratio, hepatosomatic index, and viscerosomatic index showed a decreased tendency. Dietary protein administration significantly enhanced crude protein but reduced crude lipid contents in the whole fish. Fish fed diets with 35.63%-42.66% protein had higher red blood cell counts and hematocrit percentage than fish fed 22.64% protein diet. The values of serum biochemical indices (lactate dehydrogenase, aspartate aminotransferase, and alanine aminotransferase), hepatic antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase), and gill Na+/K+-ATP activity were all elevated with the increment of dietary protein. Moreover, histological analysis indicated that dietary protein administration could prevent the ammonia-induced damages in fish gill, kidney, and liver tissues. Based on weight gain rate as a response criterion, the optimal dietary protein requirement for GIFT juveniles under chronic ammonia stress was 37.9%.

Impact of moderate dietary protein restriction on glucose homeostasis in a model of estrogen deficiency

The need to consume adequate dietary protein to preserve physical function during ageing is well recognized. However, the effect of protein intakes on glucose metabolism is still intensively debated. During age-related estrogen withdrawal at the time of the menopause, it is known that glucose homeostasis may be impaired but the influence of dietary protein levels in this context is unknown. The aim of the present study is to elucidate the individual and interactive effects of estrogen deficiency and suboptimal protein intake on glucose homeostasis in a preclinical model involving ovariectomy (OVX) and a 13 week period of a moderately reduced protein intake in 7 month-old ageing rats. To investigate mechanisms of action acting via the pancreas-liver-muscle axis, fasting circulating levels of insulin, glucagon, IGF-1, FGF21 and glycemia were measured. The hepatic lipid infiltration and the protein expression of GLUT4 in the gastrocnemius were analyzed. The gene expression of some hepatokines, myokines and lipid storage/oxidation related transcription factors were quantified in the liver and the gastrocnemius. We show that, regardless of the estrogen status, moderate dietary protein restriction increases fasting glycemia without modifying insulinemia, body weight gain and composition. This fasting hyperglycemia is associated with estrogen status-specific metabolic alterations in the muscle and liver. In estrogen-replete (SHAM) rats, GLUT4 was down-regulated in skeletal muscle while in estrogen-deficient (OVX) rats, hepatic stress-associated hyperglucagonemia and high serum FGF21 were observed. These findings highlight the importance of meeting dietary protein needs to avoid disturbances in glucose homeostasis in ageing female rats with or without estrogen withdrawal.

Influence of dietary protein levels on growth, feed utilization, body indices and serum profile of silver moony Monodactylus argenteus

Monodactylus argenteus, is a high-value euryhaline ornamental fish having a good market demand. Information about its nutrient requirement, especially protein, is essential for feed formulation to maintain good health, growth and colouration. A 3-month feeding trial on the fry of this species was carried out to evaluate the effect of varying dietary protein levels on growth, body indices, serum profile, skin carotenoid content and body composition. Hatchery-produced fry (ABW: 0.73 ± 0.08 g) were randomly distributed into 18 glass tanks (90 L water each) in a recirculatory aquaculture system (RAS) @ 10 fry per tank. Five isolipidic micro-diets (75 g kg−1) with graded levels of crude protein (CP) viz. 250 (CP25), 300 (CP30), 350 (CP35), 400 (CP40), and 450 (CP45) g kg−1 were formulated and fed to satiation twice daily. At the end of the trial, weight gain (WG), specific growth rate (SGR) and protein efficiency ratio (PER) of fish fed with CP35, CP40 and CP45 diets were observed to be significantly higher compared to those fed with CP25, and CP30 diets. Protein efficiency ratio (PER) decreased with increased dietary protein levels. The viscerosomatic index (VSI) and hepatosomatic index (HSI), exhibited a decreasing trend as the level of crude protein increased. The IPF was directly proportional to the dietary crude protein content of the diet, the maximum value being obtained in the CP45 treatment. The whole-body crude protein content showed an increasing trend with the increment in dietary protein level up to the CP40 diet and the diet with the highest crude protein exhibited the lowest whole body crude protein content. Analysis of serum profile revealed that serum triglycerides, glucose and protein levels were significantly different (P < 0.05) among the treatments. The group fed with CP40 recorded the highest concentration of carotenoids which was not significantly different from CP30 and CP35 groups. The whole body amino acids profile showed a significant variation in alanine, serine, threonine, glutamine and glycine. Broken-line regression analysis revealed that the optimum dietary protein level was in the range of 325–349 g kg−1 for maximum growth of silver moony fry. Our study revealed that a minimum of 35% protein in the diet of silver moony fry is optimal for improved growth.

Influence of dietary protein levels and some cold pressed oil supplementations on productive and reproductive performance and egg quality of laying Japanese quail

The present study was carried out to examine the effect of dietary protein levels (18, 20, and 22%) and addition of cold-pressed oils (no addition, 1 g thyme, 1 g oregano, and 0.5 g thyme + 0.5 g oregano /kg diet) on the productive and reproductive performance and egg quality of Japanese quail at the laying period. 324 mature ten-week-old Japanese quails (216 females and 108 males) were used. Quails were randomly distributed to 12 treatment groups, 27 in each group, with 3 replicates of 9 quails (6 females and 3 males) per group. Feed conversion ratio (FCR) significantly improved in the layers fed with the diets containing 20 or 22% CP in all experimental periods, except in 3- to 4-month-old birds. The diets supplemented with thyme only or interaction with oregano improved FCR significantly compared to the control or oregano -administered group in all experimental periods, except in 2- to 3-month-old birds. Dietary supplementation with thyme oil caused the egg number and egg mass to increase significantly in all experimental periods compared to the other dietary groups. Fertility percentages were significantly higher in the groups which had oregano than in the control group. Dietary supplementation with thyme oil significantly increased the egg number (P&lt;0.05) and egg mass (P&lt;0.01) in all experimental periods compared to other dietary groups. Fertility and hatchability percentages were not significantly affected due to varying dietary protein levels throughout the experiment. In conclusion, the quails fed with a diet containing 20 to 22% CP or supplemented with oregano or thyme oil exhibited an improved productive and reproductive performance without any detrimental impacts on the other parameters studied.

Low Crude Protein Diet Affects the Intestinal Microbiome and Metabolome Differently in Barrows and Gilts.

Low protein diets are commonly used in the growing-finishing pig stage of swine production; however, the effects of low dietary protein on the intestinal microbiota and their metabolites, and their association with pig sex, remain unclear. The present study aimed to assess the impact of a low crude protein (CP) diet on the gut microbiome and metabolome, and to reveal any relationship with sex. Barrows and gilts (both n = 24; initial body = 68.33 ± 0.881 kg) were allocated into two treatments according to sex. The four groups comprised two pairs of gilts and barrows fed with a high protein diet (CP 17% at stage I; CP 13% at stage II) and a low protein diet (CP 15% at stage I; CP 11% at stage II), respectively, for 51 d. Eight pigs in each group were slaughtered and their colon contents were collected. Intestinal microbiota and their metabolites were assessed using 16S rRNA sequencing and tandem mass spectrometry, respectively. The low protein diet increased intestinal microbiota species and richness indices (P < 0.05) in both sexes compared with the high protein diet. The sample Shannon index was different (P < 0.01) between barrows and gilts. At the genus level, unidentified Clostridiales (P < 0.05), Neisseria (P < 0.05), unidentified Prevotellaceae (P < 0.01) and Gracilibacteria (P < 0.05) were affected by dietary protein levels. The relative abundance of unidentified Prevotellaceae was different (P < 0.01) between barrows and gilts. The influence of dietary protein levels on Neisseria (P < 0.05), unidentified Prevotellaceae (P < 0.01) and Gracilibacteria (P < 0.05) were associated with sex. Metabolomic profiling indicated that dietary protein levels mainly affected intestinal metabolites in gilts rather than barrows. A total of 434 differentially abundant metabolites were identified in gilts fed the two protein diets. Correlation analysis identified that six differentially abundant microbiota communities were closely associated with twelve metabolites that were enriched for amino acids, inflammation, immune, and disease-related metabolic pathways. These results suggested that decreasing dietary protein contents changed the intestinal microbiota in growing-finishing pigs, which selectively affected the intestinal metabolite profiles in gilts.

Effects of Dietary Protein Levels on Growth Performance, Carcass Traits, Serum Metabolites, and Meat Composition of Tibetan Sheep during the Cold Season on the Qinghai-Tibetan Plateau.

Simple SummaryThe Tibetan sheep (Ovis aries) is an ovine breed well adapted to the harsh plateau environment. For a long period of time, Tibetan sheep farming has been an important pillar industry for native herders on the Qinghai-Tibetan Plateau. With the increasing demand for sheep meat and products, nutrition research has gained increasing importance. In this study, the effects of three different dietary protein levels (10.1%, 12.1%, and 14.1%) on growth performance, carcass traits, serum metabolites, and meat composition were investigated in Tibetan sheep during the cold season. The results showed that the diets containing 12.1% and 14.1% protein were better than a diet containing 10.1% protein for enhancing the growth performance, carcass performance, and meat products of the Tibetan sheep.Dietary protein is a critical nutrient that directly influences the health and production of livestock. Recent studies showed that protein supplements could enhance the growth performance of Tibetan sheep. However, there is a lack of information regarding the influence of dietary protein levels on carcass traits and meat composition. This study investigated the effects of dietary protein levels on growth performance, carcass traits, serum metabolites, and meat composition in Tibetan sheep during the cold season on the Qinghai-Tibetan Plateau. A total of eighteen 1-year-old, healthy, castrated Tibetan sheep with similar initial body weights (31.7 ± 0.72 kg) were randomly divided into three treatment groups with different dietary protein level (low protein (LP, 10.1%); medium protein (MP, 12.1%); high protein (HP, 14.1%)) diets. The results indicated that the Tibetan sheep fed with the MP and HP diets had greater final body weights (BWs), average daily gains (ADGs), and average daily feed intakes (ADFIs) (p < 0.05). The MP and HP diets also improved the hot carcass weight, net meat (including the fat) weight, and bone weight of the sheep significantly (p < 0.05). Besides, the dietary protein levels could significantly affect the serum concentrations of growth hormone (p < 0.05). The diameter of muscle fibers in the MP group was significantly greater than that in the LP group (p < 0.05), while the density of muscle fibers showed the opposite trend. The dietary protein levels only significantly (p < 0.05) influenced the ether extract content and profile content of the longissimus dorsi muscle but had no effect on other parameters of meat composition. In summary, our results indicate that dietary protein levels affect growth performance, carcass traits, and meat composition and that diets containing 12.1% and 14.1% protein are recommended to obtain better production performance and meat products in Tibetan sheep, rather than a diet containing 10.1% protein, during the cold season on the Qinghai-Tibetan Plateau.

Effects of dietary protein levels on the growth, body composition, serum biochemistry and digestive enzyme activity in Chinese rice field eel ( Monopterus albus ) fingerlings

A 12-week feeding trial was conducted to determine the influence of dietary protein levels on growth performance, body composition, haematological parameters and digestive enzyme activity of Chinese rice field eel (Monopterus albus) fingerlings. Six isolipidic experimental diets (27.89%, 32.23%, 35.95%, 40.06%, 43.31% and 46.53%) were formulated to randomly assign to triplicate groups of 50 rice field eel fingerlings (5.0 ± 0.5 g) cultured in plastic cages. Results indicated that the best growth performance of fish with the highest WG (158.68 ± 31.59%) and SGR (2.28 ± 0.21%) was obtained at 40.06% group. Significant alterations were demonstrated on whole-body crude protein, crude lipid and amino acid profile by different dietary protein levels. Besides, haematological parameters including triacylglycerol, aspartate aminotransferase and alkaline phosphatase decreased with various levels by the increasing of dietary protein levels. The lowest pepsin activity was observed in 27.89% protein group, which suggested lower availability of protein as substrate for protease activity. Meanwhile, the highest amylase activity in fish of 27.89% group indicated higher carbohydrate level in this group. Based on the polynomial regression analysis of WG and SGR, the dietary protein requirement for fingerlings of Monopterus albus was estimated to be 386.4–390.8 g/kg, respectively, with the lipid level of 10.08%.

Effect of Low Protein Diets on Production Performance, Egg Quality and Serum Biochemical Indices of Vanaraja Laying Hens

The effect of feeding low protein diets on production performance, egg quality and serum biochemical parameters were evaluated in Vanaraja laying hens (35–46 weeks). A total of 108, Vanaraja laying hens were randomly distributed into four treatment with three replicates of nine birds in each replicate pen in a complete randomized design. Four different diets were formulated containing different levels of protein (13, 14.5, 16 and 17.5% CP) with similar energy (2, 600 ME kcal/kg) and the ratio of lysine and methionine to CP were kept constant in all the diets. Each dietary group were offered a measured quantity of feed daily. The body weight gain was significantly higher (P<0.05) in birds fed 13% CP diet compared to birds fed 16 and 17.5% CP diets. The hen-housed egg production, egg weight, egg mass per day and feed efficiency (g egg/g feed) were not influenced by variation in CP contents of the diet. There was no influence of dietary protein levels on egg quality parameters like albumin%, yolk%, haugh unit and egg shell thickness except egg shell%. Significantly higher (P<0.05) egg shell percentage was noticed in 16% CP diet (P<0.05) compared to either 13 and 14.5% CP diet. Serum biochemical parameters like concentration of total protein, globulin, calcium, cholesterol, creatinine and alkaline phosphatase were influenced significantly (P<0.05) by dietary protein levels at 46 weeks of age. From the overall findings, it is concluded that diet containing 13% CP is adequate for optimum production performance and egg quality in Vanaraja laying hens during 35 to 46 week of age.

Effects of dietary protein levels on production performance and serum insulin-like growth factor-1 levels in sika deer

The purpose of this study was to investigate the influence of dietary protein levels on the performance of sika deer. Twenty-four male sika deer were randomly assigned into three treatments, where they were fed a diet containing either 12, 16 or 20% crude protein (CP). During the antler growth period the average bodyweight gain in 12, 16 and 20% CP levels was 17.3, 19.9 and 14.4 kg, respectively; antler yield was 2224, 2518 and 2246 g, respectively. A significant positive relationship (P &lt; 0.01) was found between serum insulin-like growth factor (IGF)-I concentration and bodyweight gain (P &lt; 0.01) and antler yield (P &lt; 0.01), using the regression equations: bodyweight gain (kg) = 0.06IGF-1 (ng/mL) – 52.14 (R2 = 0.69, n = 8) and antler yield (g) = 3.55IGF-1 (ng/mL) – 1659.4 (R2 = 0.77, n = 8), respectively. We concluded that 16% dietary protein was optimal for bodyweight gain and antler yield during the antler growth period in the sika deer.

Influence of Dietary Protein Levels on the Acute Toxicity of Inorganic Mercury in Mice

The influence of dietary protein levels on the acute toxicity of inorganic mercury (Hg) was investigated using mice fed a 24.8% protein diet (normal protein diet, NPD) or a 7.5% protein diet (low protein diet, LPD), and relationships between tissue susceptibility and both levels of Hg and metallothionein (MT) were examined. Twenty-four hr after administration of inorganic Hg, the plasma creatinine concentrations, an index of nephrotoxicity, increased in LPD-fed mice but not in NPD-fed mice at 5 mg Hg/kg, and in both dietary groups at 7.5 mg Hg/kg compared to the respective controls. However, plasma alanine aminotransferase (ALT) activities, an index of hepatotoxicity, increased in both groups only at 7.5 mg Hg/kg. Hg concentrations in the liver was higher in LPD-fed mice than in NPD-fed mice only at 5 mg Hg/kg, although dietary protein levels did not affect concentrations in the liver at 7.5 mg Hg/kg or in the kidney at both doses. MT concentrations were similar in the two dietary groups except for the liver, in which the lowered MT level was observed in LPD-fed mice only at 7.5 mg/kg. The present results suggest that dietary protein levels can modify the acute toxicity of singly administered inorganic Hg, at least in the kidney. It is also suggested that MT induction by toxic doses of inorganic Hg is suppressed by dietary protein deficiency, especially in the liver, but this difference would not lead to the variations in the toxicity or in the Hg retention at least within 24 hr.

Growth, feed utilization and liver histology of juvenile common sole (Solea solea L.) fed isoenergetic diets with increasing protein levels

This study was undertaken to determine the influence of dietary protein levels on growth, feed utilization and liver histology in common sole. Four isoenergetic diets were formulated to contain four different crude protein levels: 39 (P39), 45 (P45), 51 (P51) and 57 (P57) % dry weight. Fifty animals per tank (initial weight 10.2 ± 0.4 g) were randomly distributed into twelve 500 litre square tanks (bottom surface: 5600 cm2) connected to a closed recirculation system. The diets were tested in triplicate for 84 days. At the end of the experiment, the final weight ranged from 19.6 (P39) to 25.4 g (P57). The specific growth rate showed statistical differences between groups, with the best results in the group fed diet P57 (1.07% day−1). Significant differences between groups were also recorded for the feed conversion ratio, with values of 1.31, 1.28, 1.12 and 0.94 in P39, P45, P51 and P57 respectively. Gross lipid efficiency was also significantly affected by the dietary treatment, with the highest value (42.07%) found in P57. Ammonia excretion, expressed as g 100 g−1 protein intake, was significantly lower for group P39 (2.46) than groups P51 (4.70) and P57 (4.75). Increased incidence of lipid droplets in hepatocytes was observed when the dietary protein levels increased and/or dietary lipid decreased.

Influence of dietary protein levels on growth, digestibility, digestive enzyme activity and stress tolerance in white-leg shrimp, Litopenaeus vannamei (Boone, 1931), reared in high-density tank trials

The effects of dietary protein (DP) levels on the growth, digestibility, digestive enzyme activity and stress tolerance of Litopenaeus vannamei (Boone, 1931) were investigated in high-density (375 m(-3)) tank trials. Shrimps (6.2 +/- 0.2 g) were fed diets with five different protein levels (31%, 35%, 39%, 43% and 47%) for 60 days. The results showed that variations in DP significantly (P<0.05) influenced the growth performance, digestibility, enzyme activity and their ability to tolerate stress. Weight gain showed a linear increase in relation to crude protein (CP) up to 43% and showed a slight decrease with a further increase to 47%. Feed conversion ratio was observed to be the lowest in CP 43%: 2.53. A higher protein efficiency ratio was observed with the low-protein diet CP31 (1.07); however, it was not significantly different from the rest of the dietary treatments. Protein digestibility was the highest (75.71%) in CP47 and the lowest (71.94%) in CP31. Protease activity ranged between 63.7 and 70.2 (U Protein(-1)), and showed a positive correlation with the DP levels. Shrimp fed CP43 well tolerated a sudden decline in salinity and survived for 548.3 min in fresh water. Observations from this study indicate that a DP level around 43% could be optimum for L. vannamei in high-density culture systems in the absence of natural productivity.

Effect of Long-term Fluoride Exposure on Growth, Nutrient Utilization and Fluoride Kinetics of Calves Fed Graded Levels of Dietary Protein

In order to assess the influence of dietary protein levels on the fluoride (F) bioavailability, 30 crossbred calves (6-8 months; approximately 104 kg BW) initially exposed to different dietary protein levels were allotted into six groups in a 3 × 2 factorial design. The factors included three different levels of protein viz. normal (100%; NP), low (75%; LP), and high (125%; HP) as per Kearl recommendations besides two levels of supplemental fluorine (as sodium fluoride) at 0 or 200 mg/kg diet. The animals were fed on the respective concentrate mixture and wheat straw for 210 days. A metabolism trial was conducted at 200 days post-feeding to study digestibility, plane of nutrition, and nutrient balances. The final body weight at the end of 210 days was lower (p < 0.01) in animals fed 200 mg/kg F (164.2 ± 8.92 kg) compared to those fed no F (200.7 ± 8.05 kg). Calves on LP diets attained lower (p < 0.05) average daily gain in comparison to NP or HP fed calves. The F-supplemented calves exhibited lower (p < 0.01) voluntary feed intake than their non-supplemented control. The digestibility of proximate nutrients other than ether extract exhibited higher (p < 0.01) values in F-fed calves attributable chiefly to reduced consumption of dry matter. The calves fed extra F retained lower mean daily nitrogen; calcium, and phosphorus compared to the calves fed no F. The mean daily intake, excretion, and retention of F were higher (p < 0.01) in the F-supplemented calves. A significant (p < 0.01) interaction between protein levels and F was evident in the urinary excretion of F; calves on LP diet exhibiting lower urinary excretion. Consequently, the bioavailability of F tended to be higher on LP than NP or HP diets. From the results, it is concluded that protein levels in the diet do not impart significant influence on susceptibility to fluorosis in crossbred calves. However, the bioavailability of F tended to increase on diets low in protein.

Influence of dietary protein levels on production results and mortality in pheasants reared under controlled conditions

The effects of different levels of dietary protein content and population density in growing pheasants, up to the age of 42 days, on production results and mortality have been studied in this paper. The experiment was set as a two factorial study (2 x 2). Factor A was the influence of crude proteins in the diet (A1 = 26% up to 4 weeks of age and 20% from 4 up to 6 weeks of age; A2 = 30% crude proteins up to 4 weeks of age and 24% from 4 up to 6 weeks of age). Factor B was the population density (B1 = 450 and B2 = 550 birds/group). The total number of birds in the trial was n= 2000. Body mass was measured at hatching, 15 and 42 days of age. Up to 15 days of age the pheasants were housed in cages, but thereon they were reared under floor conditions with free access to outdoors. The highest body mass measured at 42 days of age (457.07 g) and the utmost daily body mass increase (4.22 for the first period of growth and 13.31 for the second) was achieved by the pheasants which were fed a diet with the highest protein content (30% in the first stage and 24% in the second) and reared at a lower population density (450 birds/group). These differences were significant (p<0.01). On comparison with the available literature data the mortality was at a satisfactory level (1.27 - 3.00%) and was not influenced by the studied factors. The mortality values were numerically higher for all treatments for the period up to 15 days (0.73 - 2.70%) compared to the period from 15 up to 42 days of age (0.44-1.00%). Based upon the obtained results and the previously published literature data it can be concluded that feedstuff protein content is the key factor required in order to obtain satisfactory final body weight and subsequently good quality material for the repopulation of hunting grounds.

Influence of dietary protein levels on growth performance and body composition of African bonytongue fingerlings,Heterotis niloticus(Cuvier, 1829)

Two experiments were conducted to examine the influence of dietary protein levels on growth and carcass proximate composition of Heterotis fingerlings. Four isoenergetic practical diets were formulated to contain dietary protein levels from 250 to 400 g kg−1 diet. Replicate groups of young Heterotis (initial live weight 3.96 and 26.40 g in experiments 1 and 2 respectively) were handfed twice daily to apparent satiation for a period of 42 and 28 days respectively. Statistical analysis revealed that growth rate was significantly affected by dietary protein level (P < 0.01). The highest weight gain was observed in fingerlings fed with 300 and 350 g protein kg−1 diet for fish size ranging between 3–15 and 26–62 g respectively. There was no significant difference between groups fed with 300, 350 and 400 g protein kg−1 diet for Heterotis fingerlings (3–15 g) in the one hand; in the other hand, significant differences were found between fish (26–62 g) fed with 350 g protein kg−1 diet and those receiving 300 and 400 g protein kg−1 diet, with no significant difference between each other. The specific growth rate varied from 2.4% to 3.1% day−1. The whole-body protein, lipid, moisture and ash contents were not significantly affected by dietary protein levels (P > 0.05). The relationships between percentage weight gain and dietary protein levels suggested very similar dietary protein requirement (about 310 g crude protein kg−1 diet) for Heterotis ranging from 3 to 62 g. The maximum growth occurred at about 345 g protein kg−1 diet.

Influence of Dietary Protein Levels on the Fate of Inorganic Mercury in Mice

Influence of dietary protein levels on mercury (Hg) fate and on tissue metallothionein (MT) levels was investigated in mice. Twenty-four hr after single administration of mercuric chloride (2.5 mg Hg/kg, subcutaneous), the hepatic Hg concentration was enhanced by dietary protein deficiency, whereas the levels in other tissues and excrements were not affected. At that time, MT inductions by mercuric chloride in liver and kidney were suppressed by dietary protein deficiency, despite no observable differences in basal levels. Thus, Hg levels in the liver and kidney showed little correlation with MT levels. A further experiment demonstrated an enhancement of Hg concentration in the liver by dietary protein deficiency at 3 and 12hr but not at 1hr, and the Hg concentration in the kidney was transiently enhanced at 3 hr. Accordingly, the differences in Hg fate would arise considerably earlier, probably before MT induction. The present results suggest that dietary protein status modifies the fate of inorganic Hg, especially in the liver, probably independent of the differences in dietary protein level-dependent varying levels of MT.

Influence of dietary protein levels and water temperature on growth, body composition and nutrient utilization of Cirrhinus mrigala (Hamilton, 1822) fry

The experiment was conducted to determine the protein requirement of Cirrhinus mrigala fry at three different water temperatures, 28, 30 and 32 °C, and to investigate the influence of dietary protein levels and water temperatures on weight gain, body composition, food and nutrient utilization. The 36% protein concentration in the diet yielded highest weight gain at all temperatures from 28 to 32 °C. However, daily protein intake was lower at 28 °C than at 30 and 32 °C. The diet with 36% dietary protein and 32.17% carbohydrate produced the best weight gain and gross conversion efficiency (GCE) at 30 °C. The protein-sparing effect was observed at temperatures 30 and 32 °C in diets 1 and 2, having carbohydrate levels 37.36–44.91%. Highest protein efficiency ratio (PER) was recorded at 28% dietary protein level, while it was lowest at 40% dietary protein level in all three temperatures. Lipid in the body of fishes increased at the end of the experiment in comparison to the initial body lipid. The body protein was found to be related to daily protein intake at 30 and 32 °C. Significant difference ( P<0.05) was also noted between temperatures, the hepatosomatic index (HSI) and viscerosomatic index (VSI). The diet with 36% dietary protein and 32.17% carbohydrate was observed to be the best diet for C. mrigala fry at 28–32 °C.

Influence of dietary protein levels on growth and egg quality in broodstock female bagrid catfish (Mystus nemurus Cuv. &amp; Val.)

Influence of dietary protein levels on growth and egg quality in broodstock female bagrid catfish (Mystus nemurus Cuv. &amp; Val.)

Influence of Dietary Protein Levels on the Fate of Methylmercury and on Amino Acid Transport at the Renal Brush Border Membrane in Rats

We investigated the influence of dietary protein levels on the fate of methylmercury (MeHg) in rats, and the difference in its urinary excretion was discussed from the viewpoint of the dietary protein level-dependent alteration in activity of the neutral amino acid transport system, through which MeHg metabolites such as MeHg-L-cysteine are reabsorbed, at the renal brush border membrane. When MeHg was administered to rats fed either a 24.8% protein diet (normal protein diet, NPD) or a 7.5% protein diet (low protein diet, LPD), urinary Hg excretion was much lower in LPD-fed rats than in NPD-fed rats, whereas no difference was observed in fecal excretion 1 day after MeHg administration. At that time, Hg concentrations in the brain and plasma were similar in the two dietary groups, whereas the concentrations in liver and blood were higher, but the renal concentration was lower in LPD-fed rats than in NPD-fed rats. Regardless of the presence of Na+, uptake of 14C-L-phenylalanine for the first 20 sec was higher in the renal brush border vehicles from LPD-fed rats than in those from NPD-fed rats. These results suggest that dietary protein deficiency enhances the neutral amino acid transport at the renal brush border membrane, which could lead efficient reabsorption of MeHg metabolites from the proximal luminal space, and it might play a key role in the marked decrease in urinary excretion of MeHg.

Influence of dietary protein levels on growth performance, carcass composition and liver lipid classes of juvenileSpinibarbus hollandi(Oshima)

A feeding trial was conducted to investigate the influence of dietary protein levels on growth performance, carcass proximate composition and liver lipid classes of juvenile Spinibarbus hollandi (Oshima), a cyprinid fish. White fish meal was the primary protein source in the study. Eight experimental diets containing 13–55% crude protein were fed to three replicate groups of six fish weighing nearly 8.5 g each for 10 weeks. Both percentage weight gain and feed efficiency ratio increased significantly with increasing dietary protein levels up to 31%, but there was no further increase for protein levels from 31% to 55%. Application of broken-line regression analysis to the percentage weight gain provided an estimate of 32.7±1.5% dietary protein for maximum growth. The protein efficiency ratio and productive lipid value were inversely correlated with dietary protein level. The hepatosomatic index and the viscerosomatic index were also inversely related to dietary protein level. The carcass protein of fish fed lower protein diets was significantly lower than that of the fish fed higher protein diets. Carcass lipid content decreased with increasing dietary protein levels, whereas moisture was inversely related to lipid content. Both liver glycogen and liver lipid contents decreased with increasing dietary protein levels. Triglyceride was the major component in the liver lipid, and the amount of triglyceride deposited in the liver also decreased with dietary protein levels. The results indicated that both carcass proximate composition and liver lipid class of juvenile Spinibarbus hollandi were affected by dietary treatments.