Different Levels Of Dietary Protein Research Articles

Different Dietary Levels of Protein to Lipid Ratio Affected Digestive Efficiency, Skeletal Growth, and Muscle Protein in Rainbow Trout Families

Normal Protein (NP) and High Protein (HP) diets were provided to rainbow trout families from juvenile to maturity. Muscle protein concentration increased during growth and the protein to lipid (P/L) ratio was doubled at late stage with respect to the dietary P/L ratio. The HP-diet fish showed higher protein deposition in body and white muscle, and had lower condition factor due to protein deposition associated more with body length than body weight. Fish growth rates were decreased at maturation, and the HP-diet fish showed lower growth rate including the activity ratio of trypsin to chymotrypsin (T/C ratio) and feed efficiency. Trypsin and chymotrypsin specific activities were related to dietary protein levels, and the T/C ratio was related to intestinal weight and growth rate independent of the enzymes specific activity levels. The families with high growth capacity could double increase white muscle P/L ratio levels, compared to low and medium growth families, if they were fed on HP-diet. The digestive enzyme extracts from high growth families resulted in higher in vitro protein digestibility for all diets. The effect of dietary P/L ratio on digestion, skeletal growth (length) and the white muscle P/L ratio in fish with different growth capacities is illustrated.

Adaptation of protein oxidation to protein intake in the domestic cat

It is well‐accepted that cats require more dietary protein than omnivores and herbivores. Work on hepatic enzyme activities showed that cats lack the ability to regulate the urea cycle enzymes in response to the dietary supply of protein. It was thus hypothesized that the high protein requirement of cats is due to an inability to regulate these enzymes, limiting adaptation to a low protein diet. We used indirect respiration calorimetry to assess the in vivo ability of cats to adapt substrate oxidation to different levels of dietary protein, including one below their protein requirement. In random order, eight cats consumed each of four semi‐purified diets containing 7.7% (LP), 14.6% (AP), 27.3% (MP) and 51.1% (HP) of ME from protein. Cats consumed each diet for at least 14 days and then completed a 5‐day nitrogen balance trial and at least 2, 12‐hour indirect calorimetry measurements. The data were analyzed by anova using the Mixed procedure of SAS and are expressed as mean ± SEM. There was a significant effect of diet on protein oxidation (p < 0.0001), measuring 9.8 ± 0.5%, 13.4 ± 0.9%, 23.5 ± 0.8% and 49.0 ± 1.8% of total energy expenditure on the LP, AP, MP and HP diets, respectively. The ratio of protein oxidation/protein intake was significantly higher with the LP diet (1.27 ± 0.07) than the other three diets (AP, 0.92 ± 0.06; MP, 0.86 ± 0.03; HP, 0.96 ± 0.04; p < 0.0001), indicating a net loss of protein on the LP diet. Thus, cats adapted to a wide range of dietary protein concentrations, but were unable to fully adapt to the LP diet.

Effect of Different Levels of Protein and Protexin on Broiler Performance

A feeding trail was conducted to evaluate the effects of different levels of dietary protein and protexin (a commercial probiotic compound) on broiler performance. In a completely randomized design with 2 x 3 factorial arrangement, 360 male broiler chicks were divided into 24 groups, 15 chicks per. Treatments consisted of combination of two levels of protein (NRC and 90% of NRC) and three levels of protexin (without protexin, the recommended level and 120% of recommended level). All of the diets were formulated according to the NRC tables except for protein. Protexin significantly (P<0.05) increased weight gain in growing as well as the whole production period. Feeding protexin at 120% of the recommended level caused a significant improvement in feed conversion ratio compared to the control group. Protexin had no significant effect on feed consumption, carcass percentage, abdominal fat and the cost of consumed feed. Decreasing dietary protein caused a significant decrease in feed cost (P<0.05). Inclusion of protexin into diet at 120% of the recommended level significantly (P<0.05) decreased feed cost per kilogram of live weight gain.

Effects of sunflower seed supplementation and different dietary protein concentrations on the ciliate protozoa population dynamics in the rumen of sheep

The effects of feeding a linoleic acid-rich sunflower seed supplement and different levels of dietary protein on protozoal numbers and fermentation parameters in rumen fluid were determined in an 84-d experiment with rumen-cannulated sheep. The experiment comprised four treatments, two with low crude protein diets [12% of dietary dry matter (DM)] and two with high protein diets (16% of DM). On both low and high protein diets, one treatment was without (Control) and one with the sunflower seed (high linoleic acid variety 6150) supplement (14% of dietary DM). The four diets used were based on corn silage and corn grain, and soybean meal was used to achieve the desired concentration of dietary protein. The sheep were fully fed each morning and rumen fluid samples were taken 2 h later on various days of the experiment (daily during the first 14 d for enumeration of protozoa). In addition, rumen fluid was sampled at different hours after feeding on day 43 of the experiment. Results showed a protozoa-decreasing effect (P &lt; 0.001) of sunflower seeds causing a decline in protozoa numbers after 2 d of supplementation. The effect of protein on protozoa numbers was dependent on the presence of sunflower seed supplement. Measurements on day 43 showed increased protozoa numbers (P &lt; 0.05) and ammonia nitrogen concentrations (P &lt; 0.001) due to higher dietary protein, and decreased protozoal numbers (P &lt; 0.05) and ammonia nitrogen (P &lt; 0.001) due to the sunflower seed supplement, without significant effects (P &gt; 0.05) on volatile fatty acid concentrations. The linoleic acid-rich sunflower seed supplement was highly effective in reducing both protozoa numbers and ammonia nitrogen concentrations in rumen fluid. Key words: Rumen ciliate protozoa, sunflower seeds, dietary protein, sheep

Relation between oxidative damage and dietary protein: marginal protein level which modulates oxidative damage in mice with total body irradiation

Mice were fed different levels of dietary protein (8%, 11%, 14%, 17% or 20%) and then gave total body irradiation (TBI) with X-rays. The levels of lipid peroxides and protein carbonyls in the liver and chromosomal damage in bone marrow did not differ among the groups, which were not received TBI. However, the oxidative damage of lipid and protein in the liver increased due to TBI only in the 8% or 11% protein group. The chromosomal damage in bone marrow due to TBI was higher in the 8% or 11% protein group than those in the 14%, 17% or 20% protein group. Concentrations of antioxidants (vitamins C, E and GSH) in the liver were lower, and the concentrations of non-heme iron in the liver were higher in the 8% or 11% protein group than those in the 14%, 17% or 20% protein group.

The effects of breed and different levels of dietary protein on store lamb finishing performance

Efficient lamb finishing is geared to reaching market at a specific time, this is done by regulating growth rates – this may involve using different feeds – in this case varying in crude protein content or using different breeds – crossbreds rather than purebreds. The objectives of this trial were to determine the effect of different feed crude protein level on lamb performance of two breed types.

Nutrition and chronic renal failure in rats: what is an optimal dietary protein?

In chronic uremia (CRF), malnutrition is an important determinant of morbidity in adults and impaired growth in children. Causes of malnutrition include anorexia and abnormal protein and amino acid metabolism. To determine how different levels of dietary protein and CRF interact to influence growth and nutritional status, CRF and sham-operated, pair-fed control rats were fed isocaloric diets containing 8, 17, or 30% protein for 21 d to mimic dietary regimens recommended for CRF patients: the minimum daily requirement; the recommended daily allowance; or an excess of dietary protein. Serum creatinine did not differ between groups of CRF rats but blood urea nitrogen was lowest in CRF rats fed 8% protein (P < 0.001). CRF rats eating 30% protein gained less weight and length compared to their controls or CRF rats fed 8 or 17% protein (P < 0.05); they also had acidemia. CRF rats fed 8% protein had the highest efficiency of utilization of protein for growth, while 17% protein promoted the highest efficiency of utilization of food and calories for growth. Notably, CRF rats eating 30% protein had the lowest protein efficiency; their calorie intake was also the lowest because of anorexia. Plasma branched-chain amino acids were progressively higher in control rats eating 8, 17, or 30% protein. CRF rats fed 8 or 17% protein had lower branched-chain amino acid concentrations compared with CRF rats fed 30% protein. In CRF, it is concluded that excessive dietary protein impairs growth but a low-protein diet does not impair nutritional responses and permits utilization of protein for growth if calories are sufficient.

Changes in Bone Turnover in Young Women Consuming Different Levels of Dietary Protein

Changes in Bone Turnover in Young Women Consuming Different Levels of Dietary Protein

Immune competence, resistance to Escherichia coli and growth in male broiler parent chicks fed different levels of crude protein.

Immune competence, resistance to Escherichia coli and growth were measured in female chicks of broiler male parent lines from four different commercial sources. These chicks were fed with three levels of dietary crude protein (CP) from day-old. The protein contents in the diets were 18%, 20.5% and 23%; these diets are referred to as the low-, medium- and high-protein diets, respectively. There was a significant genotype by dietary protein interaction for body weight at 35 days of age but not at 14 or 28 days of age. At 14 days of age, the chicks fed on the high-protein diet weighed significantly more than those fed on the low-protein diet, but there were no differences between the chicks fed on the medium-and low-protein diets. The influence of CP content on body weight had disappeared by 28 days of age. There were significant differences between the genotypes-in antibody production in response to sheep red blood cell (SRBC) inoculation, but no such differences were observed between the chicks fed the different levels of dietary protein. Chicks fed on the high-protein diet had lower lesion scores following E. coli inoculation than those fed on the low-protein diet. There were also significant differences in lesion scores among the genotypes. Genotypes with heavier body weights had significantly higher lesion scores and lower antibody titres than those with less body weight. Also, genotypes of lower body weight had a greater cutaneous basophilic hypersensitivity response to phytohaemaglutinin-P inoculation, and a better humoral response against SRBC and a lower heterophil to lymphocyte ratio.

Performance of Golden Montazah Male Chicks Raised for Meat Production When Fed Different Dietary Levels of Protein and Sulfur Amino Acids

Performance of Golden Montazah Male Chicks Raised for Meat Production When Fed Different Dietary Levels of Protein and Sulfur Amino Acids

Dietary Protein Level Regulates Expression of the Mitochondrial Branched-Chain Aminotransferase in Rats

The first step in the degradation of branched-chain amino acids (BCAA) is transamination catalyzed by the branched-chain aminotransferase (BCAT), which is located in extrahepatic tissues. Studies of the effect of dietary protein on BCAT activity have given contradictory results. Therefore, we established the levels of BCAT activity and mitochondrial BCAT (BCATm) mRNA expression in different organs and tissues of rats. We then determined the effect of different levels of dietary protein in well-nourished rats, the effect of feeding a 0.5% casein diet for 5 wk (protein-malnourished rats) and nutritional rehabilitation of these rats with different levels of dietary protein on BCAT activity and BCATm mRNA expression in selected tissues. Finally, the response of tissue BCAT activity and BCATm mRNA levels in rats fed a 10% casein diet and injected with glucagon (4 d) or hydrocortisone (7 d) was determined. The highest concentration of BCATm mRNA was found in stomach, followed by kidney, heart, muscle, brain, skin and lung. Low levels were found in intestine, and no BCATm mRNA was detectable in liver. Although BCAT activity was significantly higher in muscle, kidney and brain from rats adapted to consume a 50% casein diet for 7 h/d for 10 d than in rats fed 6, 18 or 35% casein diets, only muscle had significantly higher levels of BCATm mRNA. In protein-malnourished rats, BCAT activity and BCATm mRNA expression in kidney, muscle and heart were not different from those of rats with free access to an 18% casein diet. Nutritional rehabilitation of the protein-malnourished rats with 50% casein for 21 d significantly increased the BCAT activity and BCATm mRNA expression in muscle. Neither hydrocortisone nor glucagon injection affected BCAT activity or BCATm mRNA concentrations in rat kidney, muscle or heart. We conclude that the nutritional regulation of BCATm is extrahepatic, tissue specific and may involve transcriptional and post-translational mechanisms.

Dietary protein as a factor affecting vitamin B6 requirement.

Rats were fed 20 or 70% casein diets with varying amounts of vitamin B6 (B6), and the B6 content and B6-dependent enzymatic activity in their tissues were examined to determine the minimum requirement of B6 for animals subjected to different levels of dietary protein (i.e., 20%: 0, 1.45, 2.90, 5.80 mg pyridoxine (PN)/kg diet; 70%: 0, 2.90, 5.80, 8.70 mg PN/kg diet). B6 requirements for the rats were almost met in the 1.45 mg PN/kg 20% casein diet and the 2.90 mg PN/kg 70% casein diet when judged from the hepatic B6 content. However, almost twice the PN was required in both 20 and 70% casein diets when judged from PLP-enzymatic activity. The content of B6 vitamers in plasma appeared to be most sensitive to B6 status, though the satisfactory level is not known. It was confirmed that, in any case tested, a high-protein diet increased the requirement of B6.

Low protein diets posttranscriptionally repress apolipoprotein B expression in rat liver

In an attempt to elucidate molecular mechanisms related to low protein diet-induced fatty livers, apolipoprotein (apo) mRNA and its expression in the liver were studied in rats. Rats were fed for 14 days a diet containing 5% and 20% casein, and whey protein equivalent in protein to these caseins. In the protein-deficient groups, liver triacylglycerols elevated to 1.5–2 fold higher than did the diet sufficient groups. The mRNAs for apo A-IV, apo B and apo E were 20 to 50% lower in the deficient groups than in the sufficient groups, but apo A-I mRNA was not reduced. The rate of transcription of apo A-IV, B, and E genes in hepatic nuclei isolated from those animals was not altered with different levels of dietary protein. Apo B concentration in the serum was lowered and correlated positively with apo B mRNA abundance but the concentrations of apo IV and apo E were elevated in the deficient groups. It thus appears that a low protein diet decreases apo B synthesis through a posttranscriptional mechanism and thereby depresses secretion of triacylglycerol-rich lipoproteins from the liver.

Nitrogen Content of Manure from Older Broiler Breeders Fed Varying Quantities of Crude Protein

Two experiments attempted to evaluate the nitrogen balance of older broiler breeder hens fed different levels of dietary protein while maintaining adequate levels of limiting amino acids. The study also evaluated the relationship between the intake, retention, and output of nitrogen as well as the uric acid output of the birds. In Experiment 1 (14 to20% CP diets), nitrogen and uric acid excretion increase linearly (P < .01) with nitrogen intake. Proportional nitrogen retention decreased linearly (P < .01) with increased dietary protein. In Experiment 2 (9 to 15% CP diets), both nitrogen and uric acid excretion increased linearly (P < .05) with nitrogen intake. Also, a trend was observed of nitrogen retention (g/bird/day) increasing as dietary protein increased. Results indicate that an increase of nitrogen intake is positively correlated with nitrogen output, a finding suggesting that higher nitrogen intake does not cause higher nitrogen retention.

Transcriptional Control of Rat Hepatic Glutaminase Expression by Dietary Protein Level and Starvation ,

Mammalian liver possesses a unique isozyme of phosphate-activated glutaminase that is subject to long-term regulation. In rats during starvation or after consumption of diets containing high amounts of protein (60%), hepatic glutaminase activity was 100% higher than in rats fed a 20% protein diet. Conversely, rats fed low protein diets (0 and 5%) had lower hepatic glutaminase activity when compared with rats fed the 20% protein diet. Differences in activity with different dietary protein levels were not due to differences in the amount of food consumed. The relative abundance of mRNA encoding hepatic glutaminase was lower in rats fed 0% protein and higher in those starved or fed 60% protein diet when compared with rats fed the 20% protein diet. The mRNA elongation assay in hepatic nuclei isolated from these animals demonstrated that the rate of transcription of the glutaminase gene was also different in rats starved or fed different levels of dietary protein. Overall, the results indicate that differences in hepatic glutaminase activity in rats starved or fed different levels of protein are mainly due to differences in the rate of transcription of the gene. In this way the regulation of hepatic glutaminase expression is similar to that seen for other enzymes involved in hepatic amino acid catabolism but differs markedly from that of renal glutaminase, in which changes in transcription rate are not observed and alterations of mRNA turnover are the principle mechanism of long-term regulation.

Effects of Salbutamol, a β2-Adrenergic Agonist, on Muscles of Growing Pigs Fed Different Levels of Dietary Protein: I. Muscle Fibre Properties and Muscle Protein Accretion

Abstract Dietary inclusion of salbutamol (3 ppm), a β2-adrenergic agonist, to growing pigs fed either a normal or a high level of dietary protein from 25 to 90 kg body weight, resulted in a pronounced increase in the protein accretion rate of skeletal muscles. This effect was two-fold higher when pigs were fed the high level compared to the normal level of dietary protein (16 vs. 7%). Histochemical analysis of slow-twitch (ST) and fast-twitch fibres (FTa and FTb) of biopsy samples taken either in vivo by a biopsy needle or post mortem from M. longissimus dorsi (LD) and M. biceps femoris (BF) demonstrated an increase in the relative area of the muscles occupied by FTb fibres. This was mainly due to a reduced frequency of the smaller FTa fibres and an increased frequency of the larger FTb fibres, which indicates an FTa to FTb fibre type conversion induced by salbutamol. In BF, a reduction in the frequency of and the relative area occupied by ST fibres was also found. The changes had already occured at 45 kg...

The effect of dietary protein content on aggression and hyperactivity in dogs

Some behaviorists recommend feeding a low protein diet to aggressive and hyperactive dogs to modify this behavior. Evidence for the efficacy of this strategy has been largely anecdotal, though studies in laboratory animals are generally supportive. We investigated the effects of three different levels of dietary protein (18, 25 and 31%) on aggression, hyperactivity and fear in four groups of dogs. All diets were nutritionally complete and their energy densities were made equivalent by modifying the fat content. Groups 1-3 ( 12 dogs per group) comprised dogs with territorial aggression, dominance aggression and hyperactivity, respectively. Group 4 ( 14 dogs) was a control group of dogs whose owners did not consider them to have a behavior problem. The three diets were fed for 2 weeks each in a repeated Latin square design. The owners were unaware of the composition of any of the three diets. Each behavior was scored on a scale of 0-10, with 10 being the most severe rating. The data were entered into the Number Cruncher Statistical System (NCSS) statistical analysis system and analyzed using two-way General Linear Model (GLM) analysis of variance. Territorial aggression (in group 1 ) was most marked on the high protein ration and lowest on the low protein ration, with the dogs fed medium protein ration scoring midway between these extremes. The difference between scores for the high protein group, and medium and low protein group was significant (P< 0.035 ). Post-hoc analysis of a subset of the territorial group, those with a fear component to their territoriality, showed that these seven dogs responded dramatically and significantly to the reduction in dietary protein (P<0.0001). There was no significant change in the subset denoted territorial/ dominant (five dogs). Dominance aggression and hyperactivity were not significantly changed by the protein content of the diet in study groups 2 and 3. There were no changes in any of the behaviors in the control group with any of the diets. The reduced level of aggression in the territorial group when lower protein rations were fed was interpreted in terms of serotonin metabolism. It was hypothesized that low protein diets encouraged the formation of serotonin by facilitating L-tryptophan transfer across the blood brain barrier. Serotonin is thought to reduce the impact of aversive events, thus increased brain sero-

Effects of Salbutamol, a β2-Adrenergic Agonist, on Muscles of Growing Pigs Fed Different Levels of Dietary Protein: II. Aerobic and Glycolytic Capacities and Glycogen Metabolism of the Longissimus Dorsi Muscle

Abstract Dietary inclusion of salbutamol (3 ppm), a β2-adrenergic agonist, to growing pigs from 25 to 90 kg body weight reduced the activities of citrate synthetase (CS) (P<0.01) and 3-OH-acyl-CoA-dehydrogenase (HAD) (P<0.07) by 10 and 8%, respectively, measured on needle biopsies obtained from the fast-twitch-glycolytic longissimus dorsi muscle at 25, 45, 60 and 90 kg body weight. These reductions by salbutamol were induced at 60 kg body weight and remained unchanged. On the other hand, salbutamol did not affect the activities of lactate dehydrogenase (LDH), total glycogen synthetase (GS), the glucose-6-phosphate independent form of GS, and muscle glycogen content. The activity of LDH increased by 41% from 25 to 90 kg body weight (P<0.001), with the steepest increase from 25 to 45 kg body weight, while the activities of CS and HAD decreased by 25 (P<0.001) and 19% (P<0.001) in control animals, respectively. The total GS activity was decreased at 60 and 90 kg body weight by 24% (P<0.01), whereas the independent form of GS did not change in the body weight range examined. The glycogen content was reduced by 20% (P<0.05) at 90 kg body weight compared to the other body weights. These results indicate that salbutamol treatment decreases muscle oxidative capacity. In addition, a marked shift in the metabolic profile towards a higher glycolytic and a lower oxidative capacity occurs in the longissimus dorsi muscle during growth in pigs.

Recruitment experience in the full-scale phase of the modification of diet in renal disease study

The Modification of Diet in Renal Disease (MDRD) Study is a randomized, multicenter clinical trial testing the effects of three different levels of dietary protein and phosphorus intake and two levels of blood pressure control on the rate of loss of kidney function in persons with various chronic kidney diseases. During a 27-month recruitment period, 2507 persons who had objective evidence of impaired kidney function were screened at 15 centers. Eight hundred and forty men and women aged 18–70 with a glomerular filtration rate between 13 and 55 ml/min/1.73 m 2 were randomized. Medical record review was the primary means of identifying study participants at the beginning of recruitment. Later, use of mass media was instrumental in alerting both the public and the medical community of the need for MDRD Study participants. Overall, the most important sources of randomized participants were referral by personal physician (45.4%) and relative/friend (5.6%), and self-referral after hearing about the trial from newspapers (23.9%) and television (5.2%). Review of medical records from defined patient populations was the source of 22.3% of the randomized study participants. A total of 9.4% of the randomized participants called a toll-free (800) telephone number before contacting the centers.

Effects of dietary thyroxine on growth performance and carcass quality of broilers fed different levels of dietary protein

Effects of dietary thyroxine on growth performance and carcass quality of broilers fed different levels of dietary protein