Dietary Protein Level Research Articles

Relationship of Protein Synthesis to mRNA Levels in the Muscle of Chicks under Various Nutritional Conditions

The relationship between the rate of protein synthesis and the level of messenger RNA (mRNA) in the breast muscle (pectoralis major) was studied to examine the mechanisms regulating muscle protein synthesis in chicks under various nutritional conditions. The fractional synthesis rate (FSR) of protein was measured by a large-dose injection of L-[4-3H]phenylalanine. Poly(U)-Sepharose 4B affinity chromatography was used to extract Poly(A)+ RNA as mRNA. The first study examined the effect of dietary protein levels (0–60%) on protein synthesis rate and the contents of mRNA and total RNA. The fractional synthesis rate increased with increasing dietary protein levels from 0 to 20%. When chicks were fed high protein diets (40 and 60% of dietary protein), both the FSR and absolute synthesis rate (ASR) of protein were reduced compared with the 20% protein group. Multiple regression analysis indicated that for graded dietary protein levels below the dietary protein requirement, the response of muscle protein synthesis is largely regulated by variation in the ASR per unit RNA (the efficiency of RNA in synthesizing protein). At dietary protein levels above 20%, synthesis rates are also related to changes in the RNA:mRNA ratio (ribosome number relative to mRNA), the mRNA:DNA ratio (mRNA availability) and the DNA:protein ratio (DNA concentration). When chicks were food deprived for 2 d, FSR was reduced to about half that of well-fed controls. Upon refeeding of these chicks with the control diet, the FSR returned to the normal level within 0.5 h. When food-deprived chicks were refed with protein, carbohydrate or fat alone, the FSR returned to the control level within 0.5 h after consumption of each nutrient. The increase in muscle protein synthesis of unfed chicks following refeeding of various nutrients was explained by an increased ASR per unit RNA. Our results suggest that nutrient intake can change muscle protein synthesis rates in chicks largely by altering the ASR per unit RNA, in some cases associated also with changes in the levels of RNA, mRNA and DNA.

Vitamin B-6 Status of Women with a Constant Intake of Vitamin B-6 Changes with Three Levels of Dietary Protein

To determine the effect of varying levels of dietary protein with a constant intake of vitamin B-6 (B-6) on B-6 status, nine women were fed diets providing daily intakes of 1.25 mg B-6 and 0.5, 1.0 and 2.0 g protein/kg body weight. After an 8-d adjustment period, the women consumed each level of dietary protein for 14 d in a Latin-square design. Several direct and indirect B-6 status indicators were measured in blood and urine. Significant differences among protein levels were found for urinary 4-pyridoxic acid (4-PA) excretion (P < 0.01), plasma pyridoxal 5′-phosphate (PLP) concentration (P < 0.05), and urinary excretion of volatile amines (VA, kynurenine plus acetylkynurenine) after a 2-g L-tryptophan load (P < 0.05). Nitrogen intake was significantly negatively correlated with urinary 4-PA excretion (r = -0.619, P < 0.001) and plasma PLP concentration (r = -0.549, P < 0.01), and positively correlated with erythrocyte alanine aminotransferase percentage stimulation (r = 0.418, P < 0.05) and urinary post-tryptophan load excretion of xanthurenic acid (r = 0.535, P < 0.05), kynurenic acid (r = 0.563, P < 0.05) and VA (r = 0.626, P < 0.01). Compared with men consuming diets with similar B-6 to protein ratios in a previous study, the women excreted a greater percentage of the B-6 intake as 4-PA, had lower plasma PLP concentrations and excreted greater amounts of postload urinary tryptophan metabolites at all three protein levels. If the Recommended Dietary Allowance (RDA) of vitamin B-6 is to be based on the dietary B-6 to protein ratio, gender differences in response to varying protein intakes should be considered. For the levels of protein intake used in this study and a B-6 intake of 1.25 mg/d, a B-6 to protein ratio of greater than 0.020 mg/g is required for adequate vitamin B-6 status in women.

Energy Metabolism and Protein Balance in Growing Rats Housed in 18°C or 28°C Environments and Fed Different Levels of Dietary Protein

A study was performed to investigate the effect of environmental temperature and increasing levels of protein in the diet on visceral organ size, digestibility, protein balance and energy metabolism in rats. Thirty-six male Wistar rats, initial body weight 77–80 g, were used in a factorial design consisting of three levels of dietary protein and two environmental temperatures of either 18 or 28°C. Three fish meal-based diets were prepared to contain 91, 171 and 262 g protein (N × 6.25/kg diet). Gas-exchange measurements were made and urine and feces were quantitatively collected. The weights of the visceral organs from rats housed at 18°C were greater (P < 0.05) than those of rats housed at 28°C. The digestibilities of dry matter and protein were not affected by environmental temperature, whereas fat and energy digestibilities were higher (P < 0.05) at 18°C than at 28°C. As the level of protein was increased, the digestibilities of protein, energy and fat increased (P < 0.05). Protein intake and protein retention were higher at 18°C (P < 0.05) than at 28°C and increased (P < 0.05) as dietary protein concentration increased. Apparent biological value was lower (P < 0.05) at 18°C than at 28°C and decreased (P < 0.05) as dietary protein level increased. Heat production as a percentage of metabolizable energy was higher (P < 0.05) for the low protein diet than for the medium and high protein diets. The efficiency of energy utilization was depressed (P < 0.05) for the high protein diet when rats were kept at 28°C. The results suggest that thermogenesis was induced when low protein was fed. The increase in thermogenesis may have been important in regulating energy balance and maintaining a constant body temperature in a cold environment.

Effects of demand-feeding and dietary protein level on nitrogen metabolism and symbiont dinitrogen gas production of common carp (Cyprinus carpio, L.).

Ammonia accumulation is a major challenge in intensive aquaculture, where fish are fed protein-rich diets in large rations, resulting in increased ammonia production when amino acids are metabolized as energy source. Ammonia is primarily excreted via the gills, which have been found to harbor nitrogen-cycle bacteria that convert ammonia into dinitrogen gas (N2) and therefore present a potential in situ detoxifying mechanism. Here, we determined the impact of feeding strategies (demand-feeding and batch-feeding) with two dietary protein levels on growth, nitrogen excretion, and nitrogen metabolism in common carp (Cyprinus carpio, L.) in a 3-week feeding experiment. Demand-fed fish exhibited significantly higher growth rates, though with lower feed efficiency. When corrected for feed intake, nitrogen excretion was not impacted by feeding strategy or dietary protein, but demand-fed fish had significantly more nitrogen unaccounted for in the nitrogen balance and less retained nitrogen. N2 production of individual fish was measured in all experimental groups, and production rates were in the same order of magnitude as the amount of nitrogen unaccounted for, thus potentially explaining the missing nitrogen in the balance. N2 production by carp was also observed when groups of fish were kept in metabolic chambers. Demand feeding furthermore caused a significant increase in hepatic glutamate dehydrogenase activities, indicating elevated ammonia production. However, branchial ammonia transporter expression levels in these animals were stable or decreased. Together, our results suggest that feeding strategy impacts fish growth and nitrogen metabolism, and that conversion of ammonia to N2 by nitrogen cycle bacteria in the gills may explain the unaccounted nitrogen in the balance.

Optimal Dietary Protein Requirement of Subadult Australian Hybrid Abalone (Haliotis rubra × Haliotis laevigata) at Different Rearing Temperatures

Australian abalone aquaculture is characterised by a prolonged culture period and slow and variable growth, and abalone is cultured in fluctuating water temperatures ranging between 10 and 25°C with distinct seasons. Temperature is a crucial environmental factor influencing abalone’s physiology and energetics, leading to a change in nutritional requirements. However, feeds are generally formulated to match the nutritional requirements at their optimal temperature. Hence, there is a need to optimise dietary protein levels to match temperature-specific requirements during extreme conditions (winter and summer). Given this, a growth trial evaluating five experimental feeds consisting of graded protein inclusion levels (320, 350, 380, 410, and 440 g·kg−1) was conducted on subadult hybrid abalone (Haliotis rubra × H. laevigata) at three different temperatures reflecting winter (12°C), summer (22°C), and the annual average water temperature (17°C) for 143 days. At lower water temperature (12°C), there was a marginal improvement in growth performance as dietary protein levels increased from 320 to 440 g·kg−1. However, at higher water temperatures (when the culture water temperature is above 17°C), there was a significant improvement in growth performance as dietary protein levels increased from 320 to 440 g·kg−1 as evidenced by an improved weight gain, specific growth rate, and feed conversion ratio. Furthermore, increasing dietary protein levels did not compromise the nutritional quality of the abalone tissue at all three tested temperatures. Therefore, during periods of higher water temperatures, feeding Australian hybrid abalone with a relatively high dietary protein level (410 g·kg−1) is expected to result in improved growth, shorter culture duration, and profit maximisation.

Effects of extruded and pelleted diets with different protein levels on growth performance and nutrient retention of largemouth bass (Micropterus salmoides)

This study investigated effects of extruded diet (ED) and pelleted diet (PD) with differing dietary protein levels on growth performance and nutrient utilization in juvenile largemouth bass (LMB). Nine hundred LMB (initial body weight of 6.47 ± 0.1 g)were fed for eight weeks in five levels of crude protein (40%, 44%, 48%, 52% and 56%) with pelleting or extruding processing technology. The results showed the weight gain (WG, 380.65%), apparent digestibility of crude protein (ADCP, 55.76%), dry matter (DM, 89.70%) and whole-body crude protein (66.32%) of LMB fed with ED52 group were significantly higher than those of other groups (P < 0.05), and FCR (0.96) was lowest. The WGmax was obtained when dietary protein level was 51.6% in ED. Activities of digestive enzymes in liver of LMB fed ED groups were generally higher than those fed PD groups. In addition, lipase, tryptase and α-amylase activities were at higher values between ED48 to ED56. The levels of total cholesterol and triglycerides in serum of LMB were lowest at ED52 group. The liver glycogen content, GLUT1, P-GSK-3β and GYS2 gene expression level in ED groups were significantly higher than those of in PD groups at same protein level (P < 0.05), and the gene expression levels of LMB were lowest in ED52 group. However, the gene expression levels in ED56 group were significantly higher than those of the other groups (P < 0.05). These results indicated that juvenile LMB achieve maximum growth when fed diet for ED at 51.6% protein level.

The impact of early and mid-pregnant Hu ewes’ dietary protein and energy levels on growth performance and serum biochemical indices

ABSTRACT This study explored the effects of different protein and energy levels on growth performance and serum biochemical indices of ewes during early and mid-pregnancy. A total of 132 ewes were assigned to 5 groups (P1, P2 = E2, P3, E1, E3) to dietary protein levels (P1: 9.22%, P2: 10.04%, P3: 10.86%) and dietary energy levels (E1: 9.04 MJ/kg, E2: 9.53 MJ/kg, E3: 10.02 MJ/kg). Blood urea nitrogen (BUN) increased with an increase in protein levels in early pregnancy (P = .008). In the P2 group, creatinine, triglyceride, and lactate levels were lowest and total protein levels were highest in mid-pregnancy (P < .05). Final weight, total weight gain, and average daily weight gain increased with an increase in energy levels of ewes (P < .05). BUN, aspartate transaminase, cholesterol, and high-density lipoprotein decreased with an increase in energy levels in mid-pregnancy (P < .05). Alanine aminotransferase, lactate dehydrogenase, and glucose increased initially and then decreased with an increase in energy levels (P < .05). To sum up, we suggest that Hu sheep be fed diets with energy and protein levels of 10.02 MJ/kg and 10.04% in early and mid-pregnancy, respectively.

Impact of protein supply on the productive performance of growing lambs drinking natural saline water and fed low-quality forage under semi-arid conditions

Consuming saline water causes animals salinity stress, which leads to many adapting metabolic changes that could negatively affect its performance and the quality of the derived products. Therefore, this study aimed to evaluate the impact of increasing diet protein level on the productive performance of growing lambs drinking natural saline water in Egyptian semi-arid region. Twenty-four growing Barki lambs (4–5 months old) with an initial body weight of 20.7 ± 0.25 kg were randomly distributed into four similar groups for 150 days. Two diets were formulated: low protein and high protein levels (concentrate feed mixture containing 14% and 20% crude protein (CP) on dry matter basis, respectively). Within each level of CP, natural saline water was represented by low saline (LS) and high saline (HS) water, containing 658 and 2100 mg/L of total dissolved solids, respectively. Results showed that the HS water increased (p = 0.02) water intake by about 18% and had adverse effect (p < 0.001) on dry matter intake, nutrient digestibility, and growth performance. The ruminal pH values, total volatile fatty acids, and ammonia–N concentrations were not affected by drinking the HS water. However, the protein supplementation enhanced the HS lambs’ nutrients digestion and showed greater growth performance. The HS water decreased (p < 0.001) the serum concentrations of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and increased (p = 0.03) the urea-N by about 9%. The protein supplementation amended the serum ALT and AST concentrations of HS lambs. It is concluded that the dietary protein supply was affective sustainable management strategy against the deleterious effect of drinking high saline water on growing lambs.

Elevation in Rearing Temperature within Optimum Range Mitigate Immunosuppressive and Metabolic Stress Effect of High or Low Dietary Protein Level in Labeo Rohita Fingerlings

In the present study, Labeo rohita fingerlings were maintained either at ambient water temperature (26ºC) for five weeks or exposed to 32ºC for one week then later maintained at 26ºC for four weeks. Fingerlings reared under different temperature regimes were fed with any of the four experimental diets containing 20, 30, 40 or 45% protein. Serum cortisol level was higher at 26ºC compared to 32ºC, and decrease with the increase in dietary protein level up to 40%. Fingerlings fed 30% and 40% protein recorded similar WBCS count and respiratory burst activity which was lower and higher respectively compared to 20% and 45% protein fed fingerlings. Correspondingly, lower WBCS count and higher NBT were recorded following exposure to higher temperature (32ºC) for one week compared to 26ºC exposure group. Significantly lower survival was recorded in groups fed with lowest (20%) and highest (45%) dietary protein level whereas fingerlings exposed to 32ºC for one week exhibited higher survival (%) compare to 26ºC. Present results indicate that both lower and higher level of dietary protein may cause metabolic stress to fingerlings, as might consequently lead to the depressed immunity and exposure of elevated temperature (32ºC) for one week mitigates this immunosuppressive effect.

Effects of Different Dietary Protein Level on Growth Performance, Rumen Fermentation Characteristics and Plasma Metabolomics Profile of Growing Yak in the Cold Season.

This experiment was aimed to compare the effects of two diets with different protein content on the growth performance, immune indexes, rumen fermentation characteristics and plasma metabolomics of growing yak in the cold season. A total of 24, 2-year-old healthy yaks with similar body weight (142.9 ± 3.56 kg) were randomly allocated to two isoenergetic diets with different protein content (10 vs 14%) according to a non-paired experimental design, and the protein of the diets was increased by increasing soybean meal, rapeseed meal and cottonseed meal. The growth performance experiment lasted 56 days. Four days before the end of the growth experiment, the digestion trial was conducted, and the rumen fluid and plasma was collected for measurement. The results showed that the average daily feed intake (p < 0.001) and average daily gain (p = 0.006) of yak fed a high-protein diet was significantly greater, while the feed conversion ratio was lower (p = 0.021) than that of yaks fed a low-protein diet. Plasma aspartate aminotransferase (p = 0.002), alanine aminotransferase (p < 0.001), malondialdehyde (p = 0.001), tumor necrosis factor-α (p = 0.032) and interferon-γ (p = 0.017) of the high-protein group were significantly lesser, whereas superoxide dismutase (p = 0.004) and interleukin-2 (p = 0.007) was significantly greater than that of the low-protein group. The rumen microbial crude protein (p < 0.047) and crude protein digestibility (p = 0.015) of yak fed a high-protein diet was significantly greater than that of the low-protein group. The metabolomics results showed that yaks fed a high-protein diet were elevated in protein digestion and absorption, arginine and proline metabolism, tryptophan metabolism, purine metabolism, butanoate metabolism, taste transduction, pyrimidine metabolism, pantothenate and CoA biosynthesis, glutathione metabolism and renin secretion pathways. It is concluded that a high-protein diet in the cold season can promote rumen microbial crude protein synthesis, enhance antioxidant and immune function and promote growth performance of yaks.

Dietary β-Hydroxy-β-Methylbutyrate Supplementation Affects Growth Performance, Digestion, TOR Pathway, and Muscle Quality in Kuruma Shrimp (Marsupenaeus japonicas) Fed a Low Protein Diet.

An 8-week feeding trial was performed to evaluate the effects of dietary β-hydroxy-β-methylbutyrate (HMB) supplementation on growth performance and muscle quality of kuruma shrimp (Marsupenaeus japonicas) (initial weight: 2.00 ± 0.01 g) fed a low protein diet. The positive control diet (HP) with 490 g/kg protein and negative control diet (LP) with 440 g/kg protein were formulated. Based on the LP, 0.25, 0.5, 1, 2 and 4 g/kg β-hydroxy-β-methylbutyrate calcium were supplemented to design the other five diets named as HMB0.25, HMB0.5, HMB1, HMB2 and HMB4, respectively. Results showed that compared with the shrimp fed LP, the HP, HMB1 and HMB2 groups had significantly higher weight gain and specific growth rate, while significantly lower feed conversion ratio (p < 0.05). Meanwhile, intestinal trypsin activity was significantly elevated in the above three groups than that of the LP group. Higher dietary protein level and HMB inclusion upregulated the expressions of target of rapamycin, ribosomal protein S6 kinase, phosphatidylinositol 3-kinase, and serine/threonine-protein kinase in shrimp muscle, accompanied by the increases in most muscle free amino acids contents. Supplementation of 2 g/kg HMB in a low protein diet improved muscle hardness and water holding capacity of shrimp. Total collagen content in shrimp muscle increased with increasing dietary HMB inclusion. Additionally, dietary inclusion of 2 g/kg HMB significantly elevated myofiber density and sarcomere length, while reduced myofiber diameter. In conclusion, supplementation of 1-2 g/kg HMB in a low protein diet improved the growth performance and muscle quality of kuruma shrimp, which may be ascribed to the increased trypsin activity and activated TOR pathway, as well as elevated muscle collagen content and changed myofiber morphology caused by dietary HMB.

Impact of Various Dietary Protein Levels on the Growth Performance, Nutrient Profile, and Digestive Enzymes Activities to Provide an Effective Diet for Striped Catfish (Pangasius Hypophthalmus)

The present study was conducted to evaluate the effect of different dietary protein levels on digestive enzyme activities, nutrient assimilation as well as growth performance in striped catfish (Pangasianodon hypophthalmus). Fish were fed with four semi-purified formulated diets with increasing levels of protein: 30% (CP30), 35% (CP35), 40% (CP40) and 45% (CP45) for 12 weeks. At the end of the feed trial, the highest weight gain (29.88 g fish-1), specific growth rate (3.58%) and lower feed conversion ratio (1.91) were observed in fish that were fed with a 40% protein diet while CP30 treatment group had the poorest growth performance indicators (P&lt;0.05). Proximate analysis revealed that fish fed with either CP40 (18.50%) or CP45 (19.33%) diets had the highest protein content in comparison to that fed CP30 (17.13%) and CP35 (17.00%) diets. Similarly, the highest body lipid content was CP35 (4.20%) treatment group and the lowest in CP40 (3.83%). The amino acid in the harvested fillets was also significantly higher (P&lt;0.05) in both CP40 and CP45 dietary treatments. The increasing dietary protein level also elevated both protease and amylase activity, while lipase activity significantly decreased (P&lt;0.05). The study revealed that a 40 % protein level diet produced from regional ingredients in the Middle East had yielded optimal growth performance and higher muscle quality in striped catfish.

Intermittent Protein Diets Alter Hepatic Lipid Accumulation by Changing Tryptophan Metabolism in a Fast-Response Manner.

In modern life, the fluctuation of dietary protein levels is common, in particular, for low-income populations. However, its effect on human health is little known. Alternating changes of low and high casein or pork protein were used to simulate the fluctuation of dietary protein content in mice. Hepatic lipid accumulation showed a fast response to alternating changes of low- and high-protein diets. Correspondingly, some gut microbiota and tryptophan metabolite composition also showed a fast response to dietary protein changes. The fast response of 3-hydroxykynurenine (3-HK) was proven to inhibit hepatic lipid accumulation in vitro. Therefore, intermittent protein diets modulated hepatic lipid accumulation through 3-HK. These findings highlighted the sensitivity of hepatic lipid accumulation to dietary protein levels.

Interaction between SIDT2 and ABCA1 Variants with Nutrients on HDL-c Levels in Mexican Adults.

Previous studies have reported that the SIDT2 and ABCA1 genes are involved in lipid metabolism. We aimed to analyze the association-the gene x gene interaction between rs17120425 and rs1784042 on SIDT2 and rs9282541 on ABCA1 and their diet interaction on the HDL-c serum levels-in a cohort of 1982 Mexican adults from the Health Workers Cohort Study. Demographic and clinical data were collected through a structured questionnaire and standardized procedures. Genotyping was performed using a predesigned TaqMan assay. The associations and interactions of interest were estimated using linear and logistic regression. Carriers of the rs17120425-A and rs1784042-A alleles had slightly higher blood HDL-c levels compared to the non-carriers. In contrast, rs9282541-A was associated with low blood HDL-c levels (OR = 1.34, p = 0.013). The rs1784042 x rs9282541 interaction was associated with high blood HDL-c levels (p = 3.4 × 10-4). Premenopausal women who carried at least one rs17120425-A allele and consumed high dietary fat, protein, monounsaturated, or polyunsaturated fatty acids levels had higher HDL-c levels than the non-carriers. These results support the association between the genetic variants on SIDT2 and ABCA1 with HDL-c levels and suggest gene-gene and gene-diet interactions over HDL-c concentrations in Mexican adults. Our findings could be a platform for developing clinical and dietary strategies for improving the health of the Mexican population.

Dietary Protein Levels Modulate the Antioxidant Capacity during Different Growth Stages in Huanjiang Mini-Pigs.

Adequate crude protein (CP) levels in diets play potential roles in swine production. This study determined the impacts of different CP levels on the antioxidant capacity of pigs during different body weight (BW) stages. Three hundred and sixty Huanjiang mini-pigs were allocated to one of three independent experiments, including a 5-10 kg BW group, where CP levels included 14%, 16%, 18%, 20%, and 22%; a 10-20 kg BW group, where CP levels included 12%, 14%, 16%, 18%, and 20%; and a 20-30 kg BW group, where CP levels included 10%, 12%, 14%, 16%, and 18%. These independent experiments were conducted for 28, 28, and 26 days, respectively. Results showed that the 20% CP level increased (p &lt; 0.05) the plasma CAT and GSH-Px activities and the GSH concentration of pigs than in the pigs supplemented with the 14-18% CP levels, and the 20% CP level up-regulated (p &lt; 0.05) the ileal oxidative stress-related gene expression levels of pigs than in the pigs supplemented with the 14% CP level at the 5-10 kg BW. In addition, diets supplemented with 18% CP level increased (p &lt; 0.05) the ileal GSH concentration of pigs than in the pigs supplemented with the 14% and 20% CP levels, and the 16-18% CP levels increased (p &lt; 0.05) the jejunal SOD activity of pigs than in the pigs supplemented with the 14% CP level. At 10-20 kg BW, the 16% CP level presented the strongest jejunal and ileal antioxidant capacity, the 18% CP level had the lowest plasma concentrations of MDA and highest GSH, and the 14-16% CP levels increased the plasma CAT and SOD activities (p &lt; 0.05). Moreover, the 16-20% CP levels up-regulated (p &lt; 0.05) the oxidative stress-related gene expression levels. At 20-30 kg BW, diets supplemented with the 16% CP level increased the plasma CAT activity of pigs than in the pigs supplemented with the 12-14% CP levels, and the 14-16% CP levels decreased the MDA concentration compared with the 10% CP levels (p &lt; 0.05). In conclusion, these findings indicate adequate CP levels of 20%, 16%, and 14% for Huanjiang mini-pigs at the 5-10, 10-20, and 20-30 kg BW stages, respectively.

Growth performance and carcass traits of indigenous Nigerian guinea fowl fed on different dietary protein levels.

This work examined the results of different dietary protein levels on indigenous Nigerian guinea fowl growth performance and carcass yield. One hundred and eight unsexed indigenous keets were randomly assigned to three treatments with experimental diets containing 22%, 24%, and 26% crude protein (CP) in a completely randomized design, with 3 replicates with 12 keets in each replicate. The parameters were measured, including proximate composition, feed intake, growth rate, feed conversion ratio (FCR), and carcass yield. The birds fed diets containing 24% CP gained the most body weight at 619.83 gm and had the highest FCR of 3.45. The presence of CP had an impact that was significant (p < 0.05) on most carcass traits and prime cuts but not on gastrointestinal tract weight, head weight, dress percentage, or organ yield. The study concluded that the dietary CP level of 24% was optimal for body weight gain and carcass yield.

Effect of dietary protein and lipid levels on growth performances and digestive enzymes activities in grouper (Epinephelus coioides)

This study investigates the effect of dietary protein and lipid levels on growth and digestive enzymes activities in grouper (Epinephelus coioides). Furthermore, grouper juveniles (8.63±0.47 g) were separated into ten groups and cultivated in a 100-L tank. Five groups were fed in different protein levels of 35, 40, 45, 50, and 55% protein, while the remaining were fed in different lipid levels of 6, 8, 10, 12, and 14% lipid. All experimental diets were mixed with 1.0% Sauropus androgynus extract. The fishes were sampled for digestive enzyme activities at 1, 4, and 7 days. The results showed that fish receiving 55% protein affected the growth and increased the activities of protease, lipase, carboxypeptidase A (CPA), and carboxypeptidase B (CPB). Liver tissue included higher levels of lipase, as well as carboxypeptidase A and B, while digestive tract tissue contained measurable levels of protease. In conclusion, the administration of grouper juveniles with S. androgynus extract can affect growth performances and increase digestive enzyme activities.

Effect of feeding low protein diets supplemented with selected essential amino acids on growth performance and gut health in early weaned Large White Yorkshire piglets

A study was conducted to assess the effect of feeding low protein diets supplemented with selected amino acids on growth performance and gut health in early weaned Large White Yorkshire piglets. Thirty Large White Yorkshire female piglets belonging to Centre for Pig Production and Research, Mannuthy, weaned at 21 days of age were allotted to three dietary treatment groups (T1, T2 and T3) with five replicates for each treatment. Piglets were fed pre-starter ration till they gained a body weight of 5 kg and then on starter ration from 5 to 18 kg body weight. The dietary protein in treatments T2 and T3 were reduced by 15 and 25 per cent respectively than that of control treatment (T1). Five amino acids viz., lysine, methionine, threonine, valine and isoleucine were supplemented to all treatment groups to meet the requirements as per NRC (1998). Body weights of animals were taken at weekly intervals. There was no significant difference in average body weight among three treatment groups from first to third week. From fourth to eleventh week, the average weekly body weight of T1 was significantly higher than T3. The average daily gain was significantly different among three treatment groups with highest values observed for group T1, followed by T2 and T3. The feed conversion efficiency was statistically similar among treatment groups. Total viable count and coliform count were significantly lower in the faeces of piglets fed with low protein diets, indicating a reduction in microbial population in faeces of piglets in relation to reduction in dietary protein level. From the overall results, it could be concluded that reducing the dietary protein levels had resulted in reduced growth performance in early weaned piglets, in spite of being supplemented with selected essential amino acids

Анализ научных исследований по кормлению крольчих в России и за рубежом

Rabbit industry, being an advanced and highly profitable branch of animal industry, is one of the business barometers for a country. Though 78,5 % of rabbit meat is produced in Russia is produced by individual farmers, intensity of industrial rabbit breeding is growing. Feeding management underlies any branch of animal industry, since the cost of feeding takes 60–70 % of all branch expenses, and, what is more, over 90 % of animals diseases are the result of the errors in their feeding. At the end of 2020, rabbit meat production in Russia amounted to 19,6 thousand tons. During the 2016–2020 period it increased by 8 %. All over the world, scientists pay special attention to the nutrient and energy requirements of rearing, pregnant and lactating rabbits, since just these animals determine the reproduction process and, finally, production output. The review analyzes the results of scientific research on feeding rabbits during the reproduction period with complete granular compound feeds with different ratios of nutrients and energy. The authors note that the digestible energy and protein levels of the pregnant rabbit diets in Russian and foreign experiments are the same, while the fiber level differs significantly. Since researchers all over the world are concerned about the same problems of optimizing the rabbit feeding, the joint discussion of research results, especially when the scientists belong to different scientific schools, opens up new horizons for achieving goals and practical use of the new knowledge gained.

Quantifying the Contributions of Environmental Factors to Prostate Cancer and Detecting Risk-Related Diet Metrics and Racial Disparities.

The relevance of nongenetic factors to prostate cancer (PCa) has been elusive. We aimed to quantify the contributions of environmental factors to PCa and identify risk-related diet metrics and relevant racial disparities. We performed a unique analysis of the Diet History Questionnaire data of 41 830 European Americans (EAs) and 1282 African Americans (AAs) in the PLCO project. The independent variables in the regression models consisted of age at trial entry, race, family history of prostate cancer (PCa-fh), diabetes history, body mass index (BMI), lifestyle (smoking and coffee consumption), marital status, and a specific nutrient/food factor (X). P < .05 and a 95% confidence interval excluding zero were adopted as the criteria for determining a significant difference (effect). We established a priority ranking among PCa risk-related genetic and environmental factors according to the deviances explained by them in the multivariate Cox-PH regression analysis: age > PCa-fh > diabetes ⩾ race > lifestyle ⩾marital-status ⩾BMI > X. We confirmed previous studies showing that (1) high protein and saturated fat levels in diet were related to increased PCa risk, (2) high-level supplementary selenium intake was harmful rather than beneficial for preventing PCa, and (3) supplementary vitamin B6 was beneficial for preventing benign PCa. We obtained the following novel findings: high-level organ meat intake was an independent predictor for increased aggressive PCa risk; supplementary iron, copper and magnesium increased benign PCa risk; and the AA diet was "healthy" in terms of the relatively lower protein and fat levels and was "unhealthy" in that it more commonly contained organ meat. In conclusion, we established a priority ranking among the contributing factors for PCa and identified several risk-related diet metrics and the racial disparities. Our findings suggested some new approaches to prevent PCa such as restriction of organ meat intake and supplementary microminerals.