Dietary Protein Requirement Research Articles

Effects of Maternal Low-Protein Diet on Microbiota Structure and Function in the Jejunum of Huzhu Bamei Suckling Piglets.

Simple SummaryIn mammals, the intestine is the main organ where nutrients are digested and absorbed, thus serving a central role in the growth and health of animals. Low-protein diets are based on the “ideal amino acid” theory, where AA crystals are added to ensure the amino acid balance of the diet. As a result, the amino acid nutritional needs of piglets are reduced along with the total protein level of the diet as well as the metabolic burden of piglets. This typically results in reduced diarrhea and improved gut health. In this study, the microbial composition and function of jejunum chyme samples were analyzed from 30 Huzhu Bamei suckling piglets from sows fed diets with different protein levels via16S rRNA sequencing and bioinformatics. This work provides a theoretical basis for the production of low-protein diets for use in the production of Bamei pigs.The jejunum is the primary organ for digestion and nutrient absorption in mammals. The development of the jejunum in suckling piglets directly affects their growth performance post-weaning. The jejunum microbiome plays an important role in proliferation, metabolism, apoptosis, immune, and homeostasis of the epithelial cells within the organ. The composition and diversity of the gut microbiome is susceptible to the protein composition of the diet. Therefore, the effects of maternal low-protein diets on piglets’ intestinal microbial structure and function have become a hot topic of study. Herein, a maternal low-protein diet was formulated to explore the effects on jejunum microbiome composition and metabolic profiles in Bamei suckling piglets. Using 16S ribosomal RNA (16S rRNA) sequencing in conjunction with bioinformatics analysis, 21 phyla and 297 genera were identified within the gut microflora. The top 10 phyla and 10 genera are within the gut bacteria. Next, KEGG analysis showed that the low-protein diet significantly increased the gut microbial composition, transport and catabolism, immune system, global and overview maps, amino acid metabolism, metabolism of cofactors and vitamins, endocrine system, biosynthesis of other secondary metabolites, signal transduction, environmental adaptation, and cell motility. Taken together, low-protein diets do not appear to affect the reproductive performance of Bamei sows but improved the gut microbiome of the suckling piglets as well as reduced the probability of diarrhea. The data presented here provide new insights on the dietary protein requirements to support the Huzhu Bamei pig industry.

Effect of dietary valine supplementation to low protein diets on performance, intestinal morphology and immune responses in broiler chickens

The current trial was conducted to study effects of dietary valine (Val) supplementation in low crude protein (CP) diets on performance, gut development and immune responses in broiler chickens. A total of 540 day-old broiler chicks (Ross 308) were assigned to 6 dietary treatments, comprising 6 replicates of 15 birds based on a factorial arrangement of treatments (2 × 3) in a completely randomized design during 1–12, 12–24 and 24–42 days of experiment. Dietary treatments included 3 diets with 100% (CP100; starter:217 g/kg, grower: 200 g/kg, finisher: 180 g/kg), 90% (CP90; starter: 195.3 g/kg, grower: 180 g/kg, finisher: 162 g/kg) and 85% (CP85; starter: 184.5 g/kg, grower: 170 g/kg, finisher: 153 g/kg) of dietary crude protein requirement of Ross 308 broiler chickens each supplemented with or without Val. Valine was supplemented to CP85 and CP90 diets in order to fulfill Val requirement of Ross 308 broiler chickens in which CP85 contained 9 g/kg digestible Val in starter, 7.9 g/kg digestible Val in grower and 7.1 g/kg digestible Val in finisher periods and CP90 contained 9 g/kg digestible Val in starter, 7.9 g/kg digestible Val in grower and 7.1 g/kg digestible Val in finisher periods. However, Val supplemented to CP100 with equal magnitude supplemented to CP90 in order to offer chickens with Val beyond their requirement. (starter: 9.9 g/kg digestible Val; grower: 8.7 g/kg digestible Val; finisher: 7.9 g/kg digestible Val). Supplemental Val could restore the compromising effect of CP85 and CP90 on growth of broilers during starter and growing phases equal to broilers received CP100 (P < 0.05) while failed to ameliorate growth of broilers during the finishing and entire rearing periods. Supplementation of Val in low CP diets improved breast yield of broilers compared to those fed on CP90 and CP85 diets (P < 0.05). Villus height to crypt depth ratio was higher in broilers received diets supplemented with Val in low CP diets than those fed on CP100 (P < 0.05). Total serum antioxidant activity decreased in broilers fed with CP90 compared to those received CP100 (P < 0.05) whereas Val supplementation could not ameliorate the impaired serum antioxidant activity compared to CP100 (P < 0.05). In conclusion, dietary Val supplementation could decrease negative effect of feeding low CP diets in broiler chickens through the beneficial effect on protein accretion and intestinal morphology while failed to improve immune responses.

Evaluation of dietary protein requirement for the growth performance of minor carp,Cirrhinus reba(Hamilton, 1822) fingerlings

An experiment was designed to evaluate the requirement of dietary protein for Reba carp, Cirrhinus reba fingerlings using semi-purified diet. Five isocaloric diets were prepared containing 20%, 25%, 30%, 35% and 40% level of protein using casein, gelatin as a major protein source. The experiment was conducted for 105 days in triplicates to evaluate the growth, survival, feed utilization, carcass composition of C. reba. Mean weight gain was highest (p < .05) in T3. Specific growth rate was highest in T3 and lowest in T1. Similarly, significantly (p < .05) highest net fish yield were recorded in T3. No significant difference was recorded in survivability. Feed conversion ratio, protein efficiency ratio, feed conversion efficiency and protein conversion efficiency were significantly (p < .05) higher for T3 compared with other treatments. Highest carcass protein and lipid values were recorded in T3. So, conclusion can be drawn that 30% crude protein is optimum for overall performance. Furthermore, broken-line analysis for specific growth rate, final biomass and net fish yield indicated that dietary protein level of 28.148 to 28.253% is optimum for the best growth performance of fingerling C. reba.

Dietary protein requirement of Indian Butter catfish, Ompok bimaculatus (Bloch) fingerlings

ABSTRACTA 60-d feeding trial was conducted to assess the dietary protein requirement of Indian Butter catfish, Ompok bimaculatus fingerlings. Five iso-energetic semi-purified diets were formulated with varying levels of crude protein (25–45%) and fed to the experimental fish (3.29 ± 0.01 g) twice daily at satiation level in triplicate groups. Fishes were reared in indoor tanks with a stocking density of 11 fingerlings per tank. The results showed that the growth of the fish increased significantly (P < .05) with increasing protein levels upto 35% and decreased thereafter. Highest (P < .05) weight gain (247.25 ± 5.76%), carcass protein content (16.78 ± 0.04%) and protease activity (0.46 ± 0.02) coupled with lowest FCR (1.62 ± 0.04) were observed in the fish fed with 35% protein. PER and ANPR were found to decrease with increasing dietary protein levels (P < .05). Based on the second-order polynomial regression analysis of WG, it may be concluded that the dietary protein requirement of O. bimaculatus is 36.11% with a P/E ratio of 23.11 g protein MJ−1 as indicated by the maximum growth.

Low-Carbohydrate Training Increases Protein Requirements of Endurance Athletes.

Training with low-carbohydrate (CHO) availability enhances markers of aerobic adaptation and has become popular to periodize throughout an endurance-training program. However, exercise-induced amino acid oxidation is increased with low muscle glycogen, which may limit substrate availability for postexercise protein synthesis. We aimed to determine the impact of training with low-CHO availability on estimates of dietary protein requirements. Eight endurance-trained males (27 ± 4 yr, 75 ± 10 kg, 67 ± 10 mL·kg body mass·min) completed two trials matched for energy and macronutrient composition but with differing CHO periodization. In the low-CHO availability trial (LOW), participants consumed 7.8 g CHO·kg before evening high-intensity interval training (10 × 5 min at 10-km race pace, 1 min rest) and subsequently withheld CHO postexercise (0.2 g·kg). In the high-CHO availability trial (HIGH), participants consumed 3 g CHO·kg during the day before high-intensity interval training, and consumed 5 g CHO·kg that evening to promote muscle glycogen resynthesis. A 10-km run (~80% HRmax) was performed the following morning, fasted (LOW) or 1 h after consuming 1.2 g CHO·kg (HIGH). Whole-body phenylalanine flux and oxidation were determined over 8 h of recovery via oral [C]phenylalanine ingestion, according to standard indicator amino acid oxidation methodology, while consuming sufficient energy, 7.8 g CHO·kg·d, and suboptimal protein (0.93 g·kg·d). Fat oxidation (indirect calorimetry) during the 10-km run was higher in LOW compared with HIGH (0.99 ± 0.35 g·min vs 0.60 ± 0.26 g·min, P < 0.05). phenylalanine flux during recovery was not different between trials (P > 0.05) whereas phenylalanine oxidation (reciprocal of protein synthesis) was higher in LOW compared with HIGH (8.8 ± 2.7 μmol·kg·h vs 7.9 ± 2.4 μmol·kg·h, P < 0.05), suggesting a greater amino acid requirement to support rates of whole-body protein synthesis. Our findings suggest that performing endurance exercise with low-CHO availability increases protein requirements of endurance athletes.

Zebra Balığının (Dania rerio) Diyetsel Protein Gereksinimi

Zebrafish (Danio rerio) with an initial weight of 88.61±0.82 mg were fed eight isoenergetic diets containing dietary protein levels ranging from 20 to 55 % by 5 % increments. Each diet was feed in triplicate of fish for 6 weeks. Specific growth rates (SGR) at week 2 and 4 were quadratically affected by the treatments but this trend disappeared at the end of the experiment. Dietary protein levels linearly reduced the values of daily feed intake, feed conversion ratio and protein efficiency rate. The whole body dry matter, ash and lipid concentrations linearly decreased with dietary protein levels whereas whole body protein was quadratically affected. The second order polynomial and two break point linear models (TBPLM) were used to estimate dietary protein requirements. The later model generated lower residual sum of squares when SGRWeek4 and SGRFinal valueswere used as a response. Minimum dietary protein requirements for SGRWeek4 and SGRFinal were estimated by the TBPLM as 27.69 and 28.93 % respectively. Briefly, results of the study suggest a minimum dietary protein requirement of zebrafish is about 29 % for maximum growth rate.

Protein nutrition on sub-adult triploid rainbow trout (1): Dietary requirement and effect on anti-oxidative capacity, protein digestion and absorption

An 80-day feeding trial was conducted to assess the dietary protein requirement of sub-adult triploid rainbow trout (initial average weight: 233 g). Six isolipidic and isoenergetic diets were formulated to contain increasing levels of protein (31.6, 35.4, 40.7, 43.3, 45.8 and 52.4%). Each diet was fed to quadruplicate groups of fish (100 fish per group) in freshwater cages. Results showed that weight gain rate (WGR), protein gain, whole-body protein content, trypsin and chymotrypsin specific activities in intestine significantly (P < 0.05) increased with increasing dietary protein level and then plateaued (P > 0.05). Protein retention, protein efficiency ratio (PER), lipase in pyloric caeca and amylase specific activities significantly (P < 0.05) decreased with increasing dietary protein level. Fish fed the diet with 45.8% protein had higher feed efficiency (FE) and higher enteric peptide transporter 1 (Pep T1) gene expression level. Generally, fish fed diets with low dietary protein levels had lower feed intake (FI), higher hepatosomatic index (HSI), higher plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities, higher hepatic glutamate dehydrogenase (GDH) activity, as well as higher malondialdehyde (MDA) contents in plasma, liver and intestine and lower total anti-oxidative capacity (T-AOC) contents in plasma and intestine (P < 0.05). Based on WGR, the optimum dietary protein requirement of sub-adult triploid rainbow trout was 45.8% dry matter with a diet containing 20% lipid and 22 kJ gross energy/g. This optimal dietary protein level improved the digestive and absorptive abilities of rainbow trout. Diets with lower protein levels (31.6–35.4%) led to increase lipid peroxidation level in whole fish body, while the diet with excess protein (52.4%) appeared to limit enteric Pep T1gene expression level.

Optimization of Dietary Protein and Energy Requirement of Kadaknath Chicken During the Starter Phase

Optimization of Dietary Protein and Energy Requirement of Kadaknath Chicken During the Starter Phase

Dietary protein affects both the dose and pattern of insulin delivery required to achieve postprandial euglycaemia in Type 1 diabetes: a randomized trial.

To quantify the insulin requirement for a high-protein meal compared with a low-protein meal, controlling for carbohydrate and fat content. In this crossover study, young people with Type 1 diabetes were randomized to consume a high- (60 g) or low-protein meal (5 g), each containing 30 g carbohydrate and 8 g fat. A variation of the insulin clamp technique was used to determine the insulin requirements to maintain euglycaemia for the following 5 h. A total of 11 participants (mean ± sd age 16.5 ± 2.7 years, HbA1c 52 ± 8.7 mmol/mol [6.9 ± 0.8%], diabetes duration 6.9±5.1 years) completed the study. The mean insulin requirements for the high-protein meal were higher than for the low-protein meal [10.3 (CI 8.2, 12.57) vs 6.7 units (CI 4.7, 8.8); P=0.001], with inter-individual requirements ranging from 0.9 to six times the low-protein meal requirement. Approximately half the additional insulin [1.1 units/h (CI 0.5, 1.8; P=0.001)] was given in the first 2 h, compared with an additional 0.5 units/h (CI -0.2, 1.2; P=0.148) in the second 2 h and 0.1 units (CI -0.6, 0.8; P=0.769) in the final hour. A high-protein meal requires ~50% more insulin to maintain euglycaemia than a low-protein meal that contains the same quantity of carbohydrate. The majority is required within the first 2 h. Inter-individual differences exist in insulin requirements for dietary protein.

Indicator amino acid oxidation protein requirement estimate in endurance-trained men 24 h postexercise exceeds both the EAR and current athlete guidelines

Despite studies indicating increased protein requirements in strength-trained or endurance-trained (ET) individuals, the Institute of Medicine has concluded that "no additional dietary protein is suggested for healthy adults undertaking resistance or endurance exercise," and the controversy regarding exercise effects on protein requirements continues. The objective of this study was to determine the dietary protein requirement of healthy young ET men (≥1 yr training experience) 24 h post exercise (to minimize any acute effects of the previous training session) by measuring the oxidation of ingested l-[1-13C]phenylalanine to 13CO2 in response to graded intakes of protein (indicator amino acid oxidation technique). Eight men [maximal oxygen consumption 64.1 ml·kg-1·min-1 (SD 3.7)] were each studied 24 h postexercise repeatedly with protein intakes ranging from 0.3 to 3.5 g·kg-1·day-1. Protein was fed as an amino acid mixture based on the protein pattern in egg, except for phenylalanine and tyrosine, which were maintained at constant amounts across all protein intakes. For 2 days before the study day, all participants consumed 1.6 g protein·kg-1·day-1. The estimated average requirement (EAR) for protein was determined by applying a nonlinear mixed-effects change-point regression analysis to F13CO2 (label tracer oxidation in 13CO2 breath), which identified a breakpoint in the F13CO2 in response to the graded amounts of protein. The EAR for protein and the upper 95% confidence interval were 2.1 and 2.6 g·kg-1·day-1, respectively. These data suggest that the protein EAR for ET men 24 h postexercise exceeds the Institute of Medicine EAR and established athlete guidelines by ~3.5- and 1.3-fold, respectively.

Effects of dietary protein levels on growth, feed utilization and expression of growth related genes of juvenile giant grouper (Epinephelus lanceolatus)

A 6-week growth trial was conducted to study the effects of dietary protein levels on growth, feed utilization, ammonia excretion and expression of growth related genes of juvenile giant grouper (Epinephelus lanceolatus). Seven experimental diets were formulated to contain 38% (P38), 42% (P42), 46% (P46), 50% (P50), 54% (P54), 58% (P58) or 62% (P62) dietary crude protein (CP) (dry-matter basis). Experimental fish (average initial body weight: 5.39 ± 0.05 g) were randomly distributed into 21 glass tanks (length 60 cm × width 45 cm × height 50 cm) at a density of 15 fish / tank and fed their prescribed diets to apparent satiation twice daily (08: 00 and 16:30) by hand. All tanks were connected to the mechanical and biological water filters as a recycling system, and each experimental treatment had three replicates. At the end of the trial, two fish per tank were collected for whole-body composition analysis, and other three fish per tank were individually weighed and dissected to obtain liver and intraperitoneal fat (IPF) weights. Total RNA was extracted from grouper liver and pituitary using Trizol Reagent. Results showed that weight gain% (WG%) of fish was remarkably increased as dietary CP levels increased from 38% to 54%, and when it continued to rise from 54% to 62%, there only had a slight increment in values of this parameter. Analysis of a nonlinear exponential model indicated that the optimal dietary protein requirement for maximum growth of giant grouper was estimated to be 56% of dry matter. Daily feed intake (DFI) and feed conversation ratio (FCR) were decreased with the increasing of dietary CP levels. Fish fed P38 and P42 showed lower lipid retention efficiency (LRE) and lower contents of liver lipid, whole-body protein as well as muscle protein than fish fed other dietary CP levels. The water ammonia production was linearly related to dietary CP levels. Expression of pituitary growth hormone (GH) and hepatic target of rapamycin (TOR), S6 kinase 1 (S6K1) as well as insulin growth factor I (IGFI) were lower in fish fed P38, P42 and P46 than those in fish fed P50, P54, P58 and P62. Generally, the optimal dietary crude protein requirement for maximum growth of giant grouper was estimated to be 56% of dry matter.

Optimization of Dietary Protein Requirement for the Growth, Survival and Feed Utilization of Osteobrama belangeri (Valenciennes, 1844) Fingerling

In order to optimize dietary protein requirement of Osteobrama belangeri fingerling an experiment was conducted by using six semi-purified diets with graded protein levels (20, 25, 30, 35, 40 and 45%) using casein and gelatin as main protein source. Six treatments in triplicates (18 circular fiber reinforced plastics tanks; 1000 l capacity each) were used to conduct the experiment for 75 days in the wet laboratory. Ten fingerlings with mean body weight of 4.23±0.08g were stocked in each tank and fed twice daily. The mean weight gain and specific growth rate was recorded highest in fish fed with 25% protein diet. Similarly, net biomass gain, body weight gain and daily weight gain was highest in fish fed with 25% protein diet. 30% and 35% protein diets gave 100% fish survival. The lowest feed conversion ratio (FCR) and highest feed conversion efficiency (FCE) was also recorded in 25% protein diet. Moisture, crude protein, crude lipid, crude ash contents of O. belangeri did not differ significantly among the treatments. Thus, growth performance and feed utilization was optimum in fingerling of O. belangeri while they were fed semi-purified diet containing 25% protein.

Dietary protein requirements for tambaqui Colossoma macropomum (Cuvier, 1818) juvenile

The freshwater fish, tambaqui, Colossoma macropomum, is a native species of Brazilian fauna that has the potential to become a widespread aquaculture species, howerer, studies regarding the nutrient requirements remain scarce, often producing conflicting results. Hence, the currently available information is insufficient to formulate the specific diet of this species, for the different growth stages. This study aimed to evaluate the effects of dietary crude protein levels on the growth performance, body composition and ammonia excretion rates in tambaqui of 2–20 g body weight. Juvenile (average weight, 1.70 ± 0.05 g) were fed four times a day over a 60 days period using diets containing 300; 350; 400 and 450 g kg-1 crude protein in a completely randomized experimental design. The tambaqui juvenile fed diet containing 300 g kg-1 crude protein exhibited higher feed intake, specific growth rate, protein efficiency ratio, and protein productive value. This finding shows an improvement in protein utilization efficiency when fish are fed the lowest level of this nutrient in the diet; however, more viscero-somatic fat deposition and body lipid content was observed in these fish. The total ammonia excretion rates were lower in tambaqui fed diet containing 300 g kg-1 crude protein than those fed diets containing 450 g kg-1 crude protein. From the present investigation, it can be conclude that 300 g kg -1 crude protein should be fed to tambaqui juvenile of 2–20 g body weight.

Dietary protein requirement of bighead catfish (Clarias macrocephalus Gunther, 1864) fingerling

Dietary protein requirement of bighead catfish (Clarias macrocephalus Gunther, 1864) fingerling

Dietary protein requirement of Pacific white shrimp Litopenaeus vannamei in three different growth stages

A study of three feeding trials was conducted to investigate the dietary protein requirements of Pacific white shrimp (Litopenaeus vannamei) at three different growth stages. Six experimental diets were formulated to include increasing protein levels of 25, 30, 35, 40, 45, and 50% (designated as P25, P30, P35, P40, P45, and P50, respectively) for three feeding trials. The three feeding trials were conducted in different-sized shrimp at 0.65 g (trial 1), 4.80 g (trial 2), and 10.5 g (trial 3). Triplicate groups of shrimp were fed one of the experimental diets for 36, 42, and 48 days in trials 1, 2, and 3, respectively. In trial 1, the growth performance was not affected by the dietary protein levels. However, protein efficiency ratio was significantly higher in P30 diet compared to P40, P45, and P50 diets. In trial 2, growth rate was significantly higher in P35 diet than in P25 diet. In trial 3, the lowest growth performance was obtained in P25 diet which significantly differed from that of other experimental diets. Broken line analysis of growth data indicates that the optimal dietary level of crude protein is 34.5, 35.6, and 32.2% for small-, medium-, and large-sized (juvenile, sub-adult, and adult stages) Pacific white shrimp, respectively.

Dietary protein requirement for juvenile mandarin fish, Siniperca scherzeri

An 8‐week feeding trial was conducted to investigate the dietary protein requirement of juvenile mandarin fish, Siniperca scherzeri, a demersal freshwater piscivore with high commercial value in East Asia. Five isolipidic (100 g/kg) and isoenergetic (20 MJ/kg) practical diets were formulated to contain graded levels of 450, 500, 550, 600, and 650 g/kg crude protein, using mackerel fishmeal as the sole source of protein. Each of the five test diets was fed to visual satiety to triplicate groups of fish (initial mean body weight ± SE; 20.1 ± 0.2 g) reared in a recirculating freshwater system over the experimental period. Fish growth performance in terms of weight gain tended to improve with increasing dietary protein level, and the highest values were observed in those fish fed the 600–650 g/kg diets. Feed intake significantly declined as the protein content of the diet increased. Feed efficiency and protein retention tended to increase with increasing dietary protein levels, from 450 to 600 g/kg, and then declined when dietary protein content further increased to 650 g/kg. A similar trend was also found for the protein efficiency ratio, although the observed changes did not reach statistical significance. Whole‐body composition and plasma biochemical parameters were not significantly affected by the dietary protein content. Based on these findings and a broken‐line model of growth, 614.4 g/kg seems to be the proper amount of protein in a practical diet for &gt;20 g mandarin fish.

Increased Ratio of Non-mercaptalbumin-1 Among Total Plasma Albumin Demonstrates Potential Protein Undernutrition in Adult Rats.

The redox state of plasma albumin shifts in response to dietary protein intake in growing rats, and the shift is more sensitive than that of plasma albumin level, a classical marker of protein nutritional status. While it has been suggested that plasma albumin redox state could be useful as a novel marker of protein nutritional status, the above animal model is highly sensitive to dietary protein intake and the observation may not be extrapolated widely to humans. This study aimed to investigate whether albumin redox state also reflects protein nutritional status in adult rats, which have a lower dietary protein requirement and are less responsive to protein intake. Male adult rats were placed on AIN-93M diet (14% casein), or AIN-93M-based low protein diets (10 or 5% casein) ad libitum for 24 weeks. Whereas there was no significant difference in body weight between the groups at the end of the experimental period, the 5% casein diet group had the smallest gastrocnemius muscle weight among the groups, which was significantly lower than that of the 10% casein diet group. Plasma albumin level was also lower in the 5% casein diet group compared with the other groups, but the differences were limited and inconsistent during the experimental period. Among the albumin redox isoforms such as mercaptalbumin, non-mercaptalbumin-1, and non-mercaptalbumin-2, the ratio of non-mercaptalbumin-1 among total albumin was significantly higher in the 5% casein diet group, and the increase remained constant throughout the experimental period. Increased non-mercaptalbumin-1 ratio would thus demonstrate the presence of potential protein undernutrition in adult rats, as manifested only by a decreased gain in a specific type of skeletal muscle; non-mercaptalbumin-1 among total albumin ratio could be useful as a robust marker of protein nutritional status, contributing to prevention of protein undernutrition-related diseases such as frailty and sarcopenia.

Net protein and energy requirements for weight gain of Santa Inês and Morada Nova sheep

The objective of this study was to determine the body composition and the dietary protein and energy requirements for weight gain of Santa Inês and Morada Nova sheep. A total of 48 intact lambs (24 Santa Inês and 24 Morada Nova), with initial weights of 21.7 ± 1.2 kg and 20.8 ± 0.8 kg and ages of 170 and 190 days, respectively, were used. At the beginning of the experimental phase, six lambs of each breed were slaughtered to determine body composition. The remaining 36 animals were divided into six groups of six animals each, separated by slaughter weights (25, 28 and 31 kg) and genotypes. The comparative slaughter technique was used to determine the nutritional requirements. The respective net requirements for energy gain ranged from 3.07 to 3.42 and 3.40 to 4.08 Mcal/kg gain of empty body weight (EBW), while for protein gain, the requirements ranged from 140 to 132 and 113 to 102 g/kg of EBW gain for intact genotypes lambs weighing between 22 and 31 kg. The Santa Inês sheep had higher net protein but lower net energy requirements for weight gain than the Morada Nova sheep. The body composition and the net requirements of protein and energy gains of genotypes sheep differ from the values reported by the main international committees of nutritional assessments.

Internal amino acid state modulates yeast taste neurons to support protein homeostasis in Drosophila.

To optimize fitness, animals must dynamically match food choices to their current needs. For drosophilids, yeast fulfills most dietary protein and micronutrient requirements. While several yeast metabolites activate known gustatory receptor neurons (GRNs) in Drosophila melanogaster, the chemosensory channels mediating yeast feeding remain unknown. Here we identify a class of proboscis GRNs required for yeast intake. Within this class, taste peg GRNs are specifically required to sustain yeast feeding. Sensillar GRNs, however, mediate feeding initiation. Furthermore, the response of yeast GRNs, but not sweet GRNs, is enhanced following deprivation from amino acids, providing a potential basis for protein-specific appetite. Although nutritional and reproductive states synergistically increase yeast appetite, reproductive state acts independently of nutritional state, modulating processing downstream of GRNs. Together, these results suggest that different internal states act at distinct levels of a dedicated gustatory circuit to elicit nutrient-specific appetites towards a complex, ecologically relevant protein source.

Dietary protein requirement in common snook (Centropomus undecimalis ) juveniles reared in marine and brackish water

A total of 300 Centropomus undecimalis juveniles, with an average initial weight of 3.16 0.28 g and average total length of 7.17 0.22 cm, were reared for eight weeks using a recirculating system to determine the dietary protein requirement for their growth and survival. The eect of ve experimental diets containing 40, 45, 50, 55 and 60% total protein content and two salinities (brackish water, BW at 5 UPS and marine water, MW at 36 UPS) were assessed. Fish were fed ve times per day at 2.5% of total biomass. All treatments were performed in triplicate,recording the individual weight and total length every 15 d, while weight gain and daily growth rate were recorded at the end of the experiment. Mean weight increased proportionally as protein content increased, with the greatest growth occurring with a 60% protein diet for sh reared in brackish water, and 55% for sh in marine water. We consider that the protein requirement in C. undecimalisjuveniles is high; in addition, it differs depending on the salinity, &lt;/