Dietary Protein Reduction Research Articles

Effects of L-arginine and L-citrulline supplementation in reduced protein diets for broilers under normal and cyclic warm temperature.

Heat stress causes significant economic losses in the broiler industry. Dietary supplementation of arginine (Arg) and citrulline (Cit) might increase the performance of broilers raised under warm temperature due to vasodilation effects. This study investigated the effects of L-Arg or L-Cit supplementation in broilers fed a reduced protein wheat-based diet deficient in Arg under thermoneutral (NT) and cyclic warm temperature (WT). Ross 308 cockerels (n = 720) were randomly allocated to 4 dietary treatments with 12 replicates of 15 birds per pen from d 7 to 21. The 4 treatments were: normal protein (NP), i.e., 22.3% and 20.9% crude protein in grower and finisher, respectively; reduced protein (RP), i.e., 2.5% lower protein and deficient in Arg; and RP supplemented with 0.28% Arg (RP-Arg) or 0.28% Cit (RP-Cit). A factorial arrangement of treatments was applied during the finisher phase (21 to 35 d). Factors were: diet (4 diets above); and temperature, NT (24 °C) or cyclic WT (33 ± 1 °C for 6 h per day) with 6 replicate pens per treatment. During 7 to 35 d and 21 to 35 d, the birds fed the RP diet had lower body weight gain (BWG) and higher FCR compared to the NP diet (P < 0.01). The addition of Arg or Cit to RP decreased FCR compared to RP (P < 0.01). During 21 to 35 d, the birds exposed to WT had lower feed intake (FI), lower BWG (P < 0.001) but similar FCR (P > 0.05) compared to birds exposed to NT. Diet by temperature interactions were not observed for performance parameters during the period of WT (P > 0.05). On d 35, the RP-fed birds had a lower yield of thigh and drumstick, higher fat pad, lower femur ash, and breaking strength but similar serum uric acid level and higher nitrogen digestibility on d 21 compared to those offered NP (P < 0.05). Supplementation of Arg or Cit to RP resulted in increased femur ash on d 35 (P < 0.05). Thus, feeding the NP diets is necessary to maintain growth performance in broilers regardless of the temperature conditions.

Different Proportions of Branched-Chain Amino Acids Modulate Lipid Metabolism in a Finishing Pig Model.

This study aimed to investigate the effect of the supplementation of branched-chain amino acids (BCAAs) at different ratios in protein restriction diets on lipid metabolism in a finishing pig model. The BCAA supplementation (leucine/isoleucine/valine = 2:1:1 and 2:1:2) ameliorated the poor growth performance and carcass characteristics, particularly high fat mass caused by a protein-restricted diet. Serum adiponectin increased while leptin decreased in BCAA diets in comparison to the 12% CP group. BCAA supplementation also increased the low-protein expression of AMPK and SIRT1 caused by protein restriction. The mRNA and protein levels of peroxisome proliferation-activated receptor-γ (PPARγ) and acetyl-CoA carboxylase (ACC) were highest in the protein-restricted group and lowered in the 2:1:1 or 2:1:2 group. In conclusion, BCAAs supplemented in an adequate ratio range of 2:1:1 to 2:1:2 (2:1:2 is recommended) in reduced protein diets could modulate lipid metabolism by accelerating the secretion of adipokines and fatty acid oxidation.

Response of laying hens to l-arginine, l-citrulline and guanidinoacetic acid supplementation in reduced protein diet.

A study was conducted with Hy-Line Brown laying hens to examine the effects of reduced protein diet, deficiency of arginine (Arg), and addition of crystalline Arg, citrulline (Cit) and guanidinoacetic acid (GAA) as substitutes for Arg. Hen performance, egg quality, serum uric acid, liver and reproductive organ weights, and energy and protein digestibility were measured using a completely randomized design with 5 treatments. Treatments were a standard diet (17% protein diet; SP), a reduced diet (13% protein diet deficient in Arg; RP) and RP with added Arg (0.35%, RP-Arg), GAA (0.46% equivalent to 0.35% Arg, RP-GAA) or Cit (0.35%, RP-Cit) to the level of SP. It was hypothesized that performance would decrease with Arg deficient RP diet and the addition of GAA or Cit in RP would allow birds to perform similar or greater than Arg-added RP treatment. The experiment was conducted from 20 to 39 wk of age but the treatment effect was seen only after 29 wk of age. The birds offered RP had reduced egg and albumin weights (P < 0.01), lower yolk color score (P < 0.01), lower protein intake and excretion (P < 0.01) than those offered SP. When Arg or Cit were added to RP to make them equivalent to SP, feed intake (FI) and egg production were not different than those of RP (P > 0.05). The birds offered RP-GAA decreased FI and egg production (P < 0.01) compared to those offered RP. The addition of Arg, Cit or GAA to the RP had no effect on egg quality parameters, protein and energy digestibilities (P > 0.05). However, birds offered the RP-Cit diet tended to have higher Haugh unit (P = 0.095) and lower shell breaking strength (P = 0.088) compared to all other treatments while those offered RP-GAA had higher energy digestibility (P < 0.05) than all other groups but RP. The limited performance response of hens fed RP with added Arg, GAA, or Cit may be due to deficiency of some other nutrients in RP such as phenylalanine, potassium or non-essential amino acids and other components of soybean meal in the diet.

Effect of a Phytogenic Feed Additive on Growth Performance, Nutrient Digestion, and Immune Response in Broiler-Fed Diets with Two Different Levels of Crude Protein.

Simple SummaryThe rising concerns on antibiotics resistance from using antibiotics in animal production has resulted in an increase in researches on antibiotic alternatives. A phytogenic feed additive from a blend of extracts of oregano, cinnamon, citrus peel, and fructooligosaccharides was evaluated in the present study. The objective of the present study is not only to evaluate the effect of phytogenic feed additive on broiler performance, but also to explore the potential mode of actions through immune response, digestive enzyme activities, nutrient transporter gene expressions and nutrient digestibility. Supplementation of phytogenic feed additives improved broiler FCR through stimulating ileum immunity.The aim of this experiment was to evaluate the effect of a phytogenic feed additive (PFA) on growth performance and nutrient digestibility of broilers fed corn and soybean meal-based diets containing two different levels of crude protein. A 2 × 2 completely randomized factorial arrangement (eight replicates/treatment, 30 birds/replicate) was conducted with a positive control (PC) and negative control (NC) containing crude protein at standard or reduced by 1.5% (equivalent to a reduction of 15 g/kg), respectively, and supplementation of PFA at 0 or 125 ppm of diet. There were no significant interactions found between PFA and CP levels in the current study. Main effect analysis showed that during 0–42 d of age NC diets decreased body weight gain (p < 0.05), but increased feed intake (p < 0.05) and feed conversion ratio (FCR, p < 0.01), whereas supplementation of PFA resulted in a lower FCR (p < 0.01). The ileal nutrient digestibility was reduced (p < 0.05) in the broilers fed a reduced protein diet at 21 d compared to the standard protein level group, but there were no effects for PFA levels. Similarly, supplementing PFAs showed no effects on digestive enzyme (Alkaline phosphatase, amylase, and lipase) activity in jejunal digesta and jejunal brush border enzyme (maltase, sucrase, and aminopeptidase) activity. Supplementation of PFA downregulated (p < 0.05) the mRNA expressions of cytochrome P450 1A and interleukin 6 in the ileum but had no effects on nutrient transporter genes in the jejunum. In conclusion, supplementation of PFA reduced broiler FCR during the whole grow-out period and positively regulated the immune responses in the ileum.

15 Young Scholar Presentation: Impact of a Near Ideal Amino Acid Profile on the Efficiency of Nitrogen and Energy Utilization in Lactating Sows

Abstract The objective was to determine the efficiency of EAA and energy for lactation in sows and quantify their metabolic heat production fed a reduced protein diet. We hypothesized that feeding a reduced protein diet with near ideal AA profile (NIAA) and a leucine:lysine of 1.14 improves the dietary essential AA (EAA) and energy utilization efficiency and reduces the metabolic heat associated with lactation, compared to feeding diets containing leucine:lysine of 1.63. Three diets were formulated iso-calorically (2,580 kcal/kg net energy), including 1) control diet with a 1.63 leucine:lysine (CON; 18.75% CP), 2) optimal diet with NIAA profile and 1.14 leucine:lysine (OPT; 13.75% CP) by supplementing crystalline AA to minimum requirements; and 3) OPT diet with L-Leucine (Leu) supplementation to achieve CON Leu:Lys of 1.63 (OPTLEU; 14.25% CP). Experiment 1 was to estimate maximal biological efficiency value (MBEV) of EAA in lactating sows fed CON, OPT and OPTLEU diets. Feeding OPT diet improved efficiency of nitrogen (N) (79.1%), arginine (61.1%), His (78.3%), Ile (65.4%), Leu (75.1%), Met + Cys (78.2%), Phe (53.4%), Phe + Tyr (69.5%) and Trp (70.1%) and maximized the efficiency of Lys (63.2%), Met (67.9%), Thr (71.0%) and Val (57.0%) for milk production over a 21-day lactation. Experiment 2 was to estimate dietary energetic efficiency, energy partitioning and heat production in lactating sows fed CON, OPT and OPTLEU diets. Feeding OPT led to greater energy utilization for lactation due to less urinary energy and metabolic heat loss, and triggered dietary energy deposition into milk at the expense of maternal lipid mobilization. Feeding OPTLEU compared to OPT reduced energy utilization for lactation by directing dietary energy away from the mammary gland and towards maternal pool, in part explaining the efficacy of a NIAA diet over CON. Experiment 3 was to measure heat production in lactating sows fed CON and OPT diets and exposed to thermal neutral and HS environments. Sows fed OPT diet produced less metabolic heat and had lower body temperature when exposed to HS conditions compared to CON fed sows. In conclusion, feeding a diet with NIAA profile containing Leu:Lys of 1.14 improves EAA and energy utilization efficiency for lactation, and reduces the metabolic heat associated with lactation compared to feeding a diet with Leu:Lys of 1.63.

Low dietary protein resilience is an indicator of the relative protein efficiency of individual dairy cows

Our objectives were to determine (1) the sources of variation in cow responses to dietary protein reduction, and (2) the association of low dietary protein resilience (LPR) with protein efficiency. Lactating Holstein cows in peak lactation (n = 166; 92 primiparous, 77 multiparous) with initial milk yield 41 ± 9.8 kg/d were fed high-protein (HP) or low-protein (LP) diets in 4-wk periods in a crossover design with half the cows fed LP first and half fed HP first. The study was repeated for 69 of these cows (42 primiparous, 27 multiparous) in late lactation. Low-protein diets were 14% crude protein (CP) in peak lactation and 13% CP in late lactation and were formulated to contain adequate rumen-degradable protein to maintain rumen function but inadequate rumen-undegradable protein for cows with average production in this study to maintain their production. High-protein diets were 18% CP in peak lactation and 16% CP in late lactation and contained extra expeller soybean meal to meet metabolizable protein requirements. Protein efficiency was defined as the protein captured in milk or in both milk and body tissues per unit of consumed protein. Low dietary protein resilience was calculated for each cow in peak and late lactation based on actual intake, production, and body weight measures. The ability of a cow to maintain total protein captured in milk and body gain when fed less protein varied considerably and the variation was mostly explained by a cow's captured protein per kilogram of metabolic body weight when fed HP, her parity, treatment sequence, and experiment. Protein efficiency was moderately repeatable across diets within lactation stage. Milk urea nitrogen was not associated with protein efficiency in individual cows within a diet and lactation stage. Cows with greater dietary protein resiliency (higher LPR) had similar protein efficiency on the HP diet as cows with lower LPR, but higher protein efficiency on the LP diet. In conclusion, cows generally maintained their protein efficiency rankings when switching diets between sufficient or insufficient protein; however, some high-producing cows are better able to maintain high production when fed less protein. We define this ability as LPR and suggest it might be useful for identifying cows that use protein more efficiently to enhance dairy sustainability.

Direct and maternal reduced balanced protein diet influences the liver transcriptome in chickens.

The objective of this study was to evaluate, by means of RNA sequencing, the direct and transgenerational effect of a reduced balanced protein (RP) diet on broiler breeder metabolism. Chickens of the F0 generation were fed a control (C) or RP diet, and their F1 progeny was fed a C or RP diet as well, resulting in four groups of chickens: C/C, C/RP, RP/C and RP/RP. While both direct and maternal effects were seen on body weight, breast muscle weight and abdominal fat weight in the F1 generation, the direct effect was the most dominant one. The liver transcriptome in the F1 generation showed that amino acid metabolism was up-regulated in chickens that received the control feed when compared with their respective contemporaries that received the reduced protein diet. Interestingly, chickens hatched from control-fed hens but reared on the reduced protein diet (C/RP group) activated a fatty acid metabolism, expressing more fatty acid desaturase 1 gene, fatty acid desaturase 2 gene and elongation of very long-chain fatty acids protein 2 gene, when compared with control-fed chickens hatched from control-fed hens (C/C group), while chickens hatched from reduced protein-fed hens that received themselves the same reduced protein diet (RP/RP group) triggered their glucose metabolism more, showing elevated levels of phosphofructokinase gene, 6-phosphofructo-2-kinase/fructose-2,6-biphospatase 4 and fructose-biphosphate aldolase C mRNA compared with the chickens hatched from reduced protein-fed hens but reared on a control diet (RP/C group). This suggests that the maternal protein diet has an impact on the metabolism of broilers when they are reared on a RP diet.

The Response of Broiler Chickens to Dietary Soybean Meal Reduction with Glycine and Cysteine Inclusion at Marginal Sulfur Amino Acids (SAA) Deficiency.

Simple SummaryClimate change, resource shrinkage, and greenhouse gasses emission are becoming a major issue that could be confronted by using reducing protein levels in poultry diet. Reduced protein with amino acids supplementation improved the overall performance of broiler chickens. Reduced protein diets with glycine supplementation could be the potential solution to maintain the growth performance of the chicken, thus reducing feed cost and nitrogen excretion.The responses of broiler chickens to dietary protein reduction were investigated in the presence of glycine and cysteine inclusion at the marginal deficiency of sulfur-containing amino acids. A total of 432 broiler chickens were allotted to six dietary treatments; SP1 is standard protein diet with 100% total sulfur amino acids (TSAA), SP2 is standard protein diet with 85% TSAA, RP is reduced protein diet without glycine and cysteine supplementation, RPC is reduced protein diet with cysteine supplementation at 0.1%, and RPG is reduced protein diet with 1% glycine supplementation, while RPGC is reduced protein diet with 0.1% cysteine and 1% glycine supplementation. In this study, 4.5% protein is reduced in diets—thus, 17.5% CP (crude protein) for starter phase and 15.5% CP for the grower phase. Reduced protein diets contained 85% TSAA. Broiler chickens fed standard protein diet SP2 had superior bodyweight (BW) (p ≤ 0.05) in the starter and grower phase, average daily gain (ADG) (p ≤ 0.05) in the starter and entire feeding period, average daily feed intake (ADFI) (p ≤ 0.05) in the starter phase, and better feed conversion ratio (FCR) (p ≤ 0.05) in the starter, grower and entire feeding period; however, RPGC showed higher ADG (p ≤ 0.05) in the grower phase, and ADFI (p ≤ 0.05) in the grower and entire feeding period. RPC and RPG diet improved BW (p ≤ 0.05), ADG (p ≤ 0.05), ADFI (p ≤ 0.05), and better FCR (p ≤ 0.05) in starter, grower, entire feeding period compared to RP. The RPGC group had higher BW (p ≤ 0.05), ADG (p ≤ 0.05), ADFI (p ≤ 0.05) and better FCR (p ≤ 0.05) compared to the RPC group. Blood biochemical parameters showed that Broiler chickens fed on the SP2 diet had higher levels of total protein (TP) (p ≤ 0.05), albumin (ALB) (p ≤ 0.05), creatinine (CRE) (p ≤ 0.05), and aspartate aminotransferase (AST) (p ≤ 0.05) and, lower level of uric acid (UA) (p ≤ 0.05), blood urea nitrogen (BUN) (p ≤ 0.05), glucose (GLU) (p ≤ 0.05), and alanine aminotransferase (ALT) (p ≤ 0.05) in the starter phase; however, higher level of TP (p ≤ 0.05), GLU (p ≤ 0.05), CRE (p ≤ 0.05), and AST (p ≤ 0.05), and lower level of ALB (p ≤ 0.05), UA (p ≤ 0.05), and ALT (p ≤ 0.05) in the grower phase; RPGC had higher level of TP (p ≤ 0.05), UA (p ≤ 0.05), GLU (p ≤ 0.05), ALT (p ≤ 0.05) and AST (p ≤ 0.05), and lower level of ALB (p ≤ 0.05), BUN (p ≤ 0.05), and CRE (p ≤ 0.05) in the starter phase; however, in grower phase, RPGC had higher level of TP (p ≤ 0.05), and ALB (p ≤ 0.05), and lower level of UA (p ≤ 0.05), CRE (p ≤ 0.05), ALT (p ≤ 0.05), and AST (p ≤ 0.05). Free amino acids profile showed that broiler fed on standard protein diet SP2 had reduced the methionine (p ≤ 0.05) concentration; RPC increased the concentrations of taurine (p ≤ 0.05), phosphoethanolamine (p ≤ 0.05), threonine (p ≤ 0.05), valine (p ≤ 0.05), isoleucine (p ≤ 0.05), phenylalanine (p ≤ 0.05), ornithine (p ≤ 0.05), and lysine (p ≤ 0.05) and reduced the citrulline (p ≤ 0.05) concentration; RPG increased the concentration of glutamate (p ≤ 0.05), glycine (p ≤ 0.05), cysteine (p ≤ 0.05), and arginine (p ≤ 0.05), and decreased the concentration of tyrosine (p ≤ 0.05); and RPGC increased the concentration of serine (p ≤ 0.05) and reduced the concentration of hydroxyproline (p ≤ 0.05). Serum metabolites analysis showed that reduced protein downregulated the 54 metabolites; however, glycine fortification up-regulated the Benzamide, Pro-Ser, N-Carbamylglutamate, D-gluconate, and Gamma-Glutamylcysteine. Carcass quality showed that SP2 decreased the abdominal fat percentage (p ≤ 0.05). Nitrogen digestibility was higher by the diet RP (p ≤ 0.05). This study demonstrated that protein content could be reduced up to 4.5% with 1% glycine and 0.1% cysteine fortification in diet, which has the potential to inhibit the adverse effect of reduced protein and attain the standard growth performance.

Bacillus amyloliquefaciens CECT 5940 improves performance and gut function in broilers fed different levels of protein and/or under necrotic enteritis challenge

Two studies were conducted to investigate the effect of Bacillus amyloliquefaciens CECT 5940 (BA) as a probiotic on growth performance, amino acid digestibility and bacteria population in broiler chickens under a subclinical necrotic enteritis (NE) challenge and/or fed diets with different levels of crude protein (CP). Both studies consisted of a 2 × 2 factorial arrangement of treatments with 480 Ross 308 mix-sexed broiler chickens. In study 1, treatments included 1) NE challenge (+/−), and 2) BA (1.0 × 106 CFU/g of feed) supplementation (+/−). In study 2, all birds were under NE challenge, and treatments were 1) CP level (Standard/Reduced [2% less than standard]) and 2) BA (1.0 × 106 CFU/g of feed) supplementation (+/−). After inducing NE infection, blood samples were taken on d 16 for uric acid evaluation, and cecal samples were collected for bacterial enumeration. In both studies, ileal digesta was collected on d 35 for nutrient digestibility evaluation. In study 1, the NE challenge reduced body weight gain (BWG), supressed feed conversion ratio (FCR) and serum uric acid levels (P < 0.001). Supplementation of BA increased BWG (P < 0.001) and reduced FCR (P = 0.043) across dietary treatments, regardless of challenge. Bacillus (P = 0.030) and Ruminococcus (P = 0.029) genomic DNA copy numbers and concentration of butyrate (P = 0.017) were higher in birds fed the diets supplemented with BA. In study 2, reduced protein (RCP) diets decreased BWG (P = 0.010) and uric acid levels in serum (P < 0.001). Supplementation of BA improved BWG (P = 0.001) and FCR (P = 0.005) and increased Ruminococcus numbers (P = 0.018) and butyrate concentration (P = 0.033) in the ceca, regardless of dietary CP level. Further, addition of BA reduced Clostridium perfringens numbers only in birds fed with RCP diets (P = 0.039). At d 35, BA supplemented diets showed higher apparent ileal digestibility of cystine (P = 0.013), valine (P = 0.020), and lysine (P = 0.014). In conclusion, this study suggests positive effects of BA supplementation in broiler diets via modulating gut microflora and improving nutrient uptake.

Expression of selected genes encoding mechanistic pathways, nutrient and amino acid transporters in jejunum and ileum of broiler chickens fed a reduced protein diet supplemented with arginine, glutamine and glycine under stress stimulated by dexamethasone.

Reducing crude protein and supplementation with synthetic amino acids in poultry nutrition is a recent trend to avoid wastage of protein and ammonia in production systems. Stress has been shown to impair intestinal barrier and increase inflammatory response. This study was performed on intestinal tissues of broiler chickens to understand the mechanism of stress induced by a synthetic glucocorticoid, dexamethasone (DEX) and the effect of supplementation of arginine, glutamine and glycine in reduced protein diets. Intestinal tissue samples from a previous study were utilized. Male Ross 308 chickens received a basal diet for the first seven days and then fed with crude protein that was reduced to 194g/kg in grower experimental diets supplemented with glutamine, glycine and additional arginine at 10, 10 and 5g/kg respectively. Half of the 96 individual birds were injected with DEX (0.5mg/kg body weight) or saline on days 14, 16, 18 and 20 of age. mRNA expression for jejunum and ileum for amino acid transporters (y+LAT-1, Bo,+ AT, EAAT-3 and CAT-1), mechanistic genes (SGLT-1, mTOR, IAP and FABP-2) and pro-inflammatory genes (MUC-2, NF-κB, iNOS, IL-8 and IL-1β) were analysed using real-time PCR. The results showed that DEX decreased y+ LAT1 in jejunum, Bo ,+ AT and EAAT-3 in ileum. Arginine increased CAT-1 in the jejunum and ileum under DEX treatment. Through an interaction, DEX reduced IAP in jejunum of glycine and arginine supplemented group and reduced mTOR in jejunum independently. DEX reduced MUC-2 and iNOS in jejunum and increased iNOS and IL8 in the ileum. Amino acid supplementation did not appear to ameliorate these effects; however, there were some positive effects of glycine on NF-κB and arginine through increased CAT-1. Mechanistic understanding of amino acid supplementation in broiler diets warrants further research particularly when dietary protein is reduced below the level tested in the present study.

Efficacy of reduced protein diets and the effects of indispensable amino acid supplements for Nile tilapia Oreochromis niloticus

The study was conducted to evaluate the production performance of Nile tilapia Oreochromis niloticus fed graded levels of protein with or without indispensable AA (IAA) supplemented in practical diets. A control diet containing 32 % intact protein was modified to meet the respective requirements of IAA based upon NRC recommendations for Nile tilapia. From this diet, two series of diets were formulated to confirm the efficacy of crystalline AA (CAA) used as supplements in the practical diets of fish by applying “ideal protein concept”. In the first series of diets, intact protein was reduced gradually from 32 to 24 % of the diet without IAA supplementation. In the second series of diets, the same dietary protein levels were formulated; however, the IAA profiles of these diets were modified to meet the respective requirement of Nile tilapia (NRC, 2011). Five commercially-available AAs, including methionine, lysine, tryptophan, histidine and valine, were supplemented if necessary to attain the targeted AA profile. The supplementation of all deficient IAAs was obtained in the last diet to evaluate if there is further benefit of using IAAs other than commercial AAs to balance the AA profiles of diets. Four groups of Nile tilapia (12.7 ± 0.2 g) were fed each diet four times daily to near satiation. The results obtained after eight weeks indicated that fish fed diets with IAA supplementation had significantly higher weight gain compared to fish fed diets without IAA supplementation. Fish fed intact protein levels above 27.2 % with the supplementation of IAA up to the reported requirement (NRC, 2011) showed comparable performance to fish fed the control diet. The reduction of intact protein further than that, however, resulted in reduced growth rate (thermal-unit growth coefficient) of fish even though the IAA profiles of these diets met the reported requirement of tilapia for optimal growth (NRC, 2011). Based on the data obtained from this study, it can be concluded that ideal protein concept can be applied in formulating the diets for Nile tilapia to optimize AA profile of the diets. Well-balanced IAA profile can be used to reduce the intact protein levels of feed (32 to 27.2 %) without causing impaired growth of fish.

Reduced protein diet with near ideal amino acid profile improves energy efficiency and mitigate heat production associated with lactation in sows

BackgroundThe study objective was to test the hypothesis that 1) lowering dietary crude protein (CP) increases dietary energetic efficiency and reduces metabolic heat associated with lactation, and 2) excessive dietary leucine (Leu) supplementation in a low CP diet decreases dietary energetic efficiency and increases metabolic heat associated with lactation.MethodsFifty-four lactating multiparous Yorkshire sows were allotted to 1 of 3 isocaloric diets (10.80 MJ/kg net energy): 1) control (CON; 18.75% CP), 2) reduced CP with a near ideal or optimal AA profile (OPT; 13.75% CP) and 3) diet OPT with excessive Leu (OPTLEU; 14.25% CP). Sow body weight and backfat were recorded on day 1 and 21 of lactation and piglets were weighed on day 1, 4, 8, 14, 18, and 21 of lactation. Energy balance was measured on sows during early (day 4 to 8) and peak (day 14 to18) lactation, and milk was sampled on day 8 and 18.ResultsOver 21-day lactation, sows fed OPT lost body weight and body lipid (P < 0.05). In peak lactation, sows fed OPT had higher milk energy output (P < 0.05) than CON. Sows fed OPTLEU tended (P = 0.07) to have less milk energy output than OPT and did not differ from CON. Maternal energy retention was lower (P < 0.05) in OPT and OPTLEU compared to CON sows, and did not differ between OPTLEU and OPT sows. Sows fed OPT had higher (P < 0.05) apparent energy efficiency for milk production compared to CON. Heat production associated with lactation was lower (P < 0.05) or tended to be lower (P = 0.082), respectively, in OPT and OPTLEU compared to CON sows.ConclusionThe OPT diet, in peak lactation, improved dietary energy utilization for lactation due to less urinary energy and metabolic heat loss, and triggered dietary energy deposition into milk at the expense of maternal lipid mobilization. Leucine supplementation above requirement may reduce dietary energy utilization for lactation by decreasing the energy partitioning towards milk, partially explaining the effectiveness of OPT diet over CON diets.

Using crystalline amino acids to supplement broiler chicken requirements in reduced protein diets

Reducing dietary CP can reduce N pollution. Much research has been reported in corn-based diets; however, the amino acid (AA) profiles of wheat-based diets differ. Poor performance as a result of reduced protein (RP) has been overcome in corn-based diets with essential AA and glycine (Gly) supplementation. The current study examined RP levels and Gly in wheat-based diets. An industry standard protein (SP) diet plus 3 RP diets with and without Gly supplementation, to match the SP treatment at 0.713 and 0.648% digestible Gly for the grower and finisher periods respectively, were fed to male broilers from day 10 of age. Grower CP included 22.5, 20.6, 18.3, and 17.7% (days 10–21) and finisher CP included 19.7, 17.8, 16.2, and 15.5% (days 21–35). Performance, meat yield, N efficiency, water intake, and apparent ileal digestibility of N and AA were measured. No difference in body weight gain (BWG), feed intake, or feed conversion ratio (FCR) were observed at 20% CP compared to the SP treatment. However, further reducing protein reduced BWG (P < 0.001), feed intake (P < 0.001), and increased FCR (P < 0.001). Supplementation of 0.713% Gly in the grower period increased BWG (P < 0.001) and reduced FCR (P < 0.001). Relative meat yield was not affected by dietary protein, however reducing CP increased relative fat pad weight (P < 0.001). Nitrogen efficiency increased with decreased CP in both grower (R2 = 0.69) and finisher (R2 = 0.80) treatments. Water intake decreased (R2 = 0.83) with decreasing CP intake. Apparent ileal digestibility of AA and N were higher in RP diets (P < 0.05). The benefits of reduced water intake and increased N efficiency and the disadvantages of poor performance and increased body fat in RP corn-based diets have been identified in RP wheat-based diets. Furthermore, at 18.5% CP the supplementation of crystalline AA and Gly can maintain BWG and FCR observed in SP diets.

Productive performance response of growing rabbits to dietary protein reduction and supplementation of pyridoxine, protease, and zinc.

An 8-week experiment was carried out to assess the impact of supplemental dietary pyridoxine (PY), protease (PR), zinc (Zn) and their mixture (MIX) with low protein diet (LP; 14.76% CP) or high protein diet (HP; 18.53% CP) on rabbit growth, feed utilization, and nutrients digestibility. Rabbits were divided into ten similar groups in a 2 (protein level) ×5 (treatments) factorial design. Treatments included a control group (without any additives), 5 mg PY/kg of diet, 100 mg Zn/kg of diet, 500 mg PR/kg of diet or a mixture of all tested feed additive with the same doses. Results indicated that growth performance, feed utilization, and nutrients digestibility indicators were retarded significantly with reduction of dietary crude protein. Growth performance and feed conversion were significantly enhanced as a result of PY, PR, Zn, and MIX supplementation. All feed supplements had significantly improved the digestibility of crude protein and digestible crude protein. No change in carcass traits was recorded in response to protein level and tested feed supplements. It is concluded that the growing rabbit responded positively to PY, Zn, PR, and MIX (particularly PY) supplemental of LP or HP diets, in terms of growth performance, feed conversion, and nutrient digestibility.

Response of broilers to gradual dietary protein reduction with or without an adequate glycine plus serine level

This study was aimed to probe broiler responses to the maintenance of adequate level of glycine plus serine in low crude protein (CP) diets by glycine (Gly) addition from 8 to 42 days of age. A total of 1152 7-d-old birds were divided into 8 groups and fed with one of the following diets: (I) normal CP diet; (II, III vIV V) diets with 1.5%, 3%, 4.5% and 6% points less CP than normal diet, respectively; (VI, VII, VIII) diets with 3%, 4.5% and 6% points reduced CP than the normal CP diet, respectively, and added with Gly to achieve 2.32% total Gly + Ser. Each treatment was replicated with 12 cages. Results showed that dietary CP reduction by 3% or higher compromised (p < .05) growth performance and carcase traits of broilers. Gly fortification in the diet with a 4.5% CP reduction produced similar accumulative growth performance relative to normal-CP group. When Gly fortification in the diet with a 6% CP reduction, the accumulative growth performance were improved (p < .05) but were still inferior (p < .05) to those in normal-CP group. Gly fortification supported a similar (p > .05) abdominal fat percentage of birds fed the diet containing 4.5% points less CP as compared with birds fed the normal-CP diet. Comparatively, Gly fortification in the diet with a 6% CP reduction resulted in breast muscle yield, serum UN content on d 21 and albumin content on d 42 comparable to (p > .05) those in normal-CP group. Collectively, the absence of Gly addition allowed dietary CP reduction by no more than 3% to obtain normal performance and carcase traits of broilers. Gly fortification in the diet with a 3% CP reduction induced no improvements in growth performance and carcase traits of broilers. However, maintain a level of 2.32% total Gly + Ser via Gly fortification enabled a reduction of dietary CP by 4.5% without deteriorating the accumulative growth performance and carcase traits of broilers. Highlights Gly addition that provides 2.32% total Gly + Ser allows dietary CP reduction of 4.5% without compromising the accumulative growth performance and carcase traits of broilers. Maintaining 2.32% total Gly + Ser via Gly fortification could not completely overcome the depression of growth performance in broilers fed the diet with a 6% CP reduction.

Performance, intestinal permeability, and gene expression of selected tight junction proteins in broiler chickens fed reduced protein diets supplemented with arginine, glutamine, and glycine subjected to a leaky gut model

ABSTRACTChanging dietary protein and amino acids may impact intestinal barrier function. Experiments were conducted in broiler chickens to evaluate supplementation of L-glutamine, glycine, and L-arginine in a reduced protein (RP) diet. Experiment 1 examined the growth performance of broilers fed 5 dietary treatments: 1) a standard diet; 2) an RP diet (193.9 g/kg CP in grower and 176.9 g/kg CP in finisher); 3) RP diet supplemented with 10 g/kg L-Gln; 4) RP diet supplemented with 10 g/kg Gly; 5) RP diet supplemented with 5 g/kg L-Arg. Each experimental diet was replicated 6 times with 10 birds per replicate. In a subset of 96 birds, experiment 2 tested the 4 RP diets with and without dexamethasone (DEX) to induce leaky gut. Each diet was replicated 24 times. Fluorescein isothiocyanate dextran (FITC-d) was used to test intestinal permeability (IP). Gene expression of selected tight junction proteins in ileal and jejunal tissues was assayed by quantitative PCR. From day 7 to 35, the RP diet increased feed intake (FI) (P < 0.05) and body weight gain (BWG) compared with the standard diet while Gln reduced FI and BWG (P < 0.05) compared with RP. Gly had no effect on BWG or FCR. Supplementation of Arg improved FCR from day 21 to 35 and day 7 to 35. In experiment 2, Arg tended to lower FITC-d (P = 0.086). DEX increased passage of FITC-d into the serum (P < 0.001). The villi surface area was increased in birds fed higher Arg (P < 0.05). DEX and diet interacted (P < 0.01) for jejunal claudin-3 mRNA level where DEX upregulated claudin-3 for all diets except the Arg diet. In summary, with a moderate reduction of protein, satisfactory performance can be obtained. Although Gln and Gly had no demonstrable positive effect on IP and performance of broilers, increasing the dietary Arg by approximately 140% improved FCR and showed indications of improved intestinal barrier function of birds fed an RP diet under a stress model.

Modulation of growth hormone receptor-insulin-like growth factor 1 axis by dietary protein in young ruminants.

A reduced protein intake causes a decrease in insulin-like growth factor 1 (IGF1) concentrations and modulates Ca homoeostasis in young goats. IGF1 is synthesised by the liver in response to stimulation by growth hormone (GH). Due to rumino-hepatic circulation of urea, ruminants are suitable for investigating the effects of protein reduction despite sufficient energy intake. The present study aimed to investigate the impact of a protein-reduced diet on the expression of components of the somatotropic axis. Male young goats were divided into two feeding groups receiving either a control diet (20 % crude protein (CP)) or a reduced-protein diet (9 % CP). Blood concentrations of IGF1 and GH were measured, and a 24-h GH secretion profile was compiled. Moreover, ionised Ca and insulin concentrations as well as mRNA and protein expression levels of hepatic proteins involved in GH signalling were quantified. Due to the protein-reduced diet, concentrations of ionised Ca, insulin and IGF1 decreased significantly, whereas GH concentrations remained unchanged. Expression levels of the hepatic GH receptor (GHR) decreased during protein reduction. GHR expression was down-regulated due to diminished insulin concentrations as both parameters were positively correlated. Insulin itself might be reduced due to reduced blood Ca levels that are involved in insulin release. The protein-reduced diet had an impact on the expression of components of the somatotropic axis as a disruption of the GH-IGF1 axis brought about by diminished GHR expression was shown in response to a protein-reduced diet.

Dietary protein reduction for Nile tilapia fingerlings reared in biofloc technology

AbstractThe objective of this study was to evaluate the growth performance of Nile tilapia fed diets with 28, 32, and 36% crude protein (CP) in biofloc technology (BFT) and to verify its influence on water quality and hematological parameters. The experimental design was completely randomized with three treatments (28, 32, and 36% CP) and six replicates. Nile tilapia (n = 270, 6.31 ± 0.40 g) were randomly distributed in 18 aquaria—200 L (15 fish/aquarium), over a period of 60 days. No differences (p &gt; .05) were observed among the treatments for the growth performance and hematological parameters. The volumes of nitrite and sedimentable solids showed higher values with 36% CP, which differed (p &lt; .05) in comparison to 28% CP. Different levels of dietary CP content (36, 32 and 28% CP) do not influence the growth performance and health of Nile tilapia (6–25 g) reared in BFT. Thus, an 8% reduction in dietary protein (28% CP) can generate savings in terms of the costs of production and can decrease the environmental impact of excess dietary protein.

Dietary protein and calcium modulate parathyroid vitamin D receptor expression in young ruminants

For economic reasons and in order to minimize nitrogen excretion and thus pollution, the crude protein content in the diet of livestock animals should be as low as possible without negatively affecting the animals´ health and performance. As ruminants can efficiently use dietary protein because of the ruminohepatic circulation of urea, they are considered to cope more easily with such a feeding regime than monogastric animals. However, despite unaltered daily weight gain, massive changes in mineral homeostasis and vitamin D metabolism were observed with dietary protein reduction (N-) in young, growing goats. Serum concentrations of 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) were decreased with a low N intake, even if calcium (Ca) was also restricted (Ca-). Interestingly, concentrations of cyclic adenosine monophosphate (cAMP) measured as an indirect assessment for the parathyroid hormone (PTH) activity were not affected by low protein. Therefore, it was hypothesized that the sensitivity of the parathyroid gland is modulated during these dietary interventions. Four groups of male German colored goats received a control (N+/Ca+), a reduced protein (N-/Ca+), a reduced Ca (N+/Ca-) or a reduced protein and Ca (N-/Ca-) diet. After six weeks we determined the expression of PTH, PTH receptor, Ca sensing receptor (CASR), vitamin D receptor (VDR), retinoid X receptor (RXRα), Klotho, fibroblast growth factor receptor 1c-splicing form, and the sodium-dependent Pi transporter (PiT1) in the parathyroid glands. Concentrations of cAMP were not affected, while those of Ca and 1,25-(OH)2D3were diminished and that of 25-hydroxyvitamin D3 was increased with N- feeding. The expression patterns of the described target genes were not altered. In contrast, animals fed the Ca- rations showed enhanced serum 1,25-(OH)2D3 and cAMP levels with no changes in blood Ca concentrations demonstrating an efficient adaptation. The mRNA expression of expression of VDR and CASR in the parathyroid gland was significantly diminished and RXRα, PTHR and PiT1 expression was elevated. Instead of the assumed desensitization of the parathyroid gland with N-, our results indicate elevated responsiveness to decreased blood Ca with feeding Ca-.

Effects of Dietary Supplementation of Alpha-Ketoglutarate in a Low-Protein Diet on Fatty Acid Composition and Lipid Metabolism Related Gene Expression in Muscles of Growing Pigs.

Simple SummaryAlpha-ketoglutarate (AKG) is a critical intermediate in the tricarboxylic acid cycle. AKG has been reported to participate in energy production, promote protein synthesis, and improve amino acid metabolism. However, whether AKG functionally participates in the regulation of fat metabolism remains unknown. The objective of this experiment was to evaluate the impact of dietary supplementation with AKG on lipid metabolism in a pig model. The present results suggest that AKG supplementation in a reduced-protein diet could increase the intramuscular fat (IMF) and monounsaturated fatty acid (MUFA) contents in the biceps femoris muscles of pigs. These effects could be linked to the altered lipid metabolism related gene mRNA expression, which promotes the absorption and deposition of fatty acids in the muscle tissues. The results of this study can provide better understanding of the mechanisms by which dietary AKG modulates muscle lipid metabolism in pigs, and this could help to improve pig feeding strategies and supply high-quality pork for humans.The aim of the current study was to investigate whether dietary supplementation with alpha-ketoglutarate (AKG) in a reduced crude protein (CP) diet would affect fatty acid composition and lipid metabolism related gene expression in the muscles of growing pigs. A total of 27 Large White × Landrace growing pigs at 44 ± 1 d of age (11.96 ± 0.18 kg) were randomly allocated to three treatments (n = 9). Dietary treatments included: (1) normal protein diet with 20% crude protein (CP) (NP); (2) a low crude protein diet formulated to contain approximately 17% CP (LP); and (3) a low crude protein diet with 17% CP supplemented with 1% AKG at the expense of regular corn components (ALP). The experimental trial lasted 35 d. The results showed that compared with the NP and LP diets, supplementation with AKG in a low-protein diet increased the intramuscular fat (IMF), oleic acid (C18:1n-9), and monounsaturated fatty acid (MUFA) contents (p < 0.05), and tended to increase the percentage of palmitoleic acid (C16:1) and stearic acid (C18:0) (p < 0.10) in the biceps femoris and longissimus dorsi muscles of growing pigs. These effects may be associated with increased relative mRNA expression levels of fatty acid synthase (FAS), acetyl-CoA carboxylase (ACC), adipocyte determination and differentiation factor 1 (ADD1), fatty acid binding protein 4 (FABP4), and stearoyl-CoA desaturase (SCD) in skeletal muscle, indicating that AKG might be involved in the differential regulation of some key lipogenic genes in skeletal muscles of pigs.