Studies on Reducing Nitrogen Excretion: Ⅰ. Net Energy Requirement of Finishing Pigs Maximizing Performance and Carcass Quality Fed Low Crude Protein Diets Supplemented with Crystalline Amino Acids

Two experiments were conducted to in- vestigate the effects of net energy （NE） level on the performance and carcass traits of finishing pigs fed low crude protein （CP） diets supplemented with crystalline amino acids （CAA）. A total of 216 （Exp. 1） and 360 （Exp. 2 ） barrows （ Yorkshire × Landrace× Duroc ） were allotted to one of six treatments （n =6）. The experimental diets were based on corn and soybean meal, and consisted of a high-CP diet that contained approximately 16% CP and 2.50 Mcal/kg of NE as well as five low-CP diets in which the CP level of the diet was reduced by approximately four percentage units but was supplemented with crystalline lysine, methionine, threonine, and tryptophan. The low CP diets provided 2.64, 2.58, 2.50, 2.42, or 2.36 Mcal/kg in Exp. 1 as well as 2.45, 2.40, 2.35, 2.30, or 2.25 Mcai/kg in Exp.2. In Exp. 1, a linear （P=0.03） increase in weight gain was observed with decreasing NE level while the ratio of gain to feed was unaffect- ed （P 〉 0.05） by NE level. There was a linear in-crease （P = 0.01 ） in the percentage of fat-free lean and a linear decrease （ P = 0.03 ） in the percentage of total fat with decreasing NE levels. In Exp. 2, a sig- nificant quadratic （ P = 0.03 ） effect of NE level was observed for weight gain. The ratio of gain to feed demonstrated a significant （P 〈0.01 ） quadratic effect with pigs fed 2.35 and 2.40 Mcal/kg of NE, Pigs fed the diet containing 2.40 Mcal/kg of NE had the lowest percentage of total fat （36. 95% ） and the highest percentage of fat-free lean （49.36%）. The overall results of these experiments indicate that feed- ing either a surplus or a deficiency of NE is detrimen- tal to both pig performance and carcass composition when low CP diets supplemented with CAA are fed. Our results indicate that when the CP content of the diet is reduced by four percentage units and the diet is properly supplemented with CAA, maximum per- formance and carcass quality will be obtained if the diet provides approximately 2.42 Mcal/kg of NE.

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

Background:The 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.Methods:Fifty-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.Results:Over 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.Conclusion:The 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.

The optimal dietary arginine level of laying hens fed with low-protein diets

Background:Arginine(Arg)is an essential amino acid(EAA)in poultry,an important substrate for protein synthesis and a precursor of several molecules.Supplementation of EAAs with low protein(LP)diet increases the utilization efficiency of dietary crude protein(CP).However,if the EAA requirement is changed in hens fed a LP diet remains to be elucidated.The aim of the present study was to evaluate the optimal level of dietary Arg in the LP diet of hens.A total of 1350 Hy-Line Brown laying hens were randomly allocated to six dietary treatments:a basal diet(16%CP,positive control),or an isoenergetic LP diet(14%CP,0.80%Arg)supplemented 0,0.05%,0.10%,0.15%,and 0.20%L-Arg,corresponding to 0.80%,0.85%,0.90%,0.95%and 1.00%dietary Arg,respectively.Results:The feed efficiency was decreased(P<0.05)by 0.80%and 1.00%Arg-LP diets,compared to control.Within LP diets,dietary Arg level had significant quadratic effects(P<0.05)on laying rate,egg mass,and feed efficiency.Compared to control,the plasma CAT activity or T-AOC content were decreased by 0.80%(P<0.001).However,the hens offered 0.85%and 0.90%Arg-LP diets had higher CAT activity(P<0.001)than 0.80%Arg-LP diet.In contrast,1.00%Arg-LP group had the highest MDA and the lowest T-AOC content in plasma,liver,duodenal and jejunal mucosa(P<0.05).Compared to control,the villus height was decreased by 0.80%,0.95%and 1.00%Arg-LP diets,while the villus height to crypt depth(V/C)ratio was reduced by 0.95%and 1.00%Arg-LP diets in duodenum.Conclusion:The result demonstrates that LP diet(14%CP)deficient in Arg(0.80%Arg)result in augmented oxidative damage and impaired development of intestinal mucosa.According to the quadratic broken-line regression model,the optimal dietary arginine levels for Hy-Line Brown laying hens fed with low protein diet(14%CP)aged 33 to 40 weeks are 0.85%,0.86%,and 0.86%to obtained the maximum laying rate,egg mass,and feed efficiency,respectively.

Effects of Low Protein Diets Supplemented with Ami-no Acids on Production Performance,Carcass Qual-ity and Input-output Ratio of Pigs

[ Objectives ] To study the effects of low-protein diets supplemented with amino acids on the production performance, carcass quality and input-output ratio of fattening pigs and growing-finishing pigs. [ Methods] Two studies were conducted on fattening pigs and growing pigs respectively. Pigs in two experimental groupswere fed with low-protein diets supplemented with amino acids and normal diets respectively, and the initial weight, final weight, feed consumption and car- cass index of the tested pigs were measured. [ Results] The average final weight of fattening pigs in test group was 2.4 kg lower than that in control group, while the difference was not significant （P 〉 0.05 ）. The average daily gain of fattening pigs in test group was 60 g lower than that in control group, indicating that low protein diets had a tendency to decrease the growth rate （P 〉 0.05 ）, and reduction of daily weight gain in low protein diet pigs reached 7.6%. The development of pigs in low protein diet group was poor, however, the difference was not significant. Carcass backfat thickness in low-protein diet group was slightly higher than that in control group, the difference was significant （ P 〈 0.05 ）. There was no significant difference in input-output ratio between low-protein diet group and control group. Finalweight of growing-finishing pigs in low-protein diet group was 3.22 % lower than that in control group, the average daily weight gainwas 6.91% lower than that in control group, feed intake in test group was 5.48% lower than that in control group, and difference between the two treatments was significant （P 〈 0.05 ）. Feed meat ratio in low-protein diet group improved, however, the difference was not significant（P 〉0.05）. [ Conclusions] Production performance of the pigs would be decreasedand the input-output ratio could not be improvedwhen the adding contents of crude protein in diets was reduced 3% -4%. Therefore, it is recommended that the crude protein level should be enough when pigs were fed with low-protein diets.

Effect of low-protein diet with supplementing different levels of DL-methionine on production performance of minks in growing-furring period

A study was conducted to evaluate production performance of minks in growing-furring period with supplementing DL-Methinnine （Met） in low protein diet. Seventy healthy male minks were randomly divided into five groups of 14 minks each. The minks were fed in five kinds of experiment diets （HP, LP, LP＋M1, LP＋M2 and LP＋M3）. The dietary protein levels, expressed as percentage of dry matter （DM）, were 32% （high protein, HP） and 24% （low protein, LP）. LP was supple- mented with Met 0.4% （M1）, 0.8% （M2） and 1.2% （M3） DM. From mid of September to December 10, apparent digestibility of CP （crude pro- tein）, N intake and urinary N excretion were decreased with declining dietary protein levels （p 〈 0.05） and N retained was the highest in treat- ment LP＋M2. No significant difference was found in total serum protein （TP） and serum urea nitrogen （SUN） among all treatment groups （p 〉 0.05）. Skin length of treatment HP and LP^M2 was higher than that of other groups （p 〈 0.05）. Body length, skin weight, length of guard hair and under hair were not affected by different dietary protein levels （p〉0.05）. The best performance could be observed in treatment LP＋M2. In diet, 24% （DM） protein level with 1.54% Met supplementing was enough for minks during growing-farring period. Dietary protein lowered from 32% to 24% with supplementing Met in diets would result in a37.9% decrease in urinary N excretion. Furthermore, addition of Met in diets for minks would be beneficial in terms of reducing feed expenses and lessening nitrogen emissions to the environment.

Effects of Low Protein Diets on Nutrient Digestibility and Excretion in Finishing Pigs

The experiment was conducted to study the effects of low protein diets on nutrient digestibility and excretion of finishing pigs. For the 30-d trial,fortytwo duroc × landrace × yorkshire( DLY) finishing pigs with the initial weight of( 91. 13 ± 1. 64) kg were randomly divided into two groups,with three replicates in each group. The pigs in the two groups were fed with different crude protein( CP) levels( control groups: 15. 49% and low protein groups: 12. 59%). The results showed that:( 1) The digestibility of dry matter and crude fat( CF) in low protein groups were increased significantly( P < 0. 01),but there were no significant differences in digestibility among CP,calcium( Ca) and phosphorus( P);( 2) The digestibility of arginine( Arg) in low protein groups were 2. 02%( P <0. 05) lower than that in control groups. However,the digestibility of other amino acid were no difference between two groups;( 3) The nitrogen( N) excretion in low protein groups was 23. 96%( P < 0. 05) lower than that in control groups,but there were no significant differences in excretion among organic matter,P and Ca( P > 0. 05). The results showed that 2. 9% reduction of the CP in diets could improve nutrient digestibility and reduce the excretion of N,but reduced the digestibility of Arg.

Maternal low protein diet and fetal programming of lean type 2 diabetes

Maternal nutrition is found to be the key factor that determines fetal health in utero and metabolic health during adulthood.Metabolic diseases have been primarily attributed to impaired maternal nutrition during pregnancy,and impaired nutrition has been an immense issue across the globe.In recent years,type 2 diabetes(T2D)has reached epidemic proportion and is a severe public health problem in many countries.Although plenty of research has already been conducted to tackle T2D which is associated with obesity,little is known regarding the etiology and pathophysiology of lean T2D,a variant of T2D.Recent studies have focused on the effects of epigenetic variation on the contribution of in utero origins of lean T2D,although other mechanisms might also contribute to the pathology.Observational studies in humans and experiments in animals strongly suggest an association between maternal low protein diet and lean T2D phenotype.In addition,clear sex-specific disease prevalence was observed in different studies.Consequently,more research is essential for the understanding of the etiology and pathophysiology of lean T2D,which might help to develop better disease prevention and treatment strategies.This review examines the role of protein insufficiency in the maternal diet as the central driver of the developmental programming of lean T2D.

Low-protein diets supplemented with casein hydrolysate favor the microbiota and enhance the mucosal humoral immunity in the colon of pigs

Background:High-protein diets can increase the colonic health risks.A moderate reduction of dietary crude-protein(CP)level can improve the colonic bacterial community and mucosal immunity of pigs.However,greatly reducing the dietary CP level,even supplemented with all amino acids(AAs),detrimentally affects the colonic health,which may be due to the lack of protein-derived peptides.Therefore,this study evaluated the effects of supplementation of casein hydrolysate(peptide source)in low-protein(LP)diets,in comparison with AAs supplementation,on the colonic microbiota,microbial metabolites and mucosal immunity in pigs,aiming to determine whether a supplementation of casein hydrolysate can improve colonic health under very LP level.Twenty-one pigs(initial BW 19.90±1.00 kg,63±1 days of age)were assigned to three groups and fed with control diet(16%CP),LP diets(13%CP)supplemented with free AAs(LPA)or casein hydrolysate(LPC)for 4 weeks.Results:Compared with control diet,LPA and LPC diet decreased the relative abundance of Streptococcus and Escherichia coli,and LPC diet further decreased the relative abundance of Proteobacteria.LPC diet also increased the relative abundance of Lactobacillus reuteri.Both LP diets decreased concentrations of ammonia and cadaverine,and LPC diet also reduced concentrations of putrescine,phenol and indole.Moreover,LPC diet increased total short-chain fatty acid concentration.In comparison with control diet,both LP diets decreased protein expressions of Toll-like receptor-4,nuclear factor-κB,interleukin-1βand tumor necrosis factor-α,and LPC diet further decreased protein expressions of nucleotide-binding oligomerization domain protein-1 and interferon-γ.LPC diet also increased protein expressions of G-protein coupled receptor-43,interleukin-4,transforming growth factor-β,immunoglobulin A and mucin-4,which are indicators for mucosal defense activity.Conclusions:The results showed that supplementing casein hydrolysate showed beneficial effects on the colonic microbiota and mucosal immunity and barrier function in comparison with supplementing free AAs in LP diets.These findings may provide new framework for future nutritional interventions for colon health in pigs.

Apoptosis induced by a low-carbohydrate and high-protein diet in rat livers

AIM: To determine whether high-protein, high-fat, and low-carbohydrate diets can cause lesions in rat livers.METHODS: We randomly divided 20 female Wistar rats into a control diet group and an experimental diet group. Animals in the control group received an AIN-93 M diet, and animals in the experimental group received an Atkins-based diet(59.46% protein, 31.77% fat, and 8.77% carbohydrate). After 8 wk, the rats were anesthetized and exsanguinated for transaminases analysis, and their livers were removed for flow cytometry, immunohistochemistry, and light microscopy studies. We expressed the data as mean ± standard deviation(sd) assuming unpaired and parametric data; we analyzed differences using the student's t-test. statistical significance was set at P < 0.05.RESULTS: We found that plasma alanine aminotransferase and aspartate aminotransferase levels were significantly higher in the experimental group than in the control group. According to flow cytometry, the percentages of nonviable cells were 11.67% ± 1.12% for early apoptosis, 12.07% ± 1.11% for late apoptosis, and 7.11% ± 0.44% for non-apoptotic death in the experimental diet group and 3.73% ± 0.50% for early apoptosis, 5.67% ± 0.72% for late apoptosis, and 3.82% ± 0.28% for non-apoptotic death in the control diet group. The mean percentage of early apoptosis was higher in the experimental diet group than in the control diet group. Immunohistochemistry for autophagy was negative in both groups. sinusoidal dilation around the central vein and small hepatocytes was only observed in the experimental diet group, and fibrosis was not identified by hematoxylin-eosin or Trichrome Masson staining in either group.CONCLUSION: Eight weeks of an experimental diet resulted in cellular and histopathological lesions in rat livers. Apoptosis was our principal finding; elevated plasma transaminases demonstrate hepatic lesions.

High Protein Diet that Cause Weight Loss and Lower Blood Glucose Level Have a Serious Impact on the Kidney Functions of Male Diabetic Obese Albino Rats

Background: High protein (HP) diets are increasingly being recommended as one of the management strategies for weight control in overweight and obese individuals. The health benefits of high protein diets are well-established, but the mechanisms of action on body systems responsible for the changes in body weight and glycaemic control are not well-clear. Objective: The present study aimed to examine the effect of HP diets on the kidney functions of diabetic obese albino rats. Material and Methods: Eighty male adult male albino rats were used in this study. The animals were divided into eight equal groups (10 rats for each). Type 2 DM and obesity were induced. At the end of the 12 weeks, samples were collected for biochemical analysis. Results: The high protein diet led to significant decrease in BW, FI, BG, TC, LDL, TG, Lactate dehydrogenase, albumin, urine pH and urine citrate;while serum insulin, HDL, urea, creatinine, total protein, urine volume and urinary excretion of Ca were significantly higher in high protein diet groups. Conclusion: A high protein intake in diabetic obese albino rats for 12 weeks led to changes in the serum and urine levels of markers of renal function which indicated abnormalities in the functions of the kidney.

Analysis of Overall Popularization of Low-Protein Diet

The shortage of protein feed resources and environmental pollution restrict the healthy and sustainable development of breeding industry,so it is imperative to promote low protein diet. Based on the current industry trends and national policies, this paper analyzes the background con-ditions, significance and specific measures of popularizing low-protein diets, in order to provide policy, theoretical and technical support for the im-plementation of low-protein diets throughout the year.

Protein Diet and Estimated Glomerular Filtration Rate

Chronic kidney disease (CKD) is a common health problem worldwide. CKD staging or classification, together with patients’ prognosis and treatment plan depend on the patients’ kidney function which is assessed by measurement of glomerular filtration rate (GFR). Estimated GFR can be obtained using serum or plasma creatinine as a main variable in equations or formulae such as Cockcroft-Gault equation, MDRD equation (Modification of Diet in Renal Disease), the Schwartz and Counahan-Barratt formulae. These equations, though widely accepted, still have to be adjusted or validated among different groups of patients according to the variation in some factors such as race, diet, and genetic heterogenicity. Diet, especially the high protein load, can affect GFR representing the renal functional reserve. A high protein diet can cause an increase in GFR that lasts for many hours. Long-term consumption of vegetarian diet which is low in protein and contains only protein from plant sources can cause a low baseline GFR while the renal functional reserve is still preserved. This paper aims to remind of the role of protein diet effect on GFR measurement especially when assessing the renal function in vegetarians or individuals on long-term low-protein intake.

Effects of improved amino acid balance diet on lysine mammary utilization, whole body protein turnover and muscle protein breakdown on lactating sows

Background The study objective was to test the hypothesis that low crude protein(CP)diet with crystalline amino acids(CAA)supplementation improves Lys utilization efficiency for milk production and reduces protein turnover and muscle protein breakdown.Eighteen lactating multiparous Yorkshire sows were allotted to 1 of 2 isocaloric diets(10.80 MJ/kg net energy):control(CON;19.24%CP)and reduced CP with“optimal”AA profile(OPT;14.00%CP).Sow body weight and backfat were recorded on d 1 and 21 of lactation and piglets were weighed on d 1,14,18,and 21 of lactation.Between d 14 and 18,a subset of 9 sows(CON=4,OPT=5)was infused with a mixed solution of 3-[methyl-2H3]histidine(bolus injection)and[13C]bicarbonate(priming dose)first,then a constant 2-h[13C]bicarbonate infusion followed by a 6-h primed constant[1-13C]lysine infusion.Serial blood and milk sampling were performed to determine plasma and milk Lys enrichment,Lys oxidation rate,whole body protein turnover,and muscle protein breakdown.Results Over the 21-d lactation period,compared to CON,sows fed OPT had greater litter growth rate(P<0.05).Compared to CON,sows fed OPT had greater efficiency of Lys(P<0.05),Lys mammary flux(P<0.01)and whole-body protein turnover efficiency(P<0.05).Compared to CON,sows fed OPT tended to have lower whole body protein breakdown rate(P=0.069).Muscle protein breakdown rate did not differ between OPT and CON(P=0.197).Conclusion Feeding an improved AA balance diet increased efficiency of Lys and reduced whole-body protein turnover and protein breakdown.These results imply that the lower maternal N retention observed in lactating sows fed improved AA balance diets in previous studies may be a result of greater partitioning of AA towards milk rather than greater body protein breakdown.

Growth performance,serum parameters,inflammatory responses,intestinal morphology and microbiota of weaned piglets fed 18%crude protein diets with different ratios of standardized ileal digestible isoleucine to lysine

The present study was to explore the Ile requirement of piglets fed 18%crude protein(CP)diets.Two hundred and fifty 28-day-old Duroc×Landrace×Yorkshire piglets(8.37±1.92 kg)were randomly divided into 5 dietary treatments(10 piglets per replicate,5 barrows and 5 gilts per replicate)with 45%,50%,55%,60%,65%standardized ileal digestible(SID)Ile-to-Lys ratios,and the SID Lys was formulated to1.19%.The experimental design consisted of two phases(d 1 to 14 and d 15 to 28).Results showed that average daily gain(ADG)had a tendency to quadratically increase as the SID Ile-to-Lys ratio increased(P=0.09),and the optimum SID Ile-to-Lys ratios required to maximize ADG were 48.33%and 54.63%for broken-line linear model and quadratic polynomial model,respectively.Different SID Ile-to-Lys ratios had no significant effects on average daily feed intake and gain-to-feed ratio.Dry matter(P<0.01),CP(P=0.01),ether extract(P=0.04),gross energy(P<0.01)and organic matter(P<0.01)digestibility increased quadratically.Serum total cholesterol levels decreased linearly(P=0.01)and quadratically(P<0.01);aspartate aminotransferase(P<0.01),interleukin-1β(P=0.01),and tumor necrosis factor-a(P<0.01)levels decreased quadratically;immunoglobulin G(P=0.03)and immunoglobulin M(P=0.01)concentrations increased quadratically.Serum Ser levels decreased linearly(P<0.01)and quadratically(P=0.01);Glu(P=0.02),Arg(P=0.05),and Thr(P=0.03)levels decreased quadratically;Gly(P<0.01)and Leu(P=0.01)levels decreased linearly;Ile(P<0.01)concentration increased linearly.Duodenal villus height(P<0.01)and villus height to crypt depth ratio(P<0.01)increased quadratically.The deficiency or excess of Ile decreased short chain fatty acid-producing bacteria abundance and increased pathogenic bacteria abundance.Overall,taking ADG as the effect index,the optimum SID Ile-to-Lys ratios of piglets offered 18%CP diets were 48.33%and 54.63%based on two different statistical models,respectively,and the deficiency or excess of lle negatively affected piglet growth rates and health status.

Long-term effects of early antibiotic intervention on blood parameters,apparent nutrient digestibility, and fecal microbial fermentation profile in pigs with different dietary protein levels

Backgroud： This study aimed to determine the effects of early antibiotic intervention（EAI） on subsequent blood parameters, apparent nutrient digestibility, and fecal fermentation profile in pigs with different dietary crude protein（CP） levels. Eighteen litters of piglets（total 212） were randomly allocated to 2 groups and were fed a creep feed diet with or without in-feed antibiotics（olaquindox, oxytetracycline calcium and kitasamycin） from postnatal d 7 to d 42. On d 42, the piglets within the control or antibiotic group were mixed, respectively, and then further randomly assigned to a normal-（20%, 18%, and 14% CP from d 42 to d 77, d 77 to d 120, and d 120 to d 185,respectively） or a low-CP diet（16%, 14%, and 10% CP from d 42 to d 77, d 77 to d 120, and d 120 to d 185,respectively）, generating 4 groups. On d 77（short-term） and d 185（long-term）, serum and fecal samples were obtained for blood parameters, microbial composition and microbial metabolism analysis.Results： EAI increased（P 〈 0.05） albumin and glucose concentrations in low-CP diet on d 77, and increased（P 〈 0.05） urea concentration in normal-CP diet. On d 185, EAI increased（P 〈 0.05） globulin concentration in normal-CP diets, but decreased glucose concentration. For nutrient digestibility, EAI increased（P 〈 0.05）digestibility of CP on d 77. For fecal microbiota, the EAI as well as low-CP diet decreased（P 〈 0.05） E. coli count on d 77. For fecal metabolites, on d 77, EAI decreased（P 〈 0.05） total amines concentration but increased skatole concentration in low-CP diet. On d 185, the EAI increased（P 〈 0.05） putrescine and total amines concentrations in low-CP diets but reduced（P 〈 0.05） in the normal-CP diets. The low-CP diet decreased the concentrations of these compounds.Conclusions： Collectively, these results indicate that EAI has short-term effects on the blood parameters and fecal microbial fermentation profile. The effects of EAI varied between CP levels, which was characterized by the significant alteration of glucose and putrescine concentration.

Low crude protein diets supplemented with casein hydrolysate enhance the intestinal barrier function and decrease the pro-inflammatory cytokine expression in the small intestine of pigs

To reduce nitrogen excretion and lower feeding costs,low crude protein(CP)diets are sometimes pro-posed,however,a great reduction of dietary CP concentration(>4%reduction vs.recommended con-centration),even supplemented with essential and nonessential amino acids(AA)can detrimentally affect small intestinal barrier function and immunity,possibly due to the excessive lack of peptides.Here we hypothesize that with an extremely low CP concentration diet,protein-derived peptides,rather than AA supplementation,can improve intestinal barrier development and health.To test this hypothesis,21 growing pigs(19.90±1.00 kg body weight)were randomly assigned to 3 treatments with control diet(16%CP),or low CP diets(13%CP)supplemented with AA(LCPA)or casein hydrolysate(LCPC)for 28 days.In comparison with the control diet,the LCPA diet decreased the protein expression level of jejunal barrier factor zonula occludens-1(ZO-1)and stem cell proliferation factor leucine-rich repeat-containing G-protein-coupled receptor-5,whereas the LCPC diet enhanced intestinal barrier function by increasing the protein expression level of jejunal occludin and ZO-1 and ileal mucin-2.The LCPA diet reduced Lactobacillus counts,whereas the LCPC diet increased Lactobacillus counts and reduced Escherichia coli counts in the ileum.The LCPA diet also increased protein expression levels of pro-inflammatory cytokine interleukin-6(IL-6)and IL-22,whereas the LCPC diet decreased protein expression levels of pro-inflammatory IL-1β,IL-17A and tumor necrosis factor-αin the ileum.Collectively,the casein hydroly-sate supplementation of low CP diets showed beneficial effects on the small intestinal barrier,bacterial community,and immunity in pigs,pointing to the important role of protein-derived peptides in small intestinal health in cases of low crude protein diets.

Implications of excreta uric acid concentrations in broilers offered reduced crude protein diets and dietary glycine requirements for uric acid synthesis

In a previous experiment,male Ross 308 broiler chickens were offered dietary treatments with 3 levels of crude protein(222,193,165 g/kg)and 3 feed grains(ground maize,ground wheat,whole wheat)from 7 to 35 d post-hatch.Maize-based diets supported superior growth performance in comparison to wheatbased diets.Uric acid concentrations in excreta were retrospectively determined and related to total nitrogen(N)excreta concentrations.Uric acid concentrations ranged from 28.5 to 69.4 mg/g and proportions of uric acid-N to total excreta-N ranged from 27.4%to 42.6%in broiler chickens offered the 3×3 factorial array of dietary treatments.Proportions of uric acid-N to total N in excreta in birds offered the165 g/kg CP,maize-based diet were significantly lower by 10.6 percentage units(27.4%versus 38.0%;P=0.00057)than their wheat-based counterparts.Total excreta analysed had been collected from 35 to37 d post-hatch when feed intakes and excreta outputs were monitored.There were linear relationships between proportions of uric acid-N to total N in excreta in birds offered the three 165 g/kg CP diets with weight gain(r=-0.587;P=0.010),feed intake(r=-0.526;P=0.025)and feed conversion ratios(r=0.635;P=0.005).The possibility that increasing uric acid-N proportions in excreta is indicative of excessive ammonia accumulations compromising growth performance is discussed.The mean proportion of dietary glycine involved in uric acid excretion was 49.2%across all dietary treatments but ranged from 25.0%to 80.9%.Thus,the appropriate amount of dietary glycine is variable and largely dependent on the volume of uric acid synthesised and excreted.

Dietary branched-chain amino acids modulate the dynamics of calcium absorption and reabsorption in proteinrestricted pigs

Background:Very low-protein(VLP)diets negatively impact calcium(Ca)metabolism and absorption.The objective of this study was to investigate the effect of supplemental branched-chain amino acids(BCAA)and limiting amino acids(LAA)on Ca digestibility,absorption and reabsorption in pigs fed with VLP diets.Forty-eight piglets were assigned to six treatments:positive control(PC),negative control(NC),and NC containing LAA 25%,LAA 50%,LAA+BCAA 25%(LB25)and LAA+BCAA 50%(LB50)more than recommendations.Results:Relative to PC or NC,LB25 and LB50 had higher digestibility of Ca and plasma Ca and phosphorus(P),but lower plasma vitamin D3.LB50 tended to increase vitamin D receptor transcript and protein in the gut,but decreased mRNA or protein abundance of parathyroid hormone 1 receptor(PTH1R),calbindin 1(CALB1),cytochrome P450 family 27 subfamily B member 1 and occludin in small intestine.LB50 increased the transcript of cytochrome P450 family 24 subfamily A member 1 and PTH1R but decreased the transcript of transient receptor potential cation channel subfamily V member 5,CALB1 and solute carrier family 17 member 4 in kidney.Conclusion:Overall,BCAA increased Ca digestibility through regulating the transcellular and paracellular Ca absorption in the gut and reabsorption in kidney during protein restriction.

Glutamic acid supplementation recovers the reduced performance of weanling pigs fed reduced crude protein diets

This study was conducted to evaluate the supplementation of glutamic acid(Glu)to reduced protein diets on the performance of weanling pigs.One hundred and eighty crossbred weanling pigs([YorkshireLandrace]Duroc,21 d old)having similar body weight(BW)of 6.45 kg were randomly allotted to 1 of 6 dietary treatments(5 pigs per pen[2 barrows and 3 gilts];6 pens per treatment)based on BW and sex during a 6-week trial.Dietary treatments consisted of positive control(PC)diet formulated to have 226.9,205.6,and 188.8 g crude protein(CP)during phases 1,2,and 3,respectively,and negative control(NC)diets with 20 g CP reduction from PC diets and addition of Glu with increasing levels,resulting in the calculated Lys-to-Glu ratios of 1:2.25,1:2.30.1:2.35,1:2.40,and 1:2.45,designated as NC,NC1,NC2,NC3,and NC4,respectively.The BW of pigs receiving PC diet was higher(P<0.05)than those receiving NC diet at d 7,21 and 42.A higher(P<0.05)average daily gain(ADG)from d 1 to 7,8 to 21,22 to 42 and during the overall experiment period was observed in pigs fed PC than NC diet.Pigs fed NC diets including the graded level of Glu linearly increased(P<0.05)BW at d 42,ADG and gain-to-feed ratio(G:F)during the overall experimental period.In addition,trends in linear increase in BW(P=0.056)at d 7 and ADG from d 1 to 7 and d 22 to 42(linear effect,P=0.081,P=0.058 respectively)were observed.A tendency in the linear increment of NH3(P=0.082)at d 21 and linear reduction in methyl mercaptans(P=0.054)emission at d 42 was observed in pigs fed NC diets supplemented with graded level of Glu.In conclusion,supplementing the reduced protein diet with Glu enhanced the growth performance in weanling pigs suggesting that supplementation of Glu can compensate the reduction of 2%CP in the basal diets.

Assessment of limiting dietary amino acids in broiler chickens offered reduced crude protein diets

As lowering crude protein(CP)in poultry diets continues to minimize amino acid excess,it is important to understand the limiting order of amino acids and the impact of their deficiencies.Therefore,a pair of experiments were conducted to observe the effects of individual amino acid deletions on growth performance,carcass traits,and nutrient utilization.Both experiments involved 3 control diets based on wheat and soybean meal,including a 210.0 g/kg CP industry control(IC),186.7 g/kg CP positive control(PC)supplemented with feed-grade amino acids to match the IC amino acid profile,186.7 g/kg CP negative control(NC)with reducing N corrected apparent metabolizable energy(AMEN)by 0.5 MJ/kg and removing feed-grade amino acids beyond L-Lys-HCl,DL-Met,and L-Thr from PC.Ten deletion diets where the following supplemented amino acids were individually removed from the PC:Val,Ile,Leu,Trp,Arg,His,Phe t Tyr,glycine equivalence(Glyequi),Pro,and Energy(0.5 MJ/kg reduction in AMEN of the PC).All diets were formulated to contain similar concentrations of digestible Lys,total sulfur amino acid(TSAA)and Thr.Experimental diets were offered to broiler chickens from 15 to 22 d postehatch in a cage study(Exp.1)to gain digestibility and nutrient utilization data;whereas they were offered from 15 to 35 d post ehatch in a floor-pen study(Exp.2)to gain performance and carcass yield data.The removal of supplemented Val,Arg,and Ile resulted in reduction on broiler performance(P<0.05),and the removal of Val,Arg,Ile,and Glyequi negatively influenced carcass traits(P<0.05).Results from both experiments indicate that Val and Arg are co-limiting in wheat-soybean meal diets,but that Ile and Glyequi may potentially limit breast and thigh development.