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.

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.

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.

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.

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.

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.

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.

Branched-chain amino acids partially recover the reduced growth of pigs fed with protein-restricted diets through both central and peripheral factors

The objective of this study was to assess the growth efficiency of pigs fed with protein-restricted diets supplemented with branched-chain amino acids(BCAA)and limiting amino acids(LAA)above the rec-ommended levels.Following 2 weeks of adaptation,48 young barrows were weight matched and randomly assigned to 6 treatments(8 pigs/treatment)for 4 weeks:positive control(PC)with standard protein,negative control(NC)with very low protein containing LAA(i.e.,Lys,Met,Thr and Trp)at rec-ommended levels,and NC containing LAA 25%(L25),LAA 50%(L50),LAA+BCAA(i.e.,Leu,Ile and Val)25%(LB25)and LAA+BCAA 50%(LB50)more than recommendations.Feed intake(FI)and body weight(BW)were measured daily and weekly,respectively.At week 6,blood samples were collected,all pigs euthanized and tissue samples collected.The data were analyzed by univariate GLM or mixed procedure(SPSS)and the means were separated using paired Student's t-test followed by Benjamini-Hochberg correction.Relative to PC,NC had decreased FI,BW,unsupplemented plasma essential amino acids,serum insulin-like growth factor-I(IGF-I)and hypothalamic neuropeptide Y(NPY)(P<0.01).Compared to NC,L25 or L50,LB50 had increased BW and serum IGF-I and decreased plasma serotonin and both LB25 and LB50 had higher FI,plasma BCAA,hypothalamic 5-hydroxytryptamine-receptor 2A and NPY and jejunal 5-hydroxytryptamine-receptor 7(P<0.01).Overall,supplementation of protein-restricted diets with increased levels of dietary BCAA partially recovered the negative effects of these diets on growth through improved IGF-I concentration and FI,which was associated with changed expression of serotonin receptors,blood AA and hypothalamic NPY.

Effect of dietary near ideal amino acid profile on heat production of lactating sows exposed to thermal neutral and heat stress conditions

Background:Reduced protein diet manifested potential to mitigate heat production based on the concept of ideal amino acid profile.The hypothesis of this study was that lactating sows fed a low crude protein(LCP)diet with supplemental amino acid produce less heat compared to those fed a high crude protein(HCP)diet under both thermal neutral(TN)and heat stress(HS)conditions.Methods:Thirty-two lactating sows were allotted to HCP(193 g CP/kg)and LCP(140 g CP/kg)diets under thermal neutral(TN,21±1.5°C)or cycling heat stress(HS,32±1.5°C daytime and 24±1.5°C nighttime)conditions.Diets contained 0.90%SID lysine and 10.8 MJ/kg net energy.Positive pressure indirect calorimeters were used to measure gas exchange in individual sows with litters,and individual piglets on days 4,8,14 and 18.Sow and litter weights were recorded on days 1,10 and 21.Results:Sow total heat production(THP)was calculated by subtracting litter THP from sow+litter THP based on BW0.75.Sow BW and body protein(BP)loss was greater for LCP diet compared to HCP diet in peak lactation(P<0.05 and P<0.01,respectively)and throughout the entire lactation period(P<0.05 and P=0.056,respectively)under HS conditions.Heat-stressed sows fed HCP diet had higher(P<0.05)rectal temperature at 13:00(P<0.05)and 19:00(P<0.01),and higher respiration rate at 07:00(P<0.05),13:00(P<0.05)and 19:00(P<0.05)compared to TN sows fed HCP diet.In sows fed LCP diet,those under HS tended to have higher(P=0.098)rectal temperature at 13:00 and had higher(P<0.05)respiration rate at 07:00,13:00 and 19:00 compared to TN sows.The relationship between daily THP and days in lactation of sows fed LCP diet was quadratic(P<0.05),with an ascending trend until day 14 and a descending trend from days 14 to 18.Sows fed LCP diet had lower daily THP at day 18(P<0.001)compared to those fed the HCP diet under HS conditions.Conclusion:Reduction in THP in sows fed LCP diet was largely associated with THP on day 18 of lactation under HS conditions.Feeding LCP diets alleviated the increased body temperature in sows under HS conditions throughout lactation,which was accompanied by a reduction in respiration rate.Total heat production is associated with days in lactation,in particular under HS conditions with THP appearing to peak between days 14 and 18.

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.