Effects of different energy levels in low-protein diet on liver lipid metabolism in the late-phase laying hens through the gut-liver axis

Background The energy/protein imbalance in a low-protein diet induces lipid metabolism disorders in late-phase laying hens.Reducing energy levels in the low-protein diet to adjust the energy-to-protein ratio may improve fat deposition,but this also decreases the laying performance of hens.This study investigated the mechanism by which different energy levels in the low-protein diet influences liver lipid metabolism in late-phase laying hens through the enterohepatic axis to guide feed optimization and nutrition strategies.A total of 288 laying hens were randomly allocated to the normal-energy and normal-protein diet group(positive control:CK)or 1 of 3 groups:lowenergy and low-protein diet(LL),normal-energy and low-protein diet(NL),and high-energy and low-protein diet(HL)groups.The energy-to-protein ratios of the CK,LL,NL,and HL diets were 0.67,0.74,0.77,and 0.80,respectively.Results Compared with the CK group,egg quality deteriorated with increasing energy intake in late-phase laying hens fed low-protein diet.Hens fed LL,NL,and HL diets had significantly higher triglyceride,total cholesterol,acetylCo A carboxylase,and fatty acid synthase levels,but significantly lower hepatic lipase levels compared with the CK group.Liver transcriptome sequencing revealed that genes involved in fatty acid beta-oxidation(ACOX1,HADHA,EHHADH,and ACAA1)were downregulated,whereas genes related to fatty acid synthesis(SCD,FASN,and ACACA)were upregulated in LL group compared with the CK group.Comparison of the cecal microbiome showed that in hens fed an LL diet,Lactobacillus and Desulfovibrio were enriched,whereas riboflavin metabolism was suppressed.Cecal metabolites that were most significantly affected by the LL diet included several vitamins,such as riboflavin(vitamin B2),pantethine(vitamin B5 derivative),pyridoxine(vitamin B6),and 4-pyridoxic acid.Conclusion A lipid metabolism disorder due to deficiencies of vitamin B2 and pantethine originating from the metabolism of the cecal microbiome may be the underlying reason for fat accumulation in the liver of late-phase laying hens fed an LL diet.Based on the present study,we propose that targeting vitamin B2 and pantethine(vitamin B5 derivative)might be an effective strategy for improving lipid metabolism in late-phase laying hens fed a low-protein diet.

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.

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 adding sodium dichloroacetate to low-protein diets on nitrogen balance and amino acid metabolism in the portaldrained viscera and liver of pigs

Background:Identifying regulatory measures to promote glucose oxidative metabolism while simultaneously reducing amino acid oxidative metabolism is one of the foremost challenges in formulating low-protein(LP)diets designed to reduce the excretion of nitrogen-containing substances known to be potential pollutants.In this study,we investigated the effects of adding sodium dichloroacetate(DCA)to a LP diet on nitrogen balance and amino acid metabolism in the portal-drained viscera(PDV)and liver of pigs.To measure nitrogen balance,18 barrows(40±1.0 kg)were fed one of three diets(n=6 per group):18%crude protein(CP,control),13.5%CP(LP),and 13.5%CP+100 mg DCA/kg dry matter(LP-DCA).To measure amino acid metabolism in the PDV and liver,15 barrows(40±1.0 kg)were randomly assigned to one of the three diets(n=5 per group).Four essential amino acids(Lys,Met,Thr,and Trp)were added to the LP diets such that these had amino acid levels comparable to those of the control diet.Results:The LP-DCA diet reduced nitrogen excretion in pigs relative to that of pigs fed the control diet(P<0.05),without any negative effects on nitrogen retention(P>0.05).There were no differences between the control and LP-DCA groups with respect to amino acid supply to the liver and extra-hepatic tissues in pigs(P>0.05).The net release of ammonia into the portal vein and production rate of urea in the liver of pigs fed the LP-DCA diet was reduced relative to that of pigs fed the control and LP diets(P<0.05).Conclusion:The results indicated that addition of DCA to a LP diet can efficiently reduce nitrogen excretion in pigs and maximize the supply of amino acids to the liver and extra-hepatic tissues.

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.

Lipid metabolism and m^(6)A RNA methylation are altered in lambs supplemented rumen-protected methionine and lysine in a low-protein diet

Background:Methionine or lysine has been reported to influence DNA methylation and fat metabolism,but their combined effects in N6-methyl-adenosine(m^(6)A)RNA methylation remain unclarified.The combined effects of rumen-protected methionine and lysine(RML)in a low-protein(LP)diet on lipid metabolism,m^(6)A RNA methylation,and fatty acid(FA)profiles in the liver and muscle of lambs were investigated.Sixty-three male lambs were divided into three treatment groups,three pens per group and seven lambs per pen.The lambs were fed a 14.5%crude protein(CP)diet(adequate protein[NP]),12.5%CP diet(LP),and a LP diet plus RML(LP+RML)for 60 d.Results:The results showed that the addition of RML in a LP diet tended to lower the concentrations of plasma leptin(P=0.07),triglyceride(P=0.05),and non-esterified FA(P=0.08).Feeding a LP diet increased the enzyme activity or m RNA expression of lipogenic enzymes and decreased lipolytic enzymes compared with the NP diet.This effect was reversed by supplementation of RML with a LP diet.The inclusion of RML in a LP diet affected the polyunsaturated fatty acids(PUFA),n-3 PUFA,and n-6 PUFA in the liver but not in the muscle,which might be linked with altered expression of FA desaturase-1(FADS1)and acetyl-Co A carboxylase(ACC).A LP diet supplemented with RML increased(P<0.05)total m^(6)A levels in the liver and muscle and were accompanied by decreased expression of fat mass and obesity-associated protein(FTO)and alk B homologue 5(ALKBH5).The m RNA expressions of methyltransferase-like 3(METTL3)and methyltransferase-like 14(METTL14)in the LP+RML diet group were lower than those in the other two groups.Supplementation of RML with a LP diet affected only liver YTH domain family(YTHDF2)proteins(P<0.05)and muscle YTHDF3(P=0.09),which can be explained by limited m^(6)Abinding proteins that were mediated in m RNA fate.Conclusions:Our findings showed that the inclusion of RML in a LP diet could alter fat deposition through modulations of lipogenesis and lipolysis in the liver and muscle.These changes in fat metabolism may be associated with the modification of m^(6)A RNA methylation.

Assessment of the dietary amino acid profiles and the relative biomarkers for amino acid balance in the low-protein diets for broiler chickens

Background Research on low-protein-level diets has indicated that even though the profiles of essential amino acids(EAAs)follow the recommendation for a normal-protein-level diet,broilers fed low-protein diets failed to achieve pro-ductive performance compared to those fed normal diets.Therefore,it is imperative to reassess the optimum profile of EAAs in low-protein diets and establish a new ideal pattern for amino acid balance.Furthermore,identifying novel sensitive biomarkers for assessing amino acid balance will greatly facilitate the development of amino acid nutrition and application technology.In this study,12 dietary treatments[Con(+),Con(-),L&A(-),L&A(+),M&C(-),M&C(+),BCAA(-),BCAA(+),Thr(-),Thr(+),Trp(-)and Trp(+)]were established by combining different EAAs including lysine and argi-nine,methionine and cysteine,branched-chain amino acid(BCAA),threonine,and tryptophan to observe the growth and development of the broiler chickens fed with low-protein-level diets.Based on the biochemical parameters and untargeted metabolomic analysis of animals subjected to different treatments,biomarkers associated with opti-mal and suboptimal amino acid balance were identified.Results Growth performance,carcass characteristics,hepatic enzyme activity,serum biochemical parameters,and breast muscle mRNA expression differed significantly between male and female broilers under different dietary amino acid patterns.Male broilers exhibited higher sensitivity to the adjustment of amino acid patterns than female broilers.For the low-protein diet,the dietary concentrations of lysine,arginine,and tryptophan,but not of methionine,cystine,or threonine,needed to be increased.Therefore,further research on individual BCAA is required.For untar-geted metabolomic analysis,Con(+)was selected as a normal diet(NP)while Con(-)represented a low-protein diet(LP).L&A(+)denotes a low-protein amino acid balanced diet(LPAB)and Thr(+)represents a low-protein amino acid imbalance diet(LPAI).The metabolites oxypurinol,pantothenic acid,and D-octopine in birds were significantly influ-enced by different dietary amino acid patterns.Conclusion Adjusting the amino acid profile of low-protein diets is required to achieve normal growth performance in broiler chickens fed normal-protein diets.Oxypurinol,pantothenic acid,and D-octopine have been identified as potentially sensitive biomarkers for assessing amino acid balance.

Effects of electrolyte balance on intestinal barrier,amino acid metabolism,and mTORC1 signaling pathway in piglets fed low-protein diets

A proper dietary electrolyte balance(dEB)is essential to ensure optimal growth performance of piglets.In the low-protein diet,this balance may be affected by the reduction of soybean meal and the inclusion of high levels of synthetic amino acids.The objective of this experiment was to evaluate the optimal dEB of low-protein diets and its impact on the growth performance of piglets.A total of 108 piglets(initial age of 35 d)were randomly divided into 3 groups with 6 replicates of 6 pigs each as follows:low electrolyte diet(LE group;dEB=150 milliequivalents[mEq]/kg);medium electrolyte diet(ME group;dEB=250 mEq/kg);high electrolyte diet(HE group;dEB=350 mEq/kg).Results indicated that the LE and HE diet significantly decreased the average daily gain,average daily feed intake,and crude protein digestibility(P<0.05)in piglets.Meanwhile,LE diets disrupted the structural integrity of the piglets'intestines and decreased je-junal tight junction protein(occludin and claudin-1)expression(P<0.05).Additionally,the pH and HCO3-in the arterial blood of piglets in the LE group were lower than those in the ME and HE groups(P<0.05).Interestingly,the LE diet significantly increased lysine content in piglet serum(P<0.05),decreased the levels of arginine,leucine,glutamic acid,and alanine(P<0.05),and inhibited the mammalian target of rapamycin complex 1(mTORC1)pathway by decreasing the phosphorylation abundance of key proteins.In summary,the dietary electrolyte imbalance could inhibit the activation of the mTORC1 signaling pathway,which might be a key factor in the influence of the dEB on piglet growth performance and intestinal health.Moreover,second-order polynomial(quadratic)regression analysis showed that the optimal dEB of piglets in the low-protein diet was 250 to 265 mEq/kg.

肉鸡常规与低蛋白质饲粮净能效率和氨基酸标准回肠消化率比较研究

本试验旨在比较不同日龄肉鸡对常规与低蛋白质饲粮净能利用效率和氨基酸标准回肠消化率的差异。试验分2个试验进行,试验1:分别选择7日龄爱拔益加(AA)肉鸡48只、17日龄AA肉鸡48只和30日龄AA肉鸡24只,每个日龄阶段分为2组[分别饲喂常规饲粮(饲粮粗蛋白质水平为23%)和低蛋白质饲粮(饲粮粗蛋白质水平为21%)],每组6个重复,每个重复4或2只鸡。每期试验7 d,其中预试期4 d,正试期3 d。采用家禽12室联排开路式呼吸测热装置分别测定肉鸡11~14日龄、21~24日龄和35~38日龄呼吸数据。试验2:分别选择7、17和30日龄AA肉鸡各108只,每个日龄阶段分为3组,每组6个重复,每个重复6只鸡。3组肉鸡分别饲喂常规饲粮、低蛋白质饲粮和无氮饲粮,并分别于10、20和33日龄时开展屠宰试验,测定氨基酸标准回肠消化率。结果表明:1)与常规饲粮相比,低蛋白质饲粮对3个日龄阶段肉鸡生长性能均无显著影响(P>0.05),显著降低肉鸡21~24日龄氧气消耗量(P<0.05)。2)与常规饲粮相比,低蛋白质饲粮显著提高肉鸡11~14日龄代谢能/总能值(P<0.05);显著降低21~24日龄总产热、热增耗和蛋白质沉积能(P<0.05),显著提高净能/代谢能值(P<0.05);显著提高35~38日龄净能(P<0.05)。3)与常规饲粮相比,低蛋白质饲粮显著降低肉鸡7~10日龄丙氨酸和酪氨酸标准回肠消化率(P<0.05),显著提高组氨酸标准回肠消化率(P<0.05);显著提高17~20日龄甘氨酸、胱氨酸、酪氨酸、丝氨酸、苏氨酸、天冬氨酸和缬氨酸标准回肠消化率(P<0.05);对30~33日龄氨基酸标准回肠消化率无显著影响(P>0.05)。综上所述,与常规饲粮相比,低蛋白质饲粮会显著降低肉鸡21日龄后产热量,提高净能利用率;净能体系可以更有效判断饲粮蛋白质水平对肉鸡的影响,有利于精准测定肉鸡对低蛋白质饲粮的能量代谢参数并分析体内能量调控方向;在肠道发育完善后,肉鸡对低蛋白质饲粮的氨基酸标准回肠消化率低于常规饲粮。

低蛋白质饲粮中添加发酵饲料对生长猪生长性能、血清指标和经济效益的影响

本试验旨在研究低蛋白质饲粮中添加发酵饲料(发酵菜籽粕和发酵白酒糟)对生长猪生长性能、血清指标和经济效益的影响。选择72头健康、体重[(31.21±0.31)kg]相近的“长白×荣昌”生长猪,随机分为3组,每组6个重复,每个重复4头猪。对照组和低蛋白质组饲喂玉米-豆粕型饲粮,饲粮粗蛋白质水平分别为15.15%和13.66%;低蛋白质-发酵组以发酵菜籽粕和发酵白酒糟代替饲粮中的豆粕,其添加水平分别为10%和5%,饲粮粗蛋白质水平为13.72%。预试期3 d,正试期39 d。结果表明:1)各组之间生长性能无显著差异(P>0.05)。2)与对照组相比,低蛋白质组和低蛋白质-发酵组的血清尿素氮含量显著降低(P<0.05)。3)与对照组相比,低蛋白质组和低蛋白质-发酵组的血清免疫球蛋白A含量显著提高(P<0.05),血清白细胞介素-6含量显著降低(P<0.05);低蛋白质-发酵组的血清白细胞介素-10含量显著提高(P<0.05)。4)与对照组相比,低蛋白质组和低蛋白质-发酵组的血清超氧化物歧化酶活性显著提高(P<0.05);与对照组和低蛋白质组相比,低蛋白质-发酵组的血清还原型谷胱甘肽含量和总抗氧化能力显著提高(P<0.05)。5)与对照组相比,低蛋白质组和低蛋白质-发酵组的饲料成本分别降低了0.04、0.30元/kg,毛利润分别增加了5.58、11.43元/头。由此可见,在低蛋白质饲粮中添加发酵菜籽粕和发酵白酒糟对生长猪生长性能无影响,能提高免疫功能和抗氧化能力,降低血清尿素氮含量,改善猪只健康水平,降低饲料成本,增加经济效益。

Serine-to-glycine ratios in low-protein diets regulate intramuscular fat by affecting lipid metabolism and myofiber type transition in the skeletal muscle of growing-finishing pigs

Serine and glycine are 2 of the first-affected nonessential amino acids in low crude protein(CP)diets for pigs.Therefore,we explored the effects of different dietary serine-to-glycine ratios on growth perfor-mance and lipid metabolism in growing-finishing pigs.A total of 160 crossbred healthy barrows,with a similar body weight of around 59.50 kg,were randomly allotted into 1 of 5 treatments(8 pens per treatment and 4 pigs per pen).The serine-to-glycine ratios of the 5 dietary treatments were as follows:diet A(NORMAL group),1.18∶1(16%CP);diet B(LOW group),1.2∶1(12%CP);diet C(S2G1 group),2∶1(12%CP);diet D(S1G2 group),1∶2(12%CP);and diet E(S1G1 group),1∶1(12%CP).We found that the pigs fed a low CP diet(12%CP),when maintaining serine-to-glycine ratio at 1∶2 and a total amount of 1.44%,had the same average daily gain as the pigs fed a normal CP diet(16%CP)(P>0.05),but they had increased intramuscular fat(P<0.05).Furthermore,they exhibited higher expression of genes involved in lipid oxidation(P<0.05),which was regulated by modulating methylation levels in the promoters of acyl-CoA oxidase 1(ACOX1)and acyl-CoA dehydrogenase medium chain(ACADM).When compared with the pigs fed a normal CP diet,these pigs had more oxidative myofibers(P<0.05),which were regulated by AMPK-PGC-1αand Calcineurin-MEF2/NFAT pathways in a coordinated manner.Our findings suggested that a dietary serine-to-glycine ratio of 1:2 is beneficial for improving meat quality in pigs fed a low CP diet.

低温真空长时煮制时间对猪肉肌原纤维蛋白结构和特性的影响

为探究低温真空长时煮制时间对猪肉肌原纤维蛋白结构和特性的影响,选取猪背最长肌为实验对象,进行不同煮制时间下羰基含量、总巯基含量、SDS-PAGE、微观结构及蛋白质二级结构的测定与分析。随着热处理时间的增加,肌原纤维蛋白的羰基含量呈现上升趋势(P<0.05),总巯基含量呈现先上升后下降的趋势(P<0.05)。凝胶电泳结果显示,煮制时间为30 min时,肌原纤维蛋白肌球蛋白重链和肌球蛋白轻链条带颜色更浅。由扫描电镜结果可知,60 min时,肌原纤维蛋白聚集形成大量小颗粒聚集物,其破坏程度加深。随着热处理时间的增加,α螺旋相对含量减少,β折叠相对含量先下降后上升,β转角相对含量增加,无规则卷曲相对含量先上升后下降,蛋白质的二级结构由有序向无序转变。结果表明,随着热处理时间的增加,煮制60 min时肌原纤维蛋白结构的氧化与降解明显,煮制30 min时蛋白结构变化相对较小。该研究为低温真空长时煮制工艺提高猪肉产品品质提供了理论依据。

饲用氨基酸的生物合成与产业化应用

饲用氨基酸在低蛋白质饲粮配合技术中的应用既能保障动物的营养需求,又能提高养殖经济效益,同时还具有显著的环境保护效应,在现代集约化养殖中具有广阔的应用前景。生物技术的进步推动了氨基酸生产效率的提升和成本的降低,使得合成氨基酸在饲料行业的应用更加广泛和可行。本文介绍了当前在饲料行业中已广泛应用的饲用合成氨基酸种类及功能研究进展,综述了重要饲用氨基酸(赖氨酸、苏氨酸、色氨酸、异亮氨酸、缬氨酸和亮氨酸)在大肠杆菌或谷氨酸棒杆菌中的生物合成途径,详细阐述了重要饲用氨基酸生产菌株遗传改良的代谢工程策略,并在展望中提出了未来饲用氨基酸生产菌株工程化改造的方向。

Very low-protein diet to postpone renal failure: Pathophysiology and clinical applications in chronic kidney disease

The uremic syndrome is a metabolic disorder characterized by the impairment of renal handling of several solutes, the resulting accumulation of toxic products and the activation of some adaptive but detrimental mechanisms which all together contribute to the progression of renal damage. In moderate to advanced renal failure, the dietary manipulation of nutrients improves metabolic abnormalities and may contribute to delay the time of dialysis initiation. This commentary focuses on the physiopathological rationale and the clinical application of the very low-protein diet supplemented with ketoanalogs for the management of chronic kidney disease.

Low-protein diet accelerates wound healing in mice post-acute injury

Background:Wound healing processes are influenced by macronutrient intake(protein,carbohydrate and fat).The most favourable diet for cutaneous wound healing is not known,although highprotein diets are currently favoured clinically.This experimental study investigates the optimal macronutrient balance for cutaneous wound healing using a mouse model and the Geometric Framework,a nutrient modelling method,capable of analyzing the individual and interactive effects of a wide spectrum of macronutrient intake.Methods:Two adjacent and identical full-thickness skin excisions(1 cm^(2))were surgically created on the dorsal area of male C57BL/6 mice.Mice were then allocated to one of 12 high-energy diets that varied in protein,carbohydrate and fat content.In select diets,wound healing processes,cytokine expression,energy expenditure,body composition,muscle and fat reserves were assessed.Results:Using the Geometric Framework,we show that a low-protein intake,coupled with a balanced intake of carbohydrate and fat is optimal for wound healing.Mice fed a low-protein diet progressed quickly through wound healing stages with favourable wound inflammatory cytokine expression and significantly accelerated collagen production.These local processes were associated with an increased early systemic inflammatory response and a higher overall energy expenditure,related to metabolic changes occurring in key macronutrient reserves in lean body mass and fat depots.Conclusions:The results suggest that a low-protein diet may have a greater potential to accelerate wound healing than the current clinically used high-protein diets.

乳清蛋白-果胶高内相乳液凝胶对低脂再制奶酪的品质影响

以乳清蛋白和果胶、葡聚糖为主要原料,采用酸诱导法制备乳清蛋白-果胶乳液凝胶(whey protein-pectin emulsion gel,WP)和乳清蛋白-葡聚糖乳液凝胶(whey protein-glucan emulsion gel,WG),比较35%、75%分散相体积分数凝胶(分别记为WP35、WG35、WP75、WG75)的功能特性,并进一步探究高内相乳液凝胶作为脂肪替代物在低脂再制奶酪中的代脂效果。结果表明:WP75的平均粒径最小,脂肪分布均匀,蛋白质网络结构稳定。乳液凝胶样品在0.1~10 Hz内弹性模量(G′)和黏性模量(G″)都随油相体积分数的升高呈上升趋势,其中WP75抵抗形变能力、热稳定性及持水性都优于其他样品。样品15%-WP75(添加WP75,脂肪质量分数15%的再制奶酪)油析性减弱,熔化性增强,质构特性与全脂对照无明显差异。研究表明乳清蛋白与果胶制备的高内相乳液凝胶在低脂奶酪产品有较好的脂肪替代效果,在低脂乳制品加工中具有良好的应用潜力。

基于低场核磁共振与近红外数据融合的豆粕蛋白质含量预测模型

在低场核磁共振与近红外光谱特征层数据融合的基础上建立豆粕蛋白质含量的预测模型,实现对豆粕生产过程中蛋白质含量的快速检测。采集待测样品的低场核磁共振与近红外光谱数据,对数据进行预处理。利用连续投影算法(SPA)提取低场核磁共振与近红外光谱的特征变量,应用偏最小二乘法、BP神经网络、麻雀搜索算法优化BP神经网络(SSA-BP),融合筛选出的特征变量,建立豆粕蛋白质含量预测模型。将低场核磁共振数据、近红外光谱数据单独建模与两种技术数据融合后构建的模型相比较,两种技术数据融合构建的SSA-BP模型效果最优,校正集决定系数为0.9830,校正集均方根误差为0.1273,验证集决定系数为0.9564,验证集均分根误差为0.2039。综上,本方法能够实现豆粕蛋白质含量的快速、无损及准确定量检测,也验证了低场核磁共振与近红外数据融合的可行性与有效性。

低蛋白质低豆粕多元化饲粮是养猪节粮增效的关键技术

通过补充适宜种类和数量的工业合成晶体氨基酸,低蛋白质饲粮可以精准满足猪快速生长所需的氨基酸营养需求,避免蛋白质饲料浪费及减少粪、尿氮排放。低蛋白质低豆粕多元化饲粮是以低蛋白质饲粮生产技术为基础,依据各种能量饲料和蛋白质饲料的可利用养分等,配制的原料种类多、养分互补性强、营养平衡度高的低豆粕饲粮。低蛋白质低豆粕多元化饲粮可有效增强猪对饲粮中营养物质的消化、吸收和沉积,降低饲粮中豆粕、玉米等原料的用量,对节粮增效及提高养猪效率具有重要意义。本文从研究与应用进展、对生猪养殖效率的影响、合成氨基酸与天然氨基酸效率对比、氨基酸数量需求情况及产能等方面分析,综述了猪低蛋白质低豆粕多元化饲粮技术、应用效果及前景,以期为相关研究及应用工作提供一定的参考和帮助。

反刍动物营养与日粮中的蛋白替代技术策略

“大食物观”包含了饲料在内的粮食安全供给,我国饲料粮占粮食总量48.2%,其中蛋白质饲料资源短缺,对外依存度居高不下,给畜产品稳产保供、粮食安全带来隐患,制约着我国畜牧业的发展。牛羊等反刍动物产业既是重要的畜牧产业构成,也是民生产业,文章针对非蛋白氮、低蛋白日粮配制等技术在反刍动物营养与日粮中的应用以及蛋白替代策略进行论述,旨在为反刍动物养殖过程中开源节流、绿色可持续发展提供参考。

低蛋白日粮对黄羽肉鸡生长性能及胴体品质的影响

试验旨在研究低蛋白日粮对黄羽肉鸡生长性能、胴体品质及肉质的影响。试验选取1日龄慢速型母鸡360羽,设对照组、试验组,每组6个重复,每个重复30只鸡。试验组1~6周(w)、7~13 w、14~19 w阶段日粮粗蛋白浓度,分别设定为对照组的90%、95%、100%,配方中增加玉米副产物比例、降低豆粕与大豆油用量。结果显示,相比于对照组,试验组鸡各阶段体重明显下降(P<0.05),1~6 w增重明显降低(P<0.01)、料重比增高(P<0.01),全程料重比无显著变化(P>0.05);鸡腹脂率显著下降(P<0.05),胸肌a值、肉色L值优于对照组(P<0.05);单位增重所需日粮粗蛋白下降1.7%,饲料成本下降7.1%。综上所述,在本研究条件下,下调生长前、中期日粮的粗蛋白浓度会明显降低黄羽肉鸡全期生长速度,但能节约增重饲料成本,对胴体品质、肉质有一定的改善作用。