Reduced dietary protein level influences the free amino acid and gene expression profiles of selected amino acid transceptors in skeletal muscle of growing pigs

This study was conducted to evaluate the effect of reduced dietary protein level on growth performance, muscle mass weight, free amino acids (FAA) and gene expression profile of selected amino acid transceptors in different fibre type of skeletal muscle tissues (longissimus dorsi, psoas major, biceps femoris) of growing pigs. A total of 18 cross‐bred growing pigs (Large White × Landrace × Duroc) with initial body weight (9.57 ± 0.67 kg) were assigned into three dietary treatments: 20% crude protein (CP) diet (normal recommended, NP), 17% CP diet (low protein, LP) and 14% CP diet (very low protein, VLP). The results indicated improved feed‐to‐gain ratio was obtained for pigs fed LP and NP diets (p < 0.01), while the pigs fed VLP diet showed the worst growth performance (p < 0.01). There was no significant difference in the weights of longissimus dorsi and psoas major muscle between LP and NP groups (p > 0.05). Majority of the determined FAA concentration of LP group were greater than or equal to those of NP group in both longissimus dorsi and psoas major muscle (p < 0.01). Further, the mRNA expression levels of sodium‐coupled neutral amino acid transceptor 2, L‐type amino acid transceptor 1 and proton‐assisted amino acid transceptors 2 were higher in skeletal muscle tissue in LP group compared to those of the pigs fed NP or VLP diet. These results suggested that reduced dietary protein level (3 points of percentage less than recommended level) would upregulate the mRNA expression of amino acid transceptors to enhance the absorption of FAA in skeletal muscle of growing pigs. There seems to be a relationship between response of AA transceptors to the dietary protein level in skeletal muscle tissue of different fibre type. To illustrate the underlying mechanisms will be beneficial to animal nutrition.     

Effects of two dietary crude protein levels on finishing performance,meat quality,and gene expression of market lambs

Seventeen crossbred lambs were assigned randomly to low-protein (LP; 8% crude protein [CP]; n = 9) and high-protein (HP; 13% CP; n = 8) diets for 9 weeks. The final body weight, average daily feed intake (ADFI), and average daily gain (ADG) of the HP lambs were significantly higher (P < 0.05) than the LP lambs; however, gain to feed ratio (G:F) for the LP lambs was significantly higher (P < 0.05) than the HP lambs. Hot carcass weight (HCW), adjusted fat thickness, and drip loss of longissimus dorsi (LD) muscle were significantly higher (P < 0.05) for the HP than LP lambs. In contrast, instrumental color values L*, a*, b*, C*, and hue angle (H) of meat from the LP lambs scored significantly higher (P < 0.05) than the HP lambs. The LD muscle from HP lambs had significantly greater CLA of cis-9 trans-11 isomer (P < 0.05) than the LP lambs. The gene expression of metabolism and meat quality-related genes of LP was significantly higher than HP (P < 0.05). These results suggest that a higher dietary CP level promotes growth performance for finishing lambs, whereas lower dietary CP level is beneficial for meat quality, especially when evaluating color characteristics in the final product.     

Effects of rumen‐protected folic acid and dietary protein level on growth performance,ruminal fermentation,nutrient digestibility and hepatic gene expression of dairy calves

This study evaluated the effects of rumen‐protected folic acid (RPFA) supplementation and dietary protein level on growth performance, ruminal fermentation, nutrient digestibility and hepatic gene expression in calves. Forty Holstein male calves (161 ± 5.7 days of age and 192 ± 5.4 kg of body weight) were assigned to one of four groups in a randomized experimental design with a 2 × 2 factorial arrangement. Moderate crude protein (130.1 g CP/kg [MCP] or high crude protein (150.2 g CP/kg [HCP]) diets were fed without (RPFA?) or with 3.6 mg FA (RPFA+) as RPFA per kg dietary dry matter (DM). Calves were fed a total mixed ration with a corn silage to concentrate ratio of 50:50 on a DM basis. The CP×RPFA interaction was not significant for any of the studied variables. The unchanged DM intake, higher average daily gain and lower feed conversion ratio were observed for HCP or RPFA+. Ruminal pH was lower, and total volatile fatty acids (VFA) concentration was higher for HCP or RPFA+. Acetate proportion was higher, and propionate proportion was lower for HCP or RPFA+. As a result, the higher acetate to propionate ratio was observed. Ruminal ammonia N was higher for HCP, but was lower with RPFA supplementation. The higher digestibility of DM, OM, CP and NDF was observed. Blood glucose and insulin were unchanged, but albumin, total protein, GH and IGF‐1 were higher. Similarly, the higher hepatic expression of GH, IGF‐1, GHR, IGF‐1R, PI3K, mTOR and P70S6K was observed for HCP or RPFA+. The results indicated that increasing dietary CP content or supplementation with RPFA promoted growth performance of calves by improving nutrient utilization and up‐regulating hepatic expression of gene related to protein synthesis.     

饲粮能量水平对乌金猪脂肪组织脂类合成代谢相关基因表达的影响

本试验旨在研究不同饲粮能量水平对乌金猪脂肪组织脂类合成代谢相关基因表达的影响.选取体重约15 kg的乌金猪54头,随机分为3组,每组3个重复,每个重复6头猪,分别饲喂消化能为11.74(低能组)、12.89(中能组)和14.22 MJ/kg(高能组)的3种饲粮.分别在体重为30、60和100kg时屠宰,测定胴体脂肪率,...     

利用基因芯片技术研究隐性白鸡不同时期肌肉组织相关差异表达基因

应用包含13319条鸡基因探针序列的表达谱芯片,对从隐性白鸡不同时期肌肉组织抽提及纯化的cRNA进行芯片杂交,并对基因表达谱进行分析,旨在筛选隐性白鸡不同时期肌肉组织相关差异表达基因,探讨造成不同时期肌肉组织生长发育的分子生物学机理。结果显示,在不同生长时期（2周和12周）共筛选出差异表达基因78条（表达上调34条,表达下调44条）,其中已知功能基因39条,主要涉及生长发育、分子代谢、免疫应答、生物合成、细胞通信以及蛋白质合成与分解等相关基因,其中包括一些尚未在GenBank上登陆的序列,推测可能是未知的新基因,它们在鸡生长发育、能量代谢等的过程所起到的作用还需进一步证明。     

Investigating the potential for genetic improvement of nitrogen and phosphorus efficiency in a Swiss large white pig population using chemical analysis

Pig production contributes to environmental pollution through excretion of phosphorus and nitrogenous compounds. European pig production requires annual imports of currently 36 million tons of soya bean, because domestic plant protein sources often do not meet the required protein quality. Most of the mineral phosphate sources are also imported. It is therefore desirable to improve nutrient deposition efficiency through selective breeding, that is to realise similar growth rates and carcass compositions as currently achieved but with a lower intake of dietary crude protein or phosphate. For a preliminary evaluation of the potential of selecting for increased nutrient deposition efficiency, we estimated genetic parameters for nitrogen and phosphorus efficiencies in a Swiss Large White pig population including 294 individuals. Nutrient efficiency phenotypes were obtained from wet-chemistry analyses of pigs of various live weights. Heritability of nitrogen efficiency was estimated at 41%. Heritability of phosphorus efficiency was very low (0.3%), but positive genetic correlations with nitrogen efficiency suggest that breeding for nitrogen efficiency would positively affect phosphorus efficiency. Further studies are needed to improve the quality of estimates and to obtain accurate high-throughput measures of nutrient efficiency to be implemented on farms.     

不同蛋白质水平饲粮对3~4月龄中国荷斯坦犊牛生长性能及消化率的影响

试验旨在研究3~4月龄中国荷斯坦犊牛的适宜饲粮蛋白水平。选取24头65日龄犊牛随机分为3组,分别饲喂19%、21%和23%3种蛋白水平饲粮,分析饲粮蛋白水平对犊牛生长性能、血液生化指标和消化率的影响。结果表明:饲喂19%、21%和23%3种蛋白水平饲粮后,试验全组的日增重分别为(1.19±0.16)kg/d、(1.23±0.16)kg/d、(1.24±0.13)kg/d,组间差异不显著;饲粮蛋白水平对犊牛体斜长显著影响(P<0.05)。血清尿素氮,甘油三酯和游离脂肪酸含量随着饲粮水平的增加而显著提高(P<0.01);饲粮蛋白质水平对总蛋白,白蛋白,乳酸脱氢酶,碱性磷酸酶,谷草转氨酶,总胆固醇,高密度脂蛋白胆固醇,低密度脂蛋白胆固醇,葡萄糖等的影响不显著。粗蛋白、干物质粗脂肪和中性洗涤纤维消化率随饲粮蛋白质水平提高而减低。综合试验犊牛日增重、体尺指标、血液指标和营养物质消化率等各方面的因素,在本试验条件下19%蛋白水平的饲粮对于3~4月龄犊牛最为合适。     

Effects of dietary energy levels on Pectoralis major mixed muscle protein turnover and body composition in two broiler lines housed in different grow-out environments

This study determined the Pectoralis (P) major mixed muscle protein turnover (PT) in two meat broiler lines, Line A and Line B, during the finishing grow-out feeding period (21–42 days) as affected by the dietary metabolizable energy (ME) levels and ambient temperatures. Experimental finishing diets consisted of 80, 90, 100, 110 and 120% ME of recommended nutrient guidelines for energy level. Fractional synthesis rates (FSR) or fractional degradation rates (FDR) were measured in P. major at day 36 and 42. Protein and fat mass gain were measured, and respective energy retention efficiencies as protein and fat (EREp and EREf) were determined. Metabolic heat production (HP) was also reported. Experimental feeding studies were conducted in cool season (24 hr mean: 69.91˚F and 63.98% RH) and in hot season (24 hr mean: 77.55˚F and 86.04% RH). Results showed that FSR or FDR values were not affected by dietary ME levels at day 36, whereas reduced FSR (p < .05) were observed at day 42 fed diets with reduced ME levels (≤100% ME) which could have resulted from greater maintenance energy requirement of maturing broilers at that age. Broilers fed reduced ME diets (≤100% ME) maintained protein mass (equivalent to broilers fed ≥100%–120% ME) by reduced FDR and increased feed intake. Grow-out ambient temperature did not affect FSR or FDR values across ME levels. Line B retained higher protein mass, lower fat mass and greater HP compared to Line A. This was followed by higher feed intake in Line B. Further, Line B exhibited higher EREp and lower EREf across dietary ME levels. In summary, PT homeostasis and body composition changes in broiler lines studied seemed to be regulated by the birds’ intent to normalize energy intake as per physiological need by controlling feed intake.     

猪睾丸组织中miR-375的表达及靶基因预测

生物信息学方法预测出miRNA-375可能的靶基因为DIAPH2和QKI,实时荧光定量法检测了靶基因在1日龄、1-7月龄军牧1号白猪睾丸组织中的表达量。结果表明,3月龄前猪睾丸组织中miRNA-375表达量极低,4-7月龄表达水平逐渐上调,差异显著。预测靶基因DIAPH2在1-7月龄呈显著下调趋势,OKI基因在1-7月龄睾丸组织中表达水平呈显著上调趋势。经SPSS13.0分析可知,不同时期睾丸组织中miRNA-375与2个预测靶基因DIAPH2和QKI的相关系数r分别是-0.396（P〈0.05）,0.411（P〈0.05）,2个预测靶基因DIAPH2和QKI之间的相关系数是0.151（P〉0.05）,靶基因DIAPH2和QKI无明显联系,初步证明DIAPH2可能是miRNA-375的靶基因,为探索猪睾丸组织发育提供了一定的研究基础。     

Effects of different levels of protein supplementary diet on gene expressions related to intramuscular deposition in early‐weaned yaks

This study was conducted to estimate different levels of protein supplementary diet on gene expressions related to intramuscular deposition in early‐weaned yaks. Results showed that supplementary dietary protein significantly increased final weight, average daily gain (ADG), intramuscular fat (IMF), serum free fatty acid (FFA), total triglycerides, total cholesterol (Ch), low‐density lipoprotein cholesterol (LDL) and high‐density lipoprotein cholesterol (HDL) content. There was a quadratic response of ADG, IMF, FFA, Ch, HDL and LDL to dietary crude protein (CP) level. Lipoprotein lipase (LPL), fatty acid synthase (FAS) and acetyl‐CoA carboxylase (ACC) enzyme activities were significantly increased by supplementary dietary CP, while hormone‐sensitive lipase (HSL) and carnitine palmitoyltransferase‐1 (CPT‐1) activities were significantly decreased. LPL, ACC and FAS enzyme activities showed quadratic increase as dietary CP increased. Peroxisome proliferator‐activated receptor γ (PPARγ), LPL, FAS, sterol regulatory element binding protein 1 (SREBP‐1), ACC, stearoyl‐CoA desaturase (SCD) and heart fatty‐acid binding protein (H‐FABP) gene expression were significantly increased by supplementary dietary CP, while HSL and CPT‐1 gene expression were significantly decreased. PPARγ, LPL, SREBP‐1, ACC and H‐FABP gene expression showed quadratic increase as dietary CP increased. These results indicated that supplementary dietary protein increased IMF accumulation mainly to increased intramuscular lipogenic gene expression and decreased lipolytic gene expression.     

饲粮蛋白质水平对重庆黑山羊生产性能和血液生化指标的影响

以3~6月龄重庆黑山羊为试验动物,配制了粗蛋白质水平分别为8.23%、10.42%和12.52%的饲粮,进行了饲养试验、血清生化指标测定。结果表明:(1)随着饲粮中粗蛋白质水平的提高,各组山羊的日增重有增加的趋势,高蛋白质组极显著高于低蛋白质组(P<0.01)、显著高于中蛋白质组(P<0.05),中蛋白质组与低蛋白质组差异不显著(P>0.05);各组的日采食量有提高趋势,但各组间差异不显著(P>0.05);各组饲料转化率有提高趋势,高蛋白质组极显著高于低蛋白质组(P<0.01),其余各组间差异不显著(P>0.05);低蛋白质组肥育毛利润比中蛋白质组低13.83%,而高蛋白质组比中蛋白质组高17.22%。(2)随着饲粮中蛋白质水平的提高,各组山羊血清中的尿素氮、转氨酶有增加的趋势,前白蛋白、总蛋白变化不大。     

日粮蛋白质水平对湖羊门静脉血液生化指标的影响

试验选用3只健康装有门静脉血插管的湖羊,采用4×3不完全拉丁方试验设计,研究8.4%(A)、11.2%(B)、14.0%(C)、16.8%(D)四种日粮蛋白质水平下,湖羊门静脉血液生化指标的变化。试验结果表明:(1)血浆氨态氮(NH3-N)浓度以C组最高,极显著高于A、B组(P0.01);D组显著高于A组和B组(P0.05)。(2)血浆尿素氮(PUN)浓度随蛋白质水平的升高而升高,D组极显著高于A、B组(P0.01),C组显著高于A组(P0.05)。(3)血浆肽氨基酸(PAA)浓度以D组最高,C组次之,C、D组显著高于A组(P0.05)。本试验结果提示,日粮蛋白质水平对血液生理指标有显著影响,其中以C组日粮蛋白质水平较适宜。     

镰形扇头蜱免疫球蛋白结合蛋白的表达及免疫保护分析

为在大肠杆菌中高效表达镰形扇头蜱免疫球蛋白结合蛋白(immunoglobulin binding protein,IGBP),并对表达产物进行免疫保护效果测定,将IGBP基因克隆到pGEX-4T-1载体,转化到感受态细胞BL21,在IPTG诱导下进行表达;表达产物3次免疫家兔,剂量为500μg/只。3次免疫后进行攻蜱试验,观察免疫保护效果。结果发现在IPTG的诱导下,重组质粒pGEX-4T-1-IGBP在大肠杆菌中获得高效表达,产生GST-IGBP融合蛋白,用融和蛋白免疫家兔后,试验组与对照组成蜱饱血重量和死亡率差异显著(P<0.05)。表明重组质粒pGEX-4T-1-IGBP能在大肠杆菌中高效表达,且表达蛋白能够对家兔产生一定程度的抗蜱保护性免疫力。     

Effect of L‐lysine on expression of selected genes,serum concentration of amino acids,muscle growth and performance of growing pigs

Lysine (Lys) is the first limiting amino acid (AA) in most feed formulations for pigs and most abundant, along with leucine, in muscle proteins. An experiment was conducted with 17 pigs (17.7 ± 0.05 kg initial BW) to identify a role of dietary Lys in the control of protein synthesis in pigs. Fourteen pigs were randomly assigned to one of the two wheat‐based dietary treatments: Lys‐deficient, 3.0 g/kg (DEF) and Lys‐adequate, 10.8 g/kg (ADE). Samples from jejunum mucosa, liver, Longissumus and Semitendinosus muscles, and blood were collected. The other three pigs were sacrificed at the beginning of the trial to measure basal carcass composition. Weight gain, gain:feed ratio, Lys intake and loin eye area were greater in ADE than in DEF pigs (p < 0.01). Muscle‐related carcass characteristics were better, and myosin heavy chain IIb expression (MyHC IIb) in Semitendinosus was higher in ADE than in DEF pigs. Expression of AA transporters CAT‐1 was lower (p < 0.05), serum Lys was higher and serum Val was lower in pigs fed the ADE diet. The higher muscularity, MyHC IIb expression in Semitendinosus muscle and Lys serum of pigs fed the ADE diet suggest that Lys increases growth rate not only by functioning as protein construction unit but also as potential control of the protein synthesis process.     

The response of gene expression associated with intramuscular fat deposition in the longissimus dorsi muscle of Simmental × Yellow breed cattle to different energy levels of diets

This study was designed to estimate dietary energy level on intramuscular fat (IMF) deposition in Simmental × Yellow breed cattle. Results showed that ultimate weight and average daily gain in high and medium energy groups were significantly higher than low‐energy group, yet feed conversion ratio was significantly lower. IMF content was significantly increased by dietary energy increasing, whereas longissimus muscle shear force significantly decreased. Serum‐free fatty acids, triglycerides and glucose significantly increased by dietary energy increasing, whereas growth hormone (GH) significantly decreased. Enzyme activities of lipoprotein lipase (LPL), fatty acid synthase (FAS), and acetyl‐CoA carboxylase (ACC) significantly increased by dietary energy increasing, whereas hormone‐sensitive lipase (HSL) and carnitine palmitoyltransferase‐1 (CPT‐1) significantly diminished. Peroxisome proliferator‐activated receptor γ, sterol regulatory element‐binding protein 1, stearoyl‐CoA desaturase, adipocyte‐fatty acid‐binding proteins, ACC, LPL, and FAS gene or protein expression significantly increased by dietary energy increasing, whereas HSL, CPT‐1, and GH gene or protein expression significantly decreased. These results indicated that high dietary energy promoting IMF deposition is mainly by downregulating pituitary GH gene expression, decreasing serum GH concentration, increasing lipogenic genes levels of mRNA, enzyme activities and protein expression, and decreasing lipolytic genes levels of mRNA, enzyme activities, and protein expression.     

不同钙源高钙日粮对青年蛋鸡肾损伤及p53蛋白表达的影响

将120羽40日龄伊沙蛋鸡随机分成3组,每组40羽,分别为：对照组（根据禽类营养需求饲喂正常日粮,含钙0.9%）,试验组1（石粉高钙日粮组,含钙3.78%）,试验组2（磷酸氢钙高钙日粮组,含钙3.78%）,进行为期65d的饲养试验。试验后65d,对各组鸡作血清中钙、磷、尿酸、肌酐和尿素氮的测定,并用免疫组织化学方法检测肾脏中p53蛋白的表达情况。结果表明,高钙组鸡肾脏都有一定程度的损伤,与对照组相比,试验组1中血清尿酸、尿素氮,肌酐显著升高（P〈0.05或P〈0.01）,血清磷极显著降低（P〈0.01）;试验组2中血清尿素氮极显著升高（P〈0.01）,血清磷极显著下降（P〈0.01）,血清钙、尿酸差异不显著（P〉0.05）;与试验组1相比较,试验组2血清磷极显著升高（P〈0.01）,血清钙、尿素氮、尿酸、肌酐差异不显著（P〉0.05）。试验组1鸡肾小管上皮细胞（LLC-PK1）中黄色颗粒很多,p53呈强阳性;试验组2鸡LLC-PK1中黄色颗粒较多,p53呈中等阳性。结果提示,不同钙源高钙日粮能致青年蛋鸡肾损伤,并能够促进肾小管上皮细胞p53蛋白的高表达。     

Effects of dietary protein levels on digestibility of nutrients and growth rate in young female mink (Mustela vison)

This study investigated digestibilities of nutrients and feed efficiency in female mink at the different dietary protein levels during the mink growth period. Effects of dietary protein on growth performance of minks were also measured. Sixty 45‐day‐old healthy female minks were randomly assigned to 6 treatment groups with 10 animals in each group. Animals were fed diets varying in protein levels: 28% (Group I), 30% (Group II), 32% (Group III), 34% (Group IV), 36% (Group V) and 38% (Group VI), respectively. The digestibilities of key nutrients were determined on Day 14 after initiating the experiment and the last 3 days. From the beginning of the study, body weight and feed intake were weighed and recorded every other week in order to calculate the average daily bodyweight gain and the feed efficiency. The trial had demonstrated that nitrogen intake was greatly significantly different, which was affected by dietary protein levels (p < 0.001). Growth performance of minks was impaired when dietary protein level was at 28%. When dietary protein level was at 34%, minks had the best daily gains, feed efficiency, and digestibilities of some key nutrients.     

四翅滨藜AcDREB2转录因子编码基因的克隆及其表达

脱水应答元件结合蛋白(DREB)在植物响应盐和干旱胁迫中发挥重要作用。为研究DREB在耐盐碱耐干旱的先锋植物四翅滨藜(Atriplex canescens)中的功能及其应用前景,本研究设计了一对简并引物,通过PCR扩增和RACE法克隆得到四翅滨藜DREB转录因子编码基因AcDREB2。该基因cDNA全长为867 bp,共编码242个氨基酸。序列BLAST比对与同源性分析结果表明,该基因与其他植物的DREB具有较高的同源性。利用RT-PCR方法进行表达模式分析发现,AcDREB2在四翅滨藜叶中高丰度表达,且其表达受NaCl和渗透胁迫处理的快速诱导,表明AcDREB2参与了四翅滨藜的抗逆响应。     

猪GnRH受体基因多态性分析及相关基因组织表达谱的构建

促性腺激素释放激素(GnRH)受体基因与猪的繁殖性状密切相关,本试验对不同猪种的GnRH受体基因的编码区进行了SSCP分析,未发现多态性。在GnRH受体基因5′侧翼序列上设计引物扩增了该基因大约2000 bp的侧翼序列,通过比对设计引物,对其中的一段含有GAGABox的插入突变序列和一段由于点突变而形成转录调控蛋白结合序列IRF-1的区域运用SSCP的方法进行了多态性分析。结果表明在插入突变处,基因频率在不同的猪种间存在着很大的差异性,其中民猪与其他猪种的差异性最大。IRF突变只存在于民猪中,并且只存在AA型和AB型。构建了3头大白猪母猪GnRH基因、GnRH受体基因、卵泡抑素(FST)基因、促卵泡素(FSH)基因、FSH受体基因、促黄体素(LH)基因、抑制素(inhibin)β(a)基因、inhibinβ(b)基因的组织表达谱,根据表达谱可以推测在下丘脑-脑垂体-性腺轴外不存在这些基因表达产物的相互作用系统。