Dietary copper supplementation modulates performance and lipid metabolism in meat goat kids

Forty-eight male Lezhi black goat kids with similar body weight ((12.09±1.70) kg) and age ((60±5) d) were used to determine the effect of dietary copper (Cu), in the form of reagent grade Cu sulfate (CuSO₄∙5H₂O), on performance, serum lipid profile, and the relative mRNA abundance of genes involved in lipid metabolism.  Goat kids were stratified by body weight and randomly assigned to one of 4 treatment groups.  Each treatment consisted of 12 replicate pens with each pen containing one goat kid.  Treatment groups received the basal diet with no supplemental Cu (control), basal diet plus 10 mg of Cu kg^–1 of dry matter (DM), basal diet plus 20 mg of Cu kg^–1 of DM, or basal diet plus 30 mg of Cu kg^–1 of DM.  Goats were housed individually in pens and fed a high-concentrate pelleted diet for 60 d.  Average daily gain, average daily feed intake and feed:gain of goats were not affected by dietary Cu supplementation (P>0.10).  No differences were detected in serum total cholesterol, triglyceride, and high density lipoprotein cholesterol concentrations of goat kids fed with different Cu concentrations (P>0.05).  However, serum low density lipoprotein cholesterol concentrations decreased linearly (P=0.01) as the concentration of dietary Cu increased.  Intramuscular fat content of longissimus muscle increased (P=0.002) quadratically and liver Cu concentrations increased (P<0.001) linearly as dietary Cu concentration increased.  Compared with the control, dietary supplementation of 20 mg Cu kg^–1 DM decreased the relative mRNA abundance of fatty acid-binding protein 4 (P=0.01) and lipoprotein lipase (P=0.05), and tended to decrease the relative mRNA abundance of carnitine palmitoyltransferase I (P=0.06) in longissimus muscle of goats.  The relative mRNA abundance of peroxisome proliferator-activated receptor alpha (P<0.001), carnitine acetyltransferase (P=0.001), and carnitine palmitoyltransferase I (P=0.001) were also decreased in liver by Cu supplementation.  These results indicate that dietary supplementation of Cu modified lipid metabolism by increasing muscular fat and decreasing serum low density lipoprotein cholesterol, and the modification might be associated with the reduction of relative mRNA abundance of genes for oxidation of long-chain fatty acid in muscle and liver of Lezhi black goat kids.     

Measurement of trimethylamine concentration and evaluation of pig meat natural quality by a spectrophotometric method

Pig meat off-flavor is attributed to trimethylamine (TMA) concentration, and it is considered as the precursor of the fishy off-flavor problems. In this study, TMA concentrations in pig meat were determined, and the interactions with breed and gender effects were discussed. In addition, the TMA threshold for meat off-flavor and pig meat natural quality was measured in relation to meat storage and movement, and the influential factors including the pig breed and storage time were discussed. The results indicated positive effects on the precursor of the fishy off-flavor and the TMA threshold. Native breeds were found to have lower TMA concentrations than European breeds (P<0.01), and females and castrated males had significantly lower TMA concentration than males (P<0.01), The threshold concentration of TMA when meat was classed as off-flavored was 25 μg·g^-1, and this occurred after 35–38 h of storage. The natural qualities, such as appearance, flavor, color and overall acceptable scores declined significantly after 4 days in storage (P<0.01). It is concluded that pig meat off-flavor, breed and gender were essential factors affecting flavor for meat breeding programs, and storage time is important for pig meat natural quality.     

育肥方式对滇南小耳猪肌肉氨基酸的影响

目的 研究育肥方式对迪庆藏猪生长、胴体和肉质的影响,筛选理想的养殖方式。 方法 分养殖场标准化育肥和放养+补饲2种方式进行迪庆藏猪育肥试验,测定其生长、胴体、体组分、肉质和肌肉化学成分。 结果 与放养+补饲育肥组相比,迪庆藏猪养殖场标准化育肥组平均日增质量提高53.29% (P<0.01),胴体皮率和骨率分别降低38.76% (P<0.05)和32.85% (P<0.01),脂率提高26.61% (P<0.05),胃质量率、小肠长、小肠质量和大肠质量分别降低27.93%、15.41%、56.20%和34.86% (P<0.01),花油率和板油率分别提高147.94% (P<0.01)和46.59% (P<0.01);肉色评分降低18.59% (P<0.01),失水率降低18.40% (P<0.01),粗蛋白质含量提高10.45% (P<0.05),肌内脂肪含量降低46.96% (P<0.01),pH、大理石纹、熟肉率、水分、干物质和粗灰分含量差异不显著 (P>0.05)。 结论 迪庆藏猪场养可提高生长速度,降低胴体皮和骨比重,增加背脂和腹脂沉积,提高肌肉保水性能和粗蛋白质含量,提高产肉性能和肌肉品质。     

Reduction of N2O emissions by DMPP depends on the interactions of nitrogen sources (digestate vs. urea) with soil properties

The inhibition of nitrification by mixing nitrification inhibitors (NI) with fertilizers is emerging as an effective method to reduce fertilizer-induced nitrous oxide (N₂O) emissions.  The additive 3,4-dimethylpyrazole phosphate (DMPP) apparently inhibits ammonia oxidizing bacteria (AOB) more than ammonia oxidizing archaea (AOA), which dominate the nitrification in alkaline and acid soil, respectively.  However, the efficacy of DMPP in terms of nitrogen sources interacting with soil properties remains unclear.  We therefore conducted a microcosm experiment using three typical Chinese agricultural soils with contrasting pH values (fluvo-aquic soil, black soil and red soil), which were fertilized with either digestate or urea in conjunction with a range of DMPP concentrations.  In the alkaline fluvo-aquic soil, fertilization with either urea or digestate induced a peak in N₂O emission (60 μg N kg^–1 d^–1) coinciding with the rapid nitrification within 3 d following fertilization.  DMPP almost eliminated this peak in N₂O emission, reducing it by nearly 90%, despite the fact that the nitrification rate was only reduced by 50%.  In the acid black soil, only the digestate induced an N₂O emission that increased gradually, reaching its maximum (20 μg N kg^–1 d^–1) after 5–7 d.  The nitrification rate and N₂O emission were both marginally reduced by DMPP in the black soil, and the N₂O yield (N₂O-N per NO₂^–+NO₃^–-N produced) was exceptionally high at 3.5%, suggesting that the digestate induced heterotrophic denitrification.  In the acid red soil, the N₂O emission spiked in the digestate and urea treatments at 50 and 10 μg N kg^–1 d^–1, respectively, and DMPP reduced the rates substantially by nearly 70%.  Compared with 0.5% DMPP, the higher concentrations of DMPP (1.0 to 1.5%) did not exert a significantly (P<0.05) better inhibition effect on the N₂O emissions in these soils (either with digestate or urea).  This study highlights the importance of matching the nitrogen sources, soil properties and NIs to achieve a high efficiency of N₂O emission reduction.     

Effects of LPA on the development of sheep in vitro fertilized embryos and attempt to establish sheep embryonic stem cells

Lysophosphatidic acid (LPA) is a small molecule glycerophospholipid, which regulates multiple downstream signalling pathways through G-protein-coupled receptors to achieve numerous functions on oocyte maturation and embryo development.  In this study, sheep in vitro fertilized embryos were applied to investigate the effects of LPA on early embryos development and embryonic stem cell establishment.  At first, the maturation medium containing estrus female sheep serum and synthetic oviduct fluid (SOF) were optimized for sheep IVF, and then the effects of LPA were investigated.  From 0.1 to 10 μmol L^–1, LPA had no significant effect on the cleavage rate (P>0.05), but the maturation rate and blastocyst rate increased dependently with LPA concentration (P<0.05), and the blastocyst morphology was normal.  When the LPA concentration was 15 μmol L^–1, the maturation rate, cleavage rate and blastocyst rate decreased significantly (P<0.05), and the blastocyst exhibited abnormal morphology and could not develop into high-quality blastocyst.  Besides, the exogenous LPA increases the expression of LPAR2, LPAR4, TE-related gene CDX-2 and pluripotency-related gene OCT-4 in sheep early IVF embryos with the raise of LPA concentration from 0.1 to 10 μmol L^–1.  The expression of LPAR2, LPAR4, CDX-2 and OCT-4 from the LPA-0.1 μmol L^–1 to LPA-10 μmol L^–1 groups in early embryos were extremely significant (P<0.05), while the expression of these genes significantly decreased in 15 μmol L^–1 LPA-treated embryos compared with LPA-10 μmol L^–1 group (P<0.05).  The inner cell mass in 15 μmol L^–1 LPA-treated embryos was also disturbed, and the blastocysts formation was abnormal.  Secondly, the sheep IVF blastocysts were applied to establish embryonic stem cells.  The results showed that LPA made the blastocyst inoculated cells grow towards TSC-like cells.  They enhanced the fluorescence intensity and mRNA abundance of OCT-4 and CDX-2 as the concentration increased from 0 to 10 μmol L^–1, while 15 μmol L^–1 LPA decreased OCT-4 and CDX-2 expression in the derived cells.  The expression of CDX-2 and OCT-4 in the blastocyst inoculated cells of LPA-1 μmol L^–1 group and LPA-10 μmol L^–1 group extremely significantly increased (P<0.05), but there was significant decrease in LPA-15 μmol L^–1 group compared with LPA-10 μmol L^–1 group (P<0.05).  Meanwhile, the protein expression of LPAR2 and LPAR4 remarkably increased after treatment of LPA at 10 μmol L^–1 concentration.  This study references the IVF embryo production and embryonic stem cell research of domestic animals.      

藏猪选育群屠宰性能和肉质测定分析

目的研究迪庆藏猪与野猪×迪庆藏猪(野藏杂交猪)生长、胴体及肉质性状的差异,为迪庆藏猪的开发利用提供依据。方法选择胎次相同、出生日期相近、体质量约20 kg的迪庆藏猪及野藏杂交猪各12头进行育肥试验,体质量约60 kg时屠宰,比较其生长、胴体、体组分及肌肉品质。结果野藏杂交猪平均日增质量[(316±39) g]显著高于迪庆藏猪[(273±43) g] (P<0.05);屠宰率[(71.93±4.86)%]、骨率[(9.44±0.94)%]和瘦肉率[(50.43±2.25)%]分别比迪庆藏猪高8.94% (P<0.05)、18.74% (P<0.01)和15.59% (P<0.05),肥肉率[(30.33±3.19)%]、花油率[(2.48±0.63)%]和板油率[(4.46±0.24%)]分别比迪庆藏猪低21.30%、52.31%和41.78% (P<0.01);肌肉水分含量[(73.99±2.79)%]极显著高于迪庆藏猪[(69.14±2.65)%] (P<0.01),干物质含量[(26.01±2.79)%]和粗蛋白含量[(21.35±2.38)%]极显著低于迪庆藏猪[(31.92±2.98)%和(24.89±2.14)%] (P<0.01);肉色评分(3.81±0.26)显著高于迪庆藏猪(3.46±0.32) (P<0.05),大理石纹评分(1.88±0.23)和熟肉率[(61.30±1.96)%]显著低于迪庆藏猪[3.42±0.49、(65.37±1.54)%] (P<0.01、P<0.05),其他肉质指标与迪庆藏猪差异不显著(P>0.05)。结论与野猪杂交可提高迪庆藏猪生长速度、胴体骨率和瘦肉率,降低胴体肥肉率、花油率和板油率,且产肉性能优于迪庆藏猪,但是肌肉水分含量升高,干物质含量和蛋白质含量降低,肌肉大理石纹降低,野藏杂交猪肌肉的营养价值及食用品质不如迪庆藏猪。     

伊犁马LPL基因多态性及其与肉质性状关联性分析

【目的】研究伊犁马脂蛋白脂酶(lipoprotein lipase,LPL)基因多态性及其对肉质性状的影响,为专门化肉用马选种提供技术支撑。【方法】以41匹成年伊犁马为研究对象,采集颈静脉血液样本及其三角肌、背阔肌、臂三头肌、腹外斜肌和臀中肌5个部位肌肉样本,提取伊犁马DNA样本并测定肉质性状,利用PCR测序法筛选LPL基因突变位点并进行多态性分析,结合伊犁马肉质性状数据与LPL基因多态性进行关联性分析。【结果】所选马匹中共检测出2个突变位点(g.715T>C和g.12074C>A),均为内含子突变,2个位点均只检测出2种基因型,为低度多态位点。g.715T>C位点TT基因型马匹背阔肌和臀中肌失水率显著高于TC基因型马匹(P<0.05),背阔肌剪切力极显著大于TC基因型马匹(P<0.01),腹外斜肌剪切力极显著小于TC基因型马匹(P<0.05),三角肌和臀中肌剪切力显著大于TC基因型马匹(P<0.05);g.12074C>A突变位点CC基因型马匹臂三头肌和臀中肌失水率极显著低于CA基因型马匹(P<0.01),背阔肌和腹外斜肌失水率显著低于CA基因型马匹(P<0.05),臂三头肌熟肉率极显著高于CA基因型马匹(P<0.01),三角肌和腹外斜肌熟肉率与CA基因型马匹呈显著差异(P<0.05),臂三头肌和腹外斜肌剪切力极显著高于CA基因型马匹(P<0.01)。【结论】LPL基因g.715T>C和g.12074C>A位点是影响伊犁马肉质性状的潜在位点。     

新疆褐牛、哈萨克牛产肉性能及肉品质对比分析

【目的】研究新疆褐牛与哈萨克牛肉用性能和肉品质。【方法】选取12月龄健康新疆褐牛、哈萨克牛阉牛各5头,在同样的饲养管理条件下,持续育肥18个月后屠宰,利用体尺测定、屠宰测定和检测分析的方法对新疆褐牛和哈萨克牛体尺发育、肉用性能和肉品质分析测定。【结果】体尺测定新疆褐牛体高、十字部高均显著高于哈萨克牛(P<0.05),通过屠宰测定,新疆褐牛后腿围,大腿肉厚,胴体重,眼肌面积均显著高于哈萨克牛(P<0.05),新疆褐牛剪切力显著低于哈萨克牛(P<0.05);肉色亮度值(L^*),红色度(a^*),黄色度值(b^*)新疆褐牛均显著高于哈萨克牛(P<0.05),脂肪和蛋白质含量显著高于哈萨克牛(P<0.05)。【结论】新疆褐牛与哈萨克牛相比在体尺发育和肉用性能方面表现出显著优势,且肉品质较为突出。     

日粮中不同藜麦添加水平对芦花鸡肉品质及微量元素的影响

为研究日粮中不同藜麦添加水平对芦花鸡肉品质、肌肉营养成分及微量元素的影响,选取49日龄健康脱温芦花鸡150只,随机分为5组:不添加藜麦及其副产物的对照组(CK)和添加4%(Q4)、8%(Q8)、12%(Q12)的藜麦籽实(原粮)及12%藜麦糠(QS)的处理组,饲喂75 d后屠宰并取胸肌和腿肌样品,测定肉品质、营养成分和微量元素。结果表明,胸肌Q12组45 min肉色(亮度L^*、黄度b^*),Q4、QS组剪切力、蒸煮损失、滴水损失及各试验组的失水率均显著低于CK组(P<0.05);Q8、QS组红度a^*和QS组熟肉率均显著高于CK组(P<0.05);标准化评分表明Q12组胸肌肉品质最好;腿肌Q4、Q12组亮度L^*(45 min、24 h),Q12组黄度b^*(45 min)、滴水损失,Q4组剪切力,Q8、Q12、QS组蒸煮损失均显著低于CK组(P<0.05);而Q8、QS组45 min肉色(红度a^*)则显著高于CK组(P<0.05);标准化评分结果表明,Q8组腿肌肉品质最好;Q8组胸肌水分、Q4组腿肌粗灰分及各试验组胸肌、腿肌粗蛋白均显著高于CK组(P<0.05);胸肌Q12组铜元素含量,腿肌Q8组钙元素、Q12组锰元素含量均显著高于CK组(P<0.05)。由此可见,日粮中添加藜麦对芦花鸡肉品质、肌肉营养成分、微量元素有一定改善作用,且添加8%藜麦籽实对肉品质改善效果更佳。     

基于乌金猪深度发掘的优质高效新品种选育

目的揭示宣和猪PRKAG3基因外显子5多态性及其与肉质性状的关联。方法采用PCR产物直接测序法检测了120头宣和猪PRKAG3基因外显子5区域的SNP位点,借助最小二乘模型分析了各位点不同基因型及合并基因型对6个肉质性状的影响。结果宣和猪PRKAG3基因外显子5区域检出3个SNP位点,包括2个同义突变位点(T579C、T580C)和1个错义突变位点(G595A),分别以TT、TT、GA基因型和T、T、G等位基因的频率最高,且都处于Hardy-Weinberg平衡状态。T579C、T580C位点的TT和TC基因型可显著提高大理石纹(P<0.05)和降低失水率(P<0.01),分别呈显著的加性效应及加性—显性效应(P<0.05或P<0.01);G595A位点的AA基因型失水率最低(P<0.05)、熟肉率最高(P<0.05),呈显著的加性效应(P<0.05);3个位点的合并基因型TTTTGG、TCTCGG和TTTTAA分别具有最高的大理石纹、pH₁和最低的失水率(P<0.05或P<0.01),CCCCGG基因型的大理石纹和pH₁最低、失水率最高(P<0.05或P<0.01)。结论研究结果进一步确认宣和猪PRKAG3基因外显子5多态性与肌肉大理石纹、pH值和失水率显著关联,T579C、T580C位点的CC基因型和G595A位点的GG基因型具有协同降低猪肉品质的效应。     

伊犁马不同部位肉食用品质与脂肪酸组成差异性分析

【目的】 研究伊犁马不同部位肉食用品质及脂肪酸含量,分析不同部位对伊犁马肉食用品质及脂肪酸组成的影响。【方法】 试验选取9匹1岁伊犁马为研究对象,采集三角肌、背阔肌、臂三头肌、腹外斜肌和臀中肌肌肉样本,分别测定其失水率、熟肉率、剪切力、粗脂肪含量及脂肪酸含量,计算饱和脂肪酸、单不饱和脂肪酸和多不饱和脂肪酸含量并进行差异性分析。【结果】 熟肉率三角肌极显著低于腹外斜肌(P<0.01),失水率背阔肌和臂三头肌显著低于臀中肌(P<0.05),十三烷酸(C13∶0)含量三角肌极显著高于背阔肌、臂三头肌和腹外斜肌(P<0.01),二十碳二烯酸(C20∶2)含量背阔肌极显著高于臀中肌(P<0.01),花生四烯酸(C20∶4N6)含量背阔肌极显著高于腹外斜肌(P<0.01),二十碳三烯酸(C20∶3N3)含量背阔肌极显著高于臀中肌(P<0.01),二十四烷酸(C24∶0)含量背阔肌、臂三头肌和腹外斜肌极显著高于臀中肌(P<0.01),多不饱和脂肪酸与饱和脂肪酸含量比值三角肌与背阔肌显著高于腹外斜肌(P<0.05)。【结论】 不同部位伊犁马肉失水率、熟肉率等食用品质及脂肪酸含量存在差异,富含不饱和脂肪酸,是具有高开发价值的肉类。     

不同饲养方式对肉羊胴体及肉品质影响的研究进展

目的探究运动对苏尼特羊肠道内环境及肉品质的影响。方法选取3月龄苏尼特羊12只,随机分为舍饲组(C组)和运动+舍饲组(T组),试验90 d后屠宰,测定2组苏尼特羊的肠道黏膜形态、肠道菌群结构、代谢产物(短链脂肪酸)含量、屠宰性能和肉品质等指标。结果T组苏尼特羊十二指肠和回肠的绒毛高度显著增加(P<0.05),回肠和结肠的隐窝深度显著降低(P<0.05);运动可显著提高苏尼特羊回肠的绒毛高度/隐窝深度值(P<0.05)。16S rDNA基因高通量测序显示：门水平上,拟杆菌门(Bacteroidetes)和厚壁菌门(Firmicutes)为苏尼特羊肠道内主要优势菌门,T组肠道内拟杆菌门相对丰度显著高于C组(P<0.05);属水平上,T组拟杆菌属(Bacteroides)和普雷沃菌属-1 (Prevotella-1)的相对丰度较C组显著增加(P<0.05)。T组肠道内丙酸含量显著高于C组(P<0.05)。与C组相比,T组的屠宰率、宰后24 h肌肉pH值和剪切力显著提高(P<0.05),色差值(L^*、a^*和b^*)显著降低(P<0.05)。结论一定的运动量可以提高舍饲苏尼特羊回肠消化吸收能力,增加十二指肠上皮表面积,改变肠道内菌群结构,改善肠道内环境,提高屠宰率,但会使其背最长肌嫩度降低。     

Quantifying in situ N2 fluxes from an intensively managed calcareous soil using the 15N gas-flux method

Denitrification-induced nitrogen (N) losses from croplands may be greatly increased by intensive fertilization.  However, the accurate quantification of these losses is still challenging due to insufficient available in situ measurements of soil dinitrogen (N₂) emissions.  We carried out two one-week experiments in a maize–wheat cropping system with calcareous soil using the ¹⁵N gas-flux (¹⁵NGF) method to measure in situ N₂ fluxes following urea application.  Applications of ¹⁵N-labeled urea (99 atom%, 130–150 kg N ha⁻¹) were followed by irrigation on the 1st, 3rd, and 5th days after fertilization (DAF 1, 3, and 5, respectively).  The detection limits of the soil N₂ fluxes were 163–1 565, 81–485, and 54–281 μg N m⁻² h⁻¹ for the two-, four-, and six-hour static chamber enclosures, respectively.  The N₂ fluxes measured in 120 cases varied between 159 and 2 943 (811 on average) μg N m⁻² h⁻¹, which were higher than the detection limits, with the exception of only two cases.  The N₂ fluxes at DAF 3 were significantly higher (by nearly 80% (P<0.01)) than those at DAF 1 and 5 in the maize experiment, while there were no significant differences among the irrigation times in the wheat experiment.  The N₂ fluxes and the ratios of nitrous oxide (N₂O) to the N₂O plus N₂ fluxes following urea application to maize were approximately 65% and 11 times larger, respectively (P<0.01), than those following urea application to wheat.  Such differences could be mainly attributed to the higher soil water contents, temperatures, and availability of soil N substrates in the maize experiment than in the wheat experiment.  This study suggests that the ¹⁵NGF method is sensitive enough to measure in situ N₂ fluxes from intensively fertilized croplands with calcareous soils.     

优质型黄羽肉鸡腹脂的遗传选择

目的研究屠宰日龄对大恒肉鸡生长性能及肉品质的影响,并探讨这些性状之间的相关性,为优质肉鸡的生产提供参考。方法选取1日龄雌性大恒肉鸡200只,分别于60、90、120、150、180、240和300 d共7个日龄屠宰10只体质量相近的个体,记录活体质量、胸肌质量和腹脂质量,测定胸肌尺寸、pH值、肉色、滴水损失、蒸煮损失和剪切力,并分析生长性能和肉品质之间的相关性。结果随着日龄的增长,大恒肉鸡的活体质量、胸肌质量、腹脂质量及胸肌尺寸逐渐增加。日增质量在第60~90天达到最大,胸肌质量的增速在第60~90天显著升高(P<0.05),腹脂质量的增速在第90~120天显著升高(P<0.05)。胸肌肉的pH值和剪切力随着日龄的增长而逐渐升高,但滴水损失和蒸煮损失却整体呈下降趋势。此外,肉色也随着日龄的增长而变得更暗和更红。偏相关分析发现：剪切力与pH₁呈极显著正相关(P<0.01),滴水损失与pH₂呈极显著负相关(P<0.01)。结论综合考虑养殖成本、生长性能和肉品质,大恒肉鸡的最佳屠宰日龄约为90 d。     

谷氨酰胺对热应激肉鸡抗氧化性能的影响

目的研究运输前灌服谷氨酰胺(Gln)对运输应激肉仔鸡生长性能、血液激素水平及抗氧化能力的影响。方法选取健康初生AA肉仔鸡300只,随机分为5组,A、B组灌服1 mL生理盐水,C、D和E组按肉鸡体重分别灌服1 mL质量分数为0.50、0.75和1.00 g/kg的Gln。随后B、C、D和E组进行5 h的运输处理,A组为对照组。5 h运输应激处理后,称重并采集血液测定血清皮质酮(CORT)、丙二醛(MDA)、谷胱甘肽过氧化物酶(GSH-Px)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、乳酸脱氢酶(LDH)、肾上腺皮质激素(ACTH)和活性氧(ROS)水平;此后常规饲养14 d,测定采食量和日增重。结果(1) 5 h运输应激后,B组显著失重(P<0.05),而灌服Gln肉仔鸡则未出现失重。饲养至7日龄时,运输应激B组肉仔鸡平均日增重、平均采食量和饲料转化率仍显著低于对照组(P<0.05),但灌服不同剂量Gln可有效改善肉仔鸡平均日增重和平均采食量,其中D组平均采食量与饲料转化率恢复到了对照组水平。14日龄时,运输应激B组肉仔鸡平均日增重、平均采食量和饲料转化率仍显著低于对照组(P<0.05),灌服不同剂量Gln均可有效提高肉仔鸡平均日增重和平均采食量(P<0.05);其中D组平均日增重和平均采食量与E组平均日增重可恢复到对照组水平,而饲料转化率仍低于对照组(P<0.05)。(2)与对照组相比,运输应激可导致B组血清CORT、ACTH、ROS、MDA和LDH水平显著升高(P<0.05),而GSH-Px、SOD和CAT活性显著下降(P<0.05),运前灌服不同剂量Gln可改善上述激素水平和酶的活性,其中C组MDA水平并没有显著改善(P>0.05),D组肉仔鸡的ROS水平可恢复至对照组水平。结论5 h运输会导致肉仔鸡生长性能下降,血液激素水平和抗氧化能力发生改变;运前灌服Gln可有效缓解运输应激造成的上述影响,其中0.75 g/kg的灌服水平改善效果较好。     

A genome-wide association study of five meat quality traits in Yorkshire pigs

Meat quality is an important trait in the pig industry. To identify genomic regions and haplotype blocks responsible for meat quality traits in pigs, a genome-wide association study was conducted for five traits including intramuscular fat content, pH at 45 min and 24 h, drip loss within 24 h and water-holding capacity in 231 Yorkshire barrows using illumina porcine 60k SNP chips. The results showed that a total of 344 single nucleotide polymorphisms (SNP) were significantly associated with five meat quality traits (P<1×10^-4). Moreover, 323 SNPs were within the reported QTL regions, of which 21 were novel. Also, 158 SNPs fell into the proximal region of meat quality related genes. In addition, 25 haplotype blocks based on 116 SNPs were revealed with SNP combination patterns for five traits. Our study added new SNP information for identification of meat quality traits in pigs and will help elucidate the mechanisms of meat quality in pigs.     

Grain zinc and iron concentrations of Chinese wheat landraces and cultivars and their responses to foliar micronutrient applications

Grain zinc(Zn) and iron(Fe) concentrations and their responses to foliar application of micronutrients in 28 Chinese wheat landraces and 63 cultivars were investigated in a two-year field experiment. The average grain Zn and Fe concentrations were 41.8 mg kg^–1(29.0-63.3 mg kg^–1) and 39.7 mg kg^–1(27.9-67.0 mg kg^–1), respectively. Compared with cultivars, landraces had greater grain Zn(11.0%) and Fe(4.8%) concentrations but lower harvest index(HI), grain...     

Identification of genome regions and important variations associated with expression level of MYH genes and its correlation with meat quality traits in pigs

Meat quality is one of the most important economic traits in pig breeding. It has been reported that the composition of type II muscle fibers is correlated with meat quality in pigs. Type II muscle fibers contain three isoforms, IIa, IIb and IIx, which contain specific myofibrillar proteins MYH2, MYH4 and MYH1, respectively. In this study, the expression levels of MYH1, MYH2, and MYH4 genes in the Longissimus thoracis (LT) muscle were measured in 114 Yorkshire pigs. Further, the correlations between the expression level of MYH genes and the meat quality traits of intramuscular fat, drip loss, water-holding capacity and postmortem pH values were analyzed. The results showed that the expression level of MYH2 was positively correlated with the intramuscular fat (R= 0.20, P<0.05). The expression levels of MHY1 and MYH4 were negatively correlated with the pH at 24 h post mortem (pH_24h ; R= －0.28, P<0.01; R= －0.25, P<0.01, respectively). Besides, the 60K SNP chip was used for genotyping the individuals. Genome wide association analysis indicated that 15 SNPs were significantly associated with the expression levels of these three MYH genes. The results indicated the expression levels of MYH1, MYH2 and MYH4 genes could be useful markers for improvement of meat quality in pigs.     

卷烟成品烟丝中不同长度烟丝的化学特性

目的分析卷烟成品烟丝中不同长度烟丝色度值、常规化学成分的变化及其相关性,为色差法快速评价烟丝掺配均匀度提供技术依据。方法选择云烟品牌2种规格卷烟的成品烟丝作为材料,利用6层筛网的旋转筛分仪分别对成品烟丝进行筛分,得到2种规格卷烟不同长度的烟丝样品,制成粉末后测定其CIE‒L^*a^*b^*色空间值和常规化学成分,并对不同长度烟丝的明度值(L^*)、红度值(a^*)、黄度值(b^*)、总色差值(ΔE)及常规化学成分的差异、变化趋势以及色度值与常规化学成分间的Pearson相关性进行分析,最后对b^*与PV值(糖碱比与钾含量的乘积)进行回归分析。结果(1)在同一规格卷烟的成品烟丝中,不同长度烟丝的4个色度指标及6项常规化学成分均存在显著差异(P<0.05)。(2)随着烟丝长度的减小,a^*和ΔE值及总糖、还原糖和总植物碱含量逐渐降低,总氮含量逐渐升高,L^*和b^*值及钾和氯含量先升高后降低。(3) L^*值与总糖、还原糖和总植物碱含量显著负相关(P<0.05),与总氮、钾和氯含量显著(P<0.05)或极显著(P<0.01)正相关;a^*、ΔE值与总糖、还原糖和总植物碱含量极显著正相关(P<0.01),与总氮和钾含量显著(P<0.05)或极显著(P<0.01)负相关;b^*值与氯含量和PV值显著(P<0.05)或极显著(P<0.01)正相关,且b^*值与PV值之间存在高度拟合的线性关系。结论在卷烟成品烟丝中,色度值与其常规化学成分之间存在较高的相关性,为色差法快速评价烟丝掺配均匀度提供了技术依据。     

不同来源ATP表征冷鲜羊肉新鲜度

【目的】通过系统研究冷鲜羊肉不同来源的三磷酸腺苷（adenosine triphosphate,ATP。包括肉中ATP、微生物ATP、肉表面ATP）在贮藏期间的变化规律,筛选能够表征冷鲜羊肉新鲜度变化的ATP指标,构建菌落总数和挥发性盐基氮预测模型,探究冷鲜羊肉新鲜度的预测新方法。【方法】以小尾寒羊背最长肌为试验材料,在空气密封包装0℃条件下分别贮藏0、1、3、5、7、9、11、13、15、17和21 d,分析冷鲜羊肉贮藏期间新鲜度指标（pH、色泽、挥发性盐基氮、菌落总数）与3种来源ATP（肉中ATP、微生物ATP、肉表面ATP）的变化,利用数据统计评价不同来源ATP的变化规律,并构建新鲜度指标的预测模型。【结果】冷鲜羊肉贮藏期间新鲜度指标菌落总数、挥发性盐基氮均呈现上升趋势,并均在贮藏17 d时超过国家标准限值;肉中ATP呈现不断下降趋势,微生物ATP与肉表面ATP均呈现上升趋势,与新鲜度指标变化趋势保持一致;冷鲜羊肉贮藏期间,肉中ATP、微生物ATP、肉表面ATP含量与菌落总数、挥发性盐基氮的相关系数（R）分别为-0.399、0.910、0.943和-0.357、0.725、0.9...