肉鸡肠道PepT1 mRNA表达的肠段差异性与发育性变化

选用遗传背景相同的1日龄父母代雄性Arbor Acre(AA)鸡和父母代雄性岭南黄肉雏鸡各120羽,采用相对定量RT-PCR方法,以30 d时岭南黄鸡肠道样品为模板,研究肉鸡肠道寡肽转运载体1(Peptide transporter 1,PepT1)mRNA表达的肠段差异性;以AA肉鸡和岭南黄鸡十二指肠和空肠样品为模板,研究不同品种肉鸡肠道PepT1 mRNA表达的发育性变化。结果显示:(1)岭南黄肉鸡肠道PepT1 mRNA的表达丰度从十二指肠、空肠、回肠到结直肠依次降低,其中十二指肠显著高于结直肠(P<0.05);(2)AA鸡和岭南黄肉鸡PepT1 mRNA在十二指肠及空肠中的表达具有相同的发育模式,16 d表达丰度最高,16~44 d逐渐下降,58 d略微回升;不同基因型之间PepT1 mRNA丰度比较,AA鸡和岭南黄肉鸡两品种间PepT1 mRNA的表达没有显著差异(P>0.05)。以上结果说明:(1)随着肠道空间位置的后移,岭南黄肉鸡肠道PepT1 mRNA的表达丰度逐渐降低,其中十二指肠的表达丰度显著高于结直肠(P<0.05);(2)不同品种肉鸡十二指肠及空肠PepT1 mRNA的表达具有相同的发育模式,且同日龄两品种间的表达丰度未见明显差异,表明PepT1 mRNA表达受到发育阶段的调控,但品种间具有稳定性。     

GHSR—1a在奶山羊胃肠道的分布与表达

试验采用免疫组织化学、Real—timePCR和Western blotting方法测定ghrelin的功能性受体GHSR-1a（Growth hormone seeretagogue receptor-1a,GHSR-1a）在奶山羊胃肠道的分布和表达。免疫组织化学结果显示,GHSR—1a免疫阳性细胞广泛分布于奶山羊胃肠道。在皱胃主要定位于黏膜层和肌层;瘤胃、网胃和瓣胃黏膜层及肌层中也可见GHSR-1a免疫阳性细胞;在小肠主要位于十二指肠、空肠和回肠的黏膜层、黏膜下层和肌层;在结肠、盲肠和直肠GHSR—1a免疫阳性细胞也有广泛分布;GHSR—1a主要表达于内在神经丛神经细胞、胃底腺上皮细胞、肠腺上皮细胞、复层鳞状上皮细胞、平滑肌细胞中。real—timePCR和Westernblotting结果显示,皱胃、十二指肠、空肠、回肠、盲肠、结肠和直肠GHSR—1a的表达水平相对较高,显著高于瘤胃、网胃和瓣胃的表达（P〈0．05）。结果表明,ghrelin可能通过GHsR-1a对奶山羊胃肠功能具有重要的调节作用。     

鸡肠道SGLT1和GLUT2 mRNA表达的组织特异性研究

运用相对定量RT-PCR方法，研究不同肠段Arbor Acre（AA）肉鸡肠道葡萄糖吸收转运主要载体SGLT1和GLUT2mRNA表达的组织特异性。结果发现。随着肠道空间位置的后移，SGLT1 mRNA的表达量逐步降低。十二指肠SGLT1 mRNA的丰度比结直肠高76．19Vo，差异极显著（P〈0．01）；而空肠和回肠SGLT1 mRNA的表达量分别比结直肠高42．86％和38．10％，差异不显著（P〉0．05），但有提高的趋势（P值分别为0．06和0．07）。十二指肠与空肠和回肠相比，SGLTlmRNA的表达量虽然分别高23．33％和27．59％，但差异不显著（P值分别为0．18和0．10）。相对定量分析表明，十二指肠和空肠GLUT2 mRNA丰度非常接近，差异不显著（P〉0．05）。定性研究显示，十二指肠与空肠GLUT2 mRNA丰度高于回肠和结直肠。鸡肠道SGLT1和GLUT2 mRNA表达的组织特异性之生理功能，有待于进一步研究。     

鸡不同肠段碱性氨基酸转运载体mRNA表达的差异性研究

为研究肉鸡肠道不同肠段碱性氨基酸转运载体rBAT(系统b0, )、y LAT2(系统y L)、CAT1(系统y )、CAT4(系统y )mRNA表达的差异性,以快大型黄羽肉鸡为动物模型,采集30日龄接近平均体重黄羽肉鸡的十二指肠、空肠、回肠和结直肠样品,采用相对定量RT-PCR方法研究不同肠段rBAT、y LAT2、CAT1、CAT4mRNA表达丰度。结果显示:结直肠rBAT、y LAT2的mRNA表达丰度极显著低于十二指肠、空肠和回肠(P<0.01),其在回肠表达丰度高于空肠、十二指肠,差异不显著(P>0.05)。结直肠CAT1 mRNA表达丰度极显著高于十二指肠、空肠和回肠(P<0.01),回肠极显著高于空肠(P<0.01),高出十二指肠27.9%(P=0.111)。结直肠CAT4 mRNA的表达丰度极显著高于其他各个肠段(P<0.01),十二指肠、空肠、回肠CAT4 mRNA的表达丰度依次降低,但相互之间无显著差异。结果表明,位于肠上皮黏膜细胞顶端的碱性氨基酸转运系统b0, 和基底部位的系统y L转运载体mRNA的表达在肠道中的分布类似,显著区别于系统y 。     

Functional characterization of a cloned pig intestinal peptide transporter (pPepT1)

Absorption of dietary protein can be mediated through the uptake of AA as free AA or small peptides. A H(+)-coupled, peptide transport protein, PepT1, is responsible for the absorption of small peptides arising from digestion of dietary proteins in the small intestine. The magnitude of peptide absorption and the nutritional significance of PepT1 are unknown for many food-producing animals; thus, the objective of this study was to clone and determine the functional characteristics of the pig PepT1 (pPepT1). Two cDNA-encoding pPepT1 were isolated, which contain alternative polyadenylation sites. The predicted pPepT1 is a 708-AA protein, which shows 82.8, 85.7, and 64.7% AA identity to human, sheep, and chicken PepT1, respectively. On northern blots, two pPepT1 mRNA of approximately 2.9 and 3.5 kb were detected in the duodenum, jejunum, and ileum of the small intestine and are presumed to result from alternative polyadenylation. Uptake of [(3)H]-Gly-Sar was measured in Chinese hamster ovary cells transiently transfected with a pPepT1 expression vector to study the functional expression of pPepT1. Peptide transport was H(+)-dependent, with an optimal pH of 6.0 to 6.5. The ability of pPepT1 to transport various peptides was assayed by calculating the concentration of unlabeled peptide that inhibited 50% of [(3)H]-Gly-Sar uptake (IC(50)) in transfected cells. Eleven dipeptides and two tripeptides had IC(50) values that ranged from 0.004 to 0.53 mM. Three peptides, Lys-Lys, Arg-Lys, and Lys-Trp-Lys, had IC(50) values greater than 1. 38 mM and seem to be poor substrates for pPepT1. For all three tetrapeptides examined, uptake of Gly-Sar was too small to measure, even at a concentration of 10 mM tetrapeptide; therefore, IC(50) values could not be calculated. These results demonstrate that pPepT1 can transport a variety of dipeptides and tripeptides but not tetrapeptides.     

Effect of cereal straw and alfalfa hay diet on amino acid profile of gastrointestinal digesta in lactating dairy cows

This study was conducted to evaluate the effects of replacing alfalfa hay with rice straw (RS) or corn stover (CS) on amino acid (AA) profiles of gastrointestinal digesta in lactating cows. Eighteen lactating dairy cows were randomly assigned to one of three groups (n = 6) and fed identical concentrate and corn silage with different forages on dry matter basis: (i) 23% alfalfa hay and 7% Chinese wild rye hay (AH); (ii) 30% CS; and (iii) 30% RS. After the 14‐week feeding, a total of 18 cows were slaughtered to collect digesta from four representative organs, including rumen, omasum, duodenum and jejunum. The AA profiles of ruminal microbial fraction were similar among the treatments, except for greater Arg in cows fed RS than in cows fed AH or CS. Most of the analysed AA changed under different diets. Significant differences were found among the microbial fraction, rumen fluid and rumen digesta, with greater essential AA in digesta than in microbial fraction or rumen fluid and greater essential AA in microbial fraction than rumen fluid. Significant differences in individual AA profiles of digesta and relevant fluid were found across the four representative digestive tract parts, including rumen, omasum, duodenum and jejunum, showing much lower Leu proportion in CS and RS than in AH in duodenal fluid. In summary, ruminal microbes may prefer using essential AA, rather than non‐essential AA. The AA profile of ruminal microbes was constant except for Arg. The AA composition of digesta across the four digestive tracts changed dramatically, which indicated differences in the ability and efficiency of AA absorption. The lower duodenum absorbable Leu proportion in cows fed CS or RS indicated the shortage of Leu in CS or RS diets, which might also restrict the balanced AA absorption.     

Benchmarking carcass characteristics and muscles from commercially identified beef and dairy cull cow carcasses for Warner-Bratzler shear force and sensory attributes

The objective of this study was to benchmark carcasses and muscles from commercially identified fed (animals that were perceived to have been fed an increased plane of nutrition before slaughter) and nonfed cull beef and dairy cows and A-maturity, USDA Select steers, so that the muscles could be identified from cull cow carcasses that may be used to fill a void of intermediately priced beef steaks. Carcass characteristics were measured at 24 h postmortem for 75 carcasses from 5 populations consisting of cull beef cows commercially identified as fed (B-F, n = 15); cull beef cows commercially identified as nonfed (B-NF, n = 15); cull dairy cows commercially identified as fed (D-F, n = 15); cull dairy cows commercially identified as nonfed (D-NF, n = 15); and A-maturity, USDA Select grade steers (SEL, n = 15). Nine muscles were excised from each carcass [m. infraspinatus, m. triceps brachii (lateral and long heads), m. teres major, m. longissimus dorsi (also termed LM), m. psoas major, m. gluteus medius, m. rectus femoris, and m. tensor fasciae latae] and subjected to Warner-Bratzler shear force testing and objective sensory panel evaluation after 14 d of postmortem aging. Carcass characteristics differed (P < 0.05) among the 5 commercially identified slaughter groups for the traits of lean maturity, bone maturity, muscle score, HCW, fat color, subjective lean color, marbling, ribeye area, 12th-rib fat thickness, and preliminary yield grade. Carcasses from commercially identified, fed cull cows exhibited more (P < 0.01) weight in carcass lean than did commercially identified, nonfed cull cows. There was a group x muscle interaction (P = 0.02) for Warner-Bratzler shear force. Warner-Bratzler shear force and sensory overall tenderness values demonstrates that muscles from the SEL group were the most tender (P < 0.01), whereas muscles from the B-NF group were the least tender (P < 0.01). Sensory, beef flavor intensity was similar (P > 0.20) among cull cow carcass groups and more intense (P < 0.01) than the SEL carcass group. Muscles from the SEL group exhibited less (P < 0.01) detectable off-flavor than the cull cow carcass groups, whereas the B-NF group exhibited the most (P < 0.01) detectable off-flavor. Although carcass and muscle quality from commercially identified, fed, cull beef and dairy cows was not similar to A-maturity, USDA Select beef, they did show improvements when compared with nonfed, cull, beef and dairy cow carcasses and muscles.     

肉鸡肠道NHE2 mRNA表达的组织特异性与发育性变化

选用遗传背景相同的1日龄父母代雄性Arbor Acre（AA）肉雏鸡120羽,随机分为4个重复,采用相对定量RT-PCR方法,以30日龄AA肉鸡肠道RNA为模板,研究肉鸡肠道钠/氢交换载体2（Sodium hydrogen exchanger 2,NHE2）mRNA表达的组织特异性;以AA肉鸡十二指肠和空肠RNA为模板,研究肉鸡肠道NHE2mRNA表达的发育性变化。结果显示：①AA肉鸡十二指肠和空肠NHE2 mRNA的表达丰度显著高于回肠和结直肠（P〈0.05）,而十二指肠和空肠之间、回肠和结直肠之间无显著差异（P〉0.05）;②AA肉鸡NHE2 mRNA在十二指肠及空肠中的表达具有相同的发育模式,2～16日龄升高,30～44日龄下降,55日龄略微回升;在16和30日龄时的表达丰度显著高于2、44和58日龄（P〈0.05）。以上结果说明：AA肉鸡肠道近端NHE2 mRNA的表达丰度显著高于远端（P〈0.05）。AA肉鸡十二指肠及空肠NHE2 mRNA的表达具有相同的发育模式,表明NHE2mRNA表达受到发育阶段的调控,且在十二指肠和空肠间具有稳定性。     

滩羊羔羊瘤胃和小肠菌群多样性的比较研究

目的 研究滩羊羔羊瘤胃和小肠菌群多样性的差异。方法 选取健康的断奶滩羊公羔,屠宰后采集瘤胃、十二指肠、空肠和回肠内容物,利用16S rDNA高通量测序技术分析瘤胃和小肠菌群结构及多样性。结果 十二指肠样品Chao1指数高于瘤胃、空肠和回肠,瘤胃样品Shannon指数和Simpson指数均高于其他部位,但差异不显著（P>0.05）。瘤胃液中拟杆菌门（Bacteroidetes）、螺旋菌门（Spirochaetae）、丝状杆菌门（Fibrobacteres）的相对丰度显著（P<0.05）高于十二指肠、空肠和回肠,十二指肠中广古菌门（Euryarchaeota）的相对丰度与瘤胃相比有升高的趋势（0.05<P<0.10）,空肠和回肠中厚壁菌门（Firmicutes）的相对丰度显著（P<0.05）高于十二指肠。瘤胃中的未鉴定菌属（Unidentified）、理研菌属_RC9（Rikenellaceae_RC9_gut_group）、密螺旋体属_2（Treponema_2）、瘤胃球菌属_NK4A214（Ruminococcaceae_NK4A214_group）、普雷沃菌属_UCG-001（Prevotellaceae_UCG-001）相对丰度显著（P<0.05）高于十二指肠、空肠和回肠,空肠中Family_ⅩⅢ_AD3011_group相对丰度显著（P<0.05）高于其他部位。结论 滩羊羔羊瘤胃中细菌的多样性更丰富,瘤胃微生物与十二指肠、空肠和回肠的细菌区系显著不同。     

Expression of Proton-dependent Oligopeptide Transporters (POTs) in Calves' Tissues

This test was designed to study the expression of POTs (PepT1, PepT2, PHT1 and PHT2) mRNA in calves'tissues.Tissue-specific expression of the mRNA corresponding to peptide transporter protein in four 3-month-old Chinese Holstein calves was examined by relative quantitative RT-PCR analysis.The results showed that the expression of PepT1 mRNA in the rumen was extremely significantly higher than that in the heart and muscle (P<0.01);The expression of PepT2 mRNA in the liver and kidney was extremely significantly higher than that in the heart, spleen, thymus, muscle, rumen, reticulum, omasum and abomasum (P<0.01);The expression of PHT1 mRNA in the lung and spleen was extremely significantly higher than that in the heart and muscle (P<0.01);The expression of PHT2 mRNA in the lung and thymus was significantly higher than that in the heart, liver, kidney, spleen, muscle, rumen, reticulum, omasum and abomasum (P<0.05).The results indicated that PepT1, PepT2, PHT1 and PHT2 mRNA were respectively abundantly expressed in rumen, kidney and liver, spleen and lung, lung and thymus.     

Mineral content of various tissues in cattle. 4. Studies on dry matter, Ca, Mg, Na and K concentration in mucous membrane and muscle layer of various bovine gastrointestinal sections]

Samples of the following parts of the gastrointestinal tract were collected from 20 slaughter cattle: - oesophagus, reticulum, omasum, rumen, abomasum, duodenum, jejunum, ileum, colon (beginning and end). There were considerable differences in mineral content, related to the differing functions of each part. Forestomach mucosa contained high concentrations of Ca and Mg, attributable to accumulation and separation of mineral salts. In the three segments of small intestine there was generally more Mg than Ca, with high concentrations of Na and K. The tabulated results are intended to provide a basis for comparison with pathological states.     

Crossbreeding experiment with beef and dual-purpose sire breeds on Danish dairy cows IV. Physical,chemical and palatability characteristics of longissimus dorsi and semitendinosus muscles from crossbred young bulls

The results presented are part of a beef × dairy cross breeding experiment in which Simmental, Charolais, Danish Red and White Cattle (DRK), Romagnola, Chianina, Hereford, Blonde d'Aquitaine and Limousin bulls are crossbred with cows of Danish Red Cattle (RDM) and Black Pied Danish Cattle (SDM).Young bulls were slaughtered at 300 kg ($\text{7}\text{1}\text{2}$ months of age on average), 12 months and 15 months of age. Samples of m. longissimus dorsi and m. semitendinosus from 305 animals were examined by a taste panel, by chemical analysis and measurements of colour, by shear force, and by adhesion measurements.Sire breed had a significant influence on chemical composition and colour in both muscles. Taste panel scores and shear force values showed that all sire breeds gave tender meat in the longissimus dorsi. Significant differences in tenderness between sire breeds were found only for the semitendinosus, where Hereford crossbreeds obtained the lowest scores, and Limousin and Blonde d'Aquitaine crossbreeds the highest. Corresponding differences between sire breeds were found for adhesion value, collagen content and solubility of collagen in semitendinosus.Meat quality differences are discussed in relation to early and late maturing breeds.     

犊牛组织中小肽转运体(POTs)的表达研究

为研究犊牛部分组织中小肽转运体(proton-dependent oligopeptide transporters,POTs) (PepT1、PepT2、PHT1、PHT2) mRNA的表达,试验选用4头3月龄的中国荷斯坦犊牛进行屠宰,采用实时荧光定量PCR方法来定量组织中小肽转运蛋白表达水平。结果表明,犊牛PepT1 mRNA在瘤胃中表达丰度极显著高于心脏和肌肉(P<0.01);犊牛PepT2 mRNA在肝脏和肾脏中表达丰度极显著高于心脏、脾脏、胸腺、肌肉、瘤胃、网胃、瓣胃、皱胃(P<0.01);犊牛PHT1 mRNA在肺脏和脾脏中表达丰度极显著高于心脏和肌肉(P<0.01);犊牛PHT2 mRNA在肺脏和胸腺中表达丰度显著高于心脏、肝脏、肾脏、脾脏、肌肉、瘤胃、网胃、瓣胃、皱胃(P<0.05)。综上所述,PepT1、PepT2、PHT1、PHT2 mRNA分别在犊牛瘤胃、肾脏和肝脏、脾脏和肺脏、肺脏和胸腺中表达量最高。     

Variation in proteolysis, sarcomere length, collagen content, and tenderness among major pork muscles

The objectives of this experiment were to determine the extent of variation in proteolysis, sarcomere length, and collagen content among pork muscles and the association of those factors with tenderness variation among muscles at 1 d postmortem. Twenty-three white composite barrows were slaughtered and carcasses (66 kg) were chilled at 0 degrees C for 24 h. At 1 d postmortem, the longissimus lumborum, biceps femoris, semimembranosus, semitendinosus, and triceps brachii, long head were dissected from one side of each carcass and frozen. Trained sensory panelists evaluated tenderness, amount of connective tissue, juiciness, and pork flavor intensity of grilled (70 degrees C) chops on 8-point scales. Raw chops were used for total collagen content, sarcomere length, and the extent of desmin proteolysis. Tenderness ratings were highest (P < .05) for semitendinosus (7.2) and triceps brachii (7.1), followed by longissimus lumborum (6.4) and semimembranosus (5.7) and were lowest (P < .05) for biceps femorus (4.0). The simple correlations between longissimus lumborum tenderness and the tenderness of other muscles were .54 (semimembranosus), .34 (semitendinosus), .36 (triceps branchii), and .17 (biceps femorus). Total collagen was highest (P < .05) for biceps femorus (7.1 mg/g muscle), followed by triceps branchii (6.0 mg/g) and semitendinosus (5.3 mg/g), and lowest for semimembranosus (4.5 mg/g) and longissimus lumborum (4.1 mg/g). Sarcomere length was longest (P < .05) for semitendinosus (2.5 microm) and triceps branchii (2.4 microm), followed by semimembranosus (1.8 microm), longissimus lumborum (1.8 microm), and biceps femorus (1.7 microm). Proteolysis of desmin was greatest (P < .05) in longissimus lumborum (39.3%), followed by semimembranosus (21.0%) and biceps femoris (18.5%), then semitendinosus (.2%) and triceps brachii (.2%). Multiple linear regression using total collagen, sarcomere length, and proteolysis accounted for 57% of the variation in tenderness rating among all samples. Piecewise linear regression was used to account for the interaction of sarcomere length with proteolysis and collagen. This analysis accounted for 72% of the variation in tenderness rating. Variation in collagen, proteolysis, and sarcomere length and the degree of their interaction with one another determine the tenderness of individual muscles.     

Comparison of mucosal drug conjugative rates along the gastrointestinal tract of female sheep

The comparative distribution of p-nitrophenol UDP-glucuronosyl-transferase, 1-chloro-2,4-dinitrobenzene glutathione-S-transferase and sulphamethazine N-acetyltransferase activities was studied along the gastrointestinal mucosa of female Lacaune sheep. Gastrointestinal mucosa was characterized by a very low and unequal N-acetyltransferase activity when activities were expressed per g of wet organ. The duodenum contained highest activities (4.1 nmol/g min). When results were expressed per mg of cytosolic protein, the duodenal activity (0.64 nmol/mg min) was sixfold higher than in liver (0.11 nmol/mg min). There was a lack in N-acetyltransferase activity accepting isoniazid as substrate. Glucuronosyltransferase activity was approximately threefold higher in microsomal fractions of the mucosal lining of gastric and colonic intestine (0.43-0.58 nmol/g min) than in small intestine or caecum (0.10-0.26 nmol/mg min). Concerning cytosolic glutathione S-transferase activity, two- to threefold higher activities were obtained in omasum, jejunum, duodenum and ileum (1021-2164 nmol/g min) than in other parts (341-799 nmol/g min) when results were expressed per g of wet organ. These data were compared with corresponding hepatic activities determined in the same six female sheep.     

Analysis of DNA Methylation and mRNA Expression Level of MSTN Gene in Xinjiang Bashiby Sheep

In order to investigate DNA methylation and expression levels of myostatin (MSTN) gene in mscule and fat, 5 months of age of Bashiby sheep were selected, the promoter region and exon 1 methylation levels of MSTN gene was analyzed using bisulfite sequencing PCR (BSP). Real-time PCR was used to detect the expression level of MSTN gene in biceps femoris, femoral triceps, semitendinosus, semimembranosus, longissimus dorsi muscle and tail fat of Bashiby sheep. The results showed that the methylation probability of muscle was higher than fat, the methylation probability of biceps femoris, femoral triceps, semitendinosus, semimembranosus, longissimus dorsi muscle and tail fat were 74.2%, 74.2%, 83.2%, 83.7%, 82.1% and 25.3%, respectively. The expression levels of MSTN gene in biceps femoris, femoral triceps, semitendinosus, semimembranosus, longissimus dorsi muscle were significantly lower than tail fat in Bashiby sheep (P < 0.05), but there were no significant difference among biceps femoris, femoral triceps, semitendinosus, semimembranosus and longissimus dorsi muscle (P > 0.05).The DNA methylation was negatively correlated with the expression levels in muscle and fat of Bashiby sheep (r=-0.886, P < 0.05).     

猪小肠抗菌肽的抑菌作用研究

本文以乙酸浸提法获得的猪小肠抗菌肽粗提物为对象,通过纸片扩散法研究其在肠道内的分布、抑菌活性及其与添加水平之间的量效关系。结果表明:空肠抗菌肽的含量高于十二指肠与回肠。来源于十二指肠和回肠的抗菌肽对大肠杆菌的杀灭效果均好于沙门氏菌;在空肠则未见明显差异。说明猪小肠抗菌肽的抑菌效果随添加水平减少而不断下降,呈明显的剂量-效应关系。     

The effect of postexsanguination infusion of beef on composition, tenderness, and functional properties.

Ninety culled dairy cows were used in this study and were paired by weight and conformation similarity. Forty-five cows were arterially infused immediately after bleeding with 10% volume by weight of a solution composed of dextrose (.23%), glycerin (.21%), a phosphate blend (.14%) and maltose (.1%). The remaining cows (45) served as controls. In infused carcasses, some quantity of solution retained was in the following order: supraspinatus, chuck greater than longissimus, loin greater than semitendinosus, round muscles. Accordingly, percentage of protein, ether-extractable fat, and protein fat-free amounts were lowered (P less than .05) and percentage of moisture and moisture protein ratio were raised (P less than .05) in the supraspinatus muscle. Tenderness (P less than .01) and protein extractability (P less than .15) were improved. No difference was observed in water-holding capacity between infused and control carcasses. Percentages of moisture fat-free (r = .85) and protein fat-free (r = -.97) were highly correlated to moisture-protein ratio. Moisture percentage of the fat-free tissue was shown to be a more consistent indicator of added moisture in infused whole carcasses compared with moisture:protein ratio and percentage of protein fat-free. Very low correlations were observed between tenderness, percentage of moisture, percentage of water-holding capacity, and ether-extractable fat. The economics of the infusion process to the beef industry is discussed.     

断奶仔猪小肠黏膜脂肪酸结合蛋白和二肽转运载体1mRNA表达发育性变化及谷氨酰胺对其的影响

本试验旨在研究断奶仔猪小肠黏膜脂肪酸结合蛋白( Ⅰ-FABP)和二肽转运载体1( PEPT1) mRNA表达的发育性变化及谷氨酰胺对其的影响.以69头(21±3)日龄断奶杜×长×大仔猪为试验动物,断奶当天选取3头猪进行屠宰,剩余66头随机分为2组,每组3个重复,每个重复11头.对照组饲喂基础饲粮,试验组饲喂基础饲粮+1％谷氨酰胺.断奶后第3、5、7、14天试验组和对照组分别选取3头猪进行屠宰(共计27头),取十二指肠、空肠和回肠黏膜组织样品,通过实时定量PCR法测定Ⅰ-FABP和PEPT1 mRNA的表达量.结果表明:1)Ⅰ-FABP和PEPT1 mRNA的表达量各肠段间无显著差异(P＞0.05);2)Ⅰ-FABP和PEPT1 mRNA在十二指肠、空肠和回肠的表达量均在断奶后急剧下降,断奶第3天的表达量最低,显著低于断奶当天(P＜0.05),而后逐渐升高,第14天达到峰值;3)试验组Ⅰ-FABP和PEPT1 mRNA表达量与对照组无显著差异(P＞0.05),但试验组表现出促使十二指肠、空肠、回肠黏膜的Ⅰ-FABP和十二指肠PEPT1 mRNA表达提前恢复至断奶前水平的趋势.结果提示,断奶仔猪Ⅰ-FABP和PEPT1 mRNA表达量随时间而变化,谷氨酰胺对断奶后Ⅰ-FABP和PEPT1 mRNA表达量的恢复有一定的促进作用.