不同品种猪背最长肌肌苷酸含量及相关基因表达的比较

以安徽地方品种圩猪、安庆六白猪以及国外瘦肉型品种长白猪为研究对象,采用高效液相色谱法测定3种猪背最长肌肌苷酸(IMP)含量。利用家畜或家禽中已鉴定的影响肉质性状的QTLs信息与猪的基因组比对,得到可能与猪肉质相关的目的基因:ADSL与GARS-AIRS-GART基因。定量PCR法比较影响肌苷酸含量的ADSL与GARS-AIRS-GART基因mRNA在肝脏、心脏和背最长肌组织中的表达水平,并研究2种基因在不同猪种中的表达量与IMP含量的相关性。结果表明:长白猪的背最长肌肌苷酸含量高于圩猪和六白猪。ADSL mRNA在3种猪的表达模式均表现为背最长肌中最高,心脏次之,肝脏最低的趋势。而GARS-AIRS-GART mRNA的表达模式为背最长肌最高,肝脏次之,心脏最低的趋势。ADSL mRNA在长白猪肝脏的表达量,GARS-AIRS-GART mRNA在圩猪肝脏和六白猪心脏的表达量均与IMP含量显著负相关。     

A theoretical approach of the relationships between collagen content, collagen cross-links and meat tenderness

This work concerns the relationship between meat tenderness and the rubber-like properties, i.e. pressure and elastic modulus, that endomysium and perimysium connective tissues develop when meat has been heated to a temperature above which collagen contracts. For rest length meats with similar intramuscular connective tissue morphology, and which are at the same ageing state and pH, the elastic modulus of the collagenous fraction of connective tissues is approximately proportional to the total number of collagen cross-links present per volume of meat. Calculations from various published experiments concerned with the effect on tenderness of muscle type, animal age, type, and sex from different species show that this modulus follows most of the variations of meat toughness. Moreover, the proportionality between the increase in this elastic modulus and the increase in meat toughness approaches unity in situations where toughness mainly depends on connective tissues. This work demonstrates the decisive role of rubber-like properties of connective tissues in meat tenderness variations.     

Comparative study of the histochemical properties, collagen content and architecture of the skeletal muscles of wild boar crossbred pigs and commercial hybrid pigs

The histochemical properties, collagen content and architecture of Musculus longissimusthoracis (LT), Musculus pectoralis profundus (PP) and Musculus biceps femoris (BF) were compared in F(1) (half blood) and F(2) (quarter blood) wild boar crossbred pigs and commercial hybrid pigs, and Japanese wild pigs. F(1) pigs showed the lowest growth rate, followed by F(2) pigs. The most rapid growth was shown by the commercial pigs. The percentage weights of LT and PP muscle to body weight were larger in the wild boar crossbred pigs than commercial pigs. The muscles of the crossbred pigs contained type I and IIA myofibers at higher frequency and type IIB at lower frequency than the commercial pigs, except for LT muscle of F(2) pigs. The myofiber diameter in each type of muscle did not differ between pigs except for the smaller type IIA in BF muscle in commercial pigs. The total amount of intramuscular collagen was less in LT muscles than the others. More intramuscular collagen was found in the wild boar crossbred pigs than the commercial pigs in LT and PP muscles. With an increase of collagen content, the perimysial collagen architecture developed but not the endomysial architecture. Traits characteristic of the crossbred pigs seem to be inherited from the wild boar. Our results clarify that cross breeding with wild boar results in pigs with distinctive muscle characteristics in terms of histochemical properties, collagen content and architecture.     

Effect of feeding partially hydrogenated lard on trans-fatty acid content of muscle and backfat of heavy pigs

The incorporation of fat in diets for heavy pigs may be necessary in order to increase their energy intake in the finishing period. Lard may be a good lipid source but it contains 10–13% of linoleic acid, which makes the subcutaneous fat less suitable for long term curing of raw ham. Partial hydrogenation of lard decreases linoleic acid content, but increases trans-fatty acid content.

This trial involved two groups of pigs of 114 kg live weight, fed for the last two months before slaughter with diets containing 3% lard (L) or 3% partially hydrogenated lard (PHL). The PHL contained about 10% trans-fatty acids and 2.5% linoleic acid.

Rearing performance and carcass characteristics were unaffected by treatment. The group fed PHL showed a lower percentage of linoleic acid in the backfat (PHL 12.28% vs. L 13.04%) and a higher percentage of C18:1 trans-fatty acids both in backfat (0.5% vs. 0.06%) and in intramuscular fat (0.2% vs. 0.04%).     

浓香型烤烟叶片单叶重与中性香气成分含量的关系研究

以豫中烟区主栽品种NC89为试验材料,研究了中上部叶片单叶重与中性香气成分含量的关系.结果表明:中部叶多数类胡萝卜素降解产物、棕色化反应产物及茄酮含量在单叶重12 g时达到最大值,随着单叶重的继续增加含量迅速降低并趋于平缓;大部分苯丙氨酸裂解产物在单叶重10 g时达到最大值,随单叶重的增加而逐渐降低.上部叶大部分中性香气成分含量在单叶重12～15 g时达到最大值,茄酮含量在单叶重为9 g时含量最高,随单叶重的增加逐渐降低.除新植二烯外的香气成分总量变化幅度表现为中部叶大于上部叶,且二者均在单叶重12 g时达到最大值.综合各香气成分的含量,中部叶与上部叶的最适单叶重范围分别为10～12 g和12～15 g.     

凹凸棒石黏土对生长育肥猪生产性能、金属含量及肉品质的影响

研究凹土原土及热改性凹土对生长育肥猪生产性能、金属含量和肉品质的影响。选用体重约47kg健康"杜×长×大"三元杂交的生长育肥猪60头,随机分为3组,每组4个重复。对照组饲喂基础日粮,试验组饲喂在基础日粮中添加2%凹土原土、2%热改性凹土的试验日粮。结果表明:1)凹土原土和热改性凹土对生长育肥猪生产性能无显著影响(P0.05);2)凹土原土和热改性凹土降低血液中As、Pb、Cr含量和腿肌中Cr的含量(P0.05),热改性凹土显著提高血液中Mg含量(P0.05);3)凹土原土降低眼肌MDA(P0.05),凹土原土和热改性凹土降低眼肌中T-AOC的活性(P0.05);4)凹土原土提高眼肌p H45 min、a*45 min(P0.05),降低L*45 min、b*24 h和压力损失(P0.05)。添加凹土原土和热改性凹土能降低重金属在动物机体中的沉积、提高抗氧化能力进而改善肉品质,热改性凹土效果优于原土。     

Relationship between rate of post mortem pH fall and ageing of Longissimus muscle in pietrain pigs

Twenty-six pietrain pigs exhibiting wide variability in pH₄₅ (pH value 45 min post mortem) values were used to assess the mechanical behaviour of cooked and raw Longissimus muscle at 24 h and 8 days post mortem. Rheological behaviour was studied in compression under strain conditions which allow specific determination of myofibrillar resistance. The muscles were divided into three groups on the basis of pH₄₅ values: (Severe pale, soft and exudative (PSE), pH₄₅ = 5.49 ± 0.03 (n = 9); PSE pH₄₅ = 5.78 ± 0.04 (n = 10); Normal, pH₄₅ = 6.35 ± 0.05 (n = 7). The three groups did not differ significantly for ultimate pH (pH_u = 5.57 ± 0.02 for the 26 muscles). A lower mechanical resistance of raw samples was found in the Normal group, regardless of the time post mortem. Although this difference was not significant, a significant relationship was found between this trait and pH₄₅ at both times post mortem (r = ?0.43, P < 0.05, at 24 h and r = ?0.44, P < 0.05, at 8 days post mortem). However, no significant effect of pH₄₅ was found on the mechanical resistance of cooked muscles. The relative decrease in myofibrillar strength after an 8-day ageing period was not affected by pH₄₅ but this was due to the fact that the three groups exhibited different starting points. Mechanical resistance of raw and cooked muscles at 24 h post mortem were significantly related to pH_u (r = ?0.55, P < 0.01, and r = ?0.49, P < 0.05, respectively). The present results show that after an 8-day ageing period, PSE muscles are not fully aged.     

Relationship between lipid peroxidation and fat content in Japanese Black beef Longissimus muscle during storage

We examined the relationship of crude fat content to lipid peroxidation of beef during storage. Longissimus muscle samples (fat content; 6.5–39.4%) from 27 Japanese Black beef steers were stored for 1, 4, 7 and 10 days, and thiobarbituric acid reactive substances (TBARS) and lipid hydroperoxides (LOOH) were determined. TBARS values increased significantly (P<0.05), but LOOH did not change during the 10- day storage period. TBARS values were negatively correlated (P<0.05) with fat content in samples stored for 1, 4, 7 and 10 days. LOOH values, however, were not significantly correlated with fat content except on day 1. Phospholipid contents were correlated (P< 0.01) with LOOH values on each measurement day, but not significantly correlated with TBARS values except on day 1. These findings indicated that: (1) high-fat beef had high preservative properties, and that; (2) TBARS formation was correlated with LOOH derived from phospholipid oxidation in the initial period of storage, and was correlated directly with fat content in a later period.     

导电纤维在防静电针织物中的含量及性能研讨

研究了防静电针织物中导电纤维的间隔距离与导电纤维的含量以及织物的抗静电性能的关系，通过计算机曲线模拟，求出变量之间的回归曲线方程，根据织物的允许电荷面密度计算出导电丝的理论间距和理论含量。     

The relationship between animal age and the thermal stability and cross-link content of collagen from five goat muscles

The thermal stability of intramuscular collagen, as determined using differential scanning calorimetry, was measured in five muscles from 75 goats with known birth dates ranging in age from one day to 13 years. The collagen cross-link pyridinoline, and the collagen-associated, and putative cross-link, Ehrlich Chromogen were also measured. Five different muscles were examined and the effects of age compared to those found in the tendon of the longissimus dorsi muscle. The differences between intramuscular collagen and tendon collagen were found to be much greater than those between the intramuscular collagens of different muscles. Intramuscular collagen is more thermally stable than tendon collagen due to higher levels of heat-stable cross-links. However the increase in thermal stability of intramuscular collagen with age could not be explained simply in terms of the cross-links measured.     

Relationships between structural characteristics of bovine intramuscular connective tissue assessed by image analysis and collagen and proteoglycan content

Three muscles (Longissimus thoracis, Semimembranosus, Biceps femoris) of 40 young bulls from 3 breeds were used to quantify structural characteristics of bovine connective tissue by image analysis, with both macroscopic and microscopic approaches. Collagen and proteoglycan content was also investigated. Perimysium occupied a greater area (8 vs 6%), and was wider (42 vs 2 μm) and shorter per unit area (1.9 vs 30 mm mm^− 2) than endomysium. Perimysium and endomysium from Longissimus were thinner, less ramified than in Biceps. Longissimus showed less total collagen and cross-linking and more proteoglycans (P < 0.0001) than Biceps muscle. Blond d'Aquitaine perimysium occupied less area, was more ramified and muscles contained less collagen, cross-linking and more proteoglycans than Angus (P < 0.001). Limousin was intermediate. High proteoglycan content in muscle containing less total collagen suggested a complementarity between these molecules. They might influence mechanical properties of intramuscular connective tissue. This was especially true given that proteoglycans and total collagen were negatively and positively linked with structural parameters, respectively.     

Influence of breed and muscle metabolic type on muscle glycolytic potential and meat pH in pigs

Glycolytic potential and activities of myofibrillar ATPase, lactate dehydrogenase, citrate synthase, glycogen synthetases and glycogen phosphorylases were measured in five muscles from five Large White, eight Pietrain, seven Belgian Landrace and eight Penshire pigs (Penshire is a composite line including 50% Hampshire, 35% Duroc and 15% Large White blood). Additionally, ultimate pH was measured on the loin and four ham muscles. Muscles could be classified as follows on the basis of enzyme activities: Longissimus dorsi and Semimembranosus as 'fast white', Rectus abdominis as 'intermediate'. Trapezius and Masseter as 'slow red'. Small breed differences were observed in enzyme activities except for citrate synthase activity and degree of activation of glycogen phosphorylase in the 'fast white' muscles. Large Whites, Pietrains and Belgian Landraces did not differ in glycolytic potential whatever the muscle involved. Compared with these three breeds, Penshires had much higher glycolytic potential values in the 'fast white' muscles (+51 to 75%) and in the 'intermediate' muscle (+29 to 56%). However, in the 'slow red' muscles, there was almost no difference in this trait between the four breeds. The Penshire pigs showed lower ultimate pH than the pigs from the other breeds in three of the four ham muscles studied. It is concluded that muscle metabolic type must be considered when assessing breed variation in glycolytic potential, and that the high muscle glycolytic potential characterizing the Hampshire could be inherited as a dominant trait in Hampshire crosses.     

胶原蛋白的应用及其发展前景

结合胶原蛋白的结构特点及性能 ,说明它在生物、医学、食品、化妆品中的应用进展及其前景     

胶原蛋白的应用及其发展前景(续)

结合胶原蛋白的结构特点及性能 ,说明它在生物、医学、食品、化妆品中的应用进展及其前景。     

Characterisation and development of 'the shield' in male pigs

A project was undertaken to characterise boar shield, study its development and determine whether it presents carcass quality problems in young boars used for meat production. In two old boars (>2·5 years) 'backfat' from the scapular region consisted mainly of a dense white tissue with a high collagen content (>20% of fresh weight) and a low lipid content (<10%) compared with normal backfat. Histologically and chemically it resembled the dermis of skin. In a development study in boars and castrates from the Large White and Pietrain breeds, collagen concentration in scapular backfat increased between 91 and 118 kg liveweight in all pigs but the increase was greater in boars than castrates and especially marked in Pietrain boars in which the mean collagen concentration was 18% at 118 kg. This was probably because of the older age of Pietrains since there was a high correlation between age and collagen concentration (r = 0·93). The results suggest that, at 'heavy hog' weights, boar shield could present a carcass quality problem in slow-growing breeds such as the Pietrain.     

The incidence of watery muscle in commercial British pigs

Measurements of the pH of the leg muscle approximately 45 min after slaughter (pH₁) have been made in 4737 commercial pigs slaughtered at eight factories in Great Britain. The values found lie on a single-peaked distribution curve with a maximum at pH 6.4–6.5. No evidence was obtained of any marked influence on pH₁ distribution due to sex, weight or period of lairage. Indications of watery muscle were observed in about two per 1000 of the pigs examined. The distribution of watery muscle between factories was very irregular, most of the watery carcases being observed in a single factory.     

A high dietary iodine increases thyroid iodine stores and iodine concentration in blood serum but has little effect on muscle iodine content in pigs

There is still iodine deficiency in many populations, which justifies efforts to increase this trace element in food such as milk, eggs and meat by fortifying compound animal feeds with extra iodine. The iodine requirement of growing pigs is in the order of 100-200μg/kg feed (as a supplement) and the effects of this dosage range or higher on pork iodine concentration should be determined including the action of relevant iodine antagonists in feed, e.g., rapeseed. In three experiments on a total of 208 pigs [Pietrain×(Landrace×Large White)] the iodine concentration of meat (m. longissimus) - 71 samples -, blood serum - 100 samples - and of the thyroid - 100 samples - was analysed by intracoupled plasma-MS. In Experiment 1, 4×10 pigs received diets without or with rapeseed cake (0 and 3.2mmol glucosinolates/kg diet) either with 125 or with 250μg iodine/kg. In Experiment 2, the three groups with 46 pigs each were fed high iodine diets (1200μg supplementary iodine/kg) without or with 100 or 150g solvent extracted rapeseed meal/kg diet (0; 0.8 and 1.2mmol glucosinolates/kg). In Experiment 3, 3×10 pigs received either 600μg iodine/kg feed (1) or the 5-fold dosage (600+2400μg iodine/kg diet) administered 7 days (2) or 18 days (3) before slaughtering. The group means of pork iodine content were in the relatively small range from 3 to 16μg/kg, which contrasted to the enormously varying dosage range from 125 to 3000μg iodine/kg diet. There was a certain iodine dosage effect in Experiment 3 when - in comparison to the control - a 3-fold higher meat iodine concentration resulted from a 5-fold higher diet iodine concentration. In Experiment 1 with the low iodine offer, rapeseed cake with glucosinolates decreased the serum iodine level whereas in Experiment 2 this did not happen due to higher iodine fed and lower glucosinolates exposure. The thyroid iodine reflected the dietary iodine better than blood serum iodine and the serum better than muscle. However, in Experiment 2, 1200μg iodine/kg diet produced only half the serum iodine concentration than half as much dietary iodine in Experiment 3 (600μg iodine/kg diet), which may result from rapid elimination of blood iodine and a higher urinary excretion by longer duration of feed withdrawal before blood sampling. The muscle of pigs has to be classified as a low iodine food. Thus, there are no possibilities to concentrate this trace element reproducibly in amounts relevant for human nutrition in pork.     

Interactions between genotype,dietary fat saturation and vitamin A concentration on intramuscular fat content and fatty acid composition in pigs

The effect of dietary fat saturation (dFat) and dietary vitamin A (dVitA) level (0 IU vs. 100,000 IU) on performance, carcass characteristics and fatty acid composition in the offspring of two terminal sires: Duroc (DU) and Landrace × Large White (LD × LW) was studied. In the inner backfat layer, the DU-sired pigs had higher C16:0 proportion (P < 0.05) and tended (P < 0.07) to have higher total saturated fatty acids (SFA) and lower C18:1 n-9 proportions than LD × LW-sired pigs. An interaction sire line × dVitA was observed for intramuscular fat (IMF) content (P < 0.005). The effect of supplementation with the high dVitA level in DU-sired pigs was associated with a 20% increase in IMF while no effect was observed in LD × LW pigs. Fatty acid pattern was affected by dFat and sire line. In the inner backfat layer, LD × LW-sired pigs receiving the low dVitA level increased C18:0 proportions by 8% in comparison to animals receiving the high dVitA, whereas in DU-sired pigs the effect of vitamin A was opposite. It is concluded that the effect of dFat and dVitA concentration on IMF content and fatty acid profile of subcutaneous backfat and IMF is variable according to pig genotype.     

胶原蛋白肽产业现状及发展趋势

胶原蛋白肽作为一种新兴的功能性蛋白配料近年来在国内外发展迅速。文中综述了胶原蛋白肽的定义、特性、制备工艺以及国内外胶原蛋白肽产业的发展现状,厘清了胶原蛋白肽推广过程中下游生产企业和消费者关注的3方面问题,包括胶原蛋白肽产品品质与原料来源间关系,胶原蛋白肽功效与分子量间关系以及胶原蛋白肽应用法规,展望了胶原蛋白肽产品的研究发展趋势,以期科学引导从事和关注胶原蛋白肽产业人群,促进国内胶原蛋白肽产业的健康持续发展。