猪肉嫩度及其影响因素

嫩度是猪肉的主要食用品质之一,也是消费者评判猪肉质优劣最常用的指标.本文论述了猪肉嫩度形成的组织学原理及其评定方法,并从遗传与饲料营养的角度综述了影响猪肉嫩度的因素.     

猪肉嫩度及其影响因素

嫩度是猪肉的主要食用品质之一,也是消费者评判猪肉质优劣最常用的指标。本文论述了猪肉嫩度形成的组织学原理及其评定方法,并从遗传与饲料营养的角度综述了影响猪肉嫩度的因素。     

猪肉嫩度的调控

肉的嫩度是衡量肉质的一个重要指标。影响猪肉嫩度的因素很多,有遗传因素和非遗传因素。此文就猪肉致嫩原理的理论基础及肌纤维的种类、结构和性质;结缔组织的性质和含量;肌内脂肪含量和分布;肌肉组织中的蛋白降解酶和肌肉的持水力作一综述。     

影响猪肉嫩度因素及嫩化方法

肉的嫩度是肉类最重要的感官指标,可以用来评价食用肉的品质,也是消费者十分重视的感官特征。肉的嫩度在一定意义上也可以理解为肉的硬度[1],而肉的硬度有本底硬度和肌动球蛋白硬度之分。前者是由结缔组织蛋白和其它基质蛋白决定,后者是由肌原纤维蛋白质决定。肉的嫩度包括以下四个方面的含义[2]:①肉对舌或颊的柔软性,即当舌头或颊接     

影响牛肉嫩度的因素及其机制

结合国内有关材料,综述国外多年来在牛肉嫩度方面的大量研究资料,系统地阐述了影响牛肉嫩度的各种因素及其作用机制的研究进展,有助于我国肉牛业和牛肉加工业的发展.     

影响肉品嫩度的因素及其候选基因的研究进展

肉品嫩度是评价肌肉食用品质的一项重要指标。同时,也是消费者评价肌肉质量高低的标准。结合国内外对肉品嫩度研究的现状,系统总结影响猪肉嫩度的因素,同时,着重对决定猪肉嫩度的候选基因及其致嫩机理加以综述。     

畜禽肉嫩度及其影响因素

嫩度是肉质性状的主要感官指标,通过现代育种手段培育肉嫩度较好的畜禽品种是目前育种工作的任务之一.论文综述了肉嫩度的物质基础,并从肌肉组成及屠宰后熟化过程的分析了影响嫩度的各种因素.     

猪肉品质及其影响因素——影响猪肉品质的遗传因素

对猪肉品质及其主要影响因素进行了综合评价。这些影响因素包括：遗传、营养、饲养管理、肉猪屠宰前、屠宰以及屠宰后的处理方式等，着重讨论了遗传因素、营养因素对猪肉实用品质（肉色、风味、系水力）的影响，并从遗传、营养以及饲养管理等多方面提出了提高猪肉品质的综合措施。     

Genetic factors affecting susceptibility to udder pathogens

Many studies have identified genetic factors underlying resistance or susceptibility to mastitis in dairy cows and heifers. Some authors focused on polygenic variation while others searched for genes and/or quantitative trait loci with major effects on mastitis. Classical traits related to mastitis include somatic cell counts, electrical conductivity and clinical cases of the disease. With the development of automatic milking devices and '-omics' technologies, new traits are considered, such as acute phase proteins, immunological assays, and milk flow patterns, and new biological pathways are discovered, for example the role of mammary epithelium and the nervous system. The usefulness of these traits for the identification of resistant cows is discussed in relation to the biological mechanisms underlying the development of the disease. In addition, the utility of these traits for genetic improvement is reviewed. Finally, the problem of durability in resistance is addressed, including co-evolution and the cost of resistance.     

Chilling rate effects on pork loin tenderness in commercial processing plants

The present experiment was conducted to provide a large-scale objective comparison of pork LM tenderness and other meat quality traits among packing plants that differ in stunning method and carcass chilling rate. For each of 2 replicates, pigs were sourced from a single barn of a commercial finishing operation that fed pigs from a single terminal crossbred line. On each day, 3 trucks were loaded, with each of those trucks delivering the pigs to a different plant. Plant A used CO(2) stunning and conventional spray chilling; Plant B used CO(2) stunning and blast chilling; and Plant C used electrical stunning and blast chilling. The boneless, vacuum-packaged loin was obtained from the left side of each carcass (n = 597; 100 · plant(-1) · replicate(-1)). As designed, HCW, LM depth, and LM intramuscular fat percentage did not differ among plants (P > 0.05). By 1.67 h postmortem (1 h after the carcasses exited the harvest floor), the average deep LM temperature was >10°C warmer for Plant A than Plants B and C (32.1°C, 21.6°C, and 19.3°C, for Plants A, B, and C, respectively) and deep LM temperature continued to be >10°C warmer for Plant A until 4.17 h or 6.33 h postmortem than for Plants C and B, respectively. Both plants that used blast chilling produced loins with greater LM slice shear force at 15 d postmortem than did the plant that used conventional spray chilling (P < 0.0001). The frequency of loins with excessively high (>25 kg) LM slice shear force values was greater for Plant B than Plant A (14.7% vs. 1%; P < 0.01). Among all the traits studied, including visual and instrumental evaluations of LM color, ultimate pH, marbling score, and lean color stability, the only other difference between Plants A and B was that purge loss during 13 d (from d 1 to 14) of vacuum-packaged storage was greater for Plant B (P < 0.05). That is, with this sample of pigs and CO(2) stunning, no loin quality advantages were detected for blast chilling. Regardless of chilling method, CO(2) stunning resulted in darker LM lean color and greater LM water-holding capacity than did electrical stunning (P < 0.05). This research shows that differences in chilling systems among pork packing plants can have a strong influence on loin chop tenderness.     

影响奶牛乳房炎抗性性状的贵传因素

乳房炎是造成世界各国奶牛业中损失最多的一种疾病.当前严重依赖于抗生素治疗和疫苗预防来减少乳房炎的发生,这种方法并不十分奏效,而抗乳房炎育种则是一种很重要的替代方法.作者将从动物机体、细胞/激素和分子水平对影响奶牛乳房炎抗性性状的遗传因素进行论述,只有在遗传和免疫水平上具有优良特点的性状才能在获得乳房炎抗性的遗传改良中发挥作用.     

Genetic factors affecting susceptibility of dairy cows to udder pathogens

Bovine mastitis remains the most costly disease in dairy cattle. Breeding for resistance to udder pathogens has been proposed as a complementary tool to therapeutic and prophylactic measures not totally effective against the disease. This paper reviews factors affecting cows' susceptibility to pathogens at the animal, cellular/hormonal and DNA levels. Such factors will be useful in achieving genetic improvement for resistance only if they have desirable properties at the genetic and immunological levels. Because such properties are not always of significant magnitude, further research is necessary to identify characteristics of resistance in cows, considering the constant and complex interactions that occur between hosts and pathogens.     

Genetic parameters for pork carcass components

Data from 456 homozygous halothane normal purebred Yorkshire, Duroc, and Other-breed pigs from two national progeny testing and genetic evaluation programs were utilized to estimate genetic parameters for carcass components in pigs. Carcass components were cut and weighed according to Institutional Meat Purchase Specifications. Primal cut weights evaluated included 401 Ham (HAM), 410 Loin (LOIN), 405 Picnic shoulder (PIC), 406 Boston Butt (BB), and 409 Belly (BELLY). Individual muscle weights included the inside (INS), outside (OUT), and knuckle (KNU) muscles of the ham, the longissimus dorsi (LD) and psoas major (TEND) of the loin, and the boneless components of both the Boston Butt (BBUTT) and picnic (BPIC). Muscle weights from each primal were summed to yield a boneless subprimal weight (BHAM, BLOIN, BSHLDR), and all boneless subprimals were summed to yield total primal boneless lean (LEAN). Heritability estimates for HAM, LOIN, and BELLY were 0.57, 0.51, and 0.51, respectively. Heritability estimates for BB and PIC were 0.09 and 0.21, respectively. Heritability estimates for the boneless components of each primal were higher than those for the intact primals. Genetic correlations for HAM, LOIN, and PIC with loin muscle area (LMA) were 0.53, 0.78, and 0.70, respectively, and-0.62, -0.51, and -0.60, respectively, with 10th rib off-midline backfat (BF10). Boneless subprimal components were highly correlated with LEAN. Gilts had heavier weights (P < 0.01) than barrows for all boneless subprimals, individual muscles, LEAN, and for all primal cuts except BELLY. Gilts also had less BF10 and more LMA (P < 0.01) than barrows. Duroc pigs had a heavier (P < 0.01) weight for HAM and PIC when compared to Yorkshires. Yorkshire pigs had more (P < 0.01) LOIN weight than did the Durocs. Results suggest primal, boneless subprimal, and individual muscle weights in pigs should respond favorably to selection.     

The influence of ultimate pH and intramuscular fat content on pork tenderness and tenderization

Intramuscular fat (IMF) and ultimate pH (pHu) influence tenderness, but their roles have not been conclusively determined. Length of storage also affects tenderness and may interact with IMF and pHu. We evaluated the effects of pHu, IMF, and storage time on the tenderness of pork longissimus muscle and determined whether the contribution of the various factors was dependent on genetic line. To obtain variation in IMF, Berkshire (B), Duroc (D) and Hampshire (H) boars were crossed with Yorkshire-Landrace sows. In four trials, a total of 176 pigs were used. To obtain a range in pHu, half of the pigs were deprived of feed before slaughter. Warner-Bratzler shear force (WBS) of each loin was assessed after 2, 7, and 14 d of storage at 0 to 2 degrees C. Warner-Bratzler shear force decreased (P < 0.05) from 4.89 kg at d 2 to 4.16 kg at d 7 to 3.52 kg at d 14. The H pork (n = 62) had a lower (P < 0.05) WBS than the other pork at d 2. After 7 d of storage, this difference had disappeared. Based on glycolytic potential, 30 of the H pigs were carriers of the Rendement Napole (RN) gene. When these pigs were excluded from the analysis, there was no difference in tenderness or tenderization of H, D, and B pork. The correlation between IMF and WBS was -0.11 at d 2, -0.21 at d 7, and -0.19 at d 14. In D pork, the relationship between IMF and WBS was linear, and IMF accounted for 47% of the differences in WBS. In H and B pork, the relationship between IMF and WBS was not significant. For each cross, the relationship between pHu and WBS was different; in D pork it was quadratic, in H pork WBS increased linearly, and in B pork there was no significant relationship between WBS and pHu. The 30 kDa/actin ratio, a measure of myofibrillar degradation, increased (P < 0.05) during storage. Differences in 30 kDa/actin ratio did not explain differences in pork tenderness or tenderization. Further research on determinants and mechanisms of pork tenderness and pork tenderization is needed before production of consistently tender pork will be possible.     

猪肉风味的影响因素

风味是评价猪肉品质的重要指标之一,它受很多因素影响。本文论述了饲养管理方式、日粮来源与营养素、贮藏条件、季节等因素对猪肉风味的影响,讨论了建立客观的风味评定体系的迫切性。     

牛肉嫩度营养调控技术研究

牛肉嫩度是影响牛肉消费的最重要的因素之一,到目前为止通过非营养调控的方式来改善牛肉嫩度的方法已经比较成熟;随着营养调控技术研究的进一步发展,发现屠宰前适时改变日粮的组成可以提高牛肉嫩度。