木质化鸡胸肉的形成及营养调控

近年来,在肉鸡养殖业中快速生长的肉鸡木质化鸡胸肉的发生率不断提高,严重影响鸡肉品质,造成巨大的经济损失。目前关于木质化鸡胸肉主要由国外学者进行研究,国内少有报道。因此,本文综述了木质化鸡胸肉的理化特征、导致其发生的可能机制以及营养调控,为未来国内解析木质化鸡胸肉具体的形成机制及其预防提供科学参考。     

木质化鸡胸肉的形成及营养调控北大核心CSCD

近年来,在肉鸡养殖业中快速生长的肉鸡木质化鸡胸肉的发生率不断提高,严重影响鸡肉品质,造成巨大的经济损失。目前关于木质化鸡胸肉主要由国外学者进行研究,国内少有报道。因此,本文综述了木质化鸡胸肉的理化特征、导致其发生的可能机制以及营养调控,为未来国内解析木质化鸡胸肉具体的形成机制及其预防提供科学参考。     

肉鸡木质肉和白纹肉问题及其解决方案

近年来肉鸡木质肉和白纹肉的发生率呈上升趋势,木质肉和白纹肉会影响鸡肉的口感和外观,降低鸡肉等级,影响消费者购买意愿,给肉鸡养殖业造成较大损失。本文主要综述了肉鸡木质肉和白纹肉的产生机理及其综合解决方案,以期为肉鸡养殖业健康发展提供借鉴。     

熊果酸介导HIF-1α缓解木质化鸡胸肉发生的潜在作用机制研究

木质化鸡胸肉在快大型白羽肉鸡的胸肌组织中病变率高达20%,严重降低消费者的购买欲,也不利于后期加工,造成的经济损失相对较高。缺氧是导致木质化鸡胸肉发生的重要原因,缺氧诱导因子1α(HIF-1α)是机体缺氧状态下调节细胞功能的关键因子,缺氧会造成HIF-1α过表达,导致机体氧化应激、糖代谢紊乱和炎症反应的发生,进而导致快大型白羽肉鸡罹患木质化鸡胸肉。熊果酸具有抗氧化、抗炎和调节糖代谢等功效,并可通过腺苷酸激活蛋白激酶(AMPK)、磷脂酰肌醇3激酶/蛋白激酶B(PI3K/Akt)等信号通路调节HIF-1α在机体中的表达。作者综述了缺氧所导致的木质化鸡胸肉的发病机理以及熊果酸调控HIF-1α对氧化应激、糖代谢和炎症反应的影响,进一步分析了熊果酸通过AMPK、PI3K/Akt等信号通路调控HIF-1α缓解木质化鸡胸肉发生的潜在作用机制。     

木质化鸡胸肉发生机理及缓解调控研究进展

木质化鸡胸肉（WB）是一种发生在肉鸡胸大肌上的肌肉疾病。WB在快大型肉鸡中发病率较高,可显著降低鸡胸肉的肉品质和消费者的购买欲望,给肉鸡饲养行业带来了巨额的经济损失。研究表明,对肉鸡生长速度和胸肌率的过度选育可能造成了WB的高发病率;此外,饲粮营养水平、饲养管理、孵化温度和品种也与WB的发病率有较大关联。降低饲粮中赖氨酸与蛋白质比率、限饲及饲粮中添加一定的抗氧化剂和微量元素或可在一定程度上缓解或降低WB的发病率。本文综述了WB的特点、可能的形成原因及生产中降低WB发生率的最新研究成果,以期为快大型肉鸡养殖业中降低WB发病率和降低WB带来的经济损失提供参考。     

肉鸡木质肉和白条纹肉研究进展

近年来，快大型白羽肉鸡木质肉（woody/wooden breast，WB）和白条纹肉（white striping， WS）等异质肉发生率不断提高，严重影响了鸡肉品质和肉鸡生产效率，受到业界的广泛关注。WS是指肌肉表面出现平行于肌纤维的白色脂肪沉积条纹，WB主要表现为胸肉明显硬化，WS和WB组织病理学特征类似，常常共同出现。这两种肌肉缺陷严重影响了鸡胸肉的外观、营养价值以及加工特性，降低了消费者的购买意愿，造成了巨大的经济损失。目前，国外学者对WS和WB研究较多，国内报道很少。本文综述了WS和WB的病理学特征、对肉品质的影响、发生的影响因素和可能的形成机理，为未来进一步解析WS和WB形成机制，探究综合解决方案提供科学参考。     

科技动态

科宝公司新品种肉鸡上市科宝公司已投放新品种Cobb700肉鸡于欧洲及拉丁美洲市场,公司表示:随着鸡胸肉需求的快速增加,他们培育了这种新型肉鸡,该肉鸡胸肉生长非常快且产量高,这意味着肉鸡体重也能达到一定值从而提高肉产量,可提供产品附加值。     

玉米型和高粱型饲粮添加胍基乙酸对肉鸡生长性能、肉品质和胸肌病变的影响

本试验目的是研究玉米型和高粱型饲粮添加胍基乙酸对肉鸡生长性能、屠宰性能、胴体品质、肉品质和和胸肌病变的影响。试验采用2×2二因子完全随机设计,分别设置2个饲粮类型(玉米型和高粱型)和2个胍基乙酸添加水平(0和600 g/吨),共4个处理组,每个处理10个重复,每个重复20只1日龄公雏鸡(品种Ross 708),统计1-14、14-35和35-50日龄各个阶段肉鸡日增重和肉料比;并于51日龄和55日龄,每个重复屠宰4只肉鸡,测定屠宰性能、胴体品质、肉品质和和胸肌病变指标。饲粮添加胍基乙酸显著提高50日龄肉鸡肉料比(P0.05);特别是玉米型日粮添加胍基乙酸显著提高55日龄肉鸡胸肌率(P0.05)。饲粮添加胍基乙酸对51和55日龄肉鸡胸肌滴水损失和剪切力均无影响,但降低了其p H(P0.05)。此外,饲粮添加胍基乙酸可双倍降低51日龄肉鸡胸肉木质硬度缺陷损伤程度(木质肉)。结果表明,饲粮添加胍基乙酸均可改善生长后期(50日龄-上市)肉鸡生产性能和降低木质肉发生,且不受饲粮类型影响;特别是在玉米型饲粮中添加胍基乙酸显著提高其胸肌率。     

高温运输应激诱导类PSE鸡肉的形成机理

快速增长和肌肉增生型肉鸡品种选育导致大量异质鸡胸肉的产生。其中,类PSE(Pale soft and exudative-like meat)肉由于颜色苍白、质软、渗出率高严重影响消费者购买欲望,且由于蛋白变性导致的加工特性差、出品率低等问题给肉类加工业造成巨大损失。宰前应激会刺激动物机体神经-内分泌系统,影响免疫系统和生理代谢功能,造成宰后初期肌肉生理生化失调,也会对肉品质产生影响。本文旨在综述高温运输诱导类PSE肉的发生机制,探讨高温运输应激对肉鸡应激反应、能量代谢、氧化还原状态、钙离子通道蛋白和热休克蛋白70的影响,以期为改善肉鸡福利和降低类PSE肉的发生提供理论指导。     

鸡木质化胸肌组织学特征及分子调控通路改变研究

旨在探究鸡木质化胸肌与正常、白条纹以及木质肉白条纹共同发生胸肌的组织形态的量化差异以及分子调控通路改变。研究以42日龄快速型白羽肉鸡终端父系为素材,根据木质肉与白条纹的表观判断标准,筛选4组胸肌组织样本,分别为正常、木质肉、白条纹和木质肉白条纹共同发生组。对61个个体肌纤维组织形态指标进行统计和分析;依据表观评分和组织学统计结果挑选正常组和木质肉组进行mRNA转录组测序。组织学检测结果表明,木质肉组肌纤维面积、肌纤维直径和肌内膜厚度显著高于其它3组(P<0.05),木质肉组的肌纤维密度显著低于白条纹组和木质肉白条纹共同发生组(P<0.05)。转录组分析筛选出木质肉组相比正常组显著上调表达差异基因1 201个,无显著下调表达差异基因。通路富集发现,上调基因主要富集在与结缔组织增生相关的通路,包括间隙连接(gap junction)、黏着斑信号通路(focal adhesion)、基质受体相互作用(ECM-receptor interaction)和胶原纤维组织(collagen fibril organization)等。从富集通路中筛选与结缔组织增生等过程相关的基因进行实时...     

Research Progress on Wooden Breast and White Striping Myopathies in Broilers

Recently, wooden breast (WB) and white striping (WS), the newly reported myopathies attracted wide attention of global poultry industry for their increasing incidences and negative effects on meat quality and broiler performance.WS is characterized by the occurrence of white fat striations parallel to muscle fibers, while WB is mainly featured with obvious hardening of breast meat fillets. These two myopathies share similar histological lesions and often appear together. They can adversely affect breast fillet’s appearance, nutrition value, ability for further processes and consumption intention, which result in huge economic loss to the industry. In recent years,most of the studies on WS and WB were reported by international research groups, few by Chinese research teams.In this review,we summarized the research progress of WS and WB from the aspect of pathological features,impacts on meat quality and nutrition value, the underlying causes and possible detailed mechanism in order to provide reference and theoretical basis for future studies.     

An investigation of a reported case of white striping in broilers

Market reports of white striping in broiler breast fillets have been increasing, which has generated concerns in the broiler meat industry regarding negative effects on consumer acceptance. This study was conducted to macro- and microscopically characterize the condition of white striping at varying degrees of severity on Cobb 500 broiler breast fillets slaughtered at 42 d of age. Carcasses of 2,512 broilers presenting white striping were slaughtered and macroscopically classified according to the degree of severity of the striations as moderate or severe; further histological microscopic evaluation demonstrated degenerative myopathy in both moderate and severe cases, but 75% of those breast fillets were classified as moderate. Typically, the samples classified macroscopically as moderate showed microscopic necrosis only (65.17%) or moderate multifocal necrosis (9.83%), whereas those classified as severe showed diffuse and strong necrosis (25.00%). The proliferation of connective tissue was not observed for either of the degrees of white striping investigated, characterizing this profile as an acute occurrence.     

Accumulation of lipofuscin in broiler chicken with wooden breast

Lipofuscin is one of the indicators of oxidative stress. To elucidate the role of oxidative stress in the development of wooden breast, this study investigates lipofuscin accumulation in various parts of wooden breast muscles. Sampling was performed using 46-day-old broiler chickens housed at a commercial Japanese poultry slaughterhouse. Fourteen wooden breast fillets and 13 normal breast fillets were collected in the deboning line. The samples used to measure shear force, 2-thiobarbituric acid reactive substance (TBARS), and for histological analysis were taken from the six portions of breast muscle fillets. In muscles affected by wooden breast, vacuolated muscle fibers were observed, and connective tissues appearing like perimysium were expanded with fibrosis. TBARS value and accumulation of lipofuscin were significantly higher in the wooden breast than in the normal breasts. A lot of lipofuscin granules were localized in the cytoplasm of collapsed muscle fibers of the wooden breast. The cranial portion of the wooden breast showed the highest shear force. The cranial position had a large amount of connective tissue and lipofuscin granules. The results of the present study strongly suggest that high oxidative stress, especially with a significant accumulation of lipofuscin, is associated with the development of wooden breasts.     

Incidence of white striping under commercial conditions in medium and heavy broiler chickens in Italy

Several types of muscle abnormalities are present in the poultry industry as a result of genetic selection, leading to decreased quality of meat and consequent economic loss. The appearance of thin (moderate) to thick (severe) white striping (WS) striations parallel to muscle fibers on the surface of broiler breast fillets is one of the most troubling issues in the poultry industry. White striping also has unfavorable implications on visual acceptance, nutritional value, and processing traits of breast meat. The aim of this survey was to assess the influence of market class (medium and heavy birds) and genotype (standard- and high-breast yield hybrids) on the incidence of WS in broiler chickens raised under commercial conditions in Italy. The incidence of WS for both medium and heavy broilers was high (43.0%), with 6.2% of samples considered severe. Heavy flocks had significantly higher percentages of both moderate (46.9 vs. 25.8%;P ≤ 0.001) and severe (9.5 vs. 2.7%;P ≤ 0.001) WS than medium flocks. Considering the effect of genotype, high-breast yield hybrids exhibited a higher incidence of both moderate (40.2 vs. 33.2%;P ≤ 0.001) and severe WS (7.2 vs. 5.0%;P ≤ 0.001) compared with standard-breast yield birds. In addition, within the medium class, the occurrence of WS reached higher levels in flocks of males. The heavy class consisted of male flocks separated into 2 slaughter weight categories. Birds that reached higher slaughtering weights (3.8–4.2 kg) exhibited higher incidence of WS than flocks slaughtered at lower weights (3.0–3.8 kg) at a similar age. In conclusion, the main broiler genotypes used for commercial production were affected by a high rate of WS; hybrids selected for higher breast yields were more prone to the WS abnormality. In addition, severe cases of WS are even more prevalent at higher slaughter age and weight, although reduced growth rate is associated with a lower incidence and severity of WS.     

The proper application of the wooden shoe: An overview

The wooden shoe provides the clinician with an alternative option to conventional farriery when treating a variety of foot problems such as acute/chronic laminitis, white line disease, distal phalanx fractures and poor-quality hoof capsules. The wooden shoe provides a simplified method to apply many of the principles of therapeutic farriery which include redistributing the load or forces on the foot, repositioning breakover and providing heel elevation when necessary. Understanding the biomechanics of the wooden shoe along with understanding good basic farriery which include the appropriate foot trim, proper size, fit and placement of the wooden shoe on the foot combined with the appropriate application are essential for consistent success. This paper outlines what is considered to be the proper application of the wooden shoe.     

White striping prevalence and its effect on meat quality of broiler breast fillets under commercial conditions

White striping (WS), characterized by white striations on the Pectoralis major muscle, is an emerging problem for the broiler industry. Thus, the impact of WS on meat quality has become a current research topic. In this context, a 2‐year follow‐up study, to reveal the prevalence of WS in broiler integrations, was undertaken. Additionally, a laboratory experiment was conducted to determine the oxidative quality during storage and the differences in proximate composition, colour and fatty acid and amino acid profiles of broiler breast fillets scored visually as normal, moderate and severe. In integrations, the WS incidence increased with increasing broiler age and more than 50% of breast fillets obtained from 32‐ to 35‐day‐old broilers and 36‐ to 39‐day‐old broilers had stripes with different scores. Lower protein and higher fat contents were measured in the moderate and severe scored fillets than the normal fillets (p < 0.001). Severe score stripes induced the formation of less redness on the ventral surface (p < 0.05) and a darker colour on the dorsal surface (p < 0.01). The lowest histidine, arginine and tryptophan amounts were determined in severe fillets (p < 0.05). Moderate and severe scored fillets were rich in polyunsaturated fatty acids implying that they were sensitive to lipid oxidation. That suggestion was further proven by the higher TBARS values. Freeze‐thawing induced the formation of carbonyl compounds, but it did not cause differences in sulphydryl groups. Briefly, we suggest that different WS scores may affect the physicochemical and oxidative quality of breast fillets; however, more studies are needed to assert an accurate and explicit judgement.     

Comparative Study of the Major White Matter Tracts Anatomy in Equine,Feline and Canine Brains by Use of the Fibre Dissection Technique

The spatial anatomy of the white matter tracts is a subject of growing interest not only for researchers but also for clinicians. Imagistic methods have some limitations so that they should be confronted with dissection studies. The aim of this paper was to provide a three‐dimensional view of the major white matter tracts in equine, feline and canine brains by use of the fibre dissection technique. Twenty cerebral hemispheres (six equine, four feline and 10 canine brains) were prepared according to the Klingler method. Stepwise mediolateral and lateromedial blunt dissections were performed using wooden sticks and spatulas. The lateromedial dissection was followed by the opening of the lateral ventricle. The use of the same multi‐stage procedures resulted in a comparable exposure of the major association, projection and commissural fibres and their spatial relation with the lateral ventricle. To conclude, the proposed techniques are reproducible in equine, feline and canine brains and they can be successfully used for teaching, training or research in the field of neurobiology.     

清末时期川江的木船运输

清末时期,重庆的开埠带动了川江木船运输业的发展,由此川江木船运输进入了一个繁荣的时期,川江木船运输的货物结构发生了很大变化。这一时期的川江木船分为挂旗船和厘金船,挂旗船是外国侵略者进行经济侵略的运输工具,但是厘金船的数目和运输量还是大大超过挂旗船;同时,川江木船运输业的发展也促进了川江上木船船帮的形成和发展,为四川经济的发展做出了积极贡献。