奶牛亚急性瘤胃酸中毒的发生与危害

亚急性瘤胃酸中毒（SARA）是一个大多数牛场普遍存在的奶牛代谢性疾病。围产期、干物质采食量（DMI）过高、日粮配制差及采食模式变化过大等奶牛均易发生亚急性瘤胃酸中毒，继而造成干物质采食量下降、纤维素消化率降低、乳成分改变及引发腹泻等疾病。本文对奶牛亚急性瘤胃酸中毒的病因及危害等方面进行了简述。     

奶牛亚急性瘤胃酸中毒的研究进展

亚急性瘤胃酸中毒(SARA)是一种普遍存在于大多数奶牛场的奶牛代谢性疾病,近年来受到了奶牛养殖者和科研人员的关注,文章综述此病的病因、危害、发病机制及预防措施,以期对奶牛生产者如何正确的预防奶牛亚急性瘤胃酸中毒提供理论参考.     

奶牛亚急性瘤胃酸中毒（SARA）的易感因素及其对瘤胃功能的影响

在奶牛养殖中,亚急性瘤胃酸中毒（subacute ruminal acidosis,SARA）是一种高发的营养代谢病。随着我国奶牛养殖集约化程度的提高,为提升奶牛生产性能饲喂大量高能谷物饲料极易诱发SARA,导致瘤胃液pH值降低,瘤胃菌群发生改变,瘤胃上皮黏膜层受损,进而影响瘤胃代谢功能。分析了奶牛不同生理阶段、择食行为以及个体差异等SARA的易感因素,探讨了SARA对奶牛瘤胃菌群变化、瘤胃上皮细胞基因表达、瘤胃屏障功能的影响,以期为阐明SARA造成瘤胃功能损伤的机制、降低奶牛发生SARA的风险提供参考。     

亚急性瘤胃酸中毒(SARA)的监测、预防与治疗

管理良好、高产的奶牛群体中亚急性瘤胃酸中毒(SARA)日益受到重视,因此监测奶牛群以预防SARA造成的损失是当前研究者必须重视的问题。瘤胃穿刺术测定瘤胃pH监测瘤胃酸中毒备受质疑,但这项技术仍然是诊断SARA可依赖的方法。持续测定瘤胃pH在将来或许成为可能。代谢性酸中毒引起的瘤胃内参数变化和乳脂率变化是监测奶牛个体SARA的另一种有效手段,但此种方法不适宜奶罐中取奶样。饲料及饲养管理优化以降低瘤胃酸的负载是降低SARA的有效手段。定期监测利于及早发现SARA和降低由此造成的经济损失。随着消费者对动物福利的日益关注,饲养管理中一些不可避免的SARA将成为奶牛产业面临的挑战。     

奶牛亚急性瘤胃酸中毒的发生原因与危害

近年来,随着奶牛产奶量的提高,奶牛日粮的营养密度也随着精料比例加大而增加。高产奶牛采食高能量、低结构性碳水化合物日粮时,有机酸在瘤胃内大量蓄积,造成瘤胃pH值降低,当瘤胃pH值每天低于5．6,累计时间达到3～5小时即出现亚急性瘤胃酸中毒（SARA）。     

奶牛亚急性瘤胃酸中毒的检测与防治措施

亚急性瘤胃酸中毒（SARA）是奶牛场近年来关注的主要问题。其因降低产奶量和产奶效率、使动物过早淘汰及增加死亡率等而给奶牛养殖场造成巨大的经济损失。为了实施有效的防治,需要尽早诊断出患病牛群。对其检测和防治措施进行了介绍,希望对奶牛生产者有所帮助。     

亚急性瘤胃酸中毒诊断研究进展

亚急性瘤胃酸中毒（SARA）会造成严重的经济损失,是高产奶牛场面临的严峻问题。为了有效防治SARA,需尽早诊断出患病动物。目前对SARA的病因、机理及防治措施有很多报道,但对SARA的监测诊断报道的相对较少。本文从SARA与其他疾病的关系、临床症状及临床诊断参数加以介绍,希望对SARA的监测和早期诊断有所帮助。     

奶牛亚急性瘤胃酸中毒的研究进展

本文论述了奶牛亚急性瘤胃酸中毒的发病机理、干物质采食量下降或无规律波动等临床症状及瘤胃炎、蹄叶炎等代谢疾病,并对目前奶牛亚急性瘤胃酸中毒诊断方法的优缺点及常用方法进行了阐述,以期为奶牛亚急性瘤胃酸中毒的防治和诊断提供参考。     

亚急性瘤胃酸中毒奶牛血液生化及粪便成分相关指标特征分析

旨在明确围产期亚急性瘤胃酸中毒奶牛血液生化及粪便干物质成分相关指标特征，为奶牛亚急性瘤胃酸中毒的诊断提供基础参考。试验于黑龙江省某集约化牛场随机选取产后7～14 d奶牛，通过瘤胃穿刺检测奶牛采食6 h后瘤胃液pH值，确定亚急性瘤胃酸中毒奶牛7头(5.26.2,无其他任何症状)。通过采集检测试验奶牛血液、生化和粪便成分，利用统计学方法分析筛选疾病预警指标。结果显示，亚急性瘤胃酸中毒奶牛血浆总胆红素(TBIL)、L-乳酸盐、磷、肌酐、肌酸激酶水平显著高于对照组，血浆钙、谷丙转氨酶(ALT)、白蛋白(ALB)、总胆固醇(TC)、低密度脂蛋白胆固醇水平显著低于对照组，粪便酸性洗涤纤维显著低于对照组。对2组间显著差异指标进行皮尔逊相关系数分析，对与亚急性瘤胃酸中毒奶牛相关的指标利用二元Logistic回归进行建模分析，确定对疾病发生预测较好的指标ALT、TC、TBIL。利用受试者工作特征曲线(ROC)分析确定了牧场TBIL≥1.85μmol/L,敏感度为95.2%,特异度为56.2%;TC≤3.725μmol/L,敏感度为100%,特...     

奶牛亚急性瘤胃酸中毒的病因及继发症

在一定的时期内，由于奶牛瘤胃内挥发性脂肪酸的累积，瘤胃pH值长时间介于5．0。5．5之间，从而发生亚急性瘤胃酸中毒。亚急性瘤胃酸中毒多发生于高产奶牛群中。泌乳初期和中期奶牛日粮及饲养管理的变化均会导致亚急性瘤胃酸中毒，继而造成奶牛的干物质采食量下降、消瘦、蹄叶炎、角化不全-瘤胃炎-肝脓肿综合征、粪便粘稠度下降、乳脂率下降等。本文对奶牛亚急性瘤胃酸中毒的病因及继发症状等方面进行了简述。     

Effects of Non-fiber Carbohydrate to Neutral Detergent Fiber Ratios on Ruminal pH Dynamics in Dairy Goats

Introduction Subacute ruminal acidosis（SARA）has become common and important economic and health issues for high-yielding dairy cows.Rumen pH takes a central position in the pathogenesis of SARA.So monitoring of rumen pH is play important role in recognizing,quantifying and subsequently controlling this disorder. The objective of the present     

Pathophysiological evaluation of subacute ruminal acidosis (SARA) by continuous ruminal pH monitoring

Evaluation of the radio‐transmission pH‐measurement system for monitoring the ruminal pH and subacute ruminal acidosis (SARA) in cattle is described. This is done in order to reveal the possible application of this system for detection and pathophysiological research of SARA by continuous ruminal pH measurement. The possibility of using this system for assessment of the ruminal pH in SARA cattle, and the presence of negative correlation between the ruminal pH and ruminal temperature in heathy and SARA cattle were determined. In addition, the 16S rRNA gene pyrosequencing analysis showed that the ruminal microbial community was simpler in SARA cattle, and the bacterial numbers in SARA cattle were lower than those in healthy hay‐fed cattle. Concentrate feeding might have reduced the diversity of the ruminal microbial community. Changes in the ruminal microbial community of SARA cattle might be related to the changes in ruminal pH followed by the decrease in the number of some bacteria. Continuous monitoring of the ruminal pH using the radio‐transmission pH‐measurement system would be applied for detection and prevention of SARA in the field and pathophysiological research of SARA, including ruminal zymology and bacteriology, which have been determined previously by sampling of the ruminal fluid and measuring of ruminal pH.     

Signals for identifying cows at risk of subacute ruminal acidosis in dairy veterinary practice

Controlling rumen disorders is critical to ensure successful dairy herd health management. Lactation diets of dairy cows are commonly rich in concentrates and low in physically effective fibre. Feeding of these diets increases the risk of rumen disorders with far‐reaching consequences for cattle health, welfare and sustainability of dairy production. The term subacute ruminal acidosis or SARA is often used as a synonym for poor rumen health. Being subclinical, SARA lacks of clear symptoms and is therefore difficult to diagnose and to control in the practice. This review article summarises common and identifies new direct and indirect cow signals related to SARA. We have performed a scientific evaluation and interpretation of each of these cow signals by highlighting their advantages and disadvantages from the practitioner's point of view. The gold standard of SARA cow signals still remains direct measurement of ruminal pH. However, continuous pH monitoring is cost‐intensive and often biased by sensor drift. Single‐point ruminal pH measurements by oral stomach tubing or rumenocentesis have strong limitations. Therefore, there is a need for reliable and robust markers of SARA that are easily accessible and inexpensive. Such indirect parameters are the observation of chewing and feeding activities, as well as the monitoring of milk, faecal, urine and blood variables. Also, novel technologies that allow rapid and non‐invasive measurement of the rumen mucosa thickness and ruminal motility patterns might provide advantages in SARA diagnosis. Due to several constraints of these indirect diagnostic tools, such as limited specificity and sensitivity, we strongly recommend using a combination of the signals to reliably identify cows at risk of SARA in a dairy herd.     

Diagnosis of subacute ruminal acidosis (SARA) by continuous reticular pH measurements in cows

The objective of this study was to determine whether subacute ruminal acidosis (SARA) could be diagnosed by continuous measurements of the reticular pH, as compared with the ruminal pH, using healthy cows fed a control diet and SARA cows fed a rumen acidosis-inducing diet. The reticular and ruminal pH were measured simultaneously by a radio transmission pH measurement system. The mean reticular pH at 1-h intervals decreased gradually from the morning feeding to the next feeding time in both healthy and SARA cows, though the decrease in the ruminal pH was observed to be more drastic as compared with that observed in the reticular pH. The threshold of the 1-h mean pH in the reticulum for a diagnosis of SARA was considered to be 6.3, and a significant positive correlation was observed between the reticular and ruminal pH. No differences in the concentrations of lactic acid, ammonia nitrogen, and volatile fatty acids were noted between the reticular and ruminal fluids in SARA cows. These results demonstrate that the reticular pH can be used to detect SARA in cows, as opposed to using the ruminal pH.     

The monitoring, prevention and treatment of sub-acute ruminal acidosis (SARA): a review

Sub-acute ruminal acidosis (SARA) has become an increasing problem in well-managed, high yielding dairy herds and the monitoring of groups of cows for signs of the condition is now crucial. Rumenocentesis may be ethically questionable but the technique remains the most reliable means of diagnosing SARA. Continuous measurement of ruminal pH may however be possible in the future. Parameters reflecting the metabolic acidosis caused by SARA are also promising tools, and measurement of milk fat content may be useful in individual mid-lactation cows although it is less valuable for bulk tank milk samples. The prevention of SARA includes the establishment of feeding and management guidelines seeking to minimize rumen acidotic load. Regular monitoring may facilitate early recognition of the condition and limit economic losses. Some degree of SARA may however be inevitable and presents a challenge to the dairy industry as consumers become increasingly concerned about the welfare of production animals.     

Subacute ruminal acidosis (SARA): a review

Subacute ruminal acidosis (SARA) is likely to arise when an easily palatable, high-energy diet meets a ruminal environment not adapted to this type of substrate. Increase of short-chained fatty acids (SCFA) will occur. Eventually, this may result in a transient nadir of ruminal pH below 5.5. Two situations are likely to represent the risk of SARA. First, fresh lactating cows are confronted with a diet considerably differing from that in the dry-period. A diet change carried out too rapidly or without proper transition management will put the animals at risk. Secondly, further in lactation, inaccurate calculation of dry-matter-intake (DMI) leading to wrong roughage/concentrate ratio, an inadequate content of structure within the diet or mistakes in preparing of total mixed rations may produce SARA. The consequences of SARA are diverse and complex. Laminitis is regularly connected to SARA and the negative impact of organic acids on the ruminal wall may lead to parakeratosis enabling translocation of pathogens into the bloodstream provoking inflammation and abscessation throughout the ruminant body. Moreover, milk-fat depression (MFD) can be related to SARA. In order to achieve a proper diagnosis, SARA has to be understood as a herd-management problem. A screening of the herd for SARA by means of a rumenocentesis, performed on a sample-group, preferably 12 individuals, may reveal the presence of SARA. The herd screening should include the risk group suspected, preferably. The prevention of SARA applies to the principles of ruminant feeding. Careful transition management from the dry to the lactation period and control of fibre-content and ration quality should be more yielding than the use of buffers or antibiotic drugs.     

亚急性瘤胃酸中毒对反刍动物瘤胃生理功能及物质吸收转运的影响

畜牧业集约化养殖越来越普遍。为提高反刍动物生产性能,饲喂大量能量饲料,进而引发亚急性瘤胃酸中毒(SARA),导致动物采食量下降、畜产品产出降低以及动物发生炎症反应。近年研究表明,SARA会改变瘤胃生理状态,而瘤胃健康对反刍动物饲养至关重要。本文综述了反刍动物SARA状态下瘤胃生理生化过程变化,结合瘤胃发酵模式变化和瘤胃微生物的改变,重点阐述了SARA引起的瘤胃上皮细胞形态结构变化、屏障功能改变、瘤胃上皮细胞中物质转运及相关载体表达及其引发的瘤胃上皮细胞炎症通路,为更好指导反刍动物饲养及为瘤胃营养生理生化研究提供参考。     

Subacute ruminal acidosis (SARA) in grazing Irish dairy cows

Subacute ruminal acidosis (SARA) is a significant production disease of dairy cattle. Previous concerns have been raised over the occurrence of SARA in pasture-fed dairy cattle and the potential consequences of laminitis and lameness. Highly digestible perennial rye grass contains high concentrations of rapidly fermentable carbohydrate and low concentrations of physical effective fibre that may result in SARA. This study conducted a point prevalence survey of rumen health status in grazing Irish dairy cattle fed predominantly perennial rye grass-based pasture. The survey assessed rumen fluid, animal health status, milk production data and pasture composition. A total of 144 cows between 80 and 150 days in milk were sampled on 12 farms. Eleven percent of cows were classified as affected with SARA (pH < or = 5.5), 42% were marginal (pH 5.6-5.8) and 47% were normal (pH>5.8). The study showed that low rumen pH is prevalent in grazing Irish dairy cattle consuming perennial rye grass-based pasture and raises concerns regarding effective pasture utilisation and possible consequences for animal health.     

Subacute rumen acidosis in lactating cows: an investigation in intensive Italian dairy herds

Subacute rumen acidosis (SARA) represents one of the most important metabolic disorders in intensive dairy farms that affects rumen fermentations, animal welfare, productivity and farm profitability. The aim of the present study was to study the occurrence of SARA in intensive Italian dairy herds and to determine the relationship between diet composition, ruminal pH and short chain fatty acids (SCFA) concentration. Ten commercial dairy herds were investigated; twelve cows in each herd were selected randomly among animal without clinical signs of disease, with good body condition and between 5 and 60 day-in-milk (DIM), to perform rumenocentesis and obtain rumen fluid. Ruminal pH was determined immediately after sampling and concentration of SCFA in ruminal fluid was determined on samples after storage. An other objective of this research was to study in detail the effects of rumenocentesis on animal health: this study could confirm the extreme validity of this technique as ruminal sampling. Results were subject to anova and correlation analysis using SIGMA STAT 2.03. The results indicated the presence of SARA in three herds (more than 33% cows with rumen pH < 5.5), a critical situation (more than 33% cows with rumen pH < 5.8) in five farms and a normal rumen pH condition in two herds. In particular, dairy herds show on average SCFA concentration of 150, 145, 123 mmol/l for low pH, critical pH and normal pH herds respectively. There were not significant differences among diet composition even if herds with SARA showed a light discordance between initially chemistry composition and residual feed. In the affected herds it was not possible to understand the exact causes of SARA. Animal management seems to be one of the most important factors in developing SARA including total mixed ration preparation.