Chronic metabolic acidosis in dairy cows]

Complex clinical and clinico-biochemical examination of the blood, urine and rumen liquor in a herd of dairy cows revealed chronical metabolic acidosis accompanied by rumen dysfunction and by a reduced butterfat content of milk. During the first examination of the acid-base state of the blood was almost at a standard level. An increased level of urea in blood plasma and a higher GOT transaminase activity testified to an excessive load on the liver. Urine pH was considerably deviated towards the acidic side and inorganic phosphorus was present in urine in a greater concentration. The pH of rumen liquor was slightly shifted towards alkalinity owing to the release of NH3 from urea in the food ration. The diagnosis--suspect chronical metabolic acidosis--was determined on the basis of the first examination. Chronical metabolic acidosis was definitely proved by the second examination when urea had been excluded from the feed ration. Repeated examinations revealed chronical metabolic acidosis which had originally been accompanied by a higher rumen liquor pH. On the basis of case histories and mechanisms of chronical acidosis, measures were proposed, resulting in an increase of the butterfat content of milk. Chronical metabolic disorders often follow a long-lasting latent pattern, manifesting themselves as a reduced milk yield and lower resistance; the clinical form of disease appears only at a later stage. The system of preventive diagnostics provides information on the changes in the composition of internal medium and of the faeces before a drop occurs in milk and fat production. These measures prevent metabolic disorders and high losses of produce which otherwise remain hidden for a long time.     

Changes in the acid-base index of blood in dairy cows in relation to the seasonal composition of feed rations and phases of the reproductive cycle

The changes in the acid-base indices of the blood of dairy cows in different stages of reproduction cycle were studied in relation to the composition of feed ration in the autumn, winter, spring and summer feeding seasons. The cows were in the following stages of their reproduction cycle: Group I the fourth to sixth month of gravidity, II eighth to ninth month of gravidity, III one to two months after calving. The seasonal composition of feed ration was demonstrated to exert a significant influence on the acid-base balance of the blood of cows in the studied stages of reproduction. A considerable occurrence of metabolic acidoses with different levels of compensation was observed when the cows were given the autumn and winter feed rations. Subclinical acid-base disorders of different directions (metabolic and respiratory alkaloses, acidoses) frequently occurred in the green feeding season. The frequency of acid-base disorders as a result of incorrect nutrition was found to be the highest in highly pregnant cows (group II) and in those one to two months after parturition (group III), i. e. in the periods with a significant influence on the reproduction process. On the whole, the best situation as to the acid-base balance was found in cows in the fourth to sixth month of their gravidity, irrespective of the seasonal effect of feed ration.     

Metabolic reactions of calves to the feeding with Laktosan or unpasteurized whole milk]

The acid-base and other metabolic reactions to nutrition with Laktosan produced by two feed plants and with unpasteurized whole milk after transport to a dairy plant were studied in calves up to the ninth week of age. Laktosan feeding reduces the metabolic component of the acid-base balance; the use of a lower-quality Laktosan mixture, containing drum-dried milk, gives a picture of metabolic acidosis lasting about 11 days. The changes are cuased by an increased intensity of dissimilation, by the release of metabolic H+, and, in part, by the loss of bases during diarrhoea. With the use of low-quality Laktosan, the utilization of the nutrients of the feed ration is much lower than the utilization of the nutrients of unpasteurized milk or high-quality Laktosan. The use of high-quality Laktosan causes much lower acid-base changes, far from reaching pathological values. At the same time, the utilization of nutrients is higher than with the use of unpasteurized milk. This milk which cannot be considered microbially or chemically undamaged offers no advantages from the health-condition and economic point of view. The facts, revealed by the study, emphasize the high health and economic importance of the production of calf feed mixtures. At the same time the results show that enither milk nor Laktosan feeding provides enough magnesium for the calves to grow. Other metabolic aspects of different calf nutrition are discussed.     

围产期奶牛能量代谢障碍性疾病的防治进展

奶牛代谢性疾病给奶牛饲养业造成重大经济损失。因此 ,如何搞好奶牛的饲养管理 ,减少代谢病的发生 ,充分发挥其生产潜力 ,是当前奶牛代谢病防治工作中亟待解决的问题。本文主要阐述了围产期奶牛能量代谢障碍病的危害、病因及防治措施     

An Evaluation of Parameters for the Detection of Subclinical Rumen Acidosis in Dairy Herds

An observational study was conducted in six Danish dairy herds. A specially designed stomach tube was compared to the rumenocentesis technique as part of the monitoring of rumen pH. In contrast to a previous study, the use of the stomach tube appeared to reduce saliva contamination. However, correlation with the rumenocentesis technique was poor ( r = 0.33; p = 0.019) and a linear model could only partly explain variations between either results. The presence of subclinical rumen acidosis (SRA) was evidenced in one herd only, as judged by results obtained by the rumenocentesis technique. The present study revealed some limitations of the rumenocentesis technique in small or medium-sized herds due to difficulties in selecting sufficient numbers of cows in the respective groups at risk. The finding of two apparently clinical normal cows with rumen pH values below 5.0 leads to the consideration that such fluctuations may be temporary and at least does not give rise to clinical symptoms. However, the long-term effect of such fluctuations is not known. In general, primiparous cows seemed more prone to low ruminal pH values (< 6.0), higher ruminal concentrations of short-chain fatty acids, and possibly to metabolic acidosis, than were multiparous cows. Ruminal propionate was the most precise predictor of rumen pH, whereas milk fat percentage varied greatly between lactational groups. Blood lactate dehydrogenase (LDH), beta-hydroxybutyrate (BHB) and fructosamine as well as urine phosphorus excretion and renal net acid-base excretion (NABE) were related to ruminal acid load, but were not predictive of rumen pH. Monitoring of dairy herds for SRA should be performed routinely and employ several diagnostic tools (rumenocentesis, renal NABE determination) as well as specific knowledge of herd management and feeding routines.     

EM发酵玉米秸秆和青贮玉米秸秆对奶牛生产性能的对比试验

本试验应用EM发酵玉米秸秆和青贮玉米秸秆饲喂奶牛,以观察两种方法处理的玉米秸秆对奶牛生产性能及经济效益的影响效果。结果表明,用EM发酵的玉米秸秆饲喂奶牛较青贮玉米秸秆饲喂奶牛,每天每头奶牛采食量提高1.03%,平均产奶量提高2.02%,经济效益提高0.13元;EM原液发酵的玉米秸秆和青贮玉米秸秆1∶1混合饲喂奶牛,每天每头奶牛采食量、平均产奶量、经济效益分别比饲喂青贮玉米秸秆的奶牛提高2.85%、2.99%和1.15元。     

发芽玉米对荷斯坦奶牛瘤胃发酵、产奶性能及乳品质的影响

试验旨在研究发芽玉米对荷斯坦奶牛瘤胃发酵、血液成分、产奶性能及乳品质的影响。选取胎次、分娩日龄、产奶量相近的荷斯坦泌乳奶牛15头,试验分为3组,每组5头。对照组饲喂基础日粮(TMR和苜蓿干草),T1、T2组分别在基础日粮中添加20%发芽玉米和20%发酵发芽玉米。结果表明,添加发芽玉米及发酵发芽玉米均能降低瘤胃pH的变化幅度,提高挥发性脂肪酸和氨态氮浓度,但差异均不显著(P＞0.05);与对照组相比,T1、T2组4%乳脂校正乳极显著提高(P＜0.01),并可显著提高T2组的饲料效率(P＜0.05),显著降低乳中体细胞数(P＜0.05);T1、T2组具有降低乳中胆固醇含量的趋势,并对血液成分无显著影响。因此,饲料中添加发芽玉米可改善瘤胃内环境,显著提高产奶量与饲料效率,显著降低乳中体细胞数,且乳中胆固醇含量有降低的趋势。     

疾病对奶牛繁殖性能的影响及其研究进展Ⅲ:营养代谢性疾病

现代规模化、集约化奶牛养殖生产模式下,不断供给高营养水平日粮是维持后备牛快速生长发育和泌乳母牛高泌乳性能的物质基础。然而,在遗传品质到达"瓶颈期"后,尽管随着日粮营养浓度的不断提高和干物质采食量（DMI）的增加,奶牛单产水平可以继续维持在一定的高水平状态,但是高产奶牛的营养代谢性疾病的发病率也呈现快速增长趋势,特别是围产期能量负平衡（negative energy balance,NEB）引起的酮病,高精日粮引发的酸中毒、高蛋白质日粮引起的血液中尿素氮升高等营养代谢性疾病,负调控奶牛繁殖性能,造成奶牛产后发情不明显,配种率和受胎率下降等,直接影响奶牛生产群的更新速度、优质牛群泌乳性能正常发挥以及奶牛养殖的经济效益。作者详细介绍了近年来国内外不同营养代谢性疾病对奶牛繁殖性能影响的相关研究资料,重点分析了酮病、低血钙、瘤胃酸中毒等围产期高发的营养代谢性疾病影响奶牛繁殖性能的分子机制,并对营养代谢性疾病与高产奶牛繁殖性能今后研究的方向提出了展望和思考,以期为提高中国规模化牧场高产奶牛群繁殖效率和母牛围产期营养管理水平提供一定的借鉴和理论依据。     

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.     

Effects of Diseases on Reproductive Performance in Dairy Cattle Ⅲ: Nutritional Metabolic Diseases

Under the modern large-scale and intensive dairy farming production mode,the continuous supply of feed with high nutrition level is the material basis for maintaining the rapid growth and development of reserve cows and the high lactation performance of lactating cows.However,after the genetic quality reaches the "bottleneck period",although the milk yield of dairy cow can continue to maintain a certain high level with the continuous improvement of the nutrient concentration of feed and the increase of dry matter intake (DMI),the incidence of nutritional metabolic diseases of high-yield dairy cows also shows a rapid growth trend,especially ketosis caused by the negative energy balance in perinatal period,acidosis caused by high-precision diet and the increase of blood urea nitrogen caused by high-protein diet,negatively regulate the reproductive performance of dairy cows,resulting in inconspicuous postpartum estrus,decreased mating rate and conception rate of dairy cows,which directly affect the update speed of dairy cows production groups,the normal performance of high-quality cattle and the economic benefits of dairy farming.In this paper,the author introduced in detail the relevant research on the current situation and its mechanism influence of different nutritional metabolic diseases on the reproductive performance of dairy cows in recent years,and focused on analyzing the molecular mechanism of nutritional and metabolic diseases with high perinatal incidence such as ketosis,low blood calcium and moderate gastric acid,and put forward the prospect and thinking on the future research direction of nutritional and metabolic diseases and reproductive performance of high-yielding dairy cows,in order to provide some reference and theoretical basis for improving the reproductive efficiency of high-yielding dairy cows in large-scale pastures in China and the perinatal nutrition management level of dairy cows.     

Diet-induced bacterial immunogens in the gastrointestinal tract of dairy cows: Impacts on immunity and metabolism

Dairy cows are often fed high grain diets to meet the energy demand for high milk production or simply due to a lack of forages at times. As a result, ruminal acidosis, especially subacute ruminal acidosis (SARA), occurs frequently in practical dairy production. When SARA occurs, bacterial endotoxin (or lipopolysaccharide, LPS) is released in the rumen and the large intestine in a large amount. Many other bacterial immunogens may also be released in the digestive tract following feeding dairy cows diets containing high proportions of grain. LPS can be translocated into the bloodstream across the epithelium of the digestive tract, especially the lower tract, due to possible alterations of permeability and injuries of the epithelial tissue. As a result, the concentration of blood LPS increases. Immune responses are subsequently caused by circulating LPS, and the systemic effects include increases in concentrations of neutrophils and the acute phase proteins such as serum amyloid-A (SAA), haptoglobin (Hp), LPS binding protein (LBP), and C-reactive protein (CRP) in blood. Entry of LPS into blood can also result in metabolic alterations. Blood glucose and nonesterified fatty acid concentrations are enhanced accompanying an increase of blood LPS after increasing the amount of grain in the diet, which adversely affects feed intake of dairy cows. As the proportions of grain in the diet increase, patterns of plasma β-hydoxybutyric acid, cholesterol, and minerals (Ca, Fe, and Zn) are also perturbed. The bacterial immunogens can also lead to reduced supply of nutrients for synthesis of milk components and depressed functions of the epithelial cells in the mammary gland. The immune responses and metabolic alterations caused by circulating bacterial immunogens will exert an effect on milk production. It has been demonstrated that increases in concentrations of ruminal LPS and plasma acute phase proteins (CRP, SAA, and LBP) are associated with declines in milk fat content, milk fat yield, 3.5% fat-corrected milk yield, as well as milk energy efficiency.     

玉米秸秆青贮饲料与全株玉米青贮饲料饲喂奶牛的差异研究

玉米秸秆和全株玉米均是制作奶牛青贮饲料的重要原料。为比较玉米秸秆青贮饲料与全株玉米青贮饲料对奶牛生产性能的影响,本研究将胎次、年龄、体重及产奶量相同的20 头奶牛分为两组——试验组1和试验组2,分别饲喂玉米秸秆青贮饲料与全株玉米青贮饲料,通过统计各组奶牛产奶量、乳脂率及乳蛋白率,分析玉米秸秆青贮饲料与全株玉米青贮饲料对奶牛生产性能的影响。试验结果表明,试验组2的日平均产奶量高于试验组1,且差异极显著（P<0.01）;试验组1和试验组2乳脂率差异不显著（P>0.05）;试验组2的平均乳蛋白率高于试验组1,且差异显著（P<0.05）,且全株玉米青贮比玉米秸秆青贮经济效益更高,一个泌乳周期可增加736.8 元/头。     

玉米秸秆饲粮条件下阴外动脉灌注氨基酸混合物对奶牛乳腺内短链脂肪酸摄取规律的影响

本试验采用动静脉血插管技术,以泌乳中期荷斯坦奶牛为研究对象,研究玉米秸秆饲粮条件下阴外动脉灌注氨基酸(AA)混合物对奶牛产奶性能、尾动脉血和乳静脉血中短链脂肪酸(SCFA)浓度及其比例以及乳腺内SCFA摄取规律的影响。采用2×2交叉试验设计,将体况良好、体重相近、日乳产量为(20.17±1.28)kg的8头经产(2~3胎)荷斯坦奶牛随机分为采食不同饲粮的2组[苜蓿组(MF组)和玉米秸秆组(CS组)],每组4头。2组奶牛饲喂的饲粮精粗比均为45∶55,精饲料组成相同,粗饲料组成不同,MF组粗饲料由苜蓿干草、玉米青贮和羊草组成,CS组以单一的玉米秸秆全部替代MF组饲粮中的粗饲料。试验分为2个阶段,每个阶段20 d,均分为饲粮适应期(预试期)14 d,载体灌注期3 d,正式灌注期3 d。在第1阶段,在载体灌注期,MF组奶牛接受载体灌注(阳性对照组1),CS组奶牛也接受载体灌注(对照组);在正式灌注期,MF组奶牛继续接受载体灌注(阳性对照组2),CS组奶牛接受AA混合物灌注;在第2阶段,将2组动物互换后处理方法同第1阶段。每个正式灌注期的最后2 d采集乳样和血样。结果显示:CS组奶牛阴外动脉灌注AA混合物可显著提高乳蛋白率(P0.05),对乳产量、4%乳脂校正乳(FCM)产量、乳脂率、乳脂产量、乳蛋白产量有一定促进效果,但部分指标仍然显著低于MF组(P0.05)。CS组奶牛阴外动脉灌注AA混合物可趋于显著地提高乳静脉血中乙酸的浓度(P=0.09),显著降低乳腺内乙酸的动静脉差(P0.05),缩小CS组与MF组奶牛在乳腺对乙酸的摄取量和摄取效率方面存在的差距。CS组奶牛阴外动脉灌注AA混合物对提高尾动脉血中乙酸/丙酸、(乙酸+丁酸)/丙酸有一定的促进效果(P0.05)。由此得出,以玉米秸秆为粗饲料的奶牛阴外动脉灌注AA混合物可显著提高乳蛋白率,增加乳静脉血中的乙酸浓度,同时缩小与以苜蓿干草、玉米青贮和羊草为粗饲料的奶牛在乳腺对乙酸的摄取量和摄取效率方面存在的差距。     

Feed‐derived volatile basic nitrogen increases reactive oxygen species production of blood leukocytes in lactating dairy cows

The present study investigated over 9 months the changes of fermentative quality of total mixed rations (TMR) containing grass silage (GS) as a major component, associated with changes in the volatile basic nitrogen (VBN) levels in an experimental dairy farm. Effects of VBN levels in TMR on metabolic parameters, reactive oxygen species (ROS) production by blood polymorphonuclear leukocytes (PMNs) and conception rates for dairy cows were analyzed. According to VBN levels in TMR during survey periods, three distinct phases were identified; phase A with low VBN; phase B with high VBN; and phase C with mid‐VBN. Metabolic parameters in blood were all within normal range. However, during phases B and C, nitrogen metabolic indices such as blood urea nitrogen and milk urea nitrogen showed higher levels compared to those in phase A, and a simultaneous increase in ROS production by blood PMNs and the load on hepatic function in metabolic parameters was observed in the cows with a lower conception rate. This suggests that feeding TMR with elevated VBN levels due to poor fermented GS results in stimulation of ROS production by PMNs by ammonia, and negatively affects metabolism and reproductive performance in lactating dairy cow.     

Functional liver disorder in relation to decreased titratable acidity of milk]

The internal environment of 17 dairy cows was observed by help of 23 variables of metabolic profile in blood and milk at lowered titratable acidity of milk (Tab. I) Average values of the observed variables were compared with reference values in a histogramme (Fig. 1). We calculated the statistical significance of differences of arithmetical means from reference average. Using correlation analysis we calculated the correlation coefficients for the observed variables. We represented the chosen correlation relations in correlogrammes (Fig. 2). We found significant correlation relations between AST and titratable acidity (degrees SH) (r = 0.791), AST and milk pH (r 0.617), AST and lactose (r = 0.69), AST and glucose (r = -0.56), blood pH and milk pH (r = -0.608), milk pH and lactose (r = -0.89). Mutual relations of titratable acidity with chosen variables of blood serum and milk were evaluated by help of regression coefficients, calculated for each parameter from the mathematical model (Fig. 3). The nearest relations were found for blood pH (regression coefficient /k/ kPH = -11.9), for AST (kAST = -3.1), for milk pH (k milk pH = -1.72) and for Mg (k Mg = -1.98). We also compared the recorded results of titratable acidity with theoretical values of titratable acidity calculated from the mathematical model (Tab. II). The differences between them were not statistically significant. It is evident from the results that the acid-base balance and functional liver condition influence the titratable acidity of milk.     

Prevalence and consequences of subacute ruminal acidosis in German dairy herds

Background

The prevalence and the clinical consequences of subacute ruminal acidosis (SARA) in dairy cows are still poorly understood. In order to evaluate the prevalence of SARA, 26 German dairy farms were included in a field study. In each herd, between 11 and 14 lactating dairy cows were examined for their ruminal pH using rumenocentesis. Milk production data and farm management characteristics were recorded. Each farm was scored for lameness prevalence among lactating animals, and body condition score was recorded three times four to five weeks apart in all animals examined. Farms were grouped on basis of ruminal pH and compared for lameness, body condition, milk production parameters and style of management. Animals were grouped on basis of their measured ruminal pH and compared accordingly for milk production parameters and body condition score.

Results

Of 315 cows examined, 63 individuals (20%) exhibited a ruminal pH of ≤ 5.5 at time of rumenocentesis. Of 26 farms examined, eleven farms had three or more of their cows experiencing a ruminal pH of ≤ 5.5 and were classified as likely experiencing subacute ruminal acidosis. These farms tended to be bigger than the others and offered less lying space to the lactating cows. There was no clear tendency regarding lameness. Among individual cows, animals with a low ruminal pH of ≤ 5.5 were found to be in significantly poorer body condition than animals with higher pH values (p < 0,05).

Conclusions

The study shows 11 out of 26 of herds likely experiencing SARA. Bigger herds tend to be at a higher risk for SARA, while individuals with low ruminal pH tend to be lower in body condition. The study points to the importance of management in preventing SARA.     

A Comparison of Simultaneously Collected Arterial, Mixed Venous, Jugular Venous and Cephalic Venous Blood Samples in the Assessment of Blood-Gas and Acid-Base Status in the Dog

Blood samples were collected simultaneously from the pulmonary artery, jugular vein, cephalic vein, and carotid artery in awake dogs. Blood-gas and acid-base values were measured from these blood samples in normal dogs and in dogs after production of metabolic acidosis and metabolic alkalosis. The values obtained from each of the venous sites were compared with those obtained from arterial blood to determine if venous blood from various sites accurately reflected acid-base balance and could therefore be used in the clinical patient. The results of this study demonstrated significant differences between the blood from various venous sites and the arterial site for PCO2 and pH in all acid-base states. Significant differences for standard bicarbonate (SHCO3) were found only when jugular and cephalic venous blood were compared with arterial blood in dogs with a metabolic acidosis. No significant differences were found for BE when blood from the venous sites was compared with arterial blood. The values for pH, HCO3, TCO2, BE, and SHCO3 measured on blood collected at the various venous sites were found to correlate well with those obtained from arterial blood, with a correlation coefficient of 0.99 for HCO3, TCO2, BE, and SHCO3. These correlation coefficients, together with similar values in BE at all collection sites, indicate that, in the dog with normal circulatory status, blood from any venous site will accurately reflect the acid-base status of the patient.     

不同方式处理的全株玉米青贮对奶牛生产性能和经济效益的影响

[目的]探究不同方式制备的全株玉米青贮饲喂奶牛后,对其生产性能和经济效益的影响。[方法]选定中国荷斯坦牛开展全株玉米青贮饲喂试验。将28头奶牛随机分为对照组和试验组,每组14头。前者饲喂不添加菌剂制备的全株玉米青贮,后者饲喂添加青贮菌剂制备的全株玉米青贮。统计各组奶牛日均干物质采食量、日均产奶量、料重比、乳脂率和乳蛋白率,计算各组奶牛日均经济效益和试验期总经济效益。[结果]采用添加青贮菌剂制备的全株玉米青贮饲喂奶牛后,奶牛日均干物质采食量和料奶比与对照组差异不显著,但日均产奶量、平均乳脂率和乳蛋白率显著提高（P<0.05）。每头牛日均产奶量增加1.91 kg,乳脂率增加0.22个百分点,乳蛋白率增加0.06个百分点。试验组经济效益明显提高,每头牛日均经济效益增加4.73元,正试期内总经济效益增加1 986.60元。[结论]采用添加青贮菌剂的全株玉米青贮饲喂奶牛,能有效提高奶牛的生产性能和经济效益。     

Milk thistle (Silybum marianum, L., Gaertn.) in the feed of ketotic cows]

Two comparative trials were performed, each with 16 cows which in the period of 2-6 weeks after parturition had 7.9 mg and more acetone in 1 litre of milk. The cows, crossbreds of the Czech Red-Pied cattle with the Holstein cattle, were divided into control and test groups, eight in each using the system of pairs. The cows of test groups were given for a fortnight feed rations containing a meal of milk thistle (Silybum marianum, L., Gaert.) seeds, at a rate of 0.3 kg per head/day with the contents of 2.34% silybin and silydianin (substances of the so called silymarin complex of the flavonolignane group). In comparison with the control cows, in the blood and milk of the former ones a decrease was demonstrated in the sum of acetone + acetoacetic acid (up to P less than 0.01) and beta-hydroxybutyric acid in the blood (up to P less than 0.05). The ketonuria degree dropped remarkably. Although there were not observed any differences in the parameters of acid-base metabolism in the blood (pH, PCO2, BE, SB, BB), the pH values and net acid-base output in urine were higher in these cows. Milk production in the cows of control groups was decreasing during the trial (up to P 0.01), but in the test cows it was higher by 7.7% (trial 1) and by 3.4% (trial 2), in comparison with the milk yield at the beginning of the trials. Differences in metabolism parameters and milk production in favour of the cows which were given milk thistle in their feed rations were observed even in a fortnight after the diet stopped to contain this ingredient.     

奶牛低淀粉型日粮研究进展

低淀粉型日粮的应用不仅可以满足高产奶牛生产阶段的能量需要,而且可以保证奶牛瘤胃健康,避免瘤胃酸中毒。常用低淀粉型饲料有优质牧草、中性洗涤可溶性纤维源饲料以及可溶性糖三大部分。饲喂低淀粉型日粮可以有效缓解挥发性脂肪酸的产生,避免瘤胃pH降低,并促进了奶牛的采食以及养分消化,提高乳品质。本文从低淀粉型日粮的实现手段,以及瘤胃发酵参数和生产性能方面阐述低淀粉型日粮在奶牛生产中的必要性,确立今后的研究重点应该在各种原料替代谷物原料的最适比例及组合效应方面,从而完善奶牛低淀粉型日粮配制技术。