Effects of osmolality on water, electrolytes and VFAs absorption from the isolated ruminoreticulum in the cow

Effect of the osmolality on the absorption of water, electrolyte and VFAs from the isolated ruminoreticulum under normal feeding condition were investigated in a series of the study to evaluate the rumen as a potential site of absorption in oral fluid therapy of adult cattle. Thirty of 40 l of the test solutions with varying osmotic pressure (100, 200, 300 and 500 mosmol/L, pH 6.8) were prepared using different concentrations of electrolytes and VFAs. These were infused into the isolated and emptied ruminoreticulum, and the absorption rate of water and each components were studied for 3 hrs. Marked absorption of water was observed with solutions more hypotonic than rumen fluid, the extent of which was more extensive with less osmotic pressure; the absorption rate as high as 47.6% was obtained with a solution 100 mosmol in osmotic pressure. When hypertonic solution (500 mosmol/L) was infused, however, water was transported on the contrary from the blood to the rumen. Absorption rates of electrolytes such as Na, K and Cl were increased according to the elevation of osmolalities and their concentrations in the test solutions. VFAs were also absorbed in large quantities (23.9-74.5%) in any test solutions, though the absorption rates were significantly decreased with the elevation of osmolalities. These results may indicate that the ruminal wall has a high absorptive function for water, electrolytes and VFAs when the osmolalities and the concentration of solutes in the ruminal fluid are maintained within a certain range. Furthermore, it is thought that they may work as a rational support for a possible oral fluid therapy even in adult cows.     

The effects of high levels of rumen degradable protein on rumen pH and histamine concentrations in dairy cows

An experiment was conducted to test the hypothesis that the supplementation of crude protein (CP) results in rumen acidosis and increased histamine concentrations in dairy cows. Six ruminally fistulated, non-pregnant dry cows were fed three experimental rations in a replicated 3 × 3 Latin square design. The CP contents in the low-CP, the high rumen undegradable protein (high-RUP) and the high rumen degradable protein (high-RDP) rations were 112, 259 and 266 g/kg dry matter (DM) respectively. The cows were fed 7.7 kg DM of the concentrates and 2.7 kg DM of rice straw. High levels of RDP in the ration significantly increased the ammonia, total volatile fatty acid (VFA) and histamine concentrations in the rumen fluid. However, supplemental CP, whether degradable or undegradable, did not significantly affect the pH of rumen fluid. Plasma urea nitrogen concentration was higher in both high-RDP and high-RUP in relation to cows fed the low-CP ration. The rise in ruminal histamine concentrations was physiologically non-relevant, most likely because rumen pH was not affected by supplemental CP at the installed level of DM intake. Therefore, it can be concluded that the issue of supplemental CP, rumen pH and ruminal histamine concentrations has not yet been settled. Further research is warranted to understand these relationships.     

Concentrations of ketones in milk in early lactation, and reproductive performance of dairy cows

Samples of blood and milk were taken from clinically ketotic cows at 12-hour intervals before and after treatment The concentration of beta-hydroxybutyrate was determined in plasma and milk, and the concentration of acetone was determined in milk. Measurement of milk acetone had the optimal combination of sensitivity, specificity and positive predictive value to identify ketotic cows and was subsequently used in a comparison of the fertility of ketotic and normal cows. Two samples of milk were taken approximately two weeks apart, between 12 and 60 days after calving, from 410 cows on three farms and the concentration of acetone in the milk was measured. Thirty cows with milk acetone concentrations of at least 0.4 mmol/litre were compared with paired control cows with milk acetone concentrations less than 0.3 mmol/litre. The ketotic cows had a significantly longer calving-to-conception interval and a significantly higher culling rate due to a failure to conceive (P<0.05).     

Herbage intake and ruminal digestion of dairy cows grazed on perennial ryegrass pasture either in the morning or evening

This study aimed to clarify diurnal fluctuations of herbage intake, ruminal fermentation of herbage carbohydrates and proteins, and digesta particulate weight in the rumen of grazing dairy cows. Six ruminally cannulated, non‐lactating dairy cows were grazed on perennial ryegrass/white clover pasture either in the morning (04.00 to 08.00 hours) or the evening (16.00 to 20.00 hours). Cows grazed in the evening spent more time (P < 0.01) and consumed more herbage (P < 0.01) compared with cows grazed in the morning. Higher (P < 0.05) daily mean concentrations of total volatile fatty acid, propionate and n‐butyrate in rumen fluid were observed for cows grazed in the evening compared with cows grazed in the morning. Although cows grazed in the evening ingested more crude protein compared with cows grazed in the morning, no significant difference in NH₃‐N concentration in rumen fluid was observed between them. The ratio of purine‐derivative concentration to creatinine concentrations was higher (P < 0.01) in the urine of cows grazed in the evening than in cows grazed in the morning. These results clearly indicated that evening grazing was advantageous for dairy cows compared with morning grazing, in terms of ruminal fermentable energy intake and nitrogen utilization efficiency.     

Effect of cereal straw and alfalfa hay diet on amino acid profile of gastrointestinal digesta in lactating dairy cows

This study was conducted to evaluate the effects of replacing alfalfa hay with rice straw (RS) or corn stover (CS) on amino acid (AA) profiles of gastrointestinal digesta in lactating cows. Eighteen lactating dairy cows were randomly assigned to one of three groups (n = 6) and fed identical concentrate and corn silage with different forages on dry matter basis: (i) 23% alfalfa hay and 7% Chinese wild rye hay (AH); (ii) 30% CS; and (iii) 30% RS. After the 14‐week feeding, a total of 18 cows were slaughtered to collect digesta from four representative organs, including rumen, omasum, duodenum and jejunum. The AA profiles of ruminal microbial fraction were similar among the treatments, except for greater Arg in cows fed RS than in cows fed AH or CS. Most of the analysed AA changed under different diets. Significant differences were found among the microbial fraction, rumen fluid and rumen digesta, with greater essential AA in digesta than in microbial fraction or rumen fluid and greater essential AA in microbial fraction than rumen fluid. Significant differences in individual AA profiles of digesta and relevant fluid were found across the four representative digestive tract parts, including rumen, omasum, duodenum and jejunum, showing much lower Leu proportion in CS and RS than in AH in duodenal fluid. In summary, ruminal microbes may prefer using essential AA, rather than non‐essential AA. The AA profile of ruminal microbes was constant except for Arg. The AA composition of digesta across the four digestive tracts changed dramatically, which indicated differences in the ability and efficiency of AA absorption. The lower duodenum absorbable Leu proportion in cows fed CS or RS indicated the shortage of Leu in CS or RS diets, which might also restrict the balanced AA absorption.     

Relationship between pH and Temperature in the Ruminal Fluid of Cows, Based on a Radio-Transmission pH-Measurement System

To assess the relationship between pH and temperature in the ruminal bottom fluid, circadian changes were monitored using cows fed a control diet (C diet) or a rumen acidosis-inducing diet (RAI diet) by using a wireless radio-transmission pH- measurement system. These two parameters were measured simultaneously at 10-min intervals on day 14 after commencement of feeding. Compared to the mean ruminal pH for 60 min immediately after the morning feeding (0 hr), significantly lower pH was noted 3-13 hr later (P<0.05) and 4-19 hr later (P<0.01) in cows fed the C and RAI diets, respectively, although the reduction in the latter was much higher than that in the former. In contrast, significantly higher ruminal temperature was found at 8 and 12-14 hr later (P<0.05) and 6, 8, and 10-19 hr later (P<0.01) in cows fed the C and RAI diets, respectively. A significant negative correlation was observed between the lowest ruminal pH and its corresponding ruminal temperature in cows fed the C and RAI diets (r=-0.722 and -0.650, P<0.01, respectively), suggesting active fermentation and volatile fatty acid production in the rumen. However, ruminal pH profiles may not be predictable by measuring only ruminal temperature because decreases in ruminal pH were preceded by increases in ruminal temperature, and circadian changes in pH and temperature were associated with ruminal fermentation.     

Detection of ketosis in dairy cows by analysis of exhaled breath

Summary

In four healthy cows an elevation of ketone bodies was induced by reduction of feed intake. Two cows became clearly ketotic while the other two cows showed only slight increases in ketone body concentrations in serum and milk. Acetone concentrations in exhaled breath were measured by gas chromatography combined with mass spectrometry. These values were correlated with concentrations of serum β‐hydroxybutyric acid (r=0.81) and milk acetoacetate+acetone (r=0.70). It is concluded that the ketotic state of dairy cows can be detected by analysis of exhaled breath. This offers a potential non‐invasive method of determining the metabolic state of dairy cows.     

添加植物油对瘤胃内共轭亚油酸前体物累积规律的影响

采用人工瘤胃法研究了豆油和棉籽油中亚油酸等多聚不饱和脂肪酸在瘤胃微生物作用下的氢化中间产物trans11油酸变化规律以及对瘤胃发酵的影响。结果表明添加豆油和棉籽油使trans11油酸得到累积,其中4%处理组显著高于对照组(P<0.05)。处理组的总挥发酸浓度均高于对照组,棉籽油处理组与对照组差异达到显著(P<0.05)。处理组NH3N浓度均高于对照组,2%豆油、2%棉籽油和4%棉籽油处理组与对照组差异达到显著(P<0.05)。     

高精料日粮对山羊瘤胃和盲肠发酵及生物胺生成与吸收的影响研究

本实验旨在探究饲喂高精料日粮对山羊瘤胃和盲肠发酵、生物胺生成与吸收的影响研究。试验选用6头装有永久性瘤胃瘘管的雄性波杂山羊,随机分成低精料组与高精料组,实验期24 d。结果显示,与低精料组相比,饲喂高精料日粮的山羊瘤胃液中总挥发性脂肪酸、乙酸、丙酸、丁酸、戊酸、总支链脂肪酸、酪胺、腐胺、组胺、甲胺和色胺浓度显著性增加(P<0.05),而瘤胃pH和乙丙比显著降低(P<0.05);饲喂高精料日粮的山羊盲肠内容物中的乙酸、丙酸、总挥发性脂肪酸浓度和上述5种生物胺浓度显著增加(P<0.05);同时,瘤胃和盲肠静脉血中的上述5种生物胺的浓度显著提高(P<0.05)。相关性分析结果表明,瘤胃液中酪胺、腐胺、甲胺和色胺浓度与瘤胃静脉血所对应的生物胺浓度呈显著正相关(P<0.05),且盲肠内容物中酪胺、腐胺、甲胺和色胺与盲肠静脉血中对应的生物胺的浓度呈显著正相关(P<0.05)。结果说明,饲喂高精料日粮促进了山羊瘤胃和盲肠发酵,提高了瘤胃与盲肠内容物中生物胺浓度,暗示高精料日粮可能提高消化道上皮的通透性,促进消化道上皮对生物胺的吸收。     

不同粗饲料日粮对西门塔尔繁殖母牛瘤胃发酵和血液指标的影响

[目的] 分析不同粗饲料日粮对西门塔尔繁殖母牛瘤胃液pH值、瘤胃挥发性脂肪酸含量及血液指标的影响。[方法] 选择体重相近的西门塔尔繁殖母牛18头,按同质原则分为3组,每组6头。日粮1组粗饲料为干玉米秸秆,日粮2组粗饲料为全株玉米青贮,日粮3组粗饲料为全株玉米青贮+干玉米秸秆。预试期14 d,正试期42 d。采集试验牛的瘤胃液和血液样本,进行瘤胃液pH值、挥发性脂肪酸（volatile fatty acid,VFA）含量及血液指标测定。[结果] 3组繁殖母牛的瘤胃液pH值差异不显著（P> 0.05）。全株玉米青贮组的瘤胃内乙酸含量显著（P<0.05）高于干玉米秸秆组,全株玉米青贮组和全株玉米青贮+干玉米秸秆组的瘤胃内丙酸含量显著（P<0.05）高于干玉米秸秆组,全株玉米青贮组的瘤胃内正丁酸和异丁酸含量显著（P<0.05）高于其他组。干玉米秸秆组的血清SOD活力和T-AOC活力显著（P<0.05）低于其他组,GSH-Px活力显著（P<0.05）低于全株玉米青贮+干玉米秸秆组。干玉米秸秆组血清中的铁（Fe）和锌（Zn）含量显著（P<0.05）低于全株玉米青贮组,干玉米秸秆组和全株玉米青贮组血清中的硒（Se）含量显著（P<0.05）高于全株玉米青贮+干玉米秸秆组。干玉米秸秆组血清中VD和VE含量显著（P<0.05）低于其他组。[结论] 饲喂以全株玉米青贮或者全株玉米青贮+干玉米秸秆为粗饲料的日粮,西门塔尔繁殖母牛的瘤胃发酵和血液生化指标优于饲喂以干玉米秸秆为主要粗饲料的日粮。结合饲养成本和农区粗饲料供给情况,生产中推荐全株玉米青贮+干玉米秸秆的粗饲料饲喂模式。     

Fatty acid composition of ruminal bacteria and protozoa,and effect of defaunation on fatty acid profile in the rumen with special reference to conjugated linoleic acid in cattle

Objectives of this study were to compare fatty acid (FA) composition of ruminal bacterial (B) and protozoal (P) cells, and to investigate effect of protozoa on FA profile in the rumen of cattle. Three cows were used to prepare ruminal B and P cells. Four faunated and three defaunated cattle (half‐siblings) were used to study effect of protozoa on ruminal FA profile. Proportions of C16:0 and C18:0 in total fatty acids in B cells were 20.7% and 37.4%, whereas those in P cells were 33.4% and 11.6%, respectively. Proportions of trans‐vaccenic acid (VA) and cis‐9, trans‐11 conjugated linoleic acid (CLA) in B cells were 3.9% and 1.0%, and those in P cells were 5.5% and 1.6%, respectively, being higher in P cells. Proportions of C18:1, C18:2 and C18:3 in P cells were two to three times higher than in B cells. Proportions of unsaturated fatty acids, VA and CLA in B cells of faunated cattle were higher than those of defaunated. VA and CLA in the ruminal fluid of faunated were also 1.6 to 2.5 times higher than those of defaunated. This tendency was similar for cell‐free fraction of ruminal fluid. These results indicate that protozoa contribute greatly in VA and CLA production in the rumen.     

Relations between plasma acetate, 3-hydroxybutyrate, FFA, glucose levels and energy nutrition in lactating dairy cows.

To clarify the implication of an energy nutrition on a metabolic alteration with advancing lactation, total 270 blood samples were taken from 16 lactating dairy cows. Amounts of dietary allowance and the refusals were measured daily, and the energy (TDN) intakes and a satisfaction (energy balance) of each cow were estimated. Plasma acetate, 3-hydroxybutyrate (3-HB), free fatty acid (FFA) and glucose levels were estimated. The data were divided into 3 groups depending on the days in milk; early (up to 70 days postpartum), mid (71 to 140 days), and late (after 141 days) lactation. There were many cases of higher FFA level in early lactation, especially with declining acetate and glucose levels. There were proportional elevations of 3-HB in connection with FFA levels in many samples of early lactation, though the 3-HB increased independently of FFA levels in the most cases of the mid and late lactations. Plasma 3-HB levels increased in many cases of decreased glucose level, especially in the early lactation. Plasma acetate level correlated positively with 3-HB level, but not correlated with glucose level. Higher FFA level and elevation of FFA/3-HB ratio were observed in the conditions of negative energy balance. This implies the metabolic importance of FFA in a ketogenesis of the early lactation.     

Evaluation of rumen transfaunation after surgical correction of left-sided displacement of the abomasum in cows

OBJECTIVE: To evaluate rumen transfaunation after surgical correction of left-sided displacement of the abomasum (LDA) in cows. DESIGN: Prospective clinical trial. ANIMALS: 20 multiparous cows with LDA. PROCEDURES: Cows with LDA were treated surgically (day 0). On days 0 (immediately after surgery) and 1, 10 cows each received 10 L of rumen fluid (transfaunated group) or 10 L of water (control group) via a stomach tube. Postoperative dietary dry-matter intake and milk yield of each cow were recorded daily for 5 days, beginning immediately after surgery. Blood and rumen fluid samples were collected prior to surgery and on days 1, 3, and 5 after surgery. Serum nonesterified fatty acid and beta-hydroxybutyrate concentrations were measured. Volatile fatty acid and ammonia concentrations and pH of rumen fluid were determined. Urine specimens were collected and tested for ketones at 8 AM and 4 PM. Cows with ketonuria were treated with 50% dextrose solution administered i.v. at the time ketonuria was first detected. Cows with ketonuria were treated twice daily until ketonuria resolved. RESULTS: All cows survived and completed their lactation. Daily and cumulative dry-matter intake and milk yield of cows in the transfaunated group were significantly greater than those of cows in the control group. Cows in the transfaunated group had significantly lower serum concentrations of beta-hydroxybutyrate and significantly lower acetate-to-propionate ratios in rumen fluid on day 1 after surgery, compared with cows in the control group. Cows that received transfaunate required a significantly lower total volume of dextrose administered i.v. than control cows. CONCLUSIONS AND CLINICAL RELEVANCE: Benefits of rumen transfaunation of cows after surgical correction of LDA included a lesser degree of ketonuria, greater feed intake, and higher milk yield, compared with nontransfaunated cows.     

Clinical evaluation of ketone bodies in body fluids of cows in late pregancy and their fetuses

Ketone body concentrations were determined in six body fluids of cows in late pregnancy and their fetuses (blood plasma and urine of cows, amniotic and allantoic fetal fluids, and fetal blood serum and urine) using the head-space gas chromatographic method. Physiological ratios 0/T% of oxidized (acetone and acetoacetic acid) to total (acetone, isopropanol, acetoacetic and 3-hydroxybutyric acids) ketone bodies were below 10% in cow blood plasma and urine, fetal serum and urine, and allantoic fluid, and below 20% in amniotic fluid. A scheme for the evaluation of the degree and duration of ketosis based on the 0/T% ratio is proposed. The existence of a renal regulatory mechanism for excretion of ketone bodies is suggested by analogy with the renal acidobasic regulation.     

Clinical evaluation of ketone bodies in body fluids of cows in late pregnancy and their fetuses

Ketone body concentrations were determined in six body fluids of cows in late pregnancy and their fetuses (blood plasma and urine of cows, amniotic and allantoic fetal fluids, and fetal blood serum and urine) using the head-space gas chromatographic method. Physiological ratios O/T% of oxidized (acetone and acetoacetic acid) to total (acetone, isopropanol, acetoacetic and 3-hydroxybutyric acid) ketone bodies were below 10% in cow blood plasma and urine, fetal serum and urine, and allantoic fluid, and below 20% in amniotic fluid. A scheme for the evaluation of the degree and duration of ketosis based on the O/T% ratio is proposed. The existence of a renal regulatory mechanism for excretion of ketone bodies is suggested by analogy with the renal acidobasic regulation.     

Effect of dietary supplementation of rutin on lactation performance,ruminal fermentation and metabolism in dairy cows

The effect of long‐term dietary supplementation with rutin on the lactation performance, ruminal fermentation and metabolism of dairy cows were investigated in this study. Twenty multiparous Chinese Holstein cows were randomly divided into four groups, and each was offered a basal diet supplemented with 0, 1.5, 3.0 or 4.5 mg rutin/kg of diet. The milk yield of the cows receiving 3.0 and 4.5 mg rutin/kg was higher than that of the control group, and the milk yield was increased by 10.06% and 3.37% (p < 0.05). On the basis of that finding, the cows supplemented with 0 or 3.0 mg rutin/kg of diet were used to investigate the effect of rutin supplementation on blood metabolites and hormone levels. Compared with the control group, the serum blood urea nitrogen (BUN) concentration of the 3.0 mg rutin/kg group is significantly decreased (p < 0.05). In another trial, four adult cows with permanent rumen fistula and duodenal cannulae were attributed in a self‐control design to investigate the peak occurrence of rutin and quercetin in different parts of the gastrointestinal tract, ruminal fermentation and microbial population in dairy cows. The cows supplemented with 3.0 mg rutin/kg in the diet differed from the control period. Samples of rumen fluid, duodenal fluid and blood were collected at 1, 2, 3, 4, 5, 6, 7 and 8 h after morning feeding. Compared to the control group, the pH, ammonia nitrogen concentration, number and protein content of rumen protozoa and blood urea nitrogen were lower, but the concentration of total volatile fatty acid (TVFA), microbial crude protein (MCP) and serum lysozyme content were higher for the cows fed the rutin diets. The addition of 3.0 mg rutin/kg to diets for a long term tended to increase the milk yield and improve the metabolism and digestibility of the dairy cows.     

亚急性瘤胃酸中毒耐受性不同的奶牛瘤胃上皮形态及功能差异研究

本试验旨在探究SARA（亚急性瘤胃酸中毒）耐受性不同奶牛的瘤胃上皮形态及其功能差异。选取12头装有永久性瘤胃瘘管的泌乳中期荷斯坦奶牛,饲喂精粗比为4∶6的日粮,并根据瘤胃pH值的高低,分为SARA易感组（SUS,n=4）和SARA耐受组（TOL,n=4）。瘤胃上皮形态及功能分析结果显示,与TOL组比较,SUS组奶牛瘤胃上皮的棘突层和基底层厚度明显增厚（P<0.05）,SUS组奶牛瘤胃上皮组织中参与挥发性脂肪酸（VFA）吸收的PAT1、MCT4和DRA基因表达量较TOL组显著下调（P<0.05）,而H+转运载体NHE1、NHE2、NHE3和调节胞内pH的vH+ATPase和Na+/K+ATPase的表达量显著升高（P<0.05）;对参与调控瘤胃VFA代谢的基因定量结果表明,SUS组PDHA1和SREBP2的表达量显著高于TOL组（P<0.05）,而HMGCL-2的表达量显著降低（P<0.05）;此外,SUS组CDK2、CDK6和Cyclin D1、Bad及Caspase-9等参与瘤胃上皮细胞增殖与凋亡的基因表达量显著高于TOL组（P<0.05）。结果说...     

Effects of an abrupt increase of starch-rich concentrates in the diet of dairy cows on concentrations of volatile fatty acids in the rumen and large intestine and on myoelectric activity of the spiral colon

OBJECTIVES: To describe the effects of an abrupt increase of concentrates in the diet of dairy cows on myoelectric activity of the spiral colon and on fermentation patterns in the rumen and large intestine. ANIMALS: 6 healthy lactating Simmental x Red-Holstein cows. PROCEDURES: The diet of 6 cows implanted with bipolar electrodes in the spiral colon was changed from hay only to a ration of 50% hay:50% starch-rich concentrates during a period of 60 hours. Myoelectric activity of the spiral colon, concentrations of absolute and undissociated volatile fatty acids (VFA), and pH of ruminal and large intestinal contents were monitored before, during, and after the dietary change. RESULTS: Significant changes in patterns of myoelectric activity of the spiral colon were restricted to phases III and IV of the bovine migrating myoelectric complex and to propagation velocity. Significant alterations were not observed in pH or VFA concentrations in ruminal fluid, but pH decreased and VFA concentrations increased significantly in fecal specimens after the change of diet. CONCLUSIONS AND CLINICAL RELEVANCE: Although rumen fluid is of limited value for measurement of certain indicators of fermentation, fecal samples can be used for measurement of pH and VFA concentrations, which serve as indicators of fermentation patterns in the large intestine. Increased concentrations of VFA and low pH in large intestinal digesta have a minimal influence on myoelectric activity of the spiral colon. Increased luminal VFA concentrations are unlikely to play an important role in the etiopathogenesis of motility disorders of the large intestine in cattle.     

Haematological and biochemical findings in cattle with dilatation and torsion of the caecum

A biochemical examination was made of the blood and rumen fluid of 111 heifers and cows suffering from caecal dilatation, with or without torsion. Haematological values were normal in the majority of cattle. Concentrations of chloride were normal in the rumen fluid of 83 per cent of the animals and higher in the remainder. Nine cows that had to be slaughtered had higher bile concentrations than those which recovered. Twenty-eight per cent had increased blood urea concentrations probably due to dehydration.     

归芪益母复方制剂对产后奶牛瘤胃微生物和短链脂肪酸的调节

本试验旨在探究归芪益母复方制剂对产后奶牛瘤胃微生物和短链脂肪酸的调节作用。将19头待产的健康荷斯坦奶牛随机分为两组,对照组10头,试验组9头。试验组奶牛产后每天灌服归芪益母复方制剂500 mL,对照组奶牛每天灌服等体积饮用水,连续6 d。产后第7天晨饲前采集瘤胃液,采用16S rRNA高通量测序和GC-MS/MS靶向代谢组学技术对两组奶牛瘤胃菌群的丰度和短链脂肪酸的含量进行了测定。结果表明,与对照组相比,试验组奶牛瘤胃变形菌门(Proteobacteria)、Escherichia-Shigella属和拟杆菌属(Bacteroides)的菌群丰度极显著升高(P<0.01),乳杆菌属(Lactobacillus)和Subdoligranulum属菌群丰度显著升高(P<0.05)。试验组奶牛瘤胃丙酸(P<0.05)和异丁酸(P<0.01)含量明显升高。本研究从瘤胃微生物菌群及短链脂肪酸角度揭示了归芪益母方对产后奶牛的保健机制。