Variability of serum bile acid concentrations over time in dairy cattle, and effect of feed deprivation on the variability.

Twelve nonlactating dairy cows, free of signs of liver disease and with normal serum activities of liver-derived enzymes and normal liver biopsy tissue, were examined over a 72-hour period for serum total bile acid concentrations. The cattle were fed hay twice daily, and blood samples were obtained every hour for 24 hours, every other hour for 24 hours, then every hour for 24 hours. After 3 weeks, the study was repeated on 6 of the cattle, thus providing data for eighteen 72-hour periods. Serum bile acid concentration varied greatly over the 72 hours, with the range being from one third to 3 times the median. There were variations by as much as 60 mumol/L from 1 hour to the next. After another 3 weeks, 8 of the cattle were deprived of hay for 48 hours and then fed hay morning and afternoon of the third (last) day of the study. There was no significant reduction in bile acid concentration after withholding the hay, but the variability was reduced (P = 0.02) during the last 20 hours of the hay-deprivation period. In 3 ancillary studies, serum bile acid concentrations were examined over a 48-hour period in 2 cows in early lactation, 3 cows in midlactation, and two 6-month-old heifers. The cows were fed hay and grain twice daily, and the heifers were fed only hay twice daily. In comparison with values for the 12 nonlactating cows fed hay twice daily, mean serum bile acid concentration in the recently freshened cows was significantly (P < 0.002) higher (62.9 vs 22.0 mumol/L).(ABSTRACT TRUNCATED AT 250 WORDS)     

Inositol and hepatic lipidosis. II. Effect of inositol supplementation and time from parturition on serum insulin, thyroxine and triiodothyronine and their relationship to serum and liver lipids in dairy cows

Percutaneous liver biopsies and blood samples were obtained from 80 dairy cows in nine Michigan herds over the peripartum period. Thirty-nine cows were fed 17 g of supplemental inositol and 41 were fed a placebo. Liver biopsies were assayed for total myoinositol and triglyceride (TG) concentrations. Blood samples were assayed for serum dextran precipitable cholesterol, nonesterified fatty acids (NEFA), insulin, thyroxine (T4), free (FT4), triiodothyronine (T3) and free T3 (FT3) concentrations. Serum concentrations of insulin and the thyroid hormones decreased near parturition, with lowest concentrations occurring in the immediate postpartum period. Concentrations of T3 correlated well with T4, and the concentrations of free thyroid hormones reflected concentrations of total thyroid hormones. The percentage of hormone in the free fraction remained constant over time. Serum insulin, T3 and T4 were negatively correlated with serum NEFA and liver TG concentrations. Thyroid hormone concentrations were positively correlated with serum dextran precipitable cholesterol concentrations. Inositol supplementation was associated with reduced circulating T3 and FT3 concentrations, but not T4 and FT4 concentrations. Changes in hormone concentrations at parturition and their relationship to liver TG and serum NEFA concentrations were consistent with a metabolic adaptation by the dairy cow to the negative energy balance of early lactation.     

Evaluation of ornithine carbamoyl transferase and other serum and liver-derived analytes in diagnosis of fatty liver and postsurgical outcome of left-displaced abomasum in dairy cows

OBJECTIVE: To evaluate postsurgical outcome in dairy cows with left-displaced abomasum (LDA) with regard to severity of fatty liver and assess the usefulness of preoperative determination of serum ornithine carbamoyl transferase (OCT) activity, bile acids concentration, and other variables for evaluating liver function during the postsurgical convalescence period. DESIGN: Prospective study. ANIMALS: 68 Holstein cows. PROCEDURES: Blood and liver biopsy specimens were obtained during standing LDA surgery. Liver tissue was examined histologically and classified by severity of fatty change. Serum activities of liver-derived enzymes and concentrations of total lipids, triglycerides, bile acids, glucose, beta-hydroxybutyric acid, bilirubin, and nonesterified fatty acids were determined. RESULTS: Most cows with LDA and cows with severe fatty liver were detected within the first month after calving. Postsurgical outcome was related to severity of fatty liver. All cows that died had severe fatty liver. Serum activities of OCT, aspartate aminotransferase, and glutamate dehydrogenase and serum total bilirubin concentration were sensitive indicators of fatty liver. Serum bile acids concentration was not an accurate indicator of fatty liver. CONCLUSIONS AND CLINICAL RELEVANCE: Postsurgical outcome of cows undergoing surgery to correct LDA was related to fatty liver severity. Assessment of serum activities of OCT, aspartate aminotransferase, and glutamate dehydrogenase and serum total bilirubin concentration is recommended for diagnosis of fatty liver in dairy cows with LDA, whereas determination of bile acids concentration is not. The strong correlation between OCT activity and degree of hepatocellular damage supports use of this enzyme for assessing severity of fatty liver and predicting postsurgical outcome in cows with LDA.     

Fatty liver in dairy cows

An increase in liver fat concentration during the peripartum period is extremely common in dairy cows and, to some degree, is probably normal. When severe, it is associated with clinical problems including increased morbidity and mortality and reduced breeding efficiency. Fatty liver develops when serum NEFA concentrations rise and hepatic uptake of NEFA exceeds the liver's ability to synthesize and secrete lipoproteins. In most cases, hepatic lipid accumulation appears to commence prepartum, in association with rising serum NEFA concentrations and declining serum lipoprotein concentrations. Commonly used clinicopathologic tests of liver function do not yield clearly abnormal results except in animals with extremely high concentrations of liver fat. Clinically useful estimates of hepatic lipid concentration can be obtained in the field by determining the buoyancy of needle biopsy samples in liquids of various specific gravities. Clinically ill animals with liver fat concentrations of greater than 35 per cent by weight have a poor prognosis, and those that do survive will have a protracted convalescence. Treatment of dairy cows with clinical fatty liver should be aimed at reducing further adipose lipid mobilization and promoting hepatic lipoprotein synthesis; however, protocols for therapy have not as yet been evaluated critically. Prevention of fatty liver is more rewarding than treatment. Dry cows should be maintained in a moderately fat condition and fed high-quality, palatable feeds in amounts necessary to met or slightly exceed their energy requirements. Free-choice feeding of high-energy feeds should be avoided in late lactation and during the nonlactating period.     

Evaluation of serum bile acid concentrations for the diagnosis of portosystemic venous anomalies in the dog and cat

The serum concentration of bile acids was measured in dogs and cats with portosystemic venous anomalies (PSVA). In 14 dogs, the mean serum bile acid concentration after 12 hours of fasting was 61.7 +/- 68.7 mumol/L (normal, 2.3 +/- 0.4 mumol/L (SEM) and when measured 2 hours after a meal in 15 dogs was 229.9 +/- 87.7 mumol/L (normal, 8.3 +/- 2.2 mumol/L). The fasting serum bile acid concentration was within the normal range in 5 of 14 dogs. The postprandial concentration was determined in 3 of the 5 and in each case increased more than tenfold above the fasting value. The mean fasting serum bile acid concentration in 4 cats was 24.4 +/- 10.1 mumol/L (normal, 1.7 +/- 0.3 mumol/L) and in 2 of the cats increased to a mean of 120.6 mumol/L (normal, 8.3 +/- 0.8 mumol/L) 2 hours after feeding. The bile acid values in patients with PSVA were correlated with values for blood ammonia content, sulfobromophthalein (BSP) retention, and results of conventional tests of hepatic function. Bile acid concentrations were more sensitive than abnormalities in serum enzyme activities or BSP retention and equal in sensitivity to the ammonia tolerance test in detecting hepatobiliary insufficiency. Bile acid measurements were accomplished with less inconvenience to the patient and clinician, than tests of BSP excretion or ammonia tolerance. Used in combination with conventional laboratory tests for hepatic disease, pre- and postprandial serum bile acid concentrations appear to be a sensitive and specific indicator of hepatobiliary dysfunction of value in the diagnosis of PSVA in the dog and cat.     

Serum bile acid concentrations in clinically normal cattle: comparison by type, age, and stage of lactation.

Serum total bile acid concentrations were determined for various types and ages of cattle. There was extreme variability among all the cattle, but the variance was twice as large (0.50 vs 0.22 in logarithmic scale) for beef cattle than for dairy cattle. There was no significant difference in serum total bile acid concentrations between beef cattle and dairy cattle in midlactation. Values for calves < 6 weeks old and for 6-month-old heifers were significantly (P = < 0.05) lower than values for lactating dairy cows. The 5th to 95th percentile range of values (mumol/L) for beef cattle was 9 to 126; for lactating dairy cattle, 15 to 88; and for 6-month-old dairy heifers, 11 to 64.     

柑橘渣对奶牛泌乳性能、养分消化率及乳成分的影响

试验评估不同水平柑橘渣对奶牛泌乳性能、养分消化及乳成分的影响。将32头泌乳性能一致的奶牛随机分为4个组,每组4个重复,每个重复2头。对照组饲喂粗脂肪水平为3%的日粮,处理组分别饲喂粗脂肪水平为5.5%的日粮同时添加0(T1)、5%(T2)和10%(T3)柑橘渣。结果显示,与对照组相比,处理组奶牛的粗脂肪摄入量、干物质和粗脂肪表观消化率显著提高(P<0.05),T2和T3组奶牛粗蛋白表观消化率显著高于对照组和T1组(P<0.05)。与对照组相比,处理组乳中粗脂肪含量显著降低(P<0.05),总固形物含量显著降低(P<0.05),乳中粗脂肪产量显著降低(P<0.05)。对照组乳中C10∶0脂肪酸含量最高,而T3组乳中C8∶0脂肪酸和单不饱和脂肪酸浓度最高,饱和脂肪酸浓度表现最低。处理组乳中n-3/n-6脂肪酸显著高于对照组(P<0.05)。研究表明,在高脂肪(5.5%粗脂肪)日粮中添加5%或10%柑橘渣可以提高奶牛粗蛋白表观消化率,且对奶牛的泌乳量和乳品质无负面影响。     

Evaluation of total serum bile acid concentrations for the diagnosis of hepatobiliary disease in cattle.

Serum bile acid concentrations were measured in 41 clinically healthy cattle of different breeds. There was no diurnal variation in values and age and sex had no effect. There was no significant difference between serum and plasma bile acid concentrations in clinically healthy cattle. Serum bile acids were stable on storage at -20 degrees C. The total serum bile acid concentrations, together with other tests of hepatic disease, were evaluated in cattle with various types of hepatobiliary disease (hepatic lipidosis, hepatic abscessation, leptospirosis, biliary calculi, fascioliasis), respiratory, cardiovascular and infectious diseases, and in various other conditions not affecting the liver. Total serum bile acids were the most specific and sensitive indicators of a wide variety of hepatic diseases and were significantly correlated with the degree of clinical illness.     

Reduction of serum triacylglycerol-rich lipoprotein concentrations in cows with hepatic lipidosis

The hepatic and serum lipid concentrations in 49 dairy cows with displaced abomasum, 7 postpartum cows fasted for 6 days, and 14 healthy postpartum cows were studied. The cows with displaced abomasums were retrospectively allotted to 2 groups: those with greater than 15% liver fat (DAHF) and those with less than 15% liver fat (DALF). Liver total lipid concentrations were high in the DAHF group, exceeding these values in the fasted cows by 30% and in the healthy and DALF cows by 63% on the average. In contrast, the liver phospholipid concentrations were low in the DAHF group, intermediate in the fasted and DALF groups and high in the healthy group. On a group basis, an inverse relationship was observed between serum and liver lipid concentrations. The serum concentrations of both total and dextran-sulfate-precipitable (DSP) lipids were high in the fasted cows and were less in the DALF and healthy cows and in the DAHF cows (lowest). The between-group differences in serum total and serum DSP concentrations of triacylglycerol, cholesterol, and phospholipid followed the same quantitative pattern as the total lipids. However, the relative difference between groups was greater for each of the DSP lipid fractions. These results support the hypothesis that severe hepatic lipidosis in cattle occurs due to impaired hepatic lipoprotein synthesis and secretion.     

Total serum bile acid concentrations in dairy cows with fatty liver and liver failure

In forty-five Holstein Frisian dairy cows (1-6 weeks post partum; mean age: 5.1 +/- 1.2 years) the serum total bile acid concentrations (SBA) were measured enzymatically. In all cows a left sided abomasal displacement was corrected surgically by right side laparotomy and omentopexy three days before investigation. The liver fat content was determined in all cows histologically. Liver failure was assumed if typical clinical signs (ataxia, general depression, recumbency or coma), an increased venous plasma ammonia level (> 35 mumol/l) and a decreased plasma amino acid index (< 4.0) were found. Cows without liver failure (N = 29) were grouped according to the liver fat content as cows with mild (N = 5), moderate (N = 19) or severe hepatosteatosis (N = 5). Histological examination of liver biopsies in cows with liver failure (N = 16) revealed in twelve cases a severe fatty liver and in four cases a hydropic degeneration of the liver tissue. Although in cows without liver failure mean SBA concentrations were higher in the group with moderate (47.3 +/- 30.9 mumol/l) or severe fatty liver (32.9 +/- 21.7 mumol/l) than in that with mild lipidosis (18.0 (16.8 mumol/l), differences were not significant. The mean SBA concentration in cows with liver failure (70.5 +/- 49.5 mumol/l) was only significantly (p < 0.05) increased compared to cows with uncomplicated mild hepatic lipidosis. In conclusion, the determination of SBA concentrations is of little value in the recognition of fatty liver or even liver failure due to the considerable variance of SBA concentrations in dairy cows.     

Disturbed bovine mitochondrial lipid metabolism: a review

In mammals, excess energy is stored primarily as triglycerides, which are mobilized when energy demands arise and cannot be covered by feed intake. This review mainly focuses on the role of long chain fatty acids in disturbed energy metabolism of the bovine species. Long chain fatty acids regulate energy metabolism as ligands of peroxisome proliferator-activated receptors. Carnitine acts as a carrier of fatty acyl groups as long-chain acyl-CoA derivatives do not penetrate the mitochondrial inner membrane. There are two different types of disorders in lipid metabolism which can occur in cattle, namely the hypoglycaemic-hypoinsulinaemic and the hyperglycaemic-hyperinsulinaemic type with the latter not always associated with ketosis. There is general agreement that fatty acid β-oxidation capability is limited in the liver of (ketotic) cows. In accord, supplemental L-carnitine decreased liver lipid accumulation in periparturient Holstein cows. Of note, around parturition concurrent oxidation of fatty acids in skeletal muscle is highly activated. Also peroxisomal β-oxidation in liver of dairy cows may be part of the hepatic adaptations to a negative energy balance (NEB) to break down fatty acids. An elevated blood concentration of nonesterified fatty acids is one of the indicators of NEB in cattle among others like increased β-hydroxy butyrate concentration, and decreased concentrations of glucose, insulin, and insulin-like growth factor-I. Assuming that liver carnitine concentrations might limit hepatic fatty acid oxidation capacity in dairy cows, further study of the role of acyl-CoA dehydrogenases and/or riboflavin in bovine ketosis is warranted.     

Serum Amyloid A and Haptoglobin Concentrations and Liver Fat Percentage in Lactating Dairy Cows with Abomasal Displacement

Background: There has been increased interest in measuring the serum concentration of acute phase reactants such as serum amyloid A [SAA] and haptoglobin [haptoglobin] in periparturient cattle in order to provide a method for detecting the presence of inflammation or bacterial infection.
Objectives: To determine whether [SAA] and [haptoglobin] are increased in cows with displaced abomasum as compared with healthy dairy cows.
Animals: Fifty-four adult dairy cows in early lactation that had left displaced abomasum (LDA, n = 34), right displaced abomasum or abomasal volvulus (RDA/AV, n = 11), or were healthy on physical examination (control, n = 9).
Materials and Methods: Inflammatory diseases or bacterial infections such as mastitis, metritis, or pneumonia were not clinically apparent in any animal. Jugular venous blood was obtained from all cows and analyzed. Liver samples were obtained by biopsy in cattle with abomasal displacement.
Results: [SAA] and [haptoglobin] concentrations were increased in cows with LDA or RDA/AV as compared with healthy controls. Cows with displaced abomasum had mild to moderate hepatic lipidosis, based on liver fat percentages of 9.3 ± 5.3% (mean ± SD, LDA) and 10.8 ± 7.7% (RDA/AV). [SAA] and [haptoglobin] were most strongly associated with liver fat percentage, r _s=+0.55 ( P < .0001) and r _s=+0.42 ( P = .0041), respectively.
Conclusions and Clinical Importance: An increase in [SAA] or [haptoglobin] in postparturient dairy cows with LDA or RDA/AV is not specific for inflammation or bacterial infection. An increase in [SAA] or [haptoglobin] may indicate the presence of hepatic lipidosis in cattle with abomasal displacement.     

Decrease in stearic acid proportions in adipose tissues and liver lipids in fatty liver of dairy cows

Samples of liver and perirenal, mesenteric and subcutaneous fat were collected from 16 sick necropsied dairy cows to evaluate the fatty acid profiles in the hepatic and adipose tissues associated with advanced fatty liver or hepatic lipidosis. Hepatic triglyceride and eight fatty acids were measured in the hepatic and adipose tissues. Six cows had more than 3% triglyceride on fresh weight in their livers and were classified as having fatty liver. Stearic and linoleic acid proportions in the liver decreased markedly with increased hepatic triglyceride levels, while the proportion of palmitic and oleic acids increased. The most striking fluctuations in hepatic lipidosis were manifested as decreased stearic acid in the adipose tissues including subcutaneous fat with the trend of decreasing stearic acid. Palmitic acid was elevated in hepatic and perirenal fat in fatty liver cows. In instances of advanced hepatic lipidosis, palmitoleic acid increased in only subcutaneous fat and not in perirenal or mesenteric fat. In addition to the proportions of hepatic fatty acids in fatty liver, this study also clarified the fluctuations observed in the profiles of fatty acids of the adipose tissues in cows with advanced hepatic lipidosis, particularly the decline in the proportions of stearic acid.     

Bile acid concentrations in the diagnosis of hepatobiliary disease in the cat

The clinical usefulness of measuring serum bile acid concentrations as a diagnostic test for hepatobiliary disease was examined in 80 cats that were suspected of having hepatic disease. Serum values of total bilirubin, alkaline phosphatase (ALP), alanine transaminase (ALT), and aspartate transaminase (AST) also were measured. Fasting serum bile acid values were determined by use of solid-phase radioimmunoassay for total conjugated bile acids or by a direct enzymatic spectrophotometric method. A definitive diagnosis was established by histologic examination of the liver, and on the basis of these findings, cats were assigned to groups (1 to 8, respectively) including: extrahepatic bile duct obstruction, hepatic lipidosis, cirrhosis, intrahepatic cholestasis (cholangiohepatitis, cholangitis), neoplasia, hepatic necrosis, portosystemic vascular anomalies, and miscellaneous. Cats in group 8 had no morphologic evidence of hepatobiliary disease or had hepatic lesions that were mild. Test efficacy of fasting serum bile acids, total bilirubin, ALP, ALT, and AST were expressed by use of 4 indices: sensitivity, specificity, positive predictive value, and negative predictive value. The diagnostic efficacy of fasting serum bile acids was examined alone and in combinations with the other tests. There was wide overlapping of values of fasting serum bile acids, total bilirubin, ALP, ALT, and AST among cats in groups 1 to 7. The specificity of fasting serum bile acids for the diagnosis of hepatic disease exceeded 90% at values greater than or equal to 5 mumol/L and reached 100% at greater than or equal to 15 mumol/L.(ABSTRACT TRUNCATED AT 250 WORDS)     

Efficacy of sodium borate in the prevention of fatty liver in dairy cows

The effects of sodium borate (100 mg/kg body weight, p.o., 15 days) from a month before expected calving until a month after calving were evaluated in dairy cows susceptible to fatty liver. Cows received either sodium borate (n = 13) or no treatment (n = 10). All cows had mild fatty livers and increased plasma triglycerides and very low density lipoprotein (VLDL) concentrations at the beginning of the experiment. The control group of cows developed significant fatty liver after calving, and 2 of them had severe fatty liver associated with clinical and biochemical abnormalities. There were no clinicopathological signs related to sodium borate administration. Serum triglycerides and VLDL concentrations before calving decreased significantly at calving and after calving in controls, and they were within the normal range only after calving. There were significant alterations during the experiment in some hematological and chemical variables between groups, within period, but they were within the normal range. Unlike treated cows, serum triglycerides and VLDL concentrations correlated with liver fat content after calving in untreated cows. Our results document that sodium borate decreases the degree of fatty liver in dairy cows during early lactation.     

过瘤胃脂肪对泌乳早期奶牛血液生化指标的影响

选取高产荷斯坦牛24头,随机分为4组,每组各6头。Ⅰ组、Ⅱ组、Ⅲ组分别在基础日粮中每头每天添加200g、300g和400g过瘤胃脂肪;Ⅳ组为对照组,饲喂基础日粮。试验期20d。在饲喂前、饲喂后10d和20d检测试验奶牛血浆葡萄糖、β-羟丁酸、游离脂肪酸、尿素氮、总胆固醇和甘油三酯的水平,结果显示:与对照组比较,Ⅲ组血糖浓度显著升高(P0.05);血浆β-羟丁酸、游离脂肪酸、甘油三酯、总胆固醇、尿素氮变化均不显著(P0.05)。这些结果表明过瘤胃脂肪能提高血糖水平,从而改善奶牛的能量负平衡。     

Effect of sodium phytate supplementation on fat digestion and cholesterol metabolism in female rats

The effects of sodium phytate supplementation on fat digestion and cholesterol metabolism were investigated in female rats. On the basis of an in vitro experiment showing that phytate raised the solubility of bile acids, it was predicted that phytate feeding would depress faecal bile acid excretion, raise apparent fat digestibility and elevate serum cholesterol concentrations. The experimental diets with or without sodium phytate were either cholesterol-free or cholesterol-rich and had a normal calcium concentration. Rats fed on the cholesterol-rich diet with sodium phytate showed enhanced faecal bile acid excretion, but there was no effect on fat digestibility. In rats fed the cholesterol-free diets, phytate did neither affect fat digestion nor bile acid excretion. Sodium phytate inclusion in the cholesterol-rich diet raised serum cholesterol concentrations, but reduced liver cholesterol concentration. Thus, the in vivo data do not agree with the in vitro observations. Both phytate and cholesterol feeding influenced mineral and trace element metabolism. Liver zinc concentrations were raised by phytate feeding. Cholesterol consumption reduced hepatic concentrations of copper, iron and zinc. Both phytate and cholesterol feeding reduced the apparent absorption of calcium, magnesium and phosphorus.     

Metabolic profiles and bile acid extraction rate in the liver of cows with fasting-induced hepatic lipidosis

This study was designed to monitor lipid profile in the portal and hepatic blood of cows with fasting-induced hepatic lipidosis, and to compare the results with those in the jugular blood. The work was also carried out to investigate bile acid (BA) in these vessels, and further to investigate BA extraction rate in the liver. Five cows were equipped with catheters in the portal, hepatic and jugular veins (day 0), fasted for 4 days (day 1-day 4) and then refed (day 5-day 11). Before morning feeding, blood was sampled before, during and after fasting from the catheterized vessels. In the portal blood, the concentration of non-esterified fatty acids (NEFA) showed a progressive increase and at day 5 there was an approximate twofold rise. Increased NEFA concentrations were also found similarly in the other two veins. At day 5, beta-hydroxybutyrate (BHBA) in the portal, hepatic and jugular blood rose to 197, 190 and 186% of the pre-fasting value, respectively. However, the concentrations of NEFA and BHBA in the three veins gradually returned to pre-fasting concentration during the refeeding period. Compared with the pre-fasting value at day 0, the content of liver triglyceride (TG) increased significantly at day 5 (P < 0.01). In the liver, the hepatic extraction rate of BA dropped from 3.1 times pre-fasting to 2.2 times during fasting. There were no significant differences in the concentrations of glucose, TG, total cholesterol, cholesterol esters, free cholesterol and phospholipids. The results of the current study show that metabolic alterations occur in the portal, hepatic and jugular veins during induction of hepatic lipidosis in cows, and mostly metabolites, with exception of BA concentration, run parallel. The decreased BA extraction rate in the liver of fasted cows was considered to reflect hepatic cell impairment caused by TG accumulation. Hopefully, the findings, at least in part, contribute to the explanation of the pathophysiology of hepatic lipidosis in dairy cows.     

Changes in the serum levels of primary bile acids in dairy cows

Serum cholic acid (SCA) and serum chenodeoxycholic acid (SCDCA) concentrations were determined in healthy dairy cows by radioimmunoassay (RIA). The levels of these two primary bile acids were correlated with the cows' reproductive status. The lowest concentrations were measured in dry cows (SCA: 7.8 +/- 3.3 mumol/l, SCDCA.: 1.5 +/- 1.0 mumol/l). In freshly calved cows SCA and SCDCA was 17.8 +/- 6.9 mumol/l and 2.3 +/- 1.0 mumol/l, respectively, while in milking cows SCA and SCDCA was 15.8 +/- 5.7 and 2.3 +/- 0.8 mumol/l, respectively. SCA concentration showed a characteristic change on the days immediately after calving: on calving day it was close to the mean SCA concentration found for dry cows, then it underwent a striking abrupt rise and reached the value typical of post-parturient cows by post-partum (PP) day 4-5. Cholic acid was found to be the major primary bile acid in the blood of dairy cows. In dry cows the SCA:SCDCA ratio is 5:1. If the serum bile acid concentration rises, the SCA:SCDCA ratio will increase further.     

Hepatic Lipidosis in Anorectic, Lactating Holstein Cattle: A Retrospective Study of Serum Biochemical Abnormalities

The association between hepatic lipidosis (HL) and disease in 59 anorectic, ketotic, lactating Holstein heifers and cows was investigated. Severe HL, as determined by histologic evaluation of liver tissue, was present in 46 animals; only half of these animals required intensive treatment for ketosis, and only half had serum biochemical evidence of liver disease, as determined by the presence of a test value of 2-fold or greater than the upper limit of the reference range for at least 2 of the 4 serum tests: gamma-glutamyl transferase, aspartate aminotransferase, and sorbitol dehydrogenase activities and bile acid concentrations. Most cattle with biochemical evidence of liver disease and severe HL had been lactating for 14 or more days. Cows that required intensive treatment inconsistently had serum biochemical evidence of liver disease.
Although cattle with severe HL had significantly higher serum bilirubin concentrations and aspartate aminotransferase and sorbitol dehydrogenase activities than cattle with less severe lipidosis, the specificity of abnormally high serum sorbitol dehydrogenase activity or bilirubin concentration for severe lipidosis was only 8%. Abnormally high serum aspartate aminotransferase activity was 83% sensitive and 62% specific for severe lipidosis. Serum glucose and total carbon dioxide concentrations were significantly lower in cattle with severe lipidosis than in those with mild or moderate lipidosis, and low serum glucose or total carbon dioxide concentrations were rare in cattle without severe lipidosis. From these data, we conclude that the use of a single biochemical or histopathologic criterion to define severity of disease or degree of liver compromise in anorectic, ketotic cows results in the misidentification of many animals.