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.     

Serum Bile Acid Concentrations in Dairy Cattle With Hepatic Lipidosis

This study was designed to evaluate serum bile acid measurements as indicatory, of liver function and/or hepatic fat infiltration in dairy cattle. Serum bile acid concentrations were measured in healthy dairy cattle at different stages of lactation after fasting or feeding. Bile acid concentrations were compared with liver fat content and sulfobromophthalein (BSP) half-life (T 1/2). Serum bile acid concentrations were higher in cows in early lactation and with higher daily milk production. Compared with prefasting values, bile acid concentrations were decreased at 8,14, and 24 hours of fasting. Blood samples from fed cows at 1 - to 2-hour intervals had wide and inconsistent variations in bile acid concentration. Because serum bile acids correlated well with BSP T 1/2, it is suggested that both measurements evaluate a similar aspect of liver function. Neither bile acids nor BSP T I correlated with differences in liver fat content among cows. Because of large variability in serum bile acid concentrations in fed cows and the lack of correlation of measured values with liver fat content, bile acid determinations do not appear useful for showing changes in hepatic function in fed cows with subclinical hepatic lipidosis nor serve as a screening test for this condition.     

泌乳奶牛脂肪肝早期诊断的研究

为了寻找泌乳奶牛脂肪肝早期诊断方法,本研究从某千头奶牛场随机选取了30头乳酮阳性的奶牛,其中临床酮病牛10头,亚临床酮病牛20头,测定其肝脂含量以及血中代谢指标和肝功指标。试验结果表明,脂肪肝的奶牛存在能量负平衡现象,机体呈现高游离脂肪酸血症、高酮血症,肝脂浸润越重,能量代谢障碍越严重;乳酮阳性出现时间的早晚与脂肪肝的严重程度密切相关,乳酮阳性产后出现的越早,乳酮阳性越明显,肝脂浸润越重;随肝脂浸润程度的加重,肝功多个指标会出现异常,重度的脂肪肝会引发肝功能不全。本试验证明,酮粉法可以作为早期诊断奶牛脂肪肝的初选方法,肝功指标异常可作为诊断脂肪肝的辅助方法,两者结合可作为奶牛脂肪肝的实用、有效和准确的早期诊断方法,准确率可达80%。     

Hepatocyte apoptosis in dairy cows with fatty infiltration of the liver

The objective of the present study was to analyse the apoptotic process of liver cells in dairy cows with fatty infiltration of the liver using indicators of DNA damage and immunohistochemistry. For this purpose, sixteen dairy cows with fatty liver were examined. On clinical examination, the physical condition of the animals was fair in nine and poor in seven cows. The most dominant clinical signs were reduced ruminal motility, inappetance and/or anorexia and recumbency. Postmortem examination, in seven cases, revealed enlarged liver (18–33 kg), icteric carcasses and distended gallbladder. Laboratory results included neutrophilia, hypochloraemia, decreased concentrations of total bilirubin and increased concentrations of β-hydroxy butyric acid, non-esterified fatty acids and insulin. The activities of aspartate aminotransferase, γ-glutamyl transpeptidase, creatine kinase and lactate dehydrogenase were high. Histopathological examination of hepatic specimen showed lipid drops in cytosol with indistinct cellular membranes. In control hepatic cells, the DNA was tightly compressed and maintained the circular disposition of the normal nucleus. However, in the diseased cows, the damaged DNA migrated from the core toward the anode, forming a tail of a comet. Compared to controls, numerous ssDNA and caspase-3-positive cells were detected in the liver. To the authors’ knowledge, this is the first study to document accelerated apoptosis of hepatocytes in dairy cows with fatty infiltration of the liver.     

Hepatocyte apoptosis in dairy cows with fatty infiltration of the liver

The objective of the present study was to analyse the apoptotic process of liver cells in dairy cows with fatty infiltration of the liver using indicators of DNA damage and immunohistochemistry. For this purpose, sixteen dairy cows with fatty liver were examined. On clinical examination, the physical condition of the animals was fair in nine and poor in seven cows. The most dominant clinical signs were reduced ruminal motility, inappetance and/or anorexia and recumbency. Postmortem examination, in seven cases, revealed enlarged liver (18-33kg), icteric carcasses and distended gallbladder. Laboratory results included neutrophilia, hypochloraemia, decreased concentrations of total bilirubin and increased concentrations of β-hydroxy butyric acid, non-esterified fatty acids and insulin. The activities of aspartate aminotransferase, γ-glutamyl transpeptidase, creatine kinase and lactate dehydrogenase were high. Histopathological examination of hepatic specimen showed lipid drops in cytosol with indistinct cellular membranes. In control hepatic cells, the DNA was tightly compressed and maintained the circular disposition of the normal nucleus. However, in the diseased cows, the damaged DNA migrated from the core toward the anode, forming a tail of a comet. Compared to controls, numerous ssDNA and caspase-3-positive cells were detected in the liver. To the authors' knowledge, this is the first study to document accelerated apoptosis of hepatocytes in dairy cows with fatty infiltration of the liver.     

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.     

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.     

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.     

Comparison of cholesterol levels among lipoprotein fractions separated by anion-exchange high-performance liquid chromatography in periparturient Holstein–Friesian dairy cows

Changes in lipoprotein profiles occur in dairy cows during the periparturient period and in cows with transition cow disease. Here, the lipoprotein profiles of Holstein–Friesian dairy cows during the periparturient period were obtained by anion-exchange, high-performance liquid chromatography to evaluate the usefulness of lipoprotein profile evaluation during the periparturient period and in cows with fatty liver and milk fever. Lipoprotein levels (including total and high- (HDL-C) and low-density lipoprotein (LDL-C) cholesterol) in 10 healthy cows were low 4 weeks prepartum, with the lowest values at calving or within 1 week of calving; the values increased at 8 weeks postpartum. The lipoprotein levels were measured in 16 cows diagnosed with fatty liver (n=10) or milk fever (n=6) and compared to 10 healthy dairy cows. A significant difference was observed in HDL-C between healthy cows (at calving and 1 week postpartum), and the fatty liver and milk fever cows. Cows with fatty liver and milk fever had a lower mean HDL-C than the 10 healthy dairy cows at calving and 1 week postpartum. HDL-C might be a good indicator of energy balance for differentiating healthy cows from those with transition cow disease.     

Inositol as a lipotropic agent in dairy cattle diets

Fatty liver syndrome or hepatic lipidosis (HL) is a condition thought to contribute to an increased incidence of peripartum disease, reduced response to therapy and decreased fertility in dairy cows. This syndrome is characterized by excess triglyceride (TG) accumulation in the liver and apparent decreased hepatic lipoprotein output. In lactating rats, a similar condition results from feeding an inositol-deficient diet. It is also characterized by excess hepatic TG accumulation and decreased hepatic lipoprotein output. Myo-inositol is a necessary component of the phospholipid phosphatidyl-inositol, which is an important membrane constituent. Myo-inositol occurs in feed mainly as the inositol hexaphosphate phytic acid. Phytic acid is undigestible by the monogastric but rumen phytases are assumed to adequately hydrolyze it. In early lactation dairy cows, lipid mobilization is intense, and the myo-inositol requirement may exceed the dietary supply or availability. Myo-inositol is being tested in a field trial as a potential lipotropic agent for dairy cows. Preliminary results suggest no lipotropic benefit from added myo-inositol.     

过瘤胃烟酸和胆碱对围产期奶牛泌乳性能和肝脂质代谢的影响

旨在研究日粮中添加过瘤胃保护烟酸(rumen-protected niacin,RPN)和过瘤胃保护胆碱(rumen-protected choline,RPC)对围产期奶牛泌乳性能和肝脂质代谢的影响,为缓解奶牛脂肪肝提供理论依据.本试验选用24头健康、胎次相近的中国荷斯坦围产期奶牛,根据2×2试验设计分为4组,每组6...     

Relationship among blood indicators of lipomobilization and hepatic function during early lactation in high-yielding dairy cows

Blood indicators are used as a tool to diagnose metabolic disorders. The present work was conducted to study the relationships among blood indicators of lipomobilization and hepatic function in high-yielding dairy cows. Two groups of Holstein cows were studied: 27 early lactation cows and 14 mid lactation cows from four different herds with similar husbandry characteristics in Galicia, Spain. Blood samples were obtained to measure beta-hydroxybutyrate (BHB), non-esterified fatty acids (NEFA), triglycerides (TG), and the activity of aspartate transaminase (AST) and gamma-glutamyl transferase. Cows in early lactation had higher levels of BHB and NEFA than mid lactation cows. High lipomobilization (NEFA > 400 µmol/L) was detected in 67% and 7% of early lactation and mid lactation cows, respectively, while subclinical ketosis (BHB > 1.2 mmol/L) was detected in 41% and 28% of the early lactation and lactation cows, respectively. TG concentrations were low in all cows suffering subclinical ketosis and in 61% of the cows with high lipomobilization. During early lactation, 30% of cows suffered hepatic lipidosis as detected by levels of AST. Compromised hepatic function was observed in early lactation cows as shown by lower concentrations of glucose, total protein, and urea.     

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。     

Molecular insights into the mechanisms of liver‐associated diseases in early‐lactating dairy cows: hypothetical role of endoplasmic reticulum stress

The transition period represents the most critical period in the productive life of high‐yielding dairy cows due to both metabolic and inflammatory stimuli, which challenge the liver and predispose dairy cows to develop liver‐associated diseases such as fatty liver and ketosis. Despite the fact that all high‐yielding dairy cows are affected by marked metabolic stress due to a severe negative energy balance (NEB) during early lactation, not all cows develop liver‐associated diseases. Although the reason for this is largely unknown, this indicates that the capacity of the liver to cope with metabolic and inflammatory challenges varies between individual high‐yielding dairy cows. Convincing evidence exists that endoplasmic reticulum (ER) stress plays a key role in the development of fatty liver, and it has been recently shown that ER stress occurs in the liver of high‐yielding dairy cows. This indicates that ER stress may be involved in the development of liver‐associated diseases in dairy cows. The present review shows that the liver of dairy cows during early lactation is exposed to several metabolic and inflammatory challenges, such as non‐esterified fatty acids, tumour necrosis factor α, interleukin‐1β, reactive oxygen species and lipopolysaccharides, which are known inducers of ER stress. Thus, ER stress may represent a molecular basis for fatty liver development and account for the frequent occurrence of fatty liver and ketosis in high‐yielding dairy cows. Interindividual differences between dairy cows in the activation of hepatic stress response pathways, such as nuclear factor E2‐related factor 2, which is activated during ER stress and reduces the sensitivity of tissues to oxidative and inflammatory damage, might provide an explanation at the molecular level for differences in the capacity to cope with pathological inflammatory challenges during early lactation and the susceptibility to develop liver‐associated diseases between early‐lactating dairy cows with similar NEB and milk yield.     

Effects of Pueraria on Biochemical Indexes of Fatty Liver Hepatocytes in Dairy Cows

To explore the acting mechanism of Pueraria extract on fatty liver hepatocytes in dairy cows. The hepatocytes in dairy cows were isolated by two-step collagenase perfusion method and observed. The hepatocytes cultured in vitro were treated with different concentrations of Pueraria extract. The activities and contents of ALT, AST, TG, SOD and MDA in the hepatocytes were detected by biochemical methods. Results showed that in the administration of Pueraria extract with the concentrations of 50,100 and 500 μg/mL could extremely significantly reduce the liver cells of ALT, AST, TG, TC, MDA activity and content, increase SOD activity (P < 0.01). The Pueraria extract had significantly therapeutic effect on dairy cows fatty liver of biochemical indexes. The mechanism might be related to regulate lipid metabolism and anti lipid peroxidation.     

葛根对奶牛脂肪肝细胞生化指标的影响

为探讨葛根对奶牛脂肪肝细胞的作用机制,采用胶原酶二步灌流法分离病牛的肝细胞,并观察细胞形态。用不同浓度的葛根水提物处理肝细胞,生化法检测细胞上清液中丙氨酸氨基转移酶（ALT）、天门冬氨酸氨基转移酶（AST）活性,并测定细胞裂解液中甘油三酯（TG）、胆固醇（TC）、丙二醛（MDA）、超氧化物歧化酶（SOD）的活性及含量。结果显示,50、100、500 μg/mL葛根水提物能极显著降低肝细胞中ALT、AST、TG、TC、MDA活性及含量,增加SOD活性（P < 0.01）。葛根水提物能显著改善肝细胞的相关生化指标,其机制可能与调节脂质代谢、抗脂质过氧化作用相关。     

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.     

Influence of feed mixtures supplemented with animal fat on milk yield and milk composition]

Animal fat was administered in fat-supplemented mixtures of concentrates in amounts varying from 0%, 5%, to 10%. The trials were carried out on 12 dairy cows. The best results were obtained with mixed concentrates containing 5% of animal fat. Animals on these food rations produced 6.75% more milk (expressed in units of fat-corrected milk (FCM) and 9.87% more milk fat. Additions of animal fat affected the composition of milk fat in such a way that the milk contained smaller portions of short-chain fatty acids and higher proportions of stearic and oleic acid.     

Cholic acid levels in the serum of dairy cows with metabolically-caused liver diseases

Three groups of freshly calved dairy cows suffering from fatty liver syndrome of different stages were examined for serum cholic acid (SCA) levels to assess the value of SCA-determination as a diagnostic approach to fatty liver syndrome. A. Comparison of the SCS levels between cows with and without ketonuria: Cows with ketonuria (n = 13) and with elevated plasma ASAT activity, indicating a moderate liver damage, showed a rise of their mean SCA level to 35.3 (+/- 14.9) mumol/l. Freshly calved cows without ketonuria (n = 10) had at the same time a mean SCA level of 17.9 (+/- 6.4) mumol/l, falling practically into the physiological range. The SCA level increased above the physiological range in 10 of the 13 cases with ketonuria, in seven of them even more than twice. B. Interrelationship between SCA level and hepatic lipid content: Increase in hepatic total lipid (TL) was always associated with SCA-elevation. The mean SCA level was 55 (+/- 22.0) mumol/l in cases of severe fatty liver (TL = 200-280 g/kg), and 39.5 (+/- 6.0) mumol/l in the moderate form (TL = 180-200 g/kg) of the syndrome. C. Peripartal SCA levels of cows with fatty liver: Clinically healthy cows (n = 6) with ketonuria and an elevation of serum ASAT and FFA concentrations had a mean SCA level of 35-45 mumol/l. One cow of this group, which developed acute fatty liver syndrome and died within the period of study, showed an extreme SCA level of 100 mumol/l in it's terminal stage.(ABSTRACT TRUNCATED AT 250 WORDS)