Comparison of blood glucose concentrations after administration of a glucose solution via the jugular vein and portal vein in cows

The goals of the present study were to determine whether the infusion of a glucose solution into the portal vein is tolerated in cows and whether the glucose concentration differs after administration of glucose into the jugular vein and portal vein. Fifteen healthy Swiss Braunvieh cows were used. An indwelling catheter was placed in both jugular veins and a balloon-tipped indwelling catheter with a diameter of 2 mm was placed in the portal vein under the guidance of ultrasonography. Three cows received 500 ml of 20% glucose solution over 60 min via the left jugular vein. Three other cows received the same solution over 60 min via the portal vein. Blood samples were collected from the right jugular vein before and for 24 h after the infusion of glucose for the determination of the concentrations of glucose and bilirubin and the activities of glutamate dehydrogenase, sorbitol dehydrogenase and gamma-glutamyl transferase. Infusion via the portal vein did not result in abnormalities in the general condition of the cows or increases in the concentration of bilirubin or the activities of liver enzymes. The blood glucose concentration increased to the same extent after both intraportal and intrajugular infusion. Over a 12-h period, three cows received 10 l of 20% glucose solution via the left jugular vein and three others received the same solution over a 12-h period via the portal vein. Blood samples were collected from the right jugular vein before and for 30 h after the start of infusion. Infusion via the portal vein did not affect the general condition of the cows or the activities of the liver enzymes. There was no significant difference in the blood glucose concentration between the two groups throughout the study.     

The influence of a fermentation-resistant glucose diet on the glucose concentration and other metabolites in portal and jugular blood in cows

The goal of this study was to determine the effect of fermentation-resistant glucose on the glucose concentration and other metabolites in portal and jugular blood in 15 non-lactating cows. In all cows, an indwelling catheter was placed in the left jugular vein and the portal vein for collection of blood samples. Five control cows were fed hay as a normal diet, five control cows were fed straw to induce an energy deficit and five cows were fed hay and they received additionally 2000 g of a fermentation-resistant D-glucose product. The glucose concentration in jugular and portal blood was not influenced by feeding. The concentration of urea and bile acids were significantly higher in portal blood than jugular blood. There was no difference between portal and jugular blood of glucose and total solids. Diet had a significant effect on the concentrations of ammonia, urea, free fatty acids and triglycerides. The concentrations of ammonia and urea were higher in blood of cows fed straw than in blood of cows fed either hay or a fermentation-resistant glucose product. The concentration of urea remained constant in cows fed hay, but increased in cows fed straw and decreased in cows fed a fermentation-resistant glucose product. The concentration of free fatty acids and triglycerides were significantly higher in cows fed a fermentation-resistant glucose product than in cows fed hay. In the present study, a single administration of 300 g of fermentation-resistant glucose did not affect the concentration of blood glucose. Therefore, despite ongoing promotion of such products, there is no indication at this time that administration of fermentation-resistant glucose to cows at the start of lactation results in an increase in blood glucose concentration.     

Ultrasound-guided catheterization of the portal vein in 11 cows using the Seldinger technique

Catheterization of the portal vein using the Seldinger technique [Acta Radiol. (1958) 38, 368] was performed in 11 cows. Ultrasound-guided percutaneous portocentesis, using a 25-cm, 14-gauge steel cannula, was performed from the 10th, 11th or 12th intercostal space on the right side. A stylet was placed through the cannula, which was then removed, and a polyurethane balloon-tipped catheter was advanced over the stylet into the portal vein and sutured to the skin (Seldinger, 1952). Blood samples were collected from the catheter at least once daily. The catheter was removed 9-15 days later when blood could no longer be aspirated. The cows were then slaughtered and a post-mortem examination was performed. During the study, appetite remained normal in nine of 11 cows. In three cows, the general behaviour and demeanour were mildly, but transiently, abnormal. Four cows had leucopoenia. The most frequently encountered problem was occlusion of the catheter, which usually was resolved by flushing with heparinized saline. The most common post-mortem lesion observed was an increase in fibrous connective tissue at the site of cannulation. In nine of 11cows, there was a thrombus in the portal vein at the site of catheterization. Generally, the severity of the lesions was mild. The results of this study demonstrated that ultrasound-guided percutaneous catheterization of the portal vein, using the Seldinger technique, is possible in cows. The catheter may be left in place for collection of blood samples for up to 15 days.     

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.     

Clinicopathological findings and echocardiographic prediction of the localisation of bovine endocarditis

Thirty-six cows with confirmed vegetative endocarditis at postmortem examination were examined in this study. In 33 cows, echocardiography showed lesions of the pulmonic, tricuspid and mitral valves. Ten healthy cows were enrolled in the study as controls. In diseased cows, clinical signs included recurrent fever, dyspnoea, epistaxis, tachycardia, murmurs, weight loss, decreased milk production, jugular and mammary vein distension with palpable pulse, and ventral and submandibular oedema. Laboratory abnormalities included neutrophilic leukocytosis, elevated protein concentrations, hypoalbuminaemia, hypergammaglobulinaemia, azotaemia and elevated serum creatinine concentration. High serum activities of aspartate aminotransferase, γ-glutamyl transpeptidase and lactate dehydrogenase were also detected. Echocardiography showed small, medium-sized or large hyperechogenicity, thickening, and proliferative or vegetative lesions of the tricuspid (n=11), mitral (n=5) and pulmonic valves (n=19). Confirmatory diagnosis was made at postmortem examination. Echocardiography could detect vegetations in 33 of the 36 cows (92 per cent). The sensitivity of ultrasound in detecting valvular endocarditis was 89 per cent for tricuspid valves, 83 per cent for mitral valves and 95 per cent for pulmonic valves.     

颈静脉灌注精氨酸对奶牛血液生化指标及必需氨基酸含量的影响

试验旨在研究颈静脉灌注精氨酸(Arg)对奶牛血常规指标、血清生化指标及必需氨基酸含量的影响。选用6头体重、胎次、泌乳期、泌乳量和体况等基本一致的荷斯坦奶牛,采用3×3复拉丁方设计,随机分为3组,即对照组(灌注酪蛋白模式的氨基酸混合物)、Arg灌注组(灌注37.66 g/d)和等氮丙氨酸组(灌注77.24 g/d),进行7 d灌注期+15 d间隔期的颈静脉灌注试验。结果表明:与对照组和等氮丙氨酸组相比,Arg灌注组可降低白细胞计数(P<0.01),而对其他血常规指标无显著影响;等氮丙氨酸组高密度脂蛋白水平高于对照组(P<0.05);低密度脂蛋白以Arg灌注组最高,但3组间差异不显著;与对照组和等氮丙氨酸组相比,Arg灌注组血浆中Arg含量提高(P<0.05),但其他8种必需氨基酸和总必需氨基酸含量未见显著差异。由此可见,颈静脉灌注Arg对泌乳奶牛脂质代谢有一定的调控作用,对血常规指标和必需氨基酸含量的影响不大。     

Comparison of a new device for blood sampling in cats with a vacuum tube collection system - plasma biochemistry, haematology and practical usage assessment

Using paediatric devices to collect venous blood from a cephalic vein in cats offers numerous practical advantages over traditional jugular venepuncture and vacuum closed systems: minimal restraint is required; there is minimal risk of serious injury to the cat; the discomfort associated with venepuncture is reduced by the use of small diameter (25 gauge) needles; very small volumes (200 microl) of blood are extracted; and the risk of vein collapse or haematoma is low. The aim of this study was to compare the haematological and plasma chemistry results obtained from six healthy cats using the two sampling techniques. Five plasma biochemical analytes were measured and a complete haematological examination was performed on each specimen. No clinically relevant difference between the two blood sampling techniques was observed for any variable, indicating that paediatric devices provide a useful alternative to vacuum tubes for venous blood collection in the cat.     

Duplex ultrasonography of the common carotid artery and external jugular vein of cows

OBJECTIVE: To determine blood flow patterns in the common carotid artery and external jugular vein in cows before and after sedation achieved by administration of xylazine hydrochloride. ANIMALS: 30 clinically normal Swiss Braunvieh cows. PROCEDURE: A 5.0-MHz sector transducer was used to examine the common carotid artery and external jugular vein before and after cows were sedated by administration of xylazine. Several variables were calculated, including diameter of the blood vessels, blood flow velocity, and flow-time volume. RESULTS: The common carotid artery before sedation had a maximum systolic velocity of 89 +/- 8.5 cm/s, maximum diastolic velocity of 36 +/- 6.0 cm/s, mean velocity of 35 +/- 5.4 cm/s, and flow-time volume of 28.2 +/- 3.48 cm3/s. In all cows, sedation achieved by administration of xylazine resulted in a significant decrease in velocity of arterial blood flow and flow-time volume. The external jugular vein before sedation had a maximum velocity of 65 +/- 8.3 cm/s, maximum velocity of retrograde venous blood flow of 20 +/- 6.6 cm/s, and flow-time volume of 29.7 +/- 5.42 cm3/s. These values decreased significantly after cows were sedated by administration of xylazine. CONCLUSIONS AND CLINICAL RELEVANCE: Doppler ultrasonography is particularly suitable for evaluation of blood flow patterns in the common carotid artery and external jugular vein of healthy cows. The results reported here provide a basis for use in examination of cows with cardiac and blood vessel disease.     

Blood flow parameters associated with udder oedema in Jersey cattle affected with rectovaginal constriction

Udder oedema was studied in eight Jersey cows with rectovaginal constriction (RVC) and three normal Jersey cows. A complete physical examination was performed at least two weeks before parturition, at parturition and two weeks after parturition. Jersey cows with RVC developed udder oedema as early as 14 days before parturition, and condition persisted for three to 10 days following parturition. Mammary blood flow and cranial superficial epigastric venous blood pressure were measured in three Jersey cows with RVC with udder oedema and three normal Jersey cows. The former with udder oedema had a significant decrease in mammary blood flow at parturition compared to the normal Jersey cows (P less than 0.05); there was no significant difference in mammary blood flow between Jersey cows with RVC and normal Jersey cows two weeks before parturition (P greater than 0.05). A significant mean increase in cranial superficial epigastric venous blood pressure occurred at parturition when compared to two weeks before parturition in Jersey cows with RVC (P less than 0.05), but normal Jersey cows had no significant increase in cranial superficial epigastric vein pressure during these two periods of measurement (P greater than 0.05). There was no significant increase in jugular vein blood pressure during the two periods of measurement in Jersey cows with RVC or normal Jersey cows (P greater than 0.05). There was a significant negative correlation between mammary blood flow and cranial superficial epigastric pressure at parturition (r = 0.733, P less than 0.05).     

Ultrasonographic findings in three cows with chronic ragwort (Senecio alpinus) poisoning

Three cows with regwort (Senecio alpinus) poisoning were examined clinically, haematologically and ultrasonographically, and biopsy specimens of the liver were examined histologically. At the end of the study, the cows were euthanased and examined postmortem. The major clinical signs included severely disturbed general demeanour and behaviour, and severe diarrhoea. One cow was photosensitive. The activities of liver enzymes and the concentration of bilirubin were high in all of the cows. In two of the cows, ultrasonographic examination revealed a heavy accumulation of abdominal fluid, which was diagnosed as non-inflammatory ascites. In all the cows, the liver parenchyma was heterogeneous, and cows 1 and 2 had multiple echogenic foci 5 to 10 mm in diameter. In cow 3, the facies diaphragmatica of the liver appeared irregular in outline owing to the presence of nodules which were approximately 5 cm in diameter. The liver was also greatly enlarged and extended almost to the linea alba ventrally and beyond the reticulum cranially. All the cows had portal hypertension and the portal vein was dilated, resulting in oedema of the walls of the gall bladder, the small intestines and the omentum. The diameter of the caudal vena cava was reduced as a result of the impaired hepatic circulation. Histological examination of liver biopsy specimens revealed severe hepatic fibrosis in all the cows.     

Echo-guided studies on portal and hepatic blood in cattle

The objectives of the present study were (1) to establish and maintain catheters non-surgically in the portal and hepatic veins of cattle for long-term monitoring of postprandially absorbed metabolites, and (2) to assess the safety of the technique used. Aspiration and catheterization were not performed if there was risk of bleeding, as determined by hemostatic data and enlargement of portal and hepatic veins. In five Holstein cattle, before and 60-min after feeding, percutaneous ultrasound-guided aspiration of portal and hepatic blood, together with jugular blood, was performed utilizing 17G x 17.5 cm needles. Concentration of ammonia nitrogen tended to be higher after feeding, but that of urea nitrogen and glucose were not significantly changed. In five other Holstein cows liver veins were catheterized with 14 x 16.5 cm guide-needles attached with 50 cm polyethylene tubes and blood samples were collected from portal, hepatic and jugular veins at 30-min intervals for 4.5 hr. The concentration of plasma acetate and 3-hydroxybutyrate (3-HB) were significantly increased after feeding, while that of lactate was not changed. Catheters in the portal and hepatic veins enabled the collection of blood samples up to 15 days (mean, 7 days). After a 7-day observation period, five cows were euthanised and necropsied. Changes in the intercostal musculature, peritoneum and liver were negligible. During the observation period, clinical profiles, aspartate aminotransferase, alanine aminotransferase and total and differential WBC counts were within normal ranges.     

Blood gas and acid-base analysis of arterial blood in 57 newborn calves

The pH, partial pressure of oxygen (pO(2)), partial pressure of carbon dioxide (pCO(2)), concentration of bicarbonate (HCO(3)(-)), base excess and oxygen saturation (SO(2)) were measured in venous and arterial blood from 57 newborn calves from 55 dams. Blood samples were collected immediately after birth and 30 minutes, four, 12 and 24 hours later from a jugular vein and a caudal auricular artery. The mean (sd) pO(2) and SO(2) of arterial blood increased from 45.31 (16.02) mmHg and 64.16 (20.82) per cent at birth to a maximum of 71.89 (8.32) mmHg and 92.81 (2.32) per cent 12 hours after birth, respectively. During the same period, the arterial pCO(2) decreased from 57.31 (4.98) mmHg to 43.74 (4.75) mmHg. The correlation coefficients for arterial and venous blood were r=0.86 for pH, r=0.85 for base excess and r=0.76 for HCO(3)(-). The calves with a venous blood pH of less than 7.2 immediately after birth had significantly lower base excess and HCO(3)(-) concentrations for 30 minutes after birth than the calves with a venous blood pH of 7.2 or higher. In contrast, the arterial pO(2) was higher in the calves with a blood pH of less than 7.2 than in those with a higher pH for 30 minutes after birth.     

Portal Infusion of Low Dosage Endotoxin: A Model Simulating Translocation of Ruminai Endotoxin in Cattle

Translocation of bacteria and endotoxin from the gastro-intestinal tract to the portal blood is described to occur in healthy humans and animals, and is probably facilitated by ruminai epithelium damage in cattle (Berg 1992). Controversy exists regarding the possible role of endotoxin in the pathogenesis of ruminai acidosis. Systemic disease during ruminai acidosis is clinically characterized by forestomach stasis, anorexia, depression, tachycardia, tachypnea and fever. It has been shown that blood concentrations of arachidonic acid metabolites increase during ruminai acidosis, which may explain many of these clinical signs (Andersen et al. 1994). At the same time, we found that only few cows with experimentally induced rumen acidosis had endotoxin in the systemic blood (Andersen et al. 1990, 1994), while other authors describe systemic endo-toxaemia as an occasional finding in similar or milder cases of grain-engorgement (Boosman et al. 1990, Aiumlamai et al. 1992). Arachidonic acid metabolites are readily produced in the presence of endotoxin, but might also be expected to be produced during a chemical inflammation process of ruminai epithelium, damaged by a low pH and high osmolar concentration. The purpose of the present study was to evaluate the role of low grade portal endotoxaemia for pre-hepatic release of inflammatory mediators 6-ketoprostaglandin F_1a (6-keto-PGF) and thromboxane B₂ (TXB) and the relation to systemic disease. Four healthy cows were surgically equipped with chronic catheters in the portal vein, in a mesenteric vein 20 cm distally to portae hepa-tis and in a hepatic vein. After recovery, the cows received at maximum 3 different treatments at monthly intervals in a randomized design. Treatments were saline solution infused into the mesenteric vein at 2.5 üL/kg body weight per min (control), Escherichia coli endotoxin (055:B5 Westphals extraction, Sigma) at 0.025, 0.25 and 2.5 ng/kg body weight per min (Model I, Model II and Model III, respectively, Table 1). Infusions were continued for 180 min, or until respiratory distress (respiration rate > 40 per min) occurred. One h before a session, a jugular catheter was inserted, and blood samples were collected from the portal, hepatic and jugular vein for determination of clinical-chemical parameters (acid-base balance, packed cell volume (PCV), leukocyte and thrombocyte counts), endotoxin, TXB and 6-keto-PGF. Methods are described elsewhere (Andersen et al. 1994). After initiation of the experimental infusion, sampling was continued for 330 min at intervals of 30 min. Clinical parameters (rectal temperature, pulse and respiratory rates and ruminai movements) were determined hourly.     

Effects of estrone infusion on secretion of F series prostaglandins and on function of the corpus luteum during late gestation in cattle

Catheters were surgically implanted in the carotid artery, jugular vein, and middle uterine vein of 8 cows at 245 days of gestation. Four cows were given 4 mg of estrone/hour via continuous jugular infusion from 0800 hours on day 246 of gestation through 0800 hours on day 250 of gestation; the remaining 4 cows (controls) were given the vehicle for estrone at 10 ml/hour for the same period. Blood samples were collected from the carotid artery every 3 hours during the infusion. Samples were collected hourly from the middle uterine vein from 0 through 8, 54 through 66, and 112 through 120 hours of the infusion periods. After completion of the infusion, corpora lutea were enucleated and blood samples were collected from the carotid artery and uterine vein at hourly intervals for an additional 8 hours. Dispersed cell preparations of the corpora lutea were incubated with and without luteinizing hormone (LH) or dibutyryl cyclic adenosine monophosphate (dbcAMP). Circulating concentrations of unconjugated and conjugated estrone and estradiol-17 beta were higher (P less than 0.05) in the group infused with estrone than in the vehicle-infused group. Mean and base-line concentrations of F series prostaglandins (PGF) for each blood collection period tended to increase (P less than 0.10) during infusion with estrone, but not during infusion with vehicle. After luteectomy, mean and base-line concentrations of PGF also tended (P less than 0.10) to be greater in the estrone-infused cows than in the control cows, but a surge in PGF concentrations due to removal of the ovarian source of progesterone did not develop.(ABSTRACT TRUNCATED AT 250 WORDS)     

Udder edema in cattle: effect of furosemide, hydrochlorothiazide, acetazolamide, or 50% dextrose on venous blood pressure

Before injection of diuretic drugs, blood pressures were determined in the cranial superficial epigastric veins (milk vein) and jugular veins of 15 Holstein cows with udder edema at parturition and of 15 healthy (control) cows at parturition. Cows with udder edema had a significant (P less than or equal to 0.05) mean increase in cranial superficial epigastric venous pressure at parturition, compared with that of control cows. After IV administration of 500 mg of furosemide in cows with udder edema, the mean cranial superficial epigastric venous blood pressure significantly (P less than or equal to 0.05) decreased within 5 minutes, remained at the decreased pressure for 90 minutes, and then returned to near pretreatment pressures by 210 minutes after furosemide injection; however, furosemide did not significantly affect the jugular venous blood pressure of these cows. Furosemide injection did not significantly affect the cranial superficial epigastric or jugular venous blood pressure in the control cows. After IV administration of hydrochlorothiazide (250 mg), acetazolamide (500 mg), or 50% dextrose (500 g), the cranial superficial epigastric and jugular venous blood pressures in cows with udder edema at parturition were not significantly different from those in cows without udder edema at parturition during the 210-minute evaluation period after injection of the drugs.     

Venous blood pressure relative to the development of bovine udder edema

Cranial superficial epigastric (milk vein) and jugular venous blood pressure were measured in 8 cows with udder edema and in 3 normal control cows at least 2 weeks before parturition, at parturition, and 2 weeks after parturition. Cows with udder edema had a significant mean increase (P less than or equal to 0.05) in cranial superficial epigastric venous pressure at parturition when compared with pressures 2 weeks prepartum and 2 weeks postpartum. Unaffected control cows had an insignificant increase in cranial superficial epigastric venous pressure during these 3 periods of measurement. There was an insignificant increase in jugular venous blood pressure during the 3 periods of measurement in affected and control cows. A correlation was observed between mammary blood flow and cranial superficial epigastric blood pressure at parturition (r = -0.659, P less than or equal to 0.05).     

Prevalence of endotoxemia in healthy postparturient dairy cows and cows with abomasal volvulus or left displaced abomasum

Left displaced abomasum (LDA) and abomasal volvulus (AV) occur most commonly in postparturient dairy cows. Our main hypothesis was that endotoxemia occurred more frequently in the peripheral blood of cows with LDA or AV than in healthy cows because increased luminal pressure in AV or LDA, or the presence of a hemorrhagic strangulating obstruction in AV, may have injured the abomasal mucosa, thereby facilitating translocation of luminal endotoxin into the circulation. Therefore, our main objective was to compare the prevalence and magnitude of endotoxemia in healthy postparturient cows with the prevalence and magnitude of endotoxemia in cows with AV and LDA. We examined 60 adult dairy cows in early lactation that were diagnosed with AV (n = 15) or LDA (n = 15) or were healthy on physical examination (control group, n = 30). Jugular venous blood was obtained from cows in all 3 groups, and right gastroepiploic venous blood was obtained during surgical correction of AV and LDA immediately after repositioning of the abomasum. Platelet-rich plasma endotoxin concentrations were measured with a chromogenic limulus amoebocyte lysate assay. Endotoxin was detected in jugular vein plasma in 50% (15/30) of control cows; however, the prevalence of endotoxemia was significantly lower (P < .05) in cows with AV (7%, 1/15) or LDA (20%, 3/15). Endotoxin was detected simultaneously in right gastroepiploic and jugular vein plasma in only 1 cow with LDA and 0 cows with AV. Contrary to our hypothesis, we conclude that endotoxemia is infrequently present in postparturient dairy cows with AV or LDA.     

Sources of variation introduced into a phagocytosis assay as a result of the isolation of neutrophils from bovine blood

A study was conducted to examine sources of variation introduced into a phagocytosis assay as a result of the isolation of neutrophils from bovine blood, including variation attributable to isolation of neutrophils from blood, variation between duplicate determinations of percentage phagocytosis, and the variation in the ability of neutrophils isolated from blood (over repeated collections from the jugular vein) to phagocytose. For the phagocytosis assay, jugular venous blood from each of 4 cows was divided into 2 equal portions. The neutrophils were isolated by lysis of red blood cells with 0.2% sodium chloride. The neutrophils (2 x 10(7)) were incubated in duplicate with 32P-labeled Staphylococcus aureus ([32P]SA; 2 x 10(8)) in skimmed milk samples (2.5% final concentration) prepared from 4 cows. This process was repeated thrice on neutrophils isolated from 4 cows at 2-week intervals. The proportions of variation in percentage of 32P-labeled S aureus phagocytosed between duplicate neutrophil isolations and between duplicate assay determinations were 0 and 1%. Differences among skimmed milk sources and among runs, using blood neutrophils taken at different times from the same donor cow, accounted for 62 and 36% of the total variation. The results indicated that variation arising from blood neutrophil isolation introduced into a phagocytosis assay within a single-day trial is of no concern. The large variation among skimmed milk sample sources indicated differences among cows in the ability of their milk to support phagocytosis. The variation in neutrophil isolations over time for any cow was considered too large to allow for evaluation of physiologic and environmental effects on phagocytosis of neutrophils isolated from blood.     

Changes in Plasma Progesterone Levels in the Caudal Vena Cava and the Jugular Vein and Luteinizing Hormone Secretion Pattern After Feeding in Lactating and Non-lactating Dairy Cows

The present study was designed to assess progesterone profiles at the secreted (caudal vena cava) and circulating levels (jugular vein) and luteinizing hormone (LH) secretion pattern in lactating and non-lactating cows with reference to feeding. Four lactating and four non-lactating cycling Holstein cows were examined. Blood samples were collected simultaneously from the caudal vena cava (via a catheter inserted from the coccygeal vein) and the jugular vein every 15 min for 12 h (0500–1700 h) during the functional luteal phase. Cows were fed 50% of the daily diet 6 h after the start of blood sampling. During the 12-h sampling period, mean progesterone concentrations in the caudal vena cava did not differ between lactating and non-lactating cows (49.0 ± 2.9 and 53.3 ± 3.7 ng/ml; mean ± SE), whereas mean progesterone concentrations in the jugular vein in lactating cows were higher than those in non-lactating cows (6.4 ± 0.1 and 5.6 ± 0.1 ng/ml, P < 0.001). Lactating cows had a higher frequency of LH pulses than non-lactating cows (7.0 ± 0.7 and 4.3 ± 0.9 pulses/12 h, P<0.05). The influence of feeding was not observed on LH profiles but was observed on progesterone profiles in both veins. Progesterone concentrations in the caudal vena cava increased after feeding in both groups. Progesterone concentrations in the jugular vein decreased after feeding in lactating cows but not in non-lactating cows. These results indicate the difference in feeding-related changes in progesterone dynamics between lactating and non-lactating cows.     

Dose dependency and individual variability in selected clinical, haematological and blood biochemical responses after systemic lipopolysaccharide challenge in cattle

Previous studies have noted that susceptibility to systemic lipopolysaccharide (LPS) exposure seems to differ between individual cows. However, to date inter-individual variation in the response to intravenous injection of LPS has been reported only as an empirical finding, and its existence or extent has never been backed up by statistical analyses. The aim of the present study was therefore to investigate the dose-dependency of clinical, haematological and blood biochemical responses to intravenous LPS injection in dairy cattle and to determine the extent to which these responses differed between individual cows. Eight dairy cows each received three intravenous injections of Escherichia coli LPS (10, 100, and 1000 ng/kg, consecutively) at three-week intervals. All three LPS doses induced clinical, haematological, and blood biochemical responses lasting up to several days. The strength of all of the responses increased significantly with an increasing LPS dose. A statistically significant inter-individual variation was demonstrated for all clinical, haematological, and blood biochemical responses except for serum calcium concentrations. More than half of the statistical variation in white blood cell and thrombocyte counts could be attributed to the individual. The results of this study show that despite the existence of a dose-response relationship between LPS and ensuing clinical, haematological, and blood biochemical responses, the majority of responses to LPS differ significantly in strength and duration from cow to cow.