Serum ionized calcium concentration in clinically normal dairy cattle, and changes associated with calcium abnormalities

Serum ionized calcium (ICa) concentration was determined in 141 clinically normal dairy cattle by use of a direct-measuring calcium ion-selective electrode instrument. Mean serum ICa concentration 2 hours after blood withdrawal was 4.59 mg/dl; range varied from 3.79 to 5.25 mg/dl. Regression analysis indicated a high degree of correlation between ICa and serum total calcium concentrations if serum stored at 23 C was analyzed within 12 hours after blood withdrawal. Abnormal ICa concentration was detected in 19 of 85 dairy cows that were affected with various pathologic conditions. All 19 cows had hypocalcemia (n = 13 with parturient hypocalcemia, 4 with hypomagnesemic tetany, and 2 with renal disease). In all cases, the ICa concentration clearly related to the clinical manifestation of disease and the functional status of the cow's calcium metabolism.     

上海地区奶牛产后低钙血症及酮病发病率调查

本研究对上海地区9个牧场奶牛产后低钙血症和酮病的发病率进行了调查,结果表明:奶牛产后12 h内的低钙血症发病率平均为86.1%,血钙平均浓度为(1.82±0.02)mmol/L,产后3~7 d低钙血症发病率平均为35.2%,血钙平均浓度为(2.05±0.01)mmol/L,表明随着泌乳天数的增加,低钙血症有缓解趋势。奶牛产后12 h内酮病发病率平均为5.5%,血液β-羟丁酸(BHBA)平均浓度为(0.68±0.04)mmol/L,产后3~7 d酮病发病率平均为16.3%,血液BHBA平均浓度为(0.98±0.07)mmol/L,表明随着泌乳天数增加能量负平衡有加重趋势。奶牛产后12 h内高游离脂肪酸(NEFA)发生率平均为49.4%,血液NEFA平均浓度为(0.76±0.03)Meq/L,产后3~7 d高NEFA发生率平均为41.3%,血液NEFA平均浓度为(0.71±0.03)Meq/L,表明泌乳初期高NEFA发生率远高于酮病发病率,随着泌乳天数增加血液NEFA浓度有下降趋势。奶牛产后血液中钙的浓度与NEFA浓度呈极显著负相关(P0.01),血液中NEFA浓度与BHBA浓度呈极显著正相关(P0.01)。     

Use of a polymerase chain reaction assay to detect bovine leukosis virus in dairy cattle

OBJECTIVE: To evaluate the use of a polymerase chain reaction (PCR) assay in detecting bovine leukosis virus (BLV) in adult dairy cows. DESIGN: Prospective study. ANIMALS: 223 adult dairy cows. PROCEDURE: Cows were tested for BLV status by use of an ELISA and a PCR assay. Sensitivity, specificity, predictive values of positive and negative tests, and the percentage of cows correctly classified by PCR assay were calculated. Ninety-five percent confidence intervals were calculated for sensitivity and specificity. RESULTS: Sensitivity and specificity were 0.672 and 1.00, respectively. Prevalence of BLV in this herd was 0.807. Predictive value of a positive test was 1.00, and predictive value of a negative test was 0.421. The percentage of cows correctly classified by PCR assay was 73.5%. CONCLUSIONS AND CLINICAL RELEVANCE: A positive PCR assay result provided definitive evidence that a cow was infected with BLV. Sensitivity and negative predictive value for PCR assay were low. Consequently, PCR assay alone is unreliable for routine detection of BLV in herds with high prevalence of the disease.     

Relationship between blood calcium level and ST peak interval of electrocardiographic variables in peripartum Holstein cows

The association between blood calcium levels and electrocardiographic variables was compared in 137 normal parturient and 36 peripartum recumbent Holstein cows to determine whether hypocalcemia in peripartum dairy cows can be rapidly diagnosed using electrocardiograph. Inverse of STc (ST peak interval/SS interval^0.5) and blood ionized calcium or serum calcium concentrations were strongly correlated, and both correlation coefficients were 0.81 (P<0.001). The 95% prediction interval indicated that cows with STc >0.385 ± 0.001 sec are very likely to be hypocalcemic (blood ionized or serum calcium concentrations of <0.9 mmol/l or <7.5 mg/dl, respectively). These findings indicate that hypocalcemia in parturient cows can be non-invasively estimated using the STc.     

Preventive effect of mildly altering dietary cation-anion difference on milk fever in dairy cows

In the present study, we examined whether mildly altering dietary cation-anion difference (DCAD) contributes to the prevention of milk fever in dairy cows. Thirty multiparous cows and ten primiparous cows (heifer group) were used in this study and the multiparous cows were randomly divided into three groups of ten animals each (anion, non-anion and control groups). The cows in the anion group were given supplemental salts that slightly lowered DCAD. These salts consisted of 115 g of CaCO3, 42 g of CaHPO4, 65 g of MgSO4 x 7 H2O and 80 g of CaCl2 x 2 H2O as a daily dose for each cow, using a catheter from 21 days before the expected date of parturition until parturition. The cows in the non-anion group were given only the same Ca, Mg and ip supplement but no sulfate and chloride salts as that in the anion group. The cows in the control and heifer groups were not given any additional supplement. The incidence of hypocalcemia in the anion group decreased to approximately half of those in the non-anion and control groups, while the heifer group did not develop hypocalcemia at all. In addition, the number of days spent for the treatment of hypocalcemia and the number of drug bottles (calcium borogluconate solution) used for the treatment decreased to less than half in the anion group compared with those in the non-anion and control groups. At parturition, the serum Ca concentration in the control (6.2 +/- 1.9 mg/dl, mean +/- standard deviation) and non-anion groups (6.4 +/- 1.7 mg/dl) were significantly lower than that in the heifer group (8.3 +/- 0.4 mg/dl), and the level in the anion group was intermediate (7.3 +/- 1.3 mg/dl). The change in ionized Ca concentration was almost the same as that in serum Ca concentration, but only the concentration in the anion group tended to increase slightly from a week before parturition and was significantly higher than that in all other groups three days before parturition. Urinary pH in the anion group was maintained at a mildly acidic level (6.8-7.0) for the last two weeks before parturition, compared with those in the control (7.3-7.5) and non-anion groups (7.9-8.1), and similar to that in the heifer group (6.3-7.3). The urinary Ca excretion was the highest in the anion group among all groups during the prepartum period. There were no specific changes in the excretion of parathyroid hormone and 1,25-dihydroxyvitamin D in all groups of multiparous cows while the levels of these hormones remained low in the heifer group throughout the experimental period. The data in the present study indicates that the administration of anion salts that slightly lowered DCAD in the preparum period was effective for preventing milk fever in multiparous cows. Safe and mild metabolic acidosis induced by the anion salts could be evaluated by urinary pH (6.8-7.0), and might increase the responsiveness to Ca requirement at parturition through some complex mechanisms unrelated to the excretion of Ca-related hormones. In addition, it was clarified that primiparous cows have a high potential to respond to sudden Ca demand unrelated to hormone excretion, and their Ca metabolism was in some respects similar to that in multiparous cows fed anion salts. Therefore, manipulating mildly DCAD is expected to be an effective, safe and natural method for preventing milk fever in dairy cows.     

Evaluation of assays for determination of passive transfer status in neonatal llamas and alpacas

OBJECTIVE: To evaluate several practice-adapted assays for determination of passive transfer status in crias. ANIMALS: 24 llama and 9 alpaca crias. DESIGN: Prospective study. PROCEDURE: Serum IgG concentration was measured by use of a radial immunodiffusion assay when crias were 45 to 51 hours old. Results were compared with serum gamma-glutamyltransferase (GGT) activity, serum total protein, albumin, globulin, and total solids concentrations, and results of commercially available and traditional sodium sulfite turbidity (SST) tests. RESULTS: Mean (+/- SD) serum IgG concentration was 1,762 +/- 1,153 mg/dl. On the basis of a threshold value of 1,000 mg of IgG/dl at 48 hours of age, 5 of 33 (15.15%) crias had failure of passive transfer. Serum total solids, protein, and globulin concentrations were significantly associated with serum IgG concentration, whereas serum GGT activity and serum albumin concentration were not. Serum IgG concentrations were significantly different among crias with negative, 2+, and 3+ scores on the traditional SST test. Serum IgG concentrations were not significantly different between crias with negative and 100 mg/dl scores or 100 and 300 mg/dl scores on the commercially available SST test. However, all other comparisons between crias with different scores revealed significant differences. Sensitivity and specificity ranged between 0 and 1, depending on the test and endpoint selected. CONCLUSIONS AND CLINICAL RELEVANCE: The commercially available SST test and determination of serum total protein and globulin concentrations are suitable methods for assessing passive transfer status in llama and alpaca crias.     

Prediction of serum ionized calcium concentration by serum total calcium measurement in cats

Feline serum samples (n = 434) were classified as hypercalcemic, normocalcemic, or hypocalcemic based on both total calcium (tCa) and ionized calcium (iCa) concentrations. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), positive diagnostic likelihood ratio (PDLR), and negative diagnostic likelihood ratio (NDLR) were calculated for prediction of hypercalcemia and hypocalcemia in all samples, in hypoalbuminemic cats, and in those with chronic renal failure (CRF) as compared with cats that had other conditions. Diagnostic discordance in prediction of iCa using tCa was 40%. Sensitivity of tCa in prediction of ionized hypercalcemia was low and specificity was high. The PDLR for prediction of ionized hypercalcemia or hypocalcemia was low in all cats, especially in those with CRF. Due to the high level of diagnostic discordance, tCa should not be used to predict iCa concentration. Concentration of iCa should be measured directly when accurate assessment of calcium status is needed.     

Comparison of results of three commercial heartworm antigen test kits in dogs with low heartworm burdens

OBJECTIVE: To compare results of 3 commercial heartworm antigen test kits performed on serum samples from dogs infected with low numbers of adult female heartworms. DESIGN: Blinded laboratory evaluation. Sample Population-Serum samples from dogs (n = 208) proven at necropsy to be infected with 1 to 4 adult female heartworms and from dogs (32) without heartworms. PROCEDURE: Samples were sequentially tested with each test kit, following the manufacturers' instructions, by licensed veterinary technicians in private practice who were not aware of infection status of the dogs. The order of test kit evaluations was randomly chosen. For each test kit, sensitivity, specificity, accuracy, positive predictive value, and negative predictive value were evaluated. RESULTS: All tests yielded some false-negative results, and there were significant differences among tests in regard to ability to detect low heartworm burdens. Sensitivity of the test kits ranged from 78 to 84%. For all test kits, sensitivity increased as number of female heartworms increased. All 3 test kits had high specificity (97%). CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that sensitivity of the 3 commercially available heartworm antigen test kits ranged from 78 to 84% when used to test serum samples from dogs with low heartworm burdens, and that sensitivity varied among test kits. For all 3 test kits, specificity was 97%. All 3 test kits yielded false-positive and false-negative results for some dogs with low heartworm burdens.     

Parturient paresis and hypocalcemia in ruminant livestock

Parturient paresis (hypocalcemia) is most likely to affect dairy cattle around the time of parturition. It causes progressive neuromuscular dysfunction and flaccid paralysis. Older dairy cows, cows with a history of parturient paresis during a previous lactation, high-producing cows, and cows from the Jersey and Guernsey breeds are at highest risk for developing parturient paresis. Nonparturient hypocalcemia may also occur and is related to events other than parturition, such as severe stress, that temporarily overwhelm the mechanisms of calcium homeostasis. Beef cattle, sheep, and goats are affected less frequently by hypocalcemia than are dairy cows. Because these species are not as stressed for milk production as dairy cattle, nonparturient hypocalcemia makes up a higher proportion of cases in nondairy ruminants. Clinical signs of hypocalcemia in beef cattle, sheep, and goats tend toward hyperesthesia and tetany rather than the classic flaccid paralysis that occurs in dairy cattle with parturient hypocalcemia. Prompt and effective treatment of hypocalcemia helps to reduce the incidence of secondary complications, such as muscle damage or mastitis. The standard treatment regimen of 500 ml of 23 per cent calcium gluconate, administered intravenously, will elicit a favorable response in approximately 75 per cent of recumbent cows within 2 hours of treatment. Relapses following successful initial therapy are common and may be prevented in part by supplementation of intravenous treatment with an additional 500 ml of 23 per cent calcium gluconate administered subcutaneously. Proper nursing care following treatment speeds recovery and reduces the incidence of secondary complications owing to hypocalcemia.     

Parturient Paresis in the Cow: Serum Ionized Calcium Concentrations Before and after Treatment with Different Calcium Solutions – Classification of Different Degrees of Hypo- and Hypercalcemia

Serum ionized calcium concentrations (Ca_F) were determined in 87 Swedish red-and-white cows and 10 Swedish Friesian cows with clinical signs of parturient paresis. All cows were in the week prior to or after parturition. A classification of the severity of hypocalcemia in terms of serum ionized calcium was devised. Eight cows had normal serum ionized calcium concentrations (Cap 1.06–1.26 mmol/1); 15 had slight (Ca_F 0.80–1.05 mmol/1); 43 a moderate (Ca_F 0.50–0.79 mmol/1), and 31 asevere (Ca_F < 0.50 mmol/1) hypocalcemia.All cows were given 8 or 8.3 g of calcium intravenously. Of 8 normocalcemic cows 7 (87.5 %) reached a maximum posttreatment serum ionized calcium concentration > 1.80 mmol/1 (severe hypercalcemia). This was also found in 13 of 15 (86.7 %) slightly hypocalcemic cows and in 31 of 43 (72.1 %) moderately hypocalcemic cows. In the severe hypocalcemia group 14 of 31 (45.2 %) had maximum posttreatment Cap > 1.80 mmol/1).These findings emphazise the need of a rapid pretreatment evaluation of the degree of hypocalcemia. The present study also underlined the difficulty in predicting serum ionized calcium from serum total calcium concentrations.     

Prognostic value of anion gap calculation in cattle with abomasal volvulus: 58 cases (1980-1985)

Values for anion gap, serum chloride, and base excess were tabulated for 58 dairy cows with abomasal volvulus. Test values for survivors (n = 40) and nonsurvivors (n = 18) were compared. Surviving cattle were released for production or salvage. Nonsurviving cows died or were euthanatized. Accuracy of preoperative anion gap, serum chloride, and base excess values in predicting outcome was evaluated by calculating the sensitivity, specificity, predictive value, and negative predictive value of these at assigned cutoff values. Anion gaps greater than or equal to 30 mEq/L were indicative of a poor prognosis. At this value, the sensitivity (0.889), specificity (0.925), predictive value (0.842), negative predictive value (0.949), and efficiency (0.914) were higher than when serum chloride concentration less than or equal to 84 mEq/L or base excess value less than or equal to 0 were used to denote poor prognosis. We concluded that preoperative anion gap calculation could reliably predict the outcome of cows with abomasal volvulus and was more accurate than either serum chloride concentration or base excess value.     

产后酮病奶牛血液生化指征分析

为了比较产后一段时期内酮病奶牛与健康奶牛血液生化指标的差异,为奶牛酮病的防控及兽医临床诊治提供理论依据。本研究选取吴忠市某集约化奶牛场待产奶牛共30头进行为期3周的血液生化指标监测,根据β-羟丁酸（BHBA）的浓度将奶牛分为酮病组和对照组并进行比较研究。结果显示,酮病组与对照组在生产当天（0 d）各项检测指标未出现显著性差异;酮病组奶牛β-羟丁酸浓度在产后7 d时较对照组极显著升高（P<0.01）;天门冬氨酸氨基转移酶（AST）和总胆红素（T-bil）浓度在产后7 d和14 d时显著升高（P<0.05）;血糖（Glu）浓度在产后7 d时显著降低（P<0.05）,产后14 d时极显著降低（P<0.01）;钙（Ca）、磷（P）浓度无显著性差异,但均低于正常参考值范围,出现低血钙、低血磷症。经分析发现,本场奶牛所患酮病为Ⅱ型酮病,酮病牛高发胎次为3~6胎,产后低血钙、低血磷、低血糖现象严重,同时奶牛酮病引发了机体肝脏功能损伤,影响母牛生产性能。     

Efficacy and tolerance of a calcium-magnesium-aspartate solution in the treatment of hypocalcemic parturient paresis in cows

The systemic tolerance of a solution of calcium aspartate and magnesium aspartate was studied in 7 cows. Intravenously administered dosages of 500 ml per cow were well tolerated. A twofold increase of the serum calcium concentration was measured. In 2 cows which were treated with 1000 ml of the solution a threefold increased calcium concentration and heart arrhythmia were found. The clinical efficacy of the solution was demonstrated in a study with 44 hypocalcemic cows. A long lasting increase of the serum calcium as well as an enhanced phosphorus concentration were measurable. In conclusion, the calcium-magnesium-aspartate solution seems to be an efficacious and well tolerated alternative for the treatment of hypocalcemia in cows.     

Effects of intravenous administration of two volumes of calcium solution on plasma ionized calcium concentration and recovery from naturally occurring hypocalcemia in lactating dairy cows

OBJECTIVE: To compare the effects of administration of 2 volumes of a calcium solution (calcium oxide and calcium gluconate) on plasma ionized calcium concentration (PICaC) and clinical recovery from naturally occurring hypocalcemia (NOHC; milk fever) in lactating dairy cows. ANIMALS: 123 cows with NOHC (PICaC < 0.95 mmol/L [3.81 mg/dL]) and 20 clinically normal control cows. PROCEDURES: Affected cows were treated IV once or repeatedly with 450 (n = 56) or 750 mL (67) of calcium solution (1.65 g of calcium/100 mL) until clinical recovery was achieved. The PICaC was assessed 48 hours after the first treatment or after the treatment that achieved clinical recovery. Biochemical recovery was defined as PICaC > or = 0.95 mmol/L. Plasma from control cows was used for PICaC reference range determination. Plasma samples from both groups were assessed after storage for 20 days at 20 degrees C. RESULTS: The PICaC reference range derived from blood collected in tubes containing lithium heparin was 1.02 to 1.29 mmol/L (4.09 to 5.17 mg/dL). Following storage, plasma samples were suitable for PICaC assessment. All cows treated with > or = 1 volume of 450 and 750 mL of calcium solution recovered clinically; however, 31 of 83 (37%) evaluated cows were not biochemically recovered at 48 hours following treatment. Only cows with PICaC < 0.48 mmol/L (1.92 mg/dL) before the first treatment had to be treated > or = 3 times. CONCLUSIONS AND CLINICAL RELEVANCE: Results did not support the need to increase the administered volume of calcium solution from 450 to 750 mL for treatment of NOHC in dairy cows.     

Herd characteristics and management practices associated with seroprevalence of Mycobacterium avium subsp paratuberculosis infection in dairy herds

OBJECTIVE: To investigate herd characteristics and management practices associated with a high seroprevalence of Mycobacterium avium subsp paratuberculosis (MAP) in dairy herds in central California. SAMPLE POPULATION: 60 randomly selected cows from each of 21 dairy herds. PROCEDURES: Sera of selected cows were tested for antibodies against MAP by use of an ELISA test kit. Cows with a test sample-to-positive control sample (S:P) ratio of > or = 0.25 were considered seropositive, and herds with > or = 4% seropositive cows were considered high-seroprevalence herds. Data on herd characteristics and management practices were collected via interviews with owners. Bayesian logistic regression was used to model the predictive probability of a herd having a high seroprevalence on the basis of various herd characteristics and management practices. RESULTS: 9 of 21 (43%) herds were classified as high-seroprevalence herds. Five variables (history of previous signs of paratuberculosis in the herd, herd size, exposing cattle to water from manure storage lagoons, feeding unsalable milk to calves, and exposing heifers < or = 6 months old to manure of adult cows) were included in the predictive model on the basis of statistical and biological considerations. In large herds, the predictive probability of a high seroprevalence of MAP infection decreased from 0.74 to 0.39 when management changed from poor to good practices. In small herds, a similar decrease from 0.64 to 0.29 was predicted. CONCLUSIONS AND CLINICAL RELEVANCE: The seroprevalence of MAP infection in California dairies may be reduced by improvements in herd management practices.     

Prediction of serum ionized calcium concentration by use of serum total calcium concentration in dogs

OBJECTIVE: To determine whether total serum calcium (tCa) or adjusted tCa concentrations accurately predict ionized calcium (iCa) status in dogs. SAMPLE POPULATION: 1,633 canine serum samples. PROCEDURE: The tCa concentration was adjusted for total protein (TP) or albumin concentration by use of published equations. Correlations between iCa and tCa or adjusted tCa, tCa and TP, and tCa and albumin were calculated. Diagnostic discordance between tCa or adjusted tCa and iCa was determined. Diagnostic discordance in predicting iCa was also determined for 490 dogs with chronic renal failure (CRF). Sensitivity, specificity, positive and negative predictive values, and positive and negative diagnostic likelihood ratios were calculated for tCa, tCa adjusted forTP, and tCa adjusted for albumin. RESULTS: Diagnostic discordance was 27% when tCa concentration was used to predict iCa status. Use of adjusted tCa increased diagnostic discordance to approximately 37% for all dogs and 55% for dogs with CRF. Positive predictive value and positive diagnostic likelihood ratios were poor when tCa concentration was used to predict iCa status. The tCa concentration overestimated normocalcemia and underestimated hypocalcemia. Adjusted tCa overestimated hypercalcemia and underestimated hypocalcemia. CONCLUSIONS AND CLINICAL RELEVANCE: Adjusted tCa or tCa concentrations are unacceptable for predicting iCa status in dogs. Use of adjustment equations is not recommended. Direct measurement of iCa concentration is necessary for accurate assessment of calcium status. Use of tCa or adjusted tCa concentrations to predict iCa status in dogs could cause serious mistakes in diagnosis and case management, especially in dogs with CRF.     

Evaluation of a commercially available immunoassay for assessing adequacy of passive transfer in calves

OBJECTIVE: To evaluate diagnostic utility of a commercially available immunoassay for assessing adequacy of passive transfer of immunity in neonatal calves. DESIGN: Prospective study. ANIMALS: 123 calves. PROCEDURE: Blood and serum samples were obtained from the calves prior to 2 weeks of age. The immunoassay was performed, along with refractometry and an 18% sodium sulfite turbidity test. Serum IgG concentration was determined with a radial immunodiffusion assay. Sensitivity and specificity of the immunoassay, refractometry, and the sodium sulfite test were calculated by comparing results with results of the radial immunodiffusion assay. RESULTS: Sensitivity and specificity of the blood IgG immunoassay were 0.93 and 0.88, respectively, compared with 1.00 and 0.53 for the sodium sulfite test. For refractometry, sensitivity and specificity were 0.71 and 0.83, respectively, when a serum total solids concentration of 5.2 g/dl was used as the cutoff between positive and negative test results. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that the immunoassay performs well in detecting calves with inadequate passive transfer of immunity.     

The course of selected bone resorption marker concentrations in response to short-term hypocalcemia experimentally induced with disodium EDTA infusions in dairy cows

The collagen metabolites hydroxyproline (HYP), deoxypyridinoline (DPD), and the carboxyterminal telopeptide of type I collagen (ICTP) are suitable markers for bone resorption in humans and several animal species. The purpose of this study was to describe the course of bone resorption markers during short-term hypocalcemia induced with disodium ethylenediaminetetraacetic acid (Na2EDTA) and to investigate whether bone resorption is increased in dairy cows under these conditions. EDTA infusions have been used as a model for periparturient paresis in dairy cows and to estimate the calcium mobilization rate from body reserves in ruminants. In this study, hypocalcemia was induced by means of a 5% Na2EDTA infusion (0.55 mg/kg/min Na2EDTA for 5 h = total dose of 100.6 g). Two experiments were conducted: (1) Six 4-11 years-old Brown Swiss cows were infused intravenously with EDTA for 5 h. Blood and urine samples were taken repeatedly from 1 day before until 10 days after infusion. (2) Towards the end of the lactation, the experiment was repeated with the same animals after a 14-day-period of feeding a low calcium diet (26 g/animal per day). The EDTA-infusion induced hypocalcemia and hypophosphatemia. The HYP-, DPD- and ICTP-concentration remained mainly unaffected during both infusions. Only DPD showed an increase during infusion and HYP an increase 2 days after the infusion. In conclusion, the EDTA infusion had little effect on the concentrations of the measured bone markers, which may be due to the fact that the serum calcium pool was refilled by increased absorption of Ca via the gastrointestinal tract. From these results, it can be concluded that bone resorption was not influenced by EDTA infusion.     

Evaluation of biochemical profile of dairy cows with metabolic diseases in tropical conditions

The aims of this study were to characterize the biochemical profile, the reproductive performance and to identify potential predictive biomarkers of disease state of dairy cows with hyperketonemia, lipomobilization and hypocalcemia raised in tropical conditions in southeastern Brazil. Dairy cows (n = 50) were divided into a group of healthy cows (n = 14), cows with lipomobilization (n = 14), cows with hypocalcemia (n = 11), and a group of cows with hyperketonemia (n = 11). Evaluation of body condition score (BCS), body weight (BW) and blood samples was performed on 21, 14, 7, 4 and 2 days before calving, parturition, 1, 7, 14, 21, 30, 45 and 60 days post-partum and milk production was recorded on days 7, 14, 21, 30, 45 and 60 after parturition. Blood samples were assayed for aspartate aminotransferase (AST), gamma-glutammyltransferase (GGT), albumin, total protein, globulin, fibrinogen, total cholesterol, triglyceride, urea and creatinine concentrations. The biochemical profile, BCS, BW, milk production and reproductive performance differed (p < .05) among the groups. Our findings indicate changes in the biochemical profile of dairy cows with metabolic diseases and impaired production and fertility of dairy cows in this group. Variable importance in projection plots demonstrated that cholesterol, urea, total protein, albumin and fibrinogen in the serum were the strongest discriminators between cows with hypocalcemia and healthy cows; and AST, cholesterol, urea and triglycerides for cows with hyperketonemia and healthy cows; and cholesterol, urea, triglycerides, total protein and fibrinogen for lipomobilization and healthy cows, which might be useful as predictive biomarkers of the disease state.     

阴离子型日粮及补Ca对围产期奶牛代谢与健康及其生产性能的影响

将36头干奶后期中国荷斯坦奶牛随机分为对照组、试验Ⅰ组、试验Ⅱ组（每组12头）．分别饲喂常规日粮、阴离子型日粮及在此基础上朴Ca日粮，探讨其对奶牛体内代谢状况、健康状况及生产性能的影响。与饲喂常规日粮相比，饲喂阴离子型日粮可降低奶牛尿液pH值（P〈0．01）和血液HCO2^-浓度（P〉0．05）；增加奶牛产后12h（P〈0．05）、2d（P〈0．05）血清总钙含量．对血清无机磷、镁含量没有显著影响；明显降低奶牛亚临床性低血钙率（33％）、胎衣不下率（33％）和乳房水肿率（17％）；增加牛奶乳糖率（P〈0．05），对其他奶成分和奶产量没有显著影响（P〉0．05）。在阴离子型日粮中补Ca后．与饲喂阴离子型日粮相比．除增加奶牛产后血清镁含量外（P〈0．05）．对其他各项指标没有明显影响。