Reduced activity of lecithin:cholesterol acyltransferase in the serum of cows with ketosis and left displacement of the abomasum

Lecithin:cholesterol acyltransferase (LCAT) activity was evaluated in sera from cows with ketosis and in some with left displacement of the abomasum (LDA) that occurred during early lactation. The enzyme activities of 652 +/- 214 U (mean +/- SD) in cows with ketosis (n = 6) and 683 +/- 110 U in those with LDA (n = 5) were significantly (p < 0.01) decreased compared to those in healthy normal cows (994 +/- 65 U, n = 8). Serum concentrations of free cholesterol, cholesteryl esters (CE) and phospholipids were similarly decreased in the two diseases. Cows whose LCAT activity and CE concentration were lower than the normal values were detected while in the non-lactating stage, and some of these cows had ketosis after parturition. It is suggested that evaluation of the LCAT activity and of the CE concentration during the non-lactating stage would be useful in detecting cows that are susceptible to postparturient disorders such as ketosis.

[Clinical findings and differential diagnosis in ketosis and hypocalcemia in sheep]

Clinical and laboratory examinations were carried out in a prospective study from 1978 to 1998 on 454 spontaneously diseased sheep of different breeds aged 2-8 years. Three groups of sheep were defined by plasma concentrations of 3-hydroxybutyrate (3-OHB) and calcium. 214 ewes suffered from ketosis (pregnancy toxaemia, 3-OHB > 1.6 mmol/l), 195 ewes and 5 rams suffered from hypocalcaemia (Ca < 2.0 mmol/l), and 40 ewes were sick with booth diseases simultaneously. Clinical findings differ only slightly in all three groups. In ketosis the time until the onset of clinical signs and the duration of the disease is somewhat longer, while locomotion disturbances are less severe than in hypocalcaemia and in the combination of both. In individual cases a differential diagnosis is not possible on the basis of clinical findings, and also acetonuria is not a reliable criterion. Therefore, a therapy is suggested to treat all three possible forms of disease: daily oral application of Na-propionate, Ca-lactate and K-chloride, and additional subcutanous injection of Ca-borogluconate, vitamin D3, alpha-Tocopherol and selenium at the beginning of the disease. Pathogenesis of both diseases are discussed, recommendations for feeding management are given.

Efficacy of monensin for the prevention of subclinical ketosis in lactating dairy cows

A total of 1010 dry cows and pregnant heifers was randomly selected from 25 dairy farms near Guelph, Ontario, Canada to receive either a controlled-release capsule of monensin or a placebo at 3 wk prior to expected calving. Serum samples were obtained at the time of treatment administration, and both serum and milk samples were collected at wk 1, 2, 3, 6, and 9 postcalving. The threshold used to define subclinical ketosis was selected a priori at a concentration of > or = 1200 mumol/L of beta-hydroxybutyrate. Using this threshold, the prevalence and incidence of subclinical ketosis were significantly reduced (50%) by monensin treatment. The duration of subclinical ketosis for cows that had been treated with monensin was also shorter than that for cows treated with the placebo. Monensin treatment significantly reduced the incidence of subclinical ketosis when the threshold was defined using higher concentrations of serum beta-hydroxybutyrate (1400 and 2000 mumol/L). In addition, monensin significantly reduced the prevalence of positive milk ketone tests.

The association between selected metabolic parameters and left abomasal displacement in dairy cows

The objective of this study was to examine the association between selected metabolic parameters and subsequent left displaced abomasum (LDA) diagnosis in dairy cows. Forty-four LDA cows sampled in the third week ante partum (a.p.) which was at a median of 34 days prior to LDA diagnosis, 36 LDA cows sampled in the first week post partum (p.p.) which was at a median of 14 days prior and 28 LDA cows sampled in the second week p.p., which was at a median of 9 days prior to LDA diagnosis were used. Each case was matched to 3 controls by herd and calving date. Data were available from a large field study. Aspartate-aminotransferase (AST) activity, the concentrations of beta-hydroxybutyrate (BHB), glucose, calcium and urea in blood, and the body condition score (BCS) were studied. Logistic regression was used to analyse the association between these parameters and subsequent LDA, adjusting for the effects of parity and pretreatment. A separate model was used for each sampling week and each parameter. In the third week a.p. none of the parameters were significantly associated with LDA. AST and BHB sampled in the first week p.p. and in the second week p.p. were significantly associated with LDA diagnosis. The higher the AST and BHB, the higher the odds of being diagnosed subsequently with LDA. The lower glucose and Ca in the second week p.p. the higher the odds of subsequent LDA diagnosis. Urea and BCS were not significantly associated with LDA in any of the weeks examined. We conclude that AST and BHB in the first and second week p.p. might be used as tests for subsequent LDA. Glucose, calcium, urea and body condition were either not significantly associated with LDA or significantly associated only in the second week p.p.; this may limit their use as tests for LDA.

Recommendations for recording and calculating the incidence of selected clinical diseases of dairy cattle

The report upon which the current discussion is based was prepared in response to the increasing interest of the dairy industry in the recording of clinical disease data. The major objective was to introduce guidelines and standards for the recording and presentation of the diseases of dairy cattle. Eight clinically identifiable diseases of economic importance to the dairy industry were considered: milk fever, retained placenta, metritis, ketosis, left displaced abomasum, cystic ovarian disease, lameness, and clinical mastitis. Standardized definitions for these diseases were established through consultation with industry partners. Two approaches to summarization and reporting were proposed. For retrospective analysis, which is used when historical data are summarized for genetic evaluation for example, lactational incidence risk (cumulative incidence) has been recommended. For current analysis, which is used for herd health monitoring, a true incidence rate has been recommended. Milk fever and retained placenta were exceptions to the latter because of their short periods of risk. For these two diseases, lactational incidence risks are reported.

A review of the feeding-health-production complex in a dairy herd

Diseases may be an important link in the relationship between feeding and production in a dairy herd. The low frequency of relevant disorders calls for studies on survey data on a large population. However, this approach suffers from lack of detailed herd feeding data and consequently only few have studied feeding as a risk factor for disease. Therefore, we reviewed information from various studies to integrate what is known of the feeding-health-production complex in a dairy herd. The need for putting together information from different sources, the herd effects, and the fact that the effect of one factor cannot be kept constant for investigation in a real-life dynamic herd call for a conceptual model as a framework for the review. The complexity is minimized to allow the representation of important elements. Within-cow relationships (such as feeding-disease relationships, disease interrelationships, and disease-production relationships) are reviewed specifically for: ketosis, milk fever, displaced abomasum, acidosis, sole ulcers and laminitis, and bloat. The major feeding management factors involved are concentrate feeding (level and how it is provided) and overconditioned cows. Disease interrelationships are important. Generalization of production loss from diseases is complicated due to the variety of estimates and measures used.

Spontaneous pregnancy toxaemia (ketosis) in sheep and the role of insulin

214 ewes suffering from pregnancy toxaemia (ketosis) were examined. Clinical signs during onset and course of disease and laboratory findings were compared between animals that survived and those which died. In the latter the onset of ketosis was earlier in pregnancy (day 143 +/- 7 vs. day 146 +/- 8) and duration of the disease was shorter (10 +/- 13 vs. 14 +/- 9 days). The animals that died showed more severe clinical signs and higher values of 3-hydroxy-butyrate (4.3 +/- 3.6 vs. 3.5 +/- 2.6 mmol/l) and cortisol (72 +/- 98 vs. 52 +/- 80 mmol/l) as well as lower values of insulin (37 + 12 vs. 3.5 + 2.6 mmol/l) and potassium (4.1 + 1.0 vs. 4.4 + 1.0 mmol/1) at onset of the disease than those which survived (all of differences with P < 0.05). Glucose levels did not differ between groups. Treated animals with glucose plus fructose infusions (n = 56) or with oral application of glucose precursors plus electrolytes (n = 126) had survival rates of 53.6% and 62.7%, respectively. Oral treatment with glucose precursors plus electrolytes and an additional subcutaneous insulin treatment (n = 15) led to an enhanced survival rate of 86.7% (P < 0.05). Low insulin levels in ketotic pregnant sheep and the therapeutic effect of insulin treatment support the hypothesis that insulin plays a causative role in the pathogenesis of ovine ketosis.

Evaluation of a milk test for detection of subclinical ketosis

This study included 190 lactating cows from eight dairy farms and was designed to investigate the sensitivity and specificity of a milk test (Ketolac) for detecting subclinical ketosis in dairy cattle. Blood and milk samples were collected between 38 and 50 days post partum. At a beta-hydroxybutyric acid concentration in blood of 1.2 mmol/L, the prevalence of ketosis was 14%. A Response Operator Characteristic curve was drawn for two milk test values: 100 mumol/L and 200 mumol/L. Assessment of several beta-hydroxybutyric acid cut-off values in blood showed that when 100 mumol/L on the Ketolac milk test was defined positive, the most desirable sensitivity-specificity combination was achieved. This milk test can be routinely used to screen a herd for subclinical ketosis.

Comparative analysis of blood chemical values in primary ketosis and abomasal displacement in cows

Blood chemical values, including ketone bodies, were measured in 25 cows with abomasal displacement (displacement group), 16 cows with primary ketosis (ketosis group), and nine normal controls to investigate the pathophysiology of abomasal displacement. Increases in aspartate aminotransferase, gamma-glutamyl transpeptidase, non-esterified fatty acid (NEFA), and ketone bodies (3-hydroxybutyric acid and acetoacetic acid) were observed in the displacement and ketosis groups. Total cholesterol increased significantly in the ketosis group but decreased in the displacement group. Glucose was significantly low and reversely correlated to ketone bodies in the ketosis group but was not low and was not correlated with ketone bodies in the displacement group. While NEFA was correlated to ketone bodies in the ketosis group, it was not in the displacement group. A correlation between the values of acetoacetic acid and 3-hydroxybutyric acid was seen in both the ketosis and displacement groups. The fact that blood chemical values in ketosis cows were clearly different from those in displacement cows suggest that the biochemical mechanism of ketogenesis is different between these two groups.

[Determination of beta-hydroxybutyrate in milk using test strips: a new aid for the diagnosis of subclinical and clinical ketosis in the cow]

In order to evaluate a dipstick test for the semi-quantitative determination of beta-hydroxybutyrate (BHB) in milk, we determined the BHB content in milk samples of healthy and ketotic high yielding dairy cows with the dipsticks. BHB was analysed on an analyser in 39 of these milk samples as well as in 88 blood samples which were drawn when milk samples were obtained. There was a strong correlation between milk BHB values which were determined with the two methods (r = 0.92; BHB quantitative = -9.9 + 1.25 x BHB dipstick value). Although BHB concentration in plasma is much higher than in milk, the correlation between plasma BHB, determined on an analyser, and the dipstick test results in the corresponding milk samples was also quite strong (r = 0.84; plasma BHB in mmol/l = 0.23 + 0.009 x milk BHB in mumol/l, determined with dipsticks). The dipstick test is suitable for the diagnosis of clinical ketosis and for monitoring the energy status of high yielding dairy cows.

Effect of diseases on the culling of Holstein dairy cows in New York State

The effect of seven diseases on culling was measured in 7523 Holstein cows in New York State. The cows were from 14 herds and had calved between January 1, 1994 and December 31, 1994; all cows were followed until September 30, 1995. Survival analysis was performed using the Cox proportional hazards model to incorporate time-dependent covariates for diseases. Different intervals representing stages of lactation were considered for effects of the diseases. Five models were fitted to test how milk yield and conception status modified the effect of diseases on culling. Covariates in the models included parity, calving season, and time-dependent covariates measuring diseases, milk yield of the current lactation, and conception status. Data were stratified by herd. The seven diseases and lactational risks under consideration were milk fever (0.9%), retained placenta (9.5%), displaced abomasum (5.3%), ketosis (5.0%), metritis (4.2%), ovarian cysts (10.6%), and mastitis (14.5%). Older cows were at a much higher risk of being culled. Calving season had no effect on culling. Higher milk yield was protective against culling. Once a cow had conceived again, her risk of culling dropped sharply. In all models, mastitis was an important risk factor throughout lactation. Milk fever, retained placenta, displaced abomasum, ketosis, and ovarian cysts also significantly affected culling at different stages of lactation. Metritis had no effect on culling. The magnitude of the effects of the diseases decreased, but remained important, when milk yield and conception status were included as covariates. These results indicated that diseases have an important impact on the actual decision to cull and the timing of culling. Parity, milk yield, and conception status are also important factors in culling decisions.

Evaluation of five cowside tests for use with milk to detect subclinical ketosis in dairy cows

The objective of this study was to evaluate the characteristics of five ketone tests for use with milk to detect subclinical ketosis [defined as > 1200 mumol of beta-hydroxybutyrate (BHBA)/L of blood] in dairy cows. The tests studied were the Ketolac BHB strip to detect BHBA (Hoechst, Unterschleissheim, Germany) and four tests based on sodium nitroprusside to detect acetoacetate (Rothera tests) [Ketostix strip (Bayer, Etobicoke, ON, Canada), Bioketone powder (Societé d' Analyses Biopharmaceutiques, Laval, QC, Canada), Ketocheck powder (Great States, St. Joseph, MO), and Utrecht powder (University of Utrecht, Utrecht, The Netherlands)]. Milk samples (n = 529) from 266 cows in 25 Ontario dairy herds were used for this investigation. The Ketolac BHB strip at 50 and 100 mumol of BHBA/L of milk showed sensitivities of 92 and 72%, respectively. This test was more sensitive for subclinical ketosis than were any of the Rothera tests. The sensitivities of the Rothera tests were 43, 33, 28, and 5%, respectively, for Utrecht powder, Bioketone powder, Ketocheck powder, and Ketostix strip. The Rothera tests were highly specific, as was the Ketolac BHB strip at 200, 500, and 1000 mumol of BHBA/L of milk (specificity, > 97%). The prevalence of subclinical ketosis was highest during the first 6 wk of lactation, and a peak was detected during the 2nd wk of lactation. Of the tests evaluated in this study, Ketolac BHB strip was the most useful to monitor subclinical ketosis in dairy herds.

[Genetics of ketosis resistance in cattle]

The frequency of ketosis among the Black-pied cattle in western Siberia have been determined. The genotype of sires and genetic composition of lines were shown to affect resistance and susceptibility to ketosis. The heritability of resistance to the disease was 0.186. Variation in biochemical parameters and natural resistance in cows with ketosis and in healthy cows was studied.

Glucose and insulin responses to glucagon injection in dairy cows with ketosis and fatty liver

The purpose of this investigation was to study the metabolic situation in clinical cases of bovine ketosis and to diagnose additional diseases. Extensive clinical examination, clinical biochemistry, haematology and fine-needle aspiration biopsy of liver was performed on 17 ketotic and eight control dairy cows in the field, and on seven hospitalized hyperketonaemic fatty liver patients. Additional findings in the ketotic group were heat (n = 7), indigestion (n = 5), endometritis (n = 2), cystic ovaries (n = 1), and mastitis (n = 1), and in the fatty liver group displaced abomasum (n = 4), abomasal ulcers (n = 3), mastitis (n = 2), laminitis (n = 1), bronchopneumonia (n = 1), and hypomagnesaemia (n = 2). There were no additional findings in the control group. Aspartate aminotransferase (AST) and creatine kinase (CK) were elevated in the ketosis and fatty liver groups. Total bilirubin, gamma-glutamyl transferase (GGT) and glutamate dehydrogenase (GD) were elevated in the fatty liver group and in some animals in the ketosis group. Total bile acid was not different between the groups. The free fatty acid/cholesterol ratio was higher in the fatty liver group compared with the control and ketosis groups. There was no or only slight fatty degeneration of the liver cells in the control and ketosis groups. Glucose and insulin preinjection concentrations and changes from basal values after glucagon injection were significantly lower in the ketosis group if compared with the control group. The responses in the fatty liver animals after glucagon injection were more heterogeneous than in the control and ketosis animals, a sign of disturbance in the metabolic adaptation, which together with high free fatty acid (FFA) levels can lead to fatty liver in cows with concurrent diseases.

Use of test day milk fat and milk protein to detect subclinical ketosis in dairy cattle in Ontario

Serum beta-hydroxybutyrate (BHB) levels were determined for 1333 dairy cows in various stages of lactation and parity on 93 dairy farms in Ontario. The data were collected in a cross-sectional manner, as part of the 1992 Ontario Dairy Monitoring and Analysis Program. The median serum BHB was 536 mumol/L for all cows, with a range of 0 to 5801 mumol/L. When subclinical ketosis was defined as a serum BHB level of 1200 mumol/L or higher, the prevalence of ketosis for cows in early lactation (< 65 days in milk (DIM)) was 14.1%. Prevalences for mid lactation (65-149 DIM), late lactation (> 149 DIM), and dry cows were 5.3%, 3.2%, and 1.6%, respectively. The mean serum BHB was significantly higher in the early group compared with each of the other 3 groups (P < 0.05). There was a trend of increasing prevalence with increasing parity across all stages of lactation. Only the difference between the parity-1 group and the parity-4 and greater group was statistically significant (P < 0.05). Both test-day fat percent and test-day protein percent were significantly associated with subclinical ketosis. However, test-day fat percent and test-day protein percent, used alone or in combination, were not useful screening tests for identifying cows with subclinical ketosis.

Reduced concentrations of apolipoproteins B-100 and A-I in serum from cows with retained placenta

The purpose of the present study was to evaluate apolipoprotein B-100 and A-I concentrations in cows with retained placenta. Animals used were cows with retained placenta alone (n = 10), those with both retained placenta and ketosis (n = 7), and controls (n = 10). Apolipoprotein B-100 concentrations at 2 to 4 d after parturition were significantly (P < 0.01) decreased in cows with retained placenta alone (mean +/- SD, 0.084 +/- 0.029 mg/ML of serum) when compared with those in control cows (0.154 +/- 0.022 mg/mL). Apolipoprotein A-I concentrations (0.713 +/- 0.177 mg/ML) were also significantly (P < 0.05) lower than those of controls (0.895 +/- 0.159 mg/mL). These decreases were more distinct for apolipoproteins B-100 (55% of controls) than A-I concentrations (80% of controls). Concentrations of apolipoprotein B-100 (0.071 +/- 0.032 mg/mL; P < 0.01) and A-I (0.708 +/- 0.189 mg/mL; P < 0.05) in the cows with both retained placenta and ketosis were also reduced, when compared with values in controls. Other than apolipoproteins, cows with retained placenta alone had significantly (P < 0.01) higher serum nonesterified fatty acids, and lower triglyceride concentrations. Significantly (P < 0.01) higher nonesterified fatty acids and lower triglyceride concentrations were similarly observed in cows with both retained placenta and ketosis.

Metabolic characteristics of induced ketosis in normal and obese dairy cows

Four groups of 6 cows were used to determine the effects of body condition on induction of ketosis. At calving, obese cows were heavier by 108 kg and had a higher body condition score by 0.74 units than did normal cows. Susceptibility to induced ketosis was evaluated by restricting dry matter intake by 20% and feeding 7% 1,3-butanediol from 15 to 49 d in milk (DIM) to one group of obese cows and to one group of normal cows. No normal or obese cows fed the control diet developed ketosis. Two normal and 2 obese cows developed ketonemia because of the induction protocol, and 1 cow in each of the two groups developed clinical ketosis. Obese cows lost 59% more body weight during the first 14 DIM than did normal cows, and cows fed the restricted diet plus 7% 1,3-butanediol lost 15% more body weight than did cows fed the control diet during the induction period. Concentrations of nonesterified fatty acids increased at parturition, peaked at 7 to 14 DIM, and returned to prepartum concentrations by 21 DIM. Plasma beta-hydroxybutyrate concentrations increased after calving and was increased additionally by the induction protocol. At the onset of lactation, plasma insulin decreased, plasma glucagon increased, hepatic triacylglycerols increased, and hepatic glycogen decreased. The incidence of ketonemia and clinical ketosis was the same for obese and normal cows, but, on the basis of changes of blood and liver composition, incidence of ketosis would probably increase if obese cows were overfed throughout the entire dry period.

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 last value of 2-fold or greater than the upper limit of the reference ranges 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.

Serum apolipoprotein B-100 concentrations in healthy and diseased cattle

The purpose of this study was to establish the normal range of serum apolipoprotein B-100 (APO B-100) concentration in clinically normal cattle, and to assess its abnormalities with clinical diseases. We measured the serum concentration of APO B-100 in cattle of varying ages, breeds and sex, maintained under normal field conditions. Blood samples were obtained from 735 apparently healthy cattle and 146 cows with various diseases. The concentration of serum APO B-100 in cattle was assayed by the single radial immunodiffusion method. The concentration of serum APO B-100 in healthy adult breeding bulls (mean +/- SD: Holstein; 101 +/- 46 microg/ml, Japanese Black; 106 +/- 46 microg/ml) was significantly (P<0.001) lower than that in cows (Holstein; 259 +/- 63, Japanese Black; 210 +/- 46 microg/ml), while that of APO B-100 in steers (Holstein; 290 +/- 86 microg/ml, Japanese Black; 302 +/- 90 microg/ml) was similar to the level in cows. The concentration of serum APO B-100 in cattle varied with sex and breed. APO B-100 concentration in cattle was decreased in association with metabolic disorders such as ketosis, displaced abomasum and fatty liver. From these results, it is assumed that the level of serum APO B-100 will be applied to diagnosis of metabolic diseases in cattle.

Physiological changes at parturition and their relationship to metabolic disorders

Most of the metabolic diseases of dairy cows-milk fever, ketosis, retained placenta, and displacement of the abomasum-occur within the first 2 wk of lactation. The etiology of many of those metabolic diseases that are not clinically apparent during the first 2 wk of lactation, such as laminitis, can be traced back to insults that occurred during early lactation. In addition to metabolic disease, the overwhelming majority of infectious disease, in particular mastitis, becomes clinically apparent during the first 2 wk of lactation. Three basic physiological functions must be maintained during the periparturient period if disease is to be avoided: adaptation of the rumen to lactation diets that are high in energy density, maintenance of normocalcemia, and maintenance of a strong immune system. The incidence of both metabolic and infectious diseases is greatly increased whenever one or more of these physiological functions are impaired. This paper discusses the etiological role of each of these factors in the development of common diseases encountered during the periparturient period.

Decreased serum apolipoprotein B-100 and A-I concentrations in cows with ketosis and left displacement of the abomasum

OBJECTIVE

To assess the relevance of hepatic lipidosis (fatty liver) in the development of ketosis and left displacement of the abomasum (LDA).

SAMPLE POPULATION

Sera from 22 healthy cows in early lactation, 21 cows with ketosis, and 19 cows with LDA, and serum and liver specimens from 35 slaughtered cows with or without fatty liver, ketosis, and/or LDA.

PROCEDURE

Apolipoprotein B-100 and A-I concentrations were measured in sera of healthy farm cows and of farm cows with ketosis and LDA. Serum apolipoprotein concentration, together with liver triglyceride content, also were surveyed in a subset of slaughtered cows.

RESULTS

Compared with those in healthy cows or controls, apolipoprotein B-100 and A-I concentrations were decreased in cows with ketosis and LDA.

CONCLUSIONS

Decreases in apolipoprotein B-100 and A-I concentrations in cows with ketosis and LDA indicate that the 2 disorders may be intimately associated with fatty liver.

CLINICAL RELEVANCE

Monitoring of the apolipoprotein B-100 and A-I concentrations during the stages of nonlactation and early lactation is helpful for detecting cows susceptible to ketosis and LDA.

Comparison of ketosis, clinical mastitis, somatic cell count, and reproductive performance between free stall and tie stall barns in Norwegian dairy herds with automatic feeding

Differences in ketosis and clinical mastitis rates, mean somatic cell counts (SCC) and reproductive performance scores (fertility status index = FS-index) between herds housed in free stall (n = 533) and tie stall (n = 59) barns were measured in relation to management and environmental factors in a retrospective cohort study of Norwegian dairy farms with automatic grain feeding systems. Herds with tie stalls were found to have a higher clinical mastitis rate, (61.6 cases per 100 cow-years versus 46.4 cases per 100 cow-years (p < 0.01)); a significantly higher proportion of herds with ketosis, (relative risk = 1.59, (p < 0.01)); and a lower mean fertility status index, (67.3 versus 82.8 (p < 0.01)). No significant difference in mean SCC was found between the 2 groups of dairies (p = 0.32). Large herds had higher Loge geometric mean SCC than small herds (p < 0.01) and herds with high SCC had lower milk production than herds with low SCC (p < 0.01). Herds that scored "very good" on cow cleanliness had significantly lower adjusted mean SCC than herds with scores of "average" or "good" (p < 0.05). Herds in barns with a concrete floor had an adjusted mean number of cases of clinical mastitis of 51.4 per 100 cow-years, 14 per cent higher than herds in barns with rubber mats, litter bed or wood (45.2 cases per 100 cow-years) (p < 0.05). Herds with high milk production level had higher FS-index than herds with low milk production (p < 0.01). Lower disease rates and the higher fertility status measured in the present study favor free stall herds over tie stall herds.

Effect of bovine somatotropin administered to periparturient dairy cows on the incidence of metabolic disease

Thirty-eight dry, pregnant Jersey cows were assigned to diet and bST treatment in a 2 x 2 factorial design. During the dry period, half of the cows were fed a normal TMR (0.4% Ca; 0.3 to 0.4% P), and half of the cows were fed a high Ca TMR (1.5 to 1.6% Ca; 0.4 to 0.7% P). The high Ca diets were designed to induce milk fever and were relatively cationic (194 to 293 meq/kg) compared with the normal diets (-131 to 30 meq/kg). A standard dairy diet was fed to all cows postcalving. Cows received subcutaneous injections of either an oil-based excipient or 500 mg of bST in an oil-based excipient every 14 d from 28 d before expected calving until approximately 14 d postcalving. Peripartal bST treatment decreased the incidence of clinical mastitis, did not affect incidence of milk fever, and increased the duration, but not the incidence, of ketosis in mature Jersey cows. Blood data confirmed the clinical responses and indicated that treated cows mobilized more bone Ca than did controls, as was evidenced by increased hydroxyproline concentrations. Treatment with bST did not affect blood concentrations of 1,25-dihydroxyvitamin D, Ca, or Mg. High Ca diets increased the incidence of milk fever and downer cow syndrome compared with normal diets. The effect of bST on mastitis and milk production must be considered as preliminary given the small size of the study. Although bST treatment increased Ca mobilization, the effect was insufficient to prevent milk fever in this model.

Detection of ketosis in dairy cows by analysis of exhaled breath

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

Evaluation of bulk milk analyses of acetone, urea, and the fat-lactose-quotient as diagnostic aids in preventive veterinary medicine

The purpose of this study was to evaluate the use of additional acetone and urea analyses to the established milk quality system (protein, fat, lactose, and somatic cell count) in bulk milk samples twice a month. Samples were obtained from 44/93 herds in a lowland/highland area. When ranging herds with most acetone values over 0.24mmol/1 (90th percentile), only two out of 10 herds would be on a corresponding list when ranged for highest ketosis treatment incidence. Most high acetone values occur after periods with concentrated calvings, but also in periods without calvings, presumably because of feeding with inferior silage high in butyric acid. Milk fat concentration, milk lactose concentration and the interaction term between these, the fat-lactose-quotient, show the largest absolute values in all three models with ketosis treatment incidence, milk protein concentration, and milk yield as dependent variables in general linear analyses on standardized variables. Acetone and urea concentrations in bulk milk show only small absolute values or are omitted from the models. The practical conclusion from these analyses on bulk milk samples to be used by advisory personnel is small, but it seems that high bulk milk fat concentrations and low lactose concentrations are unfavourable when it comes to ketosis treatment incidence, but favourable when it comes to milk protein concentration. Bulk milk acetone concentrations as a measure of the energy supply in herds must only be interpreted after calving intensity and silage quality are assessed.