Thiamin and niacin in the rumen

Thiamin analogs, produced in the rumen by thiaminase I, in the presence of a cosubstrate appear to be responsible for the central nervous system disorder, polioencephalomalacia (PEM). For PEM to occur, an analog must be produced that inhibits an essential thiamin-requiring reaction, and results from a cosubstrate present in the rumen. In high concentrate diets, thiaminase I is produced by rumen microbes. However, PEM can also be caused by thiaminase I of plant origin. Based on physical characteristics and cosubstrate specificity, the thiaminase I enzymes produced by Bacillus thiaminolyticus and Clostridium sporogenes appear to be different from the enzyme produced by the rumen. Because niacin and certain antihelmentics are thiaminase I cosubstrates, they should be used cautiously. Supplementary niacin increased microbial protein synthesis in vitro and in vivo, and was more effective with urea than soybean meal. Supplementary niacin (5 to 6 g X cow-1 X d-1) increased milk production in postpartum cows but not in those in mid-lactation, and in cows fed soybean meal but not in those fed urea. We believe the heating of soybean meal during commercial processing decreased the availability of niacin for rumen protozoa. Supplementary niacin for postpartum cows increased blood glucose, decreased blood ketones and reduced the incidence of ketosis. Niacin flow to the small intestine and its absorption from the small intestine increased with niacin supplementation. Supplemental niacin prevented the postpartum decrease in red blood cell niacin observed in control cows.

Factors responsible for post parturient metritis in dairy cattle

Factors associated with retained placenta and post parturient metritis in Israeli-Friesian dairy cattle are examined. The overall incidence rate, in a total of 2017 calvings on seven farms, was 16.1 per cent for retained placenta and 37.3 per cent for primary metritis. Risk factors associated with retained placenta include rising parity, short gestations, induction of parturition, multiple births, summer calvings, left displacement of the abomasum and ketosis. Risk factors associated with metritis include declining parity, long gestations, induction of parturition, stillbirth, multiple births, low milk yield before drying off, left displacement of the abomasum, ketosis and winter calvings. A proposed aetiology of metritis is presented and the various possible factors involved are discussed.

Fetal hepatic and neural substrate utilization as affected by induced nutritional ketosis in swine

Systemic ketosis was induced in first-parity gilts by the isocaloric substitution of glucose with 1,3-butylene glycol to supply 20% of the total dietary energy beginning on d 23 (23 BG) or d 60 (60 BG) of gestation. Ketosis reduced (P less than .05) maternal plasma glucose, urea N and insulin concentrations. Fetal carcass dry matter and carcass glycogen contents were reduced (P less than .05) by maternal ketogenic calorie substitution, whereas fetal hepatic glycogen and lipid contents were not influenced by maternal treatment. Neural acetate oxidation was reduced (P less than .05) in the 23 BG and 60 BG fetuses, with a concurrent increase (P less than .05) in beta-hydroxybutyrate (BOHB) oxidation. Neural lipogenesis measured from acetate and BOHB substrates was nominal in the d 105 pig fetus. Fetal hepatic acetate and BOHB utilization for lipogenesis were increased (P less than .05) by maternal ketosis. Reproductive performance characteristics (litter size, number stillborn and birth weight) were not improved by maternal ketosis. The substantial improvement in lactation weight gain by litters from 23 BG and 60 BG dams (20%, P less than .05) may suggest a carryover effect of gestation dietary treatment on lactation performance.

Effect of propionic acid on ketogenesis in lactating sheep fed restricted rations or deprived of food

Propionic acid was used as a possible preventive agent against ketogenesis. A total of 12 Suffolk lactating sheep were allocated to groups of 4 and fed isocaloric isonitrogenous rations containing 0, 5 and 10% propionic acid for 2 wk at 1.25 kg twice daily, followed by 4 days of food restriction to .5 kg/day and 2 days of food deprivation to induce ketogenesis. During the restricted feeding, concentrations of glucose in blood plasma were higher (50 to 57 versus 41 to 53 mg/dl) and concentrations of D (--)-3-hydroxybutyrate and acetoacetate lower (3.0 to 5.9 versus 3.9 to 7.6 mg/dl; .39 to .83 versus .43 to .92 mg/dl) in animals fed propionic acid. Propionic acid did not change free fatty acid concentrations of blood plasma or milk and subcutaneous fatty acid composition. Restricted feeding and fasting markedly lowered glucose and elevated concentrations of ketone bodies and free fatty acids in plasma. Furthermore, during these periods proportions of milk fatty acids containing 4 to 14 carbon atoms were decreased and those of stearic and oleic acid (18:0 and 18:1) were increased (16.6 versus 6.5%; and 41.0 versus 17.4%).

[Clinico-experimental and clinical studies of a ketomethine preparation in sheep and cows]

Some of the clinical parameters of the preparation ketomethyne, containing propylene glycol, methyonine, and Co bichloride, were comparatively studied with the analogous preparation ursoketin at oral application to sheep and cows. It was found that ketomethyne raised more slowly the level of blood sugar than ursoketin, but maintained it by 24-35 per cent higher than the initial level from the 6th to the 24th hour following treatment. The oral application of ketomethyne had no unfavourable effect on the rumen activity, the general clinical indices body temperature, pulse, respiration), the hematologic indices as hemoglobin and erythrocyte and leukocyte count, and the appetite. Similarly to ursoketin, ketomethyne was not readily taken by animals as judged by what was noted with ruminants in cases where the preparation was given as a supplement to the ordinary amounts of feed (concentrates). It was more successfully offered to the large ruminants when 5 to 8 kg silage and the preparation at the rate of 400-500 cm3 were admixed. With cows having paraclinical signs of ûetosis (hypoglycemia and ketonuria) the oral administration of ketomethyne at 500 cm3 in the course of four consecutive days produced favourable effects (up to 100 per cent). On such basis, therefore, the use of the preparation is worthwhile in the prevention of ketosis in sheep and cows or in their treatment.

Subclinical ketosis: prevalence and associations with production and disease

Cows in 32 southern Ontario Holstein herds were monitored for subclinical ketosis for a period of two and one half years. Milk samples were routinely collected and the level of milk ketone bodies determined by the use of a commercial nitroprusside based test powder (reactions scored as negative, +1 or +2). Approximately 92% of positive reactions were observed in the first 65 days of lactation and for that time period the prevalence of ketosis was 12.1%. Based on this prevalence, the minimum possible duration of subclinical ketosis would be 7.9 days and the minimum possible lactational incidence rate would be 12.1%. The prevalence during the first 65 days of lactation in individual herds ranged from 0 to 33.9%. Subclinical ketosis was more likely to be found in cows experiencing metritis than in unaffected cows. Detection of elevated levels of milk ketones also indicated that the cow had a significantly higher risk of having clinical ketosis, metritis or cystic ovaries diagnosed within the following four days. Milk ketone scores of +1 and +2 were found to be associated with a reduction in daily milk production of 1.0 and 1.4 kg of milk respectively.

Treatment of bovine ketosis with invert sugar, glucocorticoids, and propylene glycol

Four different treatments of bovine ketosis, using 3 different pharmaceutical preparations, were monitored. The main antiketogenic and glucogenic ingredients of the preparations were as follows: invert sugar (Metabol), prednisolone and dexamethasone (Predasen), the former preparations combined (Metabol & Predasen) and propylene glycol and dexamethasone (Dexaprol). Blood samples were drained from the ketotic cows prior to the treatment. The animals were sampled again 2 and 7 days after the first sampling. The whole blood concentrations of acetoacetate (AA concn), β-hydroxybutyrate (BHB concn) and glucose (glue concn) were determined. The measures of the antiketogenic and glucogenic efficacy of the various treatments applied were their ability to reduce the AA concn and BHB concn and to elevate the gluc concn.

Invert sugar (Metabol) alone had no antiketogenic efficacy, although in some cases it led to a subjective clinical improvement as reported by the owners of the animals. Invert sugar and glucocorticoids (Metabol & Predasen) dexamethasone and prednisolone (Predasen) and dexamethason plus propylene glycol (Dexaprol) were equally effective in bringing the AA, BHB and glue concns to normal range. The mean glue concn of the cows treated with Dexaprol was higher than that of the cows in the other treatment groups at 2 days (P < 0.01). No other differences between the 3 antiketogenic treatments could be shown.

The effect of two glucocorticoids on plasma glucose and milk production in healthy cows and the therapeutic effect in ketosis

In a cross-over study of six clinically healthy cows in early lactation, injection of 10 mg dexamethasone isonicotinate caused significantly increased plasma glucose for six days and significantly decreased milk yield for one day. The corresponding effects of 10 mg dexamethasone phosphate + 20 mg dexamethasone phenylpropionate lasted for at least nine and seven days, respectively. The therapeutic effect in bovine ketosis of the two preparations was measured by means of analysis of acetone plus acetoacetate in milk sampled daily during eight days post treatment. Acetone plus acetoacetate in milk from cows given dexamethasone phosphate + dexamethasone phenylpropionate (n = 11) decreased to normal levels and from the fourth day after treatment was significantly lower than in cows given dexamethasone isonicotinate (n = 12).

Fat cow syndrome in a British dairy herd

The fat cow syndrome developed over a two year period in a 100 cow dairy herd following overfeeding in late lactation and the dry period. It was characterised clinically by a high incidence of parturient paresis and chronic unresponsive ketosis in early lactation. The reproductive performance of the herd was poor throughout this period, with extended calving indices confirming a suggested link between fatty liver and infertility.

Fatty infiltration of liver in spontaneously ketotic dairy cows

The purpose of this study was to ascertain 1) fatty infiltration of the liver in spontaneously ketotic cows and 2) the most appropriate blood components to aid diagnosis of ketotic fatty liver. Liver biopsies and blood samples were obtained under field conditions. Cows were divided into three groups (healthy, mildly ketotic, and severely ketotic) by their blood ketone body concentrations. Severely ketotic cows had a greater percent fat in the liver than healthy cows. The mildly ketotic group fell between the other two groups and was significantly different from only the severely ketotic group. There was a positive correlation between fatty infiltration and blood ketone body concentrations but a negative correlation with glucose concentrations. Liver-specific enzymes were positively correlated with fatty infiltration. Only ornithine carbamoyltransferase and iditol (sorbitol) dehydrogenase could be used to separate healthy cows from those with severe ketosis. The best equation to explain the variation of percent fat in liver included concentration of beta-hydroxybutyrate (BHB) and logarithm of ornithine carbamoyltransferase concentration (Log-OCT): % Fat = -6.15 + 2.39 (BHB) + 11.7 (LogOCT) Although this equation explained 39.5% of the variation, it could not be used to predict reliably percent fat in the liver. Liver biopsy seems still to be the only reliable method of measuring of fatty infiltration in the liver.

Effect of niacin supplementation on milk production and ketosis of dairy cattle

In two experiments with Holstein cows effects of dietary supplementation of niacin to periparturient cattle on subsequent milk production and ketosis were examined. In Experiment 1, 20 cows were assigned to two groups. The treatment group received niacin at 6 g per head per day for 2 wk prepartum and 12 g per head per day for 4 wk postpartum. The control group received no niacin. In Experiment 2, 40 cows were assigned to four groups of 10 cows. One group served as the control and the other three received 3, 6, or 12 g niacin per head per day for 10 wk postpartum. In both experiments niacin-supplemented groups produced slightly more milk than controls. There were no consistent changes of milk composition with treatment. Glucose concentration in blood serum was higher for cows receiving niacin. Concentrations of beta-hydroxybutyrate and nonesterified fatty acids in blood and plasma were generally lower for niacin-supplemented groups. Niacin supplementation had no effect on feed intake or body weight changes. In Experiment 1 there was a significant reduction of niacin concentration in red blood cells of postpartum cows not receiving supplemental niacin. Insulin concentration in blood serum in Experiment 2 was unaffected by niacin supplementation.

Association of parturient hypocalcemia with eight periparturient disorders in Holstein cows

The association between parturient hypocalcemia and 8 periparturient disorders (dystocia, retained fetal placenta, metritis, left displaced abomasum, foot problems, ketosis, mastitis, and coliform mastitis) was evaluated in 33 Holstein dairy herds (2,190 cows) that calved from March 1981 through February 1982. There were highly significant (P less than 0.0001) associations between parturient hypocalcemia and dystocia, retained fetal placenta, ketosis, and mastitis. The odds ratios (multiplicative increases in occurrence) for these associations were 6.5, 3.2, 8.9, and 8.1, respectively. There was a significantly (P less than 0.03) association between parturient paresis and coliform mastitis (odds ratio, 9.0). There was a tendency for association with left displaced abomasum (odds ratio, 3.4; P less than 0.06).

Reduction in mitogenic response of bovine lymphocytes by ketone bodies

The effect of toxic or subtoxic concentrations of ketone bodies (acetone, beta-hydroxybutyrate, acetoacetate) in blood on function of bovine lymphocytes was studied in vitro. Lymphocytes separated from peripheral bovine blood were distributed into the wells of Linbro Microtiter plates containing control medium and test medium with various concentrations of ketones and/or phytohemagglutinin. The mitogenic response of lymphocytes was measured by incorporation of [3H]thymidine into DNA of lymphocytes. Toxic and subtoxic concentrations of beta-hydroxybutyrate or the toxic concentration of acetoacetate significantly affected the mitogenic response of bovine lymphocytes. The reduction in the mitogenic response also occurred when lymphocytes were only preincubated for 2 hours or longer with beta-hydroxybutyrate or acetoacetate. The presence of the toxic concentration of acetone in the medium did not affect the mitogenic stimulation of lymphocytes.

[Hyperglycemic and therapeutic action of nontranquilizing doses of xylazine in healthy sheep and cows and in cows with subclinical ketosis]

Experiments with 19 sheep and 26 cows revealed that subcutaneous and muscular injection of xylasine (Rompun - Bayer at 0.04 to 0.08 mg/kg body mass) led to a dependable increase in the level of blood sugar by 50-220 per cent for a period of 1 to 3 hrs. At the 6th to the 24th hour the amount of blood sugar came back to normal. In cows with subclinical ketosis (ketonuria ++ to +++ after Lastradet's test) and hypoglycaemia (blood sugar 29.7 +/- 4.6 mg%) the injection of xylasine (0.05-0.08 mg/kg body mass) increased the level of blood sugar by 169 to 185 per cent, which remained at a comparatively high level up to the 24th hour. Ketonuria dropped, however, full dusapperance of ketone bodies in the urine was observed in 7 per cent of the treated animals only. It is believed that although there was a pronounced hyperglycaemic effect of the preparation it cannot be applied alone for the treatment of ketosis-affected cows. It is important as an additional means, particularly with animals affected with the nervous form of the disease.

Prevalence of bovine ketosis in relation to number and stage of lactation

The prevalence of bovine ketosis as distributed among various selected subgroups of 504 Ayrshire and Friesian cows was studied during the indoor-housing season 1978–1979 in western and eastern parts of Finland. Special attention was paid to variation by lactation number. Also the differences in prevalence at various phases of lactation and at the end of pregnancy were investigated. The whole blood concentration of acetoacetate (AA concn) was analysed and used as a measure of subclinical and clinical bovine ketosis. AA cocns below 0.35 mmol/1, between 0.36 mmol/1 and 1.05 mmol/1 and over 1.05 mmol/1 were considered to indicate normal, subclinal and clinical ketotic stages, respectively. The prevalence of clinical ketosis in cows during 3 post-calving months was 13 %. The percentage of subclinical ketosis was 34. The prevalence of clinical ketosis was 3 %, 7 %, 20 %, 22 % and 13 % at the first, second, third, fourth and fifth, or sixth and later calving, respectively, and the frequency of subclinical ketosis 31 %, 41 %, 35 %, 32 % and 32 %, respectively. No case of ketosis was found in 54 cows at the end phase of pregnancy and only one during the first postcalving week. Only 2 cows (4 %) had the AA concn at a clinically ketotic level during the 65th—92nd postcalving days, 16 %, 17 % and 16 % during the 8th—21st, 22nd—42nd and 43rd—64th postcalving days, respectively.

Major metabolic determinants of milk volume, mammary efficiency, and spontaneous ketosis in dairy cows

Mammary uptakes of glucose and long-chain fatty acids are proposed to be the major metabolic determinants of milk volume production and mammary efficiency, respectively. Moreover, the ratio of glucogenic to lipogenic nutrients in the diet is proposed to be the major determinant of spontaneous ketosis. Experimental evidence and clinical observations are adduced in support of these three interrelated propositions. Their heuristic value would be demonstrable in tests of formulations of high-fat rations and administrations of articles, such as growth hormone preparations, intended to promote maximal production and efficiency with least risk of ketosis.

Primary ketosis in the high-producing dairy cow: clinical and subclinical disorders, treatment, prevention, and outlook

Bovine ketosis typically occurs in early lactation. Clinical signs include diminished appetite, decreased milk production, loss of weight, hypoglycemia, and hyperketonemia. Susceptibility to ketosis is probably due to the combination of appetite limitation and a high degree of precedence given to the demand of the mammary gland for nutrients, in particular glucose. The precipitating cause is likely to be development of a marked imbalance between glucose supply and glucose requirement. This imbalance then leads to decreased carbohydrate status, decreased insulin secretion, increased fat mobilization, and increased hepatic ketogenesis. Hepatic ketogenesis may be augmented by the diminished carbohydrate status. The role of hormones other than insulin in the etiology of ketosis, although probably important, has not yet been elucidated satisfactorily. Treatment of ketosis involves increasing glucose supply relative to glucose demand. Incidence of clinical ketosis can be minimized by correct nutrition and management as outlined in recommended guidelines. Besides decreasing milk field, clinical ketosis may affect productivity adversely in other ways, for example, by impairing fertility. Subclinical ketosis is important because it may remain undetected and yet have effects on productivity which parallel those elicited by clinical ketosis. Future research should be directed toward understanding mechanisms conferring priority on milk production and regulating appetite.

Husbandry methods predisposing to production diseases in dairy cows

Errors in management, other than nutrition, which can be predisposing causes of disease, eg, walking on abrasive surfaces and prolonged standing in slurry (which precipitate lameness), faulty milking and a dirty environment (which are conducive to mastitis), breeding to produce oversized fetuses (leading to dystocia) and inefficient observation (leading to a failure to detect oestrus) are described. Nutritional factors affecting conception rates and the occurrence of the metabolic diseases, ketosis, hypocalcaemia and hypomagnesaemia are outlined.