Metabolic and immunocompetent traits were determined in blood of 25 potential AI-bulls both under feeding conditions and during starvation. Bulls with high pedigree breeding value (PBV) had higher glucose level (9th day of starvation), higher level of erythrocytes and lower levels of leucocytes than bulls with moderate PBV. The correlations between counts of red blood cells and counts of white blood cells were -0.38 ... -0.60. The metabolites bilirubin and glucose and the enzymes GGT and ASAT were positively correlated with erythrocytes and negatively with leucocytes in all cases. Between the concentrations of thyroxine and that of C-reactive protein positive correlations of 0,09 ... 0,35 were estimated. In contrast to this correlations between thyroxine and lymphocytes were negative in all cases (-0,04 ... -0,41).The results of this investigation suggest that metabolism and immune system are associated in many ways and therefore the genetic improvement of yields also influence the animals health.

Measurement of dorsal fat thickness is a fundamental method for investigation and characterization of energy and fat metabolism of dairy cow. A comparison is made in this paper between dorsal fat thickness and body fat and its variations in the context of live weight as well as subjective assessment of general condition. Reference is made to additional investigation methods complementary to measurement of dorsal fat thickness. Combination of measurement of dorsal fat thickness with visual inspection of animal condition is recommended for monitoring of larger dairy cattle herds.

Feed uptake and energy balance are known to have a substantive impact on the correlations between milk yield, fertility and general health of dairy cow. Significant correlations were found to exist between dorsal fat thickness and energy uptake as well as energy balance. Assessment of the behaviour of the energy balance in the course of lactation is possible by reference to the curve of dorsal fat thickness. The proposal is made for specific consideration of energy balance as body fat retention.

Title of the paper: Energy and fat metabolism, fertility and general health in dairy cows. The demand for energy is the point which four criteria (kinds) of cattle performance have in common, which are growth, milk yield, fertility, and general health. Quantitative estimation of the body fat depots may be helpful in determination of energy metabolism. Body fat reserves can be quantified by the measurement of backfat thickness. Backfat thickness or its variations show significant correlations with feed intake, energy balance, milk yield, fertility results, ketosis, and fatty liver. Resulting from these results, there is an optimum of the amount of body fat reserves, which can be established with the measurement of backfat thickness. Keeping, feeding and breeding regimes should be oriented to stabilise positive effects of fatty tissue in terms of high milk yield, enhanced fertility and general health by minimising its negative pathological potentials. Measurements of backfat thickness may be helpful in establishing threshold (reference) values for systematic monitoring and control of fatty tissue function in dairy cow. Measurement of backfat thickness as an objective method for body condition scoring should be used as an important herd management tool in dairy. farms.

From 27 dairy cows with a mean milk yield of 6900 kg FCM (4% milk fat) per 305 day lactation period liver bioptates 2 weeks post partum (p.p.), milk samples 2, 4 weeks p.p., blood samples 0 (partus), 2, 4 week p.p., measurement of backfat thickness 2 weeks prior to calving, 0, 6, 17 weeks p.p. were taken and body weight and milk yield were determined. Fertility results and disorders appearance were recorded too. Total lipid and triglyceride content were analysed in liver tissue. Acetone concentration was determined in milk and 15 clinical-chemical parameters were elucidated in blood samples. Liver fat concentration shows a great variability from 3.9% to 24%. There is no strong reference value for the distinction between physiological and pathological liver fat concentration. Assessment as to whether increased liver fat levels in dairy cow are indicative of liver damage due to a pathological process should include detection of liver cell damage on the basis of plasma enzymes with closest possible specificity of liver. Glutamate-dehydrogenase (GLDH) is recommended. Liver fat content clearly could be defined exclusively from investigation of liver tissue rather than from analysis of blood or milk parameters. Measurement of backfat thickness provided useful information on the post partum lipolysis rate with a good correlation to liver fat (r to -0.72).

Dorsal fat thickness is a measure of body fat, while its variations are indicative of mean rates of lipolysis or lipogenesis within a defined experimental period. An account is given in this paper of relationships between dorsal fat thickness or its variations, on the one hand, and milk yield, fertility, as measured by service intervals or intercalving periods, as well as behaviours of various clinico-chemical parameters as criteria for general health assessment, on the other. The findings are compared with live weight data. There is a margin of optimum fat development. Both too low or too high fat depots at the time of calving may have adverse effects on milk yield, fertility and general health of dairy cow.

In 2 tests Dairy cows (SMR) were observed during the raising and to the 2. lactation. The measuring of subcutaneous fat thickness showed correspondence of lipolysis around the 12. months of life and post partum. There were relations to the Insulinsystem. Remains of body-capacity connected with a lower feed intake reduce the efficiency of the milk production. Deficits of energy are equalized by body fat during the 1. lactation.

Liver bioptates taken 2 weeks post partum from 213 high-yielding cows (6000-8000 kg FCM per 305 days lactation) were investigated biochemically to liver lipid content (GL) and histologically to degree of lipid infiltration (GdL). Additional in 27 cases electron microscopic studies to liver cell morphology and clinico-chemical investigations (beta-OH-butyrate and acetacetate in blood; quantity of bilirubin, albumine, protein, activity of ASAT and GLDH in blood plasma) were carried out. 22.5 % of liver bioptates were histologically free of lipid infiltration (GL: 2.34 %; GdL: 0). 77.5 % of liver bioptates showed different lipid quantities (GL: 5.1-24 %; GdL: 0.3-5.7 %). 27 cases additionally investigated electron-microscopically and clinicochemically can be summarized in 3 groups (with regard to lipid contents): 1. < 5 %, n = 7; 2.5-10 %, n = 10; 3. 10-24 %, n = 10. Electron microscopic changes concerned occasional nucleus alterations, frequent RER dilation, mitochondria condensation or swelling, occurrence of secondary lysosomes and glycogen decrease. RER dilation and mitochondria swelling showed a statistical relation to liver lipid content. Ketone body (beta-OH-butyrate, acetacetate) and bilirubin concentration climed with increasing quantity of liver lipid. Activities of GLDH and ASAT failed any dependence to lipid quantity.The results are discussed under the aspect of pathogenesis and dignity of fatty degeneration of the liver post partum.

Liver biopsies taken 2 weeks post partum from 213 high-yielding cows (6000-8000 kg FCM per 305 days lactation) were investigated biochemically to liver lipid content (GL) and histologically to degree of lipid infiltration (GdL). Additional in 27 cases electron microscopic studies to liver cell morphology and clinico-chemical investigations (beta-OH-butyrate and acetate in blood; quantity of bilirubin, albumin, protein, activity of ASAT and GLDH in blood plasma) were carried out. 22.5% of liver biopsies were histologically free of lipid infiltration (GL: 2.34%; GdL: 0). 77.5% of liver biopsies showed different lipid quantities (GL: 5.1-24%; GdL: 0.3-5.7%). 27 cases additionally investigated electron-microscopically and clinico-chemically can be summarized in 3 groups (with regard to lipid contents): 1. < 5%, n = 7; 2.5-10%, n = 10; 3. 10-24%, n = 10. Electron microscopic changes concerned occasional nucleus alterations, frequent RER dilation, mitochondria condensation or swelling, occurrence of secondary lysosomes and glycogen decrease. RER dilation and mitochondria swelling showed a statistical relation to liver lipid content. Ketone body (beta-OH-butyrate, acetate) and bilirubin concentration climbed with increasing quantity of liver lipid. Activities of GLDH and ASAT failed any dependence to lipid quantity. The results are discussed under the aspect of pathogenesis and dignity of fatty degeneration of the liver post partum.

57 Dairy cows (SMR) of the 2, lactation were fed separate during the dry period. The level of energy supplying reached from 2 to 16 kg EKM (energy corrected milk) over maintenance. The change of subcutaneous fat thickness and of body weight were high correlated with the energy intake. The correlation of subcutaneous fat thickness was higher. The rate of lipolysis during the last 2 weeks of the dry period was correlated with the thickness of subcutaneous fat, the activity of Glucose-6-phosphat-Dehydrogenase in the fat tissue and the change of energy intake.A higher rate of lipolysis was correlated with the fat content of the liver and the content of Bilirubin in blood at parturition.

Four adult cows in advanced age and late lactation, all of them in average health condition, and three non-lactating cows of comparable age level with severe obesity, after having been fed ad libitum, received a low-energy diet, ten percent of maintenance demand, through four weeks. The intention was to trigger off lipolysis via negative energy balance, in order thus to provoke fatty degeneration of the liver. The late-lactating cows reached liver fat levels around 16 percent, whereas only about eight percent were reached by the non-lactating cows with severe obesity. Liver fat values continued to be increased with significance throughout the entire experimental period. Weekly liver biopsies were accompanied by simultaneous measurements of live weight and dorsal fat thickness as well as by blood sampling. The clinico-chemical blood parameters were associated with post-partum energy deficit and onset of lipolysis but failed to provide evaluable on liver fat levels. The latter could be judged only through examination of liver samples. GLDH should be determined in parallel for assessment of liver cell damage. The experimental model used proved to be suitable only for investigation of fatty degeneration of the liver in dairy cow. Measurement of dorsal fat thickness may be useful in assessment of fat mobilization.

Two series of investigations were performed on 142 or 1 00 cows in their first to tenth lactations to measure dorsal fat thickness eight and four weeks prior to parturition, at the juncture of calving as well as two, four, eight, and 16 weeks post partum. Hundred-day milk yield, interval between calving and insemination, intercalving period as well as various clinico-chemical parameters were also recorded from the two above groups of animals. Keeping, feeding, and breeding regimes should be oriented to stabilising effects of fatty tissue in terms of enhanced fertility and general health and, at the same time, to minimising its pathological potentials. Dairy cows should have sufficient fat reservoirs at the time of calving. Post partum lipolysis rate should slowly start at the beginning of lactation but may be protracted to last until 16 weeks post partum. Measurement of dorsal fat thickness may be helpful in establishing threshold values for systematic monitoring and control of fatty tissue function in dairy cow.

Insulin and glucose regulation plays a central role in regulating distribution of metabolites between udder and body tissues and, consequently, in ensuring optimum adjustment between milk yield and health stability. An experimental study was conducted into four dairy cows, between 17 weeks before and 52 weeks after calving to establish six diurnal profiles for insulin and glucose concentrations in blood plasma and undertake 18 glucose tolerance tests, nine of them simple and nine modified. The three methods used in examination provided differentiated but complementary data on the glucose-insulin system ot dairy cow. Flow of metabolites in the mammary gland, in early lactation, was found to be supported by low insulin concentrations in blood plasma, reduced pancreatic response to insulinogenic stimuli, and decreased responsiveness of peripheral cells to insulin. Endocrine adaption to catabolic metabolism had its onset as early as several weeks before calving. Alterations to insulin concentrations in blood plasma as well as to pancreatic reactivity to insulinogenic stimuli and to responsiveness of peripheral cells to insulin were found to take place at various junctures. It should be proved to use the common and modified glucose tolerance test for the description of the individual metabolic type of each single dairy cow.

Insulin and glucose regulation plays a central role in regulating distribution of metabolites between udder and body tissues and, consequently, in ensuring optimum adjustment between milk yield and health stability. An experimental study was conducted into four dairy cows, between 17 weeks before and 52 weeks after calving to establish six diurnal profiles for insulin and glucose concentrations in blood plasma and undertake 18 glucose tolerance tests, nine of them simple and nine modified. The three methods used in examination provided differentiated but complementary data on the glucose-insulin system of dairy cow. Flow of metabolites in the mammary gland, in early lactation, was found to be supported by low insulin concentrations in blood plasma, reduced pancreatic response to insulinogenic stimuli, and decreased responsiveness of peripheral cells to insulin. Endocrine adaptation to catabolic metabolism had its onset as early as several weeks before calving. Alterations to insulin concentrations in blood plasma as well as to pancreatic reactivity to insulinogenic stimuli and to responsiveness of peripheral cells to insulin were found to take place at various junctures. It should be proved to use the common and modified glucose tolerance test for the description of the individual metabolic type of each single dairy cow.

Optical light and electron microscopy were used in follow-up investigations of liver bioptates obtained from two groups of nonpregnant cows, including four individuals with delayed lactation (Group 1) and three without lactation (Group 2), which were all kept on restricted diet for four weeks (ten percent of maintenance rations). The findings recorded were related to selected clinical or biochemical parameters. The following evidence was found during the fasting period and was more strongly and regularly pronounced in Group 1 rather than in Group 2: fatty degeneration of the liver, glycogen drop, mitochondrial consolidation or condensation, dilatation and vesiculation of RER with partial detachment of ribosomes, increased occurrence of autolysosomes, occasional alterations to nuclei (condenstion of karyoplasm, karyopyknosis), hyperbilirubinaemia, increased activity of,two enzymes, GLDH and ASAT (the latter only in Group 1) as well as reduction of body weight, dorsal fat thickness and milk yield (the latter in Group 1). The morphological, ultrastructural as well as certain clinicochemical findings (bilirubin, GLDH and some ASAT behaviours) appeared to be indicative of impairement to various metabolic processes in the liver when the organism was experimentally exposed to fasting. These findings are described in some detail and are related to the degree and dynamics of incorporation of fat in hepatocytes and, finally, are discussed under the aspect of pathogenesis of fatty degeneration of the liver.

Insulin plays a central role in regulating distribution of metabolites between udder and body tissues and, consequently. in ensuring optimum adjustment between milk yield and health stability. An experimental study was conducted into five dairy cows. between 17 weeks before and 44 weeks after calving to establish six diurnal profiles for insulin and glucose concentrations in blood plasma and undertake 17 glucose tolerance tests. nine of them simple and eight modified. The three methods used in examination provided differentiated but complementary data on the glucose-insulin system of dairy cow. Flow of metabolites in the mammary gland, in early lactation, was found to be supported by low insulin concentrations in blood plasma, reduced pancreatic response to insulinogenic stumuli, and decreased responsiveness of peripheral cells to insulin. Endocrine adaptation to catabolic metabolism had its onset as early as several weeks before calving. Alterations to insulin concentrations in blood plasma as well as to pancreatic reactivity to insulinogenic stimuli and to responsiveness of peripheral cells to insulin were found to take place at various junctures.

Blood collection from the jugular vein is a major reference condition in GDR Standard TGL 34313 on metabolic monitoring of dairy cattle units. Blood samples are quite often taken from the subcutaneous abdominal vein, as well. Nine SMR cows, all in the second lactation, 4,800 kg in average milk yield, were included in an experiment to find out if agreement existed between selected clinico-chemical values in blood samples from both veins. Checks were continued from the last week before to the 20th week after calving. Sizeable discrepancies were recorded primarily from metabolites involved in udder metabolism or appearing in the milk. Blood sampling from the subcutaneous abdominal vein was found to be unsuitable for metabolic investigations and may lead ot misinterpretation, when compared to TGL reference values.

Two-year studies were conducted into 111 cows on a dairy cattle unit for a period from eight weeks prior to calving to 16 weeks post partum. Included were collection of liver bioptates, fatty tissue and blood samples, measurement of dorsal fat thickness as well as determination of milk yield and fertility results. Total lipid and triglyceride levels and liver density were recorded from liver tissue. Fat and protein levels as well as activities of NADP-dependent dehydrogenases were determined from fatty tissue, while 19 clinico-chemical parameters were elucidated in the blood samples. Liver fat reached its highest values one to three weeks postpartum. Lipotrophy clearly could be defined exclusively from investigation of liver tissue proper rather than from analysis of blood parameters. Measurement of dorsal fat thickness provided useful information on the postpartum lipolysis rate, the most important contributory factor to pathogenesis of lipotrophy. Rise in the postpartum lipolysis rate was found to act equally increasing upon milk yield and liver fat. Judgement as to whether increased liver fat levels in dairy cow are indicative of liver damage due to a pathological process cannot be made simply with reference to liver fat alone. Additional attention should rather be given to other criteria for detection of liver cell damage on the basis of an enzyme of closest possible specificity of liver in blood plasma. Glutamate-dehydrogenase (GLDH) appears to be an enzyme suitable for the purpose. A pattern for assessment of liver lipotrophy is proposed in this paper.

Proper evaluation of increased ketone body concentrations in blood or milk requires determination beforehand of the cause of higher ketogenesis. Ruminogenic (alimentary) ketogenesis is not a pathological problem per se but is simply a symptom accompanying ketogenic feed rations. It actually reflects adaptation of the dairy cow to postpartal energy deficit. Ketosis, on the other hand, is associated with pathologically increased ketogenesis with subclinical manifestations. It has adverse effects on general performance, fertility, and health. Particular reference is made in this paper to differences between spontaneous ketosis (overfeeding ketosis) and starvation ketosis (underfeeding ketosis). Also mentioned are some of the critera used to distinguish between various conditions related to increased ketone body concentrations. They are additionally explained by the example of a feeding experiment.