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.

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.