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The blood composition of 45 cows with more than 20 % fat in the liver (moderate fatty liver) was compared with that of 83 cows with less than 20 % fat in the liver (mild fatty liver). The cows were sampled at 1 week after calving and were from three Friesian and one Guernsey herds. Blood concentrations of non-esterified fatty acids, bilirubin and aspartate amino-transferase were significantly elevated in cows with more than 20 % in the liver whereas concentrations of glucose, cholesterol, albumin and magnesium were all significantly reduced. Blood samples from cows in two of the herds were analysed for ammonia, insulin and D(-)3-hydroxybutyrate. Cows with moderate fatty liver in these two herds had significantly lower insulin concentrations and higher D(-)-3-hydroxybutyrate concentrations than those with mild fatty liver. Using an equation based on blood concentrations of non-esterified fatty acids, glucose and aspartate aminotransferase it was possible to assign correctly three out of four cows to either the mild or moderate fatty liver groups.

Blood samples, taken on 6 occasions during 1 year from 172 cows resident in a dairy herd, were analysed for packed cell volume, blood glucose, haemoglobin (Hb), serum albumin, urea N, total protein, Ca, inorganic phosphate, Mg, Na and K. The data were analysed statistically, firstly with respect to date of sampling, stage of pregnancy or lactation and the interaction between stage of pregnancy or lactation and date of sampling, and secondly with milk yield as an additional factor for the data for lactating cows.Concentrations of all constituents except inorganic phosphate and K varied significantly (P < 0-001) with stage of lactation and/or pregnancy. The most significant changes in concentrations were confined to the periods up to 3 months either side of calving. The greatest changes in concentration during these periods occurred for Mg which rose during late pregnancy and for albumin which fell at or near calving. Albumin, urea and glucose were all, on average, lowest in concentration during the first month of lactation; globulin concentrations showed the reverse trend. Haemoglobin concentrations decreased during late pregnancy and early lactation and were lowest in the period 30-120 d post partum. Calcium concentrations decreased during late pregnancy and rose during early lactation. Sodium concentrations rose during late pregnancy. Interactions between dates of sampling and stages of lactation or pregnancy were significant (P < 0-001) for all constituents, and most marked for glucose, urea, albumin, Hb, Ca and Na.Haemoglobin and K concentrations fell and Mg concentrations rose with increasing milk yield, but the proportions of the total variance accounted for by differences in milk yield were small in relation to those accounted for by stage of lactation. These findings are of significance in relation to the selection of animals for sampling in the Compton Metabolic Profile Test.

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SUMMARYBlood samples were taken from groups of lactating and non-lactating cows on three occasions from each of 24 commercial dairy herds sampled eight herds at a time at 6-weekly intervals throughout 1972. The blood samples were analysed for packed cell volume, blood glucose and haemoglobin, and for the serum concentrations of albumin, total protein, urea nitrogen, Ca, inorganic phosphate, Mg, K, Na, Cu, and Fe.Clear seasonal patterns were evident for packed cell volume and the mean concentrations of urea nitrogen and haemoglobin each of which were highest during the summer months. The effect of season on the concentrations of the other constituents was smaller. Mean values of packed cell volume, haemoglobin and Fe were consistently higher in the non-lactating cows than in the lactating cows. Mean concentrations of Mg were lower in the blood of non-lactating cows throughout the year; Cu concentrations followed a similar trend in the autumn and winter.There was evidence of overall herd differences regardless of season, in particular for Cu, globulin, Fe and urea nitrogen concentrations.

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Weekly blood samples were collected from 42 Friesian cows between 5 weeks before and 10 weeks after calving, and analysed for serum cholesterol, albumin, total protein, glutamate-dehydrogenase, sorbitol-dehydrogenase and ornithine-carbamyl-transferase and blood glucose.Cholesterol concentrations increased 2^-fold during the first 8 weeks of lactation. There was also a transient decrease in glucose concentration at calving, but there was no relationship between conception rate and the concentrations of these two constituents.Albumin concentrations decreased at calving in some but not all cows and remained low for up to 2 weeks. Average concentrations of albumin determined by two analytical methods, a HABA dye-binding and a single radial diffusion assay method, were significantly lower (P < 0-05) between 0 and 2 weeks post-partum in eight cows which required four or more services than in 32 cows which conceived after fewer services. Similarly, the average decrease in concentration over calving was greater in those cows which conceived only after four or more services (P < 001).Globulin concentrations (total protein minus albumin) decreased during the 5 weeks before, and increased in the 3 weeks following calving. The net change over calving was significantly related to conception rate, and the albumin/globulin ratio was reduced (P < 0-001) in the eight cows requiring four or more services.Activities of all three enzymes doubled after calving, but there was no correlation between these increases and the decreases in albumin concentration, suggesting that, if liver insufficiency is a factor, it is probably due to malfunction rather than tissue damage. o r c l o s e t o calving, and have shown that concentrations may not return to pre-calving values until In a study of 351 dairy cows sampled between 2 or 3 months later. Little (1974) showed that the 40 and 100 days post-calving, Rowlands, Little & decrease does not occur in all cows, and concluded Kitchenham (1977) found a negative association that those affected synthesized less albumin. The between serum albumin concentration and both cows in which albumin concentrations decrease milk yield and the number of services required for least at calving, or recover most quickly, are likely conception.to be those with the highest concentrations in early Several authors (Hojovcova, 1966;Little, 1974; lactation. Manston et al. 1975;Rowlands et al. 1975; Szulc, The objectives of the study described Treacher et al. 1976) have noted decreases paper were to ascertain the degree to which indiin serum albumin concentration in dairy cows at vidual cows show such characteristic changes in • Present address: Nuffield Department of Clinical albumin concentration, to test the hypothesis Medicine, John Radcliffe Hospital, Oxford.(Rowlands, 1978) that cows which are better able