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With two groups of dairy cows (A: 12 German Black and White- and 6 German Simmental Cows; B: 16 German Black and White- and 11 German Simmental Cows) allantoin concentrations of blood plasma (A) and milk (A and B) were analysed by HPLC. There exists a close correlation (r = 0.758) between allantoin concentration in blood plasma (370.6 +/- 79.1 mumol/l) and milk (474.1 +/- 78.9 mumol/l). The relation between milk yield and allantoin excretion with milk seems to be non-linear (r = 0.936). On the other hand there is a close correlation between energy intake with feed and allantoin excretion via milk (r = 0.885). In a further experiment the allantoin concentrations in blood plasma of 5 Angler steers were monitored for 24 h every second hour with feeding twice daily. There were remarkable fluctuations in the allantoin concentration from nearly 156 to 129 mumol/l. After that the rumen of the steers was emptied, while plasma concentrations were still monitored the same way as before. Concentrations of allantoin declined for about 55% to 65 mumol/l.

In milk and blood plasma samples of 6 German Simmental and 12 German Black and White heifers it was investigated, whether purine and pyrimidine compounds are suitable indicators of the microbial protein synthesis in the rumen. Therefore the secreted quantities in milk and the concentration in blood plasma are correlated with energy intake. The results indicated significant correlation coefficients for both the secretion quantity of allantoin in milk (r = 0.942) and the concentration of allantoin in blood plasma (r = 0.694). Other investigated compounds appeared more suitable for evaluating the mammary gland metabolism (uridine-lactose synthesis, pseudouridine-protein synthesis). In an experiment with 7 male castrated pigmy goats subjected to a four-day fasting period the decrease of plasma allantoin, which was already apparent after 12 hours of fasting, was closely correlated with the increase of plasma free fatty acids.

The number of hepatic peroxisomes, cores, marginal plates, and microperoxisomes in piglets increases from a low level at birth, compared with other species e.g. the rat, to day 28 of life. The number of peroxisomes is correlated to the activity of uricase, but morphometry alone is not sufficient to quantitate uricase activity. These findings might explain the occurrence of renal uric acid deposition (infarction) during a catabolic state, where body protein is metabolized to an increased extent and purine levels rise. Due to a relative lack of uricase uric acid is not completely oxidised to allantoin.

In order to study mechanisms in ruminants responsible for glucocorticoid-induced hyperglycemia the effects of a single intravenous dose of a glucocorticoid on energy metabolism were investigated by measuring plasma levels of glucose, lactate, free fatty acids (FFA), 3-hydroxybutyrate (3-HOB) and acetoacetate (AcAc). Experiments were performed on four castrated male African pygmy goats at two metabolic states: "fed" with a single daily meal of hey and "fasted" with starvation for 3 days. The untreated goats served as their own control. The glucocorticoid application to fed animals resulted in an increase in glucose level (+43%) lasting more than 11 h and an irregular increase of lactate. The concentration of 3-HOB was increased especially before feeding (+64%). In contrast, FFA were decreased (-27%) the second day after glucocorticoid application. In fasted goats the glucocorticoid also caused an increase in glucose level (+25%). The effect was smaller than in fed animals. Concentrations of FFA, 3-HOB and AcAc were 10, 20 and 35% lower than those of untreated goats. With regard to the antiketotic use of glucocorticoids the decrease of plasma levels of FFA and ketone bodies in starving animals is of special importance. Obviously the animals were able to use glucose again as a main energy source instead of FFA.

To investigate metabolites of nucleic acids in milk as by-products of protein biosynthesis, a method for determination of pyrimidine and purine compounds by reversed-phase high-pressure liquid chromatography was developed. Reproducibility of the measured compounds was 2%. Recovery of the main constituents averaged about 99%. In addition to orotic acid, allantoin, and uric acid, the free bases hypoxanthine, xanthine, and guanine, the ribonucleosides uridine, cytidine, and pseudouridine, and the ribonucleotides, guanosine 5'-monophosphate and cytidine 5'-monophosphate, were quantified in milk samples of Holstein-Friesian cows. Milk production from days 45 to 65 of lactation influenced concentrations of individual metabolites differently. Concentrations of orotic acid, allantoin, and uric acid decreased with increasing milk production, whereas concentrations of uridine, cytidine, pseudouridine, hypoxanthine, xanthine, and guanine remained unchanged. The results allowed conclusions on rate limiting steps of catabolic pathways of pyrimidines and purines and indicated relationships with protein biosynthesis. A possible role of metabolites of nucleic acids as taste factors and as substrates for milk microbes is suggested.

After introducing into developmental aspects of "Dalmatian dog research" uric acid excretion is explained on the basis of new results by the loss of a specific transport system in liver cell membranes. Therefore, uricase which is present in normal activities is supplied only to a limited extent with uric acid for the transformation into the easily soluble allantoin. As indicated by feeding experiments, the plasma urate level is increased from about 32 mumol/l (no purine intake) up to 150-200 mumol/l at very high levels of purine intake. Thus, the influence of nutrition on plasma urate level is extraordinary. The diseases urate-urolithiasis and "bronze syndrome" associated with dalmatian urate metabolism are characterized in view of the typical pattern of the diseases and of the therapeutical and prophylactical measures to be taken.

For the evaluation of single-cell protein (SCP) the proportion of dietary purines made available by digestion and absorption was estimated with dogs (Dalmatian) in total urine collection experiments. The animals received a low purine control diet with 25% casein, diets with 25-100% replacement of casein by a bacterial SCP grown on methanol, and the control diet plus yeast RNA purine equivalent to SCP diet. Nucleic acids, bases, and purine metabolites were determined by reversed-phase high-pressure liquid chromatography. The quantitative influence of dietary purines (x) on renal purine excretion (y) was described by the equation (millimoles per day) y = 0.57x + 3.52 (r = 0.955) indicating the endogenous excretion rate of 3.5 mmol/day and the metabolic availability of 57% of ingested purines. As the ratio of urate to allantoin increased with purine intake, individual equations were established for both metabolites. On the control diet + RNA and SCP diet (100% replacement for casein), purine intakes of 20.0 and 18.2 mmol/day resulted in purine excretion values of 7.3 and 11.4 mmol/day (P less than 0.05). The proportion of free bases in the latter diet appeared as the main reason for this differences. Other influences are discussed.

In rats given D[u-14C]-labelled DL-lactate with 3.8-13.4 mmol D-lactate per kg 0.75 by stomach tube, the exhalation of CO2 produced from and the renal excretion of D-lactate and metabolites were measured. Exhalation of D-lactate-C accounted for 45-30% of the dosage given with a decreasing proportion at higher doses. The renal excretion of D-lactate averaged 0.9% and that of metabolites from D-lactate 2.4% of the doses given. The fraction of unrecovered D-lactate accounted for about 54-68% of the doses given and increased with doses. The time course of D-lactate oxidation indicated a maximum rate of about 1.5 mmol C per kg 0.75 in 1 hr which was reached at 1 hr after infusion at the earliest and extended up to 8 hr if high doses were given.