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An electromagnetic method was adapted to quantitatively measure blood flow through an external pudic artery of the udder in lactating cows during several months. Blood flow through the ipsilateral external pudic vein was blocked while blood was taken from a subcutaneous abdominal vein. Blood flow to milk yield ratio amounted to a mean value of 507:1 in three cows. Peak milk yield occurred before the time of our experiments. There was a high correlation (r = .73) between mammary arterial blood flow and milk yield. Arterio-venous differences (AV) across the udder demonstrated that essential amino acids (EAA) were taken up by the mammary gland in sufficient amounts to account for the EAA secreted as milk protein. Uptake of valine, isoleucine, lysine and particularly that of arginine was in excess of that for milk protein synthesis. There was a highly significant correlation (P<.01) between AV differences of several amino acids and their corresponding arterial concentrations. Uptake of glucose was This work was supported by grants from the lnstirut pour l'Encouragement de la Recherche Scientifique dans l'Industrie et l'Agriculture. The authors gratefully acknowledge Professor Dr. W. Welvaert of the Department of Phytopathology and Phytovirology of the University of Ghent, in whose laboratory the ultra-centrifugal analyses were carried out. They also acknowledge Dr. C. Burvenich, Mrs. M. Onghena-Anaf, Mrs. L. De NeveVan Lancker, Mrs. G. Vranken-Verhelst and Mrs. M. Buelens-Van Haute for skilled technical assistance. a Laboratory of Veterinary Physiology. State University Centre of Antwerp. 3 Laboratory of Chemical Analysis of Food from Animal Origin. Veterinary Faculty of the University of Ghent. 4 Department of Surgery. Veterinary faculty of the 19% higher than could be accounted for by secretion as milk lactose. Uptake of plasma triglycerides (TG) accounted for 45% of milk TG. The majority of the TG taken up by the udder was derived from the low density lipoprotein (LDL) fraction.

Summary To induce diarrhoea and hypovolaemia, newly‐weaned conventionally bred piglets (3‐ to 4‐ weeks‐old), were either given secretagogues or were inoculated with enterotoxigenic Escherichia coli (ETEC). Choleratoxin (n = 2), E. coli heat‐labile enterotoxin (n = 2) or castor oil (n = 2) were given intragastrically or piglets were intraperitoneally injected with DL 5‐hydroxytryptophan (n = 3). These substances induced a transient diarrhoea without clinical symptoms of dehydration. Therefore, a combination of castor oil and DL 5‐hydroxytryptophan was given two times a day during 3 consecutive days to 3 piglets. Although diarrhoea lasted for 5 days, still no hypovolaemia occurred. Probably the secretagogues have to be given continuosly to mimic the continuous release of enterotoxins during secretory colibacillary diarrhoea. It was, therefore, tried to reproduce colibacillosis in the just‐weaned piglets. Animals were inoculated with K88ac fimbriae producing ETEC strains (O149: K91: K88ac; LT, STa and STb positive) (n = 7), or pretreated with chloramphenicol followed by the ETEC inoculation (n = 8), or pretreated with the antibiotic, inoculated with an enteropathogenic coronavirus, transmissible gastroenteritis virus (TGEV), and subsequently inoculated with ETEC (n=18). Only the last procedure induced a reproducible diarrhoea (93%) and dehydration resulting in a mortality of 80%. It was concluded that the latter experimental procedure could be used to study diarrhoea and hypovolaemia in newly‐weaned piglets and to evaluate the effect of potentially antisecretory drugs on postweaning diarrhoea in piglets.

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The effect of an intravenous bolus injection of endotoxin, 0.1, 1 or 10 micrograms/kg, on rectal temperature, clinical appearance, haematological parameters, and on gastrointestinal electrical activity was examined in 11 conscious piglets of 4-5 weeks of age, with implanted electrodes in the antrum pylori, duodenum, jejunum and ileum. All doses resulted in a significant and dose-dependent increase in rectal temperature, in pronounced clinical signs and in distinct changes in haematological values. These included shivering, depression, respiratory distress, a leukopenia (0.1 micrograms/kg) or a leukocytosis (1 microgram/kg) with a shift to the left, an accelerated sedimentation rate and a decreased packed cell volume. Doses of 1 and 10 micrograms/kg induced a transient inhibition of gastroduodenal electrical activity. These results suggest that, in the piglet, endotoxin primarily manifests general clinical signs and that the gastrointestinal effects coincide with these.