Chymostatin is an effective inhibitor of intracellular proteinases in vitro. In the present experiment male rats were injected intraperitonealy during a 3 days period twice daily with a solution containing 0,9 mg Chymostatin per 100 g live weight. Reference animals received a control injection containing the same solvents but no chymostatin. During this period a daily nitrogen balance was made and metabolic faecal nitrogen and true digestibility of nitrogen were estimated using 15N-labelled animals. Furthermore, apparent biological half lives of proteins in liver and intestinal tissues were determined following the decay curves for radioactivity in proteins 48 hours after injection of L-[5-3H]-arginine und L-[guanido-14C]-arginine. The fractional rate of protein synthesis in tissues was measured by a 6 hours continuous infusion technique with L-[U-14C]-tyrosine and L-[U-14C]-leucine. Among the parameters estimated only the apparent biological half lives of proteins in liver and intestinal tissues were influenced by chymostatin. However, the prolonged half lives seemed to be rather an effect of an increased reutilisation of amino acids resulting from the intracellular protein breakdown than a decreased rate of protein degradation. The in vivo effect of the proteinase inhibitor was by far inferior compared with the action in vitro. Factors like distribution, degradation and excretion of the inhibitor could be responsible for the moderate in vivo action of chymostatin.

Animals↗

PubMedDate not supplied

Urea utilization in the large intestine of sheep.

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Animals↗

PubMedDate not supplied

Urea utilization in the large intestine of bulls.

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Ammonia↗

PubMedDate not supplied

The effects of treated straw meal on ileal and faecal digestibility of nutrients in pigs.

Four 40 kg castrated male pigs fitted with simple 'T' cannulas in the terminal ileum were given diets of varying crude fibre content in a change-over experiment with two periods. The basal diet was composed of wheat and fishmeal supplemented with minerals and vitamins. To this was added varying levels of partially hydrolysed straw meal to give crude fibre contents ranging from 40 to 132 g/kg. After adaptation to the particular levels of straw meal, faeces and ileal digesta were collected during successive 24 h periods. Nutrient digestibility values were determined by the chromic oxide ratio method. The addition of treated straw meal to the diet had little or no influence on the DM content of digesta or faeces. The excretion of N in faeces increased with increasing fibre intake but there was no effect on urine N excretion. The overall apparent digestibility of N was reduced from 89 to 79% as crude fibre intake increased from 40 to 132 g/kg but ileal apparent digestibility of N remained constant at about 68%, suggesting that the effect was mediated through hindgut bacteria. Increased fibre intake caused increased net secretion of Na in the small intestine and reduced the apparent absorption of P in the large intestine.

Animal Feed↗

PubMedDate not supplied

[Studies on nitrogen metabolism in the large intestine of ruminants. 5. Metabolism of intra-cecally infused 15N-urea without and with fermentable material in heifers].

Six heifers with a live weight of 215, 227 and 238 kg (experiment 1) and 220, 227 and 233 kg, resp. (experiment 2), were supplied with ileocaecal re-entrance cannulae, jugular venous catheters and bladder catheters. The ration consisted of 4 kg maize silage and 4 kg wheat straw pellets per animal per day. Up to 3.5 kg of the straw pellets, consisting of 73% wheat straw, 10% barley, 12% molasses, NPN salts and a mineral mixture, were consumed per animal per day. In a preliminary period 50% of the digesta flow was collected over 12 h/d on 5 consecutive days and stored in a deep-freeze. During the main trial the re-entrance cannula was disrupted and the flowing digesta were quantitatively collected at the end of the ileum; previously collected digesta were supplemented with 15N urea and every hour over 24 h infused into the caecal part of the re-entrance cannula. Between the 24th and 30th hours the digesta were infused without 15N urea supplement. In trial 2 the digesta were also supplemented with partly hydrolysed straw meal between the 1st and 30th hours (approximately 10% straw meal DM related to digesta DM). There were no differences between trials 1 and 2 with regard to the increase of atom-% 15N excess (15N') in the plasma urea. The 15N labelling decrease of the plasma urea N shows that the half-life is 7.9 h in trial 1 and 7.0 h in trial 2. The NH3 nitrogen in faeces was distinctly higher labelled in trial 2 after the supplement of straw meal than in trial 1. The total N in faeces was also twice as highly labelled as in trial 1. Atom-% 15N' in urine was significantly higher in trial 2 than in trial 1 between the 6th and 16th hours after the beginning of 15N urea supplementation. In the decrease curve of atom-% 15N' (after the 26th hour of trial) the values in trial 1 were generally higher than in trial 2. The higher bacterial protein synthesis in the large intestine in trial 2 (after the supplement of partly hydrolysed straw meal) had the effect that 13.6% of the supplemented 15N' was excreted in faeces by the 30th hour of trial, in contrast to this only 4.7% in group 1. Up to the 4th day after the 15N urea infusion these values increased to 16.2 and 6.1%, resp., only.

Animal Feed↗