Pigs fitted with ileo-rectal anastomoses (IRA) and in parallel experiments intact (INT) pigs were used to estimate the influence of the different grinding fineness of barley and wheat (coarse, medium, fine) on the apparent and true precaecal and total digestibility resp. absorption of various N free and N containing nutrients, among them crude protein and the indispensable and dispensable amino acids. Coarse grinding (25 ... 50% of the particles greater than 2 mm) resulted in significantly lower digestibility values than medium and fine grinding--with more striking differences in barley than in wheat. Precaecally most nutrients and amino acids are distinctly less digestible than at the end of the total tract. The precaecal lysine absorption determined with IRA pigs is remarkably low. The results are discussed. In order to attain a good utilization of the protein contained in cereals grains should be ground in hammermills with maximal sieve meshes of 3 mm. It is proposed to tabulate crude protein and amino acids in future on the basis of a standardized true precaecal digestibility resp. absorption.

In digestion trials using pigs fitted with ileo-rectal anastomoses and parallel intact pigs the influence of wheat straw meal (WSM) or grass meal (GM) supplemented on two different levels to a basal diet was examined with regard to nutrient and amino acid digestibility resp. absorption. Both roughages reduced, obviously because of their high cell wall contents, nearly at equal amounts and partly significantly the precaecal as well as the total digestibility of dry matter, organic matter, carbohydrates (= crude fibre + NFE), crude fibre and hemicelluloses (arabinose, xylose). By the roughage supplementations the crude protein digestibility at the terminal ileum was less reduced than at the end of the total digestive tract, the starch digestibility was hardly influenced and that of ether extract mostly increased. In comparison with precaecal glucose and fructose digestibilities it could be shown that the anthrone method is not suitable for determinations of the precaecal digestibility of water soluble carbohydrates. Beside these compounds other substances in the ileum digesta must evidently be dyed by anthrone too. The crude protein digestibility and the amino acid absorption were precaecally hardly or not reduced by WSM supplementations, therefore it can be concluded that it is possible to dilute the energy concentration in diets (e.g. for sows) by addition of WSM without impairing protein digestion and amino acid absorption. The GM supplementations, however, impaired protein digestibility and amino acid absorption of the whole diet, probably caused by the encrusted, possibly heat damaged protein present in the GM itself. When the roughage supplemented diets were fed, the excretion of nitrogen compounds in the faeces was enlarged due to the more intensive bacterial activity in the hind gut and the additional sorption effects to cell wall substances, so that a too low apparent and also true digestibility is made believe. The applicability of the difference method to the calculation of protein and amino acid digestibilities in roughages is very questionable because of their low contents and the missing additivity. The crude fibre and hemicellulose digestibility values calculated by the difference method demonstrate for the both roughages--in spite of high standard deviations--that the precaecal digestibility of crude fibre is about zero and that of the hard lignified hemicellulose fraction in contrast to the predominantly endospermic hemicelluloses of the basal diet is very low. The faecal crude fibre and hemicellulose digestibilities of WSM--especially on the lower supplementation levels--are markedly worse than those of GM.

The crude protein digestibility and the amino acid absorption of six female pigs (average live weight 61 kg) with duodenal and ileocecal re-entrant cannulae, which were fed with a wheat + wheat gluten + lysine ration and an N-free ration, were determined in various segments of the intestines. Comparative experiments concerning the N-metabolism with pigs without and with cannulae showed that the animals renormalised their metabolism 14 days after narcosis and fistulation of the intestines. The extents of secretion and absorption of the various amino acids vary as it is shown from the values of the apparent and true digestibility resp. rate of passage through various segments of the intestines. While for methionine and glutamic acid absorption exceeds endogenous secretion already in the duodenum, the amino acids with a high endogenous quota (glycine, alanine, threonine, tryptophan) are, even at the terminal ileum, not as well absorbed as the others. Methionine is obviously synthesised on a large scale by the colon flora and excreted in feces. The fractionation of the duodenal and ileum chyme after feeding wheat + wheat gluten + lysine as well as N-free mixture, into the fractions "solid particles", "peptides-free amino acids" and "proteines precipitable by trichlor-acetic acid" supplies information on the degree of protein degradation in various segments of the intestines.

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The slaughtering of female fattening pigs differently supplied with protein and lysine (nearly constant proportions) showed that a high supply (III) in comparison to the standard supply (II) did not bring about better results. The lower consumption of digestible crude protein and lysine (I) resulted in a prolonged fattening period, lower daily protein retention (by 23%) and a lower content in live weight growth (by 5%). The two feeding variants I and III are therefore ineconomical and not recommendable. There are significant positive correlations between N-retention calculated from 3 N-balance measurings in the first fattening period (up to the 44th fattening day) and N-deposit ascertained after the analysis at the carcasses at the beginning and at the end of fattening. By means of the calculated estimate functions (1) y = 4.724 + 0.5432x and (2) y = 7.850 + 0.4961x the level of the real protein deposition (y) in the total fattening period can be derived from the N-balance (x) both in g per animal and day (1) and in g per kg live weight growth (2). The four complexes of causes for the differences in N-retention according to N-balance and N-deposit according to carcass analysis: 1. high N-deposition in the first fattening period; 2. unascertainable N-losses 3. the difference between slaughtering and total body weight and 4. physiologically caused deviations in the N-storage of the living organism, are discussed. Protein and lysine utilisations are comparable with values from literature achieved under similar conditions. In the group supplied according to standard (II) it is 29.5 and 45.6% resp. or, related to the digested quota, 36.6 and 57.7% resp. Here the protein (10.1 kg) and lysine (1,640 g) assigned for a live weight growth of 80 kg (35-115 kg) in 100 fattening days were consumed, which means that 162 g lysine were needed for 1 kg deposited protein.