Ausscheidungen der Aminosäuren mit dem Harn und Kot von kolostomierten und nicht operierten Hennen — Beitrag zur Methode der Aminosäurenresorbierbarkeit

[Effect of graded dietary protein rations on the amino acid content of crude protein in various parts of the gastrointestinal tract and blood fractions of laying hens]

Four groups of four colostomized laying hens each received rations only consisting of wheat, vitamins plus a mineral mixture and a graded daily feed supply of 110 g, 88 g, 66 g and 44 g. The determination of amino acids from faeces was carried out after hydrolysis from a 6-day sampling period from the 16 laying hybrids. At the end of the experiment the animals were slaughtered. The corpuscular fractions of the blood, the contents of crop and stomach as well as of the intestines were also hydrolysed and the amino acid content in the crude protein was determined. In addition, the content of free amino acids in the blood plasma was determined. The content of amino acids in the protein of the corpuscular blood fractions remained uninfluenced by the decreasing amino acid and energy supply. The content of free basic amino acids in the blood plasma decreased with the decreasing supply with amino acids and energy, whereas the content of free amino acids with branched chains and hydroxylized ones increased. The content of glutamic acid in the contents of crop and stomach changed considerably in comparison with feed protein. The amino acid values of the crude protein in the contents of the intestines and in faeces to a large extent differ considerably from those of the wheat fed and are approximate values of body protein. Deficient supply with amino acids and energy did not influence the apparent digestibility of the amino acids.

[The substitution of protein feed by lysine supplemented high protein wheat during the rearing and laying period in hens. 9. True amino acid digestibility of rations with varying lysine levels in hens who had a colostomy]

24 experimental birds were fed the same basal ration containing 74% high-protein wheat, 4% extracted soya bean meal, 7% extracted groundnut meal, 2% feed yeast, 1.75% dried green meal, 1.25% mixed vitamins and 10% of a mineral mixture. The birds were placed in 4 groups each comprising 6 hens. The first two groups received an optimum of lysine (0.68%) added to the ration. The rations for the two other groups contained 0.55% lysine. 6 birds of each group receiving either the lysinesupplemented or the unsupplemented rations were colostomated to investigate in which way the hydrolysed urine would affect the true amino acid digestibility. 8.3% of urinary N from the total amount of faecal N were precipitated as uranyl acetate in the faeces of hens fed the lysine-supplemented ration as compared with 7.3% urinary N in birds receiving the unsupplemented ration. The corresponding figures for non-precipitable faecal N were 8.9% and 8.2%. A comparison was made between the levels of amino acids excreted by colostomated and non-colostomated hens showing that 12.4% +/- 3% and 11.7% +/- 3% more amino acids (figures for the supplemented and unsupplemented rations) were excreted in the presence of urine. On the basis of these results the authors recommend that only colostomated hens should be used in digestibility and total metabolism trials.

[The nitrogen metabolism of broiler chickens with 15N-labeled wheat. 2. Report. 15N concentration in the gastrointestinal tract and its contents]

17 broilers received a wheat-soya bean meal-pea nut ration containing an excess of 15N atom% (6.54%). The birds were slaughtered 3, 6, 12, 36, 60 and 108 hours after the last 15N'-intake. Up to 12 hrs after slaughtering the contents of the crop and the stomachs were found to contain a higher excess of 15N atom% than the food. The contents of the small intestine at that time contained only 1/4 of the 15N concentration present in the crop and the stomachs (2.7%). Later on the excess of 15N atom% decreased to 1.7%, 1.4% and 0.8% and was 4 times as high as that found in the crop and the stomach. Higher 15N' concentrations, compared with those in the small intestine, were found in the contents of the caecum, the colon, and the rectum, for a period of up to 12 hrs after administration of the last portion of labelled food. The 15N' concentrations in the crop and the stomachs are due to a more prolonged storage of wheat relative to that of the extracted meals. The interrelationship between the contents of the small intestine and the contents of the higher sections of the gastro-intestinal tract suggests that a secretion of N-containing substances takes place, although it was not possible to determine these substances quantitatively. Values for the excess of 15N atom% in the crop and oesophagus and in the muscular stomach were found to be in close correspondence both with regard to their level and time pattern. The decline in the glandular stomach was more rapid than in the muscular stomach. A very close correlation (r=0.99) was found between the 15N atom% in the contents of the intestine and in the intestinal wall. The N content of the small intestine (expressed as mg) was significantly higher after 3 hrs and 6 hrs of fasting than after a fasting period of 12 hours. Theoretical aspects of the involvement of the intestine in the process of metabolism are discussed in some detail.