F. Liebert

Ernährungsphysiologische Untersuchungen an Schweinen zur Beurteilung von modifizierten Proteinen

Modified proteins were tested in absorption investigations with eight pigs with ileocaecal re-entrant cannulae. The apparent digestibility up to the end of the small intestines showed considerable differences between the feed proteins (77-93%). The same differences could be observed with regard to the apparent absorption of amino acids. Concerning the true N-digestibility resp. the true absorption of the amino acids in the above mentioned section of the intestinal tract there were hardly any differences between the proteins given. The results show that there is a relation between the amount of endogenous N in the chyme at the end of the small intestines and the protein consumed. The amount of endogenous N in the chyme in the small intestines influence N-excretion in urine and thus the intermediary utilisation of feed protein. From the point of view of nutrition physiology it follows that the spun vicia-faba protein/casein (1 : 1) fibres (C) approximate best the value of casein (A). While the treatment of this mixed protein with dyaldehyde starch had a negligible effect on the ascertained parameters only, the treatment of the same protein with aluminium chloride diminished its value more. The isolated vicia-faba (B) was the poorest of the modified proteins tested.: Modified proteins were tested in absorption investigations with eight pigs with ileocaecal re-entrant cannulae. The apparent digestibility up to the end of the small intestines showed considerable differences between the feed proteins (77-93%). The same differences could be observed with regard to the apparent absorption of amino acids. Concerning the true N-digestibility resp. the true absorption of the amino acids in the above mentioned section of the intestinal tract there were hardly any differences between the proteins given. The results show that there is a relation between the amount of endogenous N in the chyme at the end of the small intestines and the protein consumed. The amount of endogenous N in the chyme in the small intestines influence N-excretion in urine and thus the intermediary utilisation of feed protein. From the point of view of nutrition physiology it follows that the spun vicia-faba protein/casein (1 : 1) fibres (C) approximate best the value of casein (A). While the treatment of this mixed protein with dyaldehyde starch had a negligible effect on the ascertained parameters only, the treatment of the same protein with aluminium chloride diminished its value more. The isolated vicia-faba (B) was the poorest of the modified proteins tested.

Methodical investigations about evaluation of lysine utilization In reply to: Pigs following extreme changes of protein quantity and protein quality

Aim of investigations was to measure lysine utilisation under dietary conditions which could have negative effects on well known relation between limiting amino acid and level of N‐utilisation. Incorrect conclusions about level of lysine availability (efficiency) could be drawn under such conditions. Therefore N‐balance trials were done with 32 female pigs (35–45 LW, fitted with urine bladder catheters), based on semisynthetic diets (wheatgluten / cornstarch) supplemented with glutamic acid as additional nitrogen source. Lysine concentration in the protein was further reduced by this way near to N‐balance + 0. Data calculation followed a further developed N‐utilisation model from Gebhardt (1966). Experimental conditions resulted in disturbed relationships between lysine concentration and protein utilisation and led to the conclusion, that N‐balance trials related to estimation of amino acid efficiency in feed proteins resp. to amino acid requirements should be realised under conditions of > 500 mg / LWkg ...

Untersuchungen zum N-Umsatz Wachsender Schweine unter Besonderer Beachtung der Lysinwirksamkeit Unterschiedlicher Lysinquellen

The results of measurings of N-metabolism in relation to the utilisation of the limiting amino acids are discussed on the basis of N-balance experiments with 20 growing female pigs (live weight 35-40 kg) with lysine-limited, highly digestible synthetic feed mixtures. Based on an N-utilisation model (Gebhardt, 1963), conclusions are drawn concerning the effectivity of lysine from various lysine sources. In accordance with literature, differences between synthetic lysine and microbial lysine concentrate could not be observed.

Results about lysine utilization in growing monogastric animals with special respect to different lysine sources

Object of investigations was to estimate lysine efficiency from different lysine sources (lysinemonohydrochloride and lysinesulfate resp.) for rats, piglets and broiler chickens to reach a higher level of calculation of lysine supply. Lysine limiting diets were based on wheat, soybean meal and wheat gluten, supplemented with different levels of lysine sources under investigation. Balance trials (rat, piglet, chicken) and growth trails with analyses of body composition (chicken) were done to estimate N‐balance resp. N‐deposition. N‐utilization model from Gebhardt (1966) and its further developement for efficiency estimation of feed amino acids were used for data calculation. Results allow conclusion, that there are no differences in utilization of lysine from lysinemonohydrochloride and lysinesulfate. Limitations of efficiency resulting from differences in time course of absorption between protein bound and free lysine were not observed under ad lib. feeding conditions.

N-Bilanzuntersuchungen zur Verwertung von DL-Threonin und DL-Tryptophan am Broilerküken

It was the purpose of these investigations, apart from a methodical test of the procedure for the ascertainment of the efficiency of optical isomers of synthetic amino acids in an N-balance test, to draw conclusions concerning the value of DL-threonine and DL-Tryptophane for young chickens. The ascertained efficiency of 67% for DL-threonine (D-form 34%) resp. 86% for DL-tryptophane (D-form 72%) coincides with the results described in literature and speaks in favour of the method applied on the basis of the parameters of the efficiency graph of the limiting amino acids. The supposition made here that for a zero content of limiting amino acids the b-value also equals zero, requires further investigation. The clarification of the reasons for the low effectivity of the synthetic L-form ascertained in comparison with the native amino acid also makes further investigation necessary.

Untersuchungen zum Zusammenhang Zwischen Kreatininausscheidung im Harn und der Qualität des Nahrungsproteins bei Wachsenden Schweinen

N-balance experiments, in which creatinine excretion in urine was measured, were carried out with 80 female fattening pigs. 16 protein sources of different quality were used. In addition to that, an N-increase experiment--protein quality remaining the same--and N-free experiment and results from literature were included into the assessment. The b-value (Gebhardt, 1963) served as the criterion for protein quality. The creatinine coefficient (mg creatinine in urine per kg live weight and day) could be determined as 40.2. There was a direct relation between the N-balance value and creatinine excretion, not however, in the N-increase experiment. Significant relations to the protein quality (b-value, Gebhardt, 1963) could only be established when N-excretion in urine was included.

Mechanism of action of lysine in relation to its form of supply in swine

It was the aim of this study to check the maximum value of lysine efficiency in feed proteins used as yet for the ascertainment of amino acid efficiency coefficients (cf. Liebert and Gebhardt 1988 b). For this purpose N balance measurements were carried out with 5 female pigs (30-35 kg LW) under conditions of continuous lysine infusion (duration of infusion 12 hours) through subclavian indwelling catheters with the help of a proven N utilization model. Based on defined limiting relations in the wheat/wheat gluten ration used, the lysine efficiency coefficient for infused lysine could be ascertained according to the difference method as 1.03, i.e., slightly above the maximum value for lysine efficiency determined up to now. The current standard of maximum lysine efficiency was determined as bc-1 Lys = 102, which is the basis of further calculations of lysine efficiency coefficients.

Untersuchungen zum Einfluß der Höhe der Futtergabe auf die Verwertung von synthetischem Lysin (α—15N markiert) beim Broilerküken

A total of 15 broiler chickens was fed with a diet of wheat/wheat gluten supplemented with lysine on three N-intake levels (I: 1,500; II: 2,100; III: 3,000 mgN/LW0, 67kg) between their 11th and 20th day of life and tested with regard to the characteristic data of N-metabolisation (N-balance experiment) and 15N-incorporation in selected tissues and the complete body of the chickens. While N-metabolisation did not show any differences of procedure, the results of 15N-incorporation indicated slightly more favourable utilisation conditions for synthetic lysine in III in the complete body and the liver. One can derive from the results that the level of feed intake cannot be excluded as one variable in the utilisation of synthetic lysine, the problems in connection with this, however, cannot completely be explained with this. For the restrictions of N-intake effective in the N-balance experiment no negative influence is to be expected with regard to the utilisation of synthetic lysine in comparison to ad libitum feeding.