Research note: investigation on the metabolism of glycerol in the rumen of bulls.

Two bulls, each fitted with rumen and duodenal cannulas, received (in addition to a hay-grain diet) twice daily an infusion of 200 g glycerol into the rumen over a period of six days. During this preliminary in vivo investigation, the influence of a glycerol application on the rumen environment over a six-day adaptation period was examined. Samples of rumen fluid were collected daily, two hours after glycerol infusion. An additional 15N-urea application into the rumen was given on days 1 (without glycerol infusion), 3 and 7 (with glycerol infusion). Extra samples of rumen fluid and blood plasma (from puncture of vena jungularis) were taken through the 12th hour following urea application. Rumen fluid pH was reduced due to glycerol intake from 6.3 (day 1, without glycerol) to 5.4 by day 7. Molar proportion of acetic acid to propionic acid decreased from 3.5 (day 1) to 2.1 (days 6 and 7). Average glycerol disappearance rate from the rumen was 4.7 gl-1 h-1 for the first hour. Only small amounts of glycerol could be detected in the duodenal digesta. Blood plasma glycerol content was significantly higher after glycerol application (0.061 mmol l-1 vs. 0.019 mmol l-1). The incorporation of 15N into the rumen bacteria and the proportion of bacterial N (as percent of TCA-precipitable N in the rumen fluid) were lower after glycerol influsion. These results, coupled with the lower concentration of iso-acids (isobutyric and isovaleric acids) in the rumen fluid, indicate that the high amount of glycerol infusion (10% of DMI) reduced protein metabolism of rumen bacteria throughout the experimental period.

[Glycerol supplementation in broiler rations with low crude protein content]. / Glycerineinsatz in Broilerrationen mit niedrigem Rohproteingehalt.

In connection with the utilization of glycerol, which could become available as a by-product of the fuel production from rapeseed the influence of glycerol feeding with rations of low crude protein content was proved. 61 male day old broiler chickens received ad libitum 8 experimental rations based on maize and soybean meal. The experimental design included 3 factors: 15 or 18% CP; supplementation of essential amino acids or not and a content of pure glycerol of 0 or 10%. During the experimental feeding of 23 days body weight gain, feed conversion ratio, N-balance and the intake and excretion of glycerol was obtained. At the end of the trial the utilization of 15N-methionine and the glycerol content of blood plasma, liver and breast muscle was estimated. Due to the low crude protein content of the rations the body weight gain and N-balance was very low (BWG day 1 to 23: 8.6 to 17 g/animal.d; N-balance day 19 to 23: 0.4 to 1.0 g N/animal.d). The supplementation of essential amino acids was the factor with the highest improving effect on the body weight gain, feed conversion ratio and N-balance. Especially at the begin of the trial animals which received 10% glycerol had have an increased feed intake. The excretion of the supplemented glycerol by excreta amounted to 26% of the intake. However, the glycerol content of the rations did not effect body weight gain, feed conversion ratio, N-balance or utilization of 15N-methionine significantly. The assumption of a saving effect on glucoplastic amino acids due to glycerol feeding could not be manifested. In the mean feeding of glycerol elevated the glycerol level in blood plasma in comparison to the basal level up to 23 times (from 0.6 to 13.6 mumol/ml) and in the breast muscle up to 19 times (from 0.4 to 7.5 mumol/g). Nevertheless, these values were lower than the basal level of glycerol in the liver (17.1 to 19.0 mumol/g), which was significantly increased by glycerol feeding to 128%. Regarding the utilization of glycerol as a by-product of the production of renewable fuels it can be concluded that on the basis of the estimated parameters 10% pure glycerol in broiler rations instead of corn starch is without adverse effects.

[Glycerol as a feed ingredient for broiler chickens]. / Glycerin als Futterkomponente für Broilerküken.

In a first trial glycerol was tested as a feed ingredient for broiler chickens. The influence of glycerol supplementation on weight gain, feed intake, feed conversion ratio and N-balance was proved. 90 Broiler chickens (Lohmann Meat) were fed ad libitum in 6 groups with nearly isoenergetic diets based on corn and soybean meal with 23% crude protein and 0; 5; 10; 15; 20 or 25% pure glycerol in the DM. During a feeding period of 31 days animals had have a very good intake of all experimental diets. The highest weight gains were observed in the groups with 5 and 10% glycerol (34.9 and 35.3 g/animal.d, resp.). However, this effect was not significant compared to the control group (34.3 g/animal.d), but was significant superior to the gain of groups with 20 and 25% glycerol in the diet (30.2 and 26.6 g/animal.d, resp.). The feed conversion ratio was unchanged up to 10% glycerol (1.65 kg/kg gain) and rose to 2.08 kg/kg gain with 25% glycerol. Up to 20% glycerol the N-balance (1.6 to 1.8 g N/animal.d) was positively correlated with the glycerol content in the diet (r = 0.98). The estimation of the plasma glycerol level 2 hours after feeding indicated a remarkable increase already with a 5% supplementation of glycerol from 0.65 (control) to 4.36 mmol/l. Further supplementation caused on average 11 to 54 mmol glycerol/l varying considerably between the individual animals. In general 25% glycerol in the diet caused the lowest performance and pathological changes in the crop epithelium, liver and kidneys. From the point of view of weight gain, feed intake, and feed conversion ratio as well as N-balance a supplementation of 5 to 10% glycerol seems to be beneficial.

[Methodical investigations on the metabolism oriented determination of methionine requirement of broiler chickens. 3. Degradation of 14C-(CH3)- and 35S-methionine after feeding of synthetic diets]. / Methodische Untersuchungen zur Stoffwechselorientierten Methioninbedarfsbestimmung an Broilerküken. 3. Mitteilung--14C-(CH3)- und 35S-Methionin-Abbau nach Fütterung synthetischer Diäten.

In a chicken experiment was investigated, whether the kind of applied isotope and labelling site influence the results of the metabolism oriented estimation of the methionine requirement. Furthermore it was studied, if this method can give additional informations to weight gain and N-retention data concerning methionine requirement. 48 male broiler chickens received synthetic diets with a complete amino acid mixture from day 7 posthatching. The methionine content of the 8 experimental diets varied from 2.25 to 7.5 g methionine/kg DM (1.17 to 3.87 g/16 g N). The low weight gain (13 to 22 g/d) and N-retention (0.55 to 0.87 g/d; from day 13 to 17 posthatching) was due to the inferior intake of the synthetic diets. Methionine supplementation increased weight gain and N-retention only up to 3 g methionine/kg DM. The metabolic methionine requirement was measured after i.v. injection of 14C-(CH3)- and 35S-methionine by 14CO2-excretion with breath and 35S-excretion with excrements. Both parameters gave similar results and showed an increased methionine degradation at methionine contents exceeding 4.5 g methionine/kg DM. Because there was no increase in methionine degradation up to 4.5 g/kg DM, an increased reutilization of methionine within the range between 3 and 4.5 g methionine/kg DM was supposed, which may act as a spare-mechanism. For practical feeding applications, also in case of low feed intake, a minimal methionine content of 4.5 g/kg DM is recommended.

[Glycerol as a feed component in fattening pigs]. / Glycerin als Futterkomponente in der Schweinemast.

The production of motor fuel from rapeseed oil forms large amounts of glycerol as a waste product (about 100 g per kg oil). The aim of this experiment was to test glycerol as a component in diets of fattening pigs. In two experiments received 48 pigs (Pietrain x F1, Landrace x German breed) up to 30% glycerol in barley-soya bean oil meal diets. Six pigs per group with an initial weight of 32 kg (experiment 1) and 31.2 kg (experiment 2) in average received the diets semi ad libitum during the whole fattening periods. Barley was replaced by glycerol, that the content of glycerol in diets amounted 5 and 10% (1st exp.) and 5; 10; 20 and 30% in the 2nd exp. respectively. The feed intake was in order of groups up to slaughtering in exp. 1: 1.98; 2.17 and 2.23 kg DM/animal and day and in exp. 2 over 71 days: 2.26; 2.44; 2.54; 2.32 and 2.37 kg DM/animal and day. The sweet taste and the better feed structure of diets with glycerol supplementation is the reason for the higher feed intake in the groups with a glycerol supplement. The daily live weight gain was in the same order 631; 719; 754; 731; 770; 819; 704 and 598 g/animal resp. The feed conversion ratio was only in the group with 30% glycerol significant different from all other groups (3.96 against 2.95-3.30 kg DM/kg live weight gain). 30 min. after feeding the glycerol concentration in blood rose evident with higher glycerol content in diets. It was also found a higher glycerol content in the urine in dependence on the glycerol concentration in the blood. Glycerol in diets changed not the carcass yield and the meat quality. Pathological changes of liver and kidney of animals were not found after glycerol feeding. Amounts of glycerol up to 10% in the diet are recommended.

[In vitro studies on glycerol transformation by rumen microorganisms]. / In vitro Untersuchungen zum Glycerinumsatz durch Pansenmikroorganismen.

Rumen fluid from sheep (non adapted to glycerol) was incubated up to six hours under anaerobic conditions with buffer and mineral solution. Wheat starch was added as substrate in an amount of 1g DM per vessel. Glycerol was additionally admitted to rumen fluid in amounts of 5 to 50% of starch. Carrier-free 14C-glycerol (1.3-labelled) or 15N-labelled NH4Cl were added to different incubation vessels. The disappearance rate of glycerol depended from the amount of added glycerol and incubation time. More than 90% of glycerol disappeared in 2 hours (5% addition), 4 hours (10% addition) and 6 hours (15 to 25% addition) respectively. The sum of volatile fatty acids elevated significant with a higher glycerol addition and 6 hours incubation time. The concentration of propionic acid increased also in dependence of the added glycerol amount and the longer incubation time. The proportion of acetic acid to propionic acid changed from high values (3.5 to 4.0, without glycerol) to the lowest value from 2.5 after 6 hours incubation time and 25% glycerol addition. The most radioactivity of added 14C-glycerol was found in propionic acid and only up to 11% in CO2. 14C-radioactivity was not detected in methane, lactic acid and acetic acid respectively. The 15N-labelling of TCA-precipitable N-fraction was not influenced by glycerol supplementation but the 15N-incorporation in the bacterial nitrogen fraction was lower in the vessels with glycerol.

[Use of free fatty acids in animal nutrition]. / Einsatz von freien Fettsäuren in der Tierernährung.

The description of the processes of absorption of free fatty acids in monogastric animals and in ruminants is the first part of the review. The feeding problems of free fatty acids are discussed in the second part. In pig diets is a level up 6% free fatty acids in the dry matter of the ration not disadvantageous. In the feeding of ruminants additionally free fatty acids reduce the fermentation processes in the rumen. Only protected free fatty acids (Ca-fatty acids) are favourable in feeding systems for high yielding cows.

[Determination of the protein quality of food and animal feed]. / Ermittlung der Eiweissqualität von Nahrungs- und Futtermitteln.

The estimated value of true digestibility of food and feed proteins is in dependence from the excretion of metabolic faecal nitrogen (MFN). Results of many authors showed that a high fibre content of the diet increase the MFN-excretion and lower the true digestibility of the diet protein. The exact estimation of MFN is only possible with isotopic methods. The labelling of feed proteins with isotopic nitrogen (15N) is possible in experiments with small animals. In big animals (pigs) the utilization of recycled 15N is too high following the long transit time of non digested 15N-labelled feed protein and the parallel 15N-labelling of MFN. The best method for the estimation of true digestibility of proteins is the method with 15N-labelled animals and the differentiation between nonlabelled undigested feed protein and the 15N-labelled MFN in faeces. The estimation of digestibility of essential amino acids at the end of the ileum as a measure for protein quality is not in advantage because the bacterial breakdown and synthesis of amino acids in the small intestine is unknown. The estimation of the biological value (BV) of proteins with the classical method is useful when the exact MFN was determined. The classic formula of BV [formula: see text] is only applicable in experiments with growing animals with nitrogen retention. This result of BV value is in agreement with the method only valid for growing animals with N-retention and not for animals or human beings in maintenance. The measurement of a BV of proteins with animals in maintenance is possible when the animals are labelled with 15N. The 15N-loss of the animal after the feeding of different protein sources is the smallest when the amino acid pattern of the protein is adapted to the need of amino acids for the maintenance metabolism of the animal. It was found that proteins with a high content of glutamic and aspartic acid (proteins of grains) are better proteins for the maintenance metabolism as animal proteins. Measurements with the method of the oxydation rate of essential amino acids showed that the amino acid pattern of wheat protein is in agreement with the need of amino acids for maintenance of the adult men. The evaluation of protein quality in animal nutrition for growing or lactating monogastric animals is in the present time the balance of essential amino acids in the feed protein and the need of this amino acids of the animals.

[The effect of a different protein and fiber intake on the ileal flow of endogenous protein in 15N-labeled swine]. / Untersuchungen zum Einfluss einer unterschiedlichen Protein-und Faseraufnahme auf den ilealen Fluss an endogenem Protein bei 15N-markierten Schweinen.

The endogenous N in ileal digesta of pigs was estimated in two experimental variants. In variant 1 the crud protein content of a wheat-maize-fish meal diet was 18% and the crude fibre content was 1.9% (diet 1) and 2.7% resp. (diet 2). In variant 2 the crude protein content was 12.5% (wheat-maize-diet) and the crude fibre content was 4.1% (diet 3) and 5.5% resp. (diet 4). The higher crude fibre content of the diets 2-4 was provided by means of a supplementation with partially hydroyzed straw meal plus pectin (2:1 w/w). Four miniature pigs with an average initial body weight of 29 kg, were fitted with a ileocaecal re-entrant cannula and received each one of the four different diets. 15NH4Cl, added to the diets, was given for 5 days (150 mg 15N-excess/kg0.75 BW*d) to label the animals with 15N. Ileal digesta, urine and faeces were collected over 24 hours on 8th, 10th and 12th day after the first intake of 15N. The 15N-excess of urine N was used as the comparative measure of 15N-excess of endogenous protein. The amount of nitrogen collected in ileal digesta was in order of the diets 1-4 = 258, 299, 200 and 224 mg/kg0.75 BW*d and of these amounts were 50.1, 52.1, 56.1 and 50.4% of endogenous origin. This were corresponding, after conversion into crude protein to 9.1, 11.2, 10.8 and 11.0 g/100 g crude protein intake or 16.9, 19.7, 13.8 and 13.4 g/kg dry matter intake, respectively. The bacterial N-flow were in order the diets 1-4 = 94.0; 72.7; 55.8 and 52.6 mg/kg0.75 BW*d and 73, 46, 50 and 47% resp. of the endogenous N or 36, 24, 28 and 24% of the ileal total N. The results show, that the absolute amounts of endogenous and bacterial N at the terminal ileum were significantly increased by a higher crude protein content of the diet. The percentage of endogenous and bacterial N on the total N of the ileal digesta was not affected neither by the crude protein content of the diets nor by the fibre supplements.

[Glycerol as feed component and 14C-glycerol metabolism in rats]. / Glycerin als Futterkomponente und 14C-Glycerinumsatz bei Ratten.

Male Wistar rats (initial weight 58 g) received in four groups (10 animals per group) 0.0, 10.6, 21.3, and 31.8% glycerol in the dry matter of the diet (groups 1 to 4). The live weight gain of the animals was, after a feeding time of 3 weeks in the groups 1 to 4, 2.01, 2.49, 2.57, and 2.52 g, respectively, per animal and day. The higher gain in the glycerol groups resulted from the higher feed intake in these groups. Four rats per group received on the 22nd day of the experiment, 1 h after the morning meal, an intraperitoneal injection of carrier-free 14C-glycerol. The 14C-excretion in the respiration air and in the urine was measured in the following 10 h. The 14C-excretion in the 14CO2 of the respiration air was in % of the injected 14C-glycerol doses in the groups 1 to 4 = 45.4, 44.2, 39.0, and 33.2, respectively. The 14C-excretion in the urine was 17.0, 18.1, 25.1, and 32.3%, respectively. The higher values in groups 3 and 4 resulted from the high excretion of free glycerol in the urine. In groups 3 and 4 the glycerol content of the blood plasma was 1.9- and 1.5-fold higher than in groups 1 and 2. It was concluded that up to 40 mg glycerol per hour and animal (100 gLW) was metabolized in a physiological way in group 2. As a feeding component glycerol can constitute up to 10% of the diet-DM in monogastric animals.

[The effect of feeding frequency on the results of metabolism-oriented lysine requirement determination and nitrogen balance in broiler chicks]. / Einfluss der Fütterungsfrequenz auf das Ergebnis der stoffwechselorientierten Lysinbedarfsbestimmung und der N-Bilanz bei Masthähnchen-Küken.

Two feeding regimes were used for investigation into the effect of meal frequency on the lysine requirement in chickens estimated with metabolism-oriented determination. 1-day-old male broiler chickens were fed either twice a day for 1 hour (one group) or 6 times a day for 1/2 hour (other group). 7 to 21 days posthatching the birds received a wheat-wheat gluten diet which was L-lysine-supplemented at 6 levels. Using lysine deficient diets chickens fed twice a day eat more and grow faster than chickens fed 6 times a day. The N-balance was 6 to 7% higher in the case of the feeding regime 2 times a day. After feeding period 14C-U-L-lysine was injected intravenously and 14CO2-excretion measured. The estimated range for lysine requirement was 11.9-13.1 g lysine/kg DM and 13.1-14.3 g lysine/kg DM for chickens fed 2 times and 6 times a day, respectively. A feeding regime of 6 meals a day does not improve the utilization of diets contains crystalline lysine compared with feeding of 2 meals a day.

[Methodical studies of metabolism oriented methionine requirement determination in broiler chicks. 2. Effect of feeding frequency on methionine utilization]. / Methodische Untersuchungen zur stoffwechselorientierten Methioninbedarfsbestimmung an Broilerküken. 2. Mitteilung. Einfluss der Fütterungsfrequenz auf die Methioninverwertung.

The effect of feeding frequency (daily 2 times feeding for 1 hour or 6 times feeding for 30 minutes) and a different methionine content of the diet on weight gain, N-balance and metabolic 35S-methionine degradation was investigated in broiler chickens. Weight gain and N-balance were not improved by increased feeding frequency. At the high feeding frequency, weight gain and N-balance were even depressed when diets with methionine deficiency (without methionine supplementation) were fed. No effects of feeding frequency and the amount of DL-methionine supplementation on the level of excreted 35S after i.v. injection of 35S-methionine were observed.

[The determination of a gross utilization of 15N-lysine in laboratory rats. 2. Comparative testing with an antibiotic supplement to the diet]. / Untersuchungen zur Bestimmung einer Bruttoverwertung von 15N- Lysin an Versuchsratten. 2. Mitteilung. Vergleichende Prüfung bei einer Antibiotikazulage zur Diät.

Wistar rats of a live weight of about 100 g received in 26 groups (4 animals/group) diets, each with a different lysine content. The rations given supplied the animals with 75%, 100% or 125% lysine of the calculated requirement. The source of protein in the diets was: barley (B), wheat (W), wheat gluten (WG), isolated soybean protein (assay protein) (S) or soybean meal (SM). For WG and S only the lysine levels 100% and 125% (SM = 116% and 125%) could be achieved. All diet groups were fed for 10 days with and without antibiotics (7 g Nebacitin/kg feed-DM). During the 7-day-period of the main experiment all 24 rations were supplemented with 0.5 g 15N-lysine/kg DM (48.3 atom-% 15N-excess, alpha-aminogroup 95% 15N-labelled). The nitrogen balance was improved only after feeding antibiotics with the diet S 100. It may be supposed that Nebacitin saved the second limiting amino acid methionine against microbial degradation in the digestion tract. The biological value (BV) of feed-proteins declined in the case of the diets B and W in the presence of antibiotics because the absorbed nitrogen was higher, this calculation basis for BV was therefore also higher without an improvement of the N-utilization. The 15N-excretion in faeces was significantly lower after feeding the diets B, W and WG with antibiotics. The 15N-excretion in urine was elevated in the most cases of the antibiotic supplement. The determination of a gross utilization of lysine and 15N-lysine resp. in relation to the lysine retention (availability) was not possible, neither using a labelling of diets with 15N-lysine.

[15N-labeling of fishes using 15N isotopes in aquarium water and the effect of a different protein nutrient on the 15N elimination after the labeling period]. / 15N-Markierung von Fischen über 15N-isotope im Aquarienwasser und der Einfluss einer unterschiedlichen Eiweissernährung auf die 15N-Eliminierung nach der Markierungsperiode.

In a preexperiment of 12 days fishes (Cyprinus carpio L.) were labelled with 15N by means of 15NH4Cl and 15N-urea resp. in the aquarium water and by feeding a protein free diet. 15NH4Cl yielded a higher atom-% 15N excess (15N') in the tissues of fishes. In the main experiment 75 fishes (Cyprinus carpio L.) were 15N-labelled with 100 mg 15N'/l water from 15NH4Cl (95 atom-% 15N') in a protein free preperiod of 12 days. In the following main period the fishes received different protein sources in their diets in maintenance. A group of 20 fishes received an animal protein (fish meal) and two groups of 20 fishes each received plant proteins (soybean meal and wheat gluten resp.). The atom-% 15N' reached after the 15N-labelling period following values: digestive tract with content--7.15, liver--5.65, gills--5.89, muscle--0.81 and chorda dorsalis--1.09 respectively. During the main period (with protein feeding) the atom-% 15N' decreased in the tissues with high protein turnover (liver and gills) on the 2nd and 4th day to 4.31 +/- 0.11 (animal protein) and 4.64 +/- 0.14 (plant proteins) in average. The corresponding values in the tissues with low protein turnover (muscle and chorda dorsalis) were 0.73 +/- 0.04 and 0.80 +/- 0.04 atom-% 15N' in average. From the measurements on the 6th, 8th and 10th day of protein feeding resulted an atom-% 15N' in average of liver and gills of 4.08 +/- 0.13 (animal protein) and 4.11 +/- 0.15 (plant proteins). In muscle and chorda dorsalis the atom-% 15N' ascended in this time upon 0.80 +/- 0.04 (animal protein) and 0.90 +/- 0.03 (plant proteins). It seems that the protein metabolism of fishes is favoured from the amino acid of plant protein in comparison to animal protein to reduce the 15N-loss of the 15N-labelled body in maintenance, like the results from experiments with rats (Hernandez et al., 1981).

[The labeling of feed with 15N as a possibility for the determination of the true N-loss during in situ studies in the rumen of sheep]. / Die 15N-Markierung von Futtermitteln als eine Möglichkeit zur Bestimmung ihres wahren N-Verlustes bei in situ Untersuchungen im Pansen von Schafen.

Green rye (fertilized with 15N) with 37.4% crude fibre, 6.2% crude protein in DM; and 0.31 Atom-%15N-excess (15N') was separated into the fractions stem, leaves and ear. In the same order the fractions had 39.3, 36.4, 27.8% crude fibre; 3.7, 8.1, 11.4% crude protein in the DM and 0.30, 0.27, 0.33 atom-%15N'. Differences in the 15N-label between different nitrogen fractions for one part of the plant (total-N, TCA-precipitable N, pepsin insoluble N) were also measured. The reasons for these results are the once head-fertilization with N and 15N and the following 15N-turnover in the plant. The disappearance rate of DM, N and 15N of different parts of the rye plant was measured using the nylon bag technique in the rumen of sheep. The disappearance rate after a 24-hours incubation period was in the order whole plant, stem, leaves and ear as follows: DM = 44.4; 40.7; 50.3 and 71.6% N = 39.0; -8.5 (N-influx); 55.0 and 80.1% 15N' = 88.4; 84.0 88.3 and 92.4% The label of the N-fraction in the residues of bags was differently reduced in the fractions of plant as a result of influx of foreign N. The largest effect was found for the residues of stem. The reason for this result was interpreted with strong processes of adsorption in the fibrous material for N-molecules and N-compounds. A negatively linear correlation was found between the measured N-disappearance after incubation and the relative differences between the values of the 15N- and N-disappearances. These relative differences achieved negligible values when the N-disappearance was about 80%. The labeling of feedstuffs with 15N is a useful method for the estimation of true N-disappearance in experiments with the nylon bag technique.

[Hot weather damage of wheat gluten: determination of the intermediate lysine degradation in chicks using isotope techniques (14C-U-L-lysine oxidation]. / Untersuchungen zur Hitzeschädigung von Weizengluten: Ermittlung des intermediären Lysinabbaus bei Küken mittels Isotopentechnik (14C-U-L-Lysin-Oxidation).

The aim of our experiments was to identify a restricted lysine bioavailability after heating of wheat gluten by estimating a reduced metabolic 14C-lysine degradation. In two trials, male broiler chickens were fed with six diets based on wheat and wheat gluten (gluten untreated or heated), but differing in lysine content according to lysine supplementation. In trial 1 animals were fed restrictively, in trial 2 they were fed ad libitum. For estimation of metabolic lysine degradation all animals received an additional i.v. injection of 14C-U-L-lysine 3 weeks posthatching, followed by hourly collection of 14CO2 up to 3 h after injection. There were no differences between groups receiving untreated or heated gluten concerning weight gain and N-balance if the lysine supplementation was medium or high. When applying a lysine supply close to the requirement level or above the requirement the lysine degradation to 14CO2 (% of the dose) and the specific radioactivity of CO2 in animals receiving heated gluten was significantly lower compared to the corresponding group with untreated gluten. It can be concluded that reduced bioavailability of lysine due to heat treatment of gluten might be indicated by means of weight gain or N-balance only at lysine supply levels below the requirement. In contrast, measurements of lysine degradation by means of 14CO2-excretion after i.v. lysine injection indicate the heat-damaging effect, especially at lysine levels close to the requirement.

[The nitrogen metabolism in the large intestine of ruminants. 8. Metabolism of intracecally infused 15N-urea with a supplement of pectin in heifers]. / Untersuchungen zum Stickstoffumsatz im Dickdarm von Wiederkäuern. 8. Mitteilung--Umsatz von intrazaekal infudiertem 15N-Harnstoff mit Zusatz von Pektin bei Färsen.

Three heifers with live weights of 255, 261 and 300 kg were supplied with ileo-caecal re-entrant cannulas, jugular vena catheters and bladder catheters. The ration consisted of 4 kg maize silage and 4 kg wheat straw pellets. In a previous 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 period the re-entrant cannulas were disrupted and the flowing digesta was quantitatively collected. Precollected digesta and pectin were infused into the distal part of cannula hourly for about 30 hours. During the first 24 hours the digesta was also supplemented with 15N-labelled urea. The amount of pectin corresponded to about 10% of digesta dry mater. An analysis of urine, faeces, digesta and blood plasma were carried out. The application of pectin increased the 15N-incorporation in the bacterial protein of faeces from 4.7% (without supplementation in an earlier experiment) to 10.5% of the introduced 15N. The ammonia-fraction of faeces was markedly higher than the bacterial fraction. The 15N-utilization of urea by the microbes of large intestine was lower in the actual trial evident than with supplementation of starch in the anterior experiment. During the pectin administration the amount of urine increased in comparison with earlier experiments and according to the literature to about the 4.5 fold. The amount of passage of 15N at the ileum cannula (recycled 15N) was 3.8% of the 15N intake. It is the same amount as in experiments in which starch was applied.

[ATP in the metabolism of ruminants]. / ATP im Stoffwechsel des Wiederkäuers.

The ATP yield from the carbohydrates of anaerobically living microorganisms in the rumen amounts to only 5-10% of the ATP yield of the intermediary metabolism in the presence of oxygen. Vital functions and thus microbial protein synthesis are due to protein degradation in the rumen. The ATP yield in the intermediary metabolism of ruminants is mainly achieved from propionate and microbial protein by means of gluconeogenesis because the absorption of glucose from digested starch is very low. The relationships between ATP yield in the rumen and the processes of glucose provision for the production of lactose as well as the protein content of the milk are shown. As important processes of ATP production in microorganisms from easily soluble carbohydrates take place in silage preparations before feed intake, the corresponding consequences for the metabolism of high-performance cows fed with silage are shown.

[Detection of microbial protein synthesis in the small intestine of sheep using an intraduodenal 15N-urea infusion]. / Nachweis einer mikrobiellen Proteinsynthese im Dünndarm von Schafen mittels einer intraduodenalen 15N-Harnstoffinfusion.

Sheep (3 animals, 50 kg LW) with reentrant cannulas in duodenum and at the end of the ileum received 700 g hay and 800 g alfalfa pellets per animal and day. In a previous 1st period of three days duodenal digesta and in a 2nd period of four days ileal digesta were collected and stored deep frozen. In the main period the digesta flow was interrupted for 28 hours. The duodenal and ileal digesta were collected quantitatively. The previously collected duodenal and ileal digesta portions were introduced hourly. The duodenal digesta was supplemented with 15N-labelled urea for a 24 hour period. 4.5% of the introduced 15N-excess were detected at the end of the ileum in the 24 hour period. 5.6% of the 15N-excess at the end of the ileum were incorporated in bacterial protein. It was measured that the ileal digesta contained 4.62 g N in the TCE precipitable fraction and 24.4% of the TCE precipitable N-fraction was bacterial nitrogen.

[The determination of a gross utilization of 15N-lysine in laboratory rats. 1. Experiment with normal intestinal flora (without antibiotic supplement)]. / Untersuchungen zur Bestimmung einer Bruttoverwertung von 15N-Lysin an Versuchsratten. 1. Mitteilung. Versuch bei normaler Darmflora (ohne Antibiotikazusatz).

Wistar rats of a live weight of about 100 g were divided into 14 groups (5 animals/group). The rations given supplied the animals with 75%, 100% and 125% lysine, which brought about a moderate growth of the animals of approximately 2 g/animal and day achieved by limited feeding. The 3 lysine levels mentioned could be achieved by lysine supplements (L-lysine-HCl) for the following rations: barley (B), wheat (W), and wheat gluten (WG). For isolated soybean protein (assay protein) (S) the lysine levels 100% and 125% and for soybean meal (SM) the levels 116% and 125% could only be achieved. A control group with whole egg ration (W) (with its natural lysine content of 125% of the requirement) were also tested as comparison. During the 10-day period of the main experiment all 14 rations were supplemented with 0.5 g 15N-lysine (alpha amino group, 95% labelled with 15N). The N balance could only be significantly improved by lysine supplements in the rations B, W and SM with the lysine level of 125%. The biologic value of the protein sources was in rations B and WG also significantly improved by the highest lysine supplement. 15N excess (15N') from the deaminated 15N lysine was excreted with diet B rich in crude fibre mainly in faeces (more than 15% of the intake) and only about 10% in urine. With the diets without native crude fibre the excretion quota changed in favour of urine. The following 15N' amounts in per cent of 15N' intake from lysine were excreted in urine and faeces: B 75 = 31.3, B 100 = 30.9, B 125 = 28.0, W 75 = 24.3, W 100 = 32.2, W 125 = 32.6, GW 75 = 18.3, WG 100 = 24.2, WG 125 = 28.1, S 100 = 39.4, S 125 = 50.4, SM 116 = 34.9, SM 125 = 32.9, W 125 = 19.1. 15N excretion in urine and faeces increased in comparable relations in 6 cases of lysine increase levels only. Gross utilization of lysine can only conditionally be quantified by 15N labelled lysine supplement.