7
44 KNOCHEL, J. P.; DOTIN, L. N.; HAMBURGER, R. J., 1972: J. Clin. Invest. 51, 242-253. KOLLE, H., 1984: Uberdie Fiitterungspraxis von Hochleistungspferden sowie die Trankwasseraufnahme (mit und ohne Salz/Glucosezusatz) bei Pferden wahrend und nach korperlicher Belastung. Hannover, Tier- .irztl. Hochsch., Diss. E. Sakagurhi, R. Heller, G. Becker and W v. Engrlhardl LINDEMANN, R. D., 1976: Am. J. Med. Sci. 272, 5-17. LINDNER, A,; SCHMIDT, M.; MEYER, H.; TELEB, H. M., 1984: Z. Tierphysiol., Tierernahrg. u. Futtermittelkde. MALHOTRA, M. S.; SRIDHARAN, K.; VENKATASWAMY, Y.; RAI, R. M.; PICHAN, G.!; RADHAKRISHAN, U.; GROVER, MANSMANN, R. A.; CARLSON, G. P.; WHITE, N. A,; MILNE, D. W., 1974: J. Am. Vet. Med. Ass. 165,265-270. MEYER, H.; WINKEL, C.; AHLSWEDE, L.; WEIDENHAUPT, C., 178: Tierarztl. Umsch. 6, 330-336. MEYER, H.; SCHMIDT, M.; LINDNER, A,; PFERDEKAMP, M., 1984: Z. Tierphysiol, Tierernihrg. u. Futter- MuNrwYLER, E.; GRIFFIN, G. E.; ARENDS, R. L., 1953: Am. J. Physiol. 174, 283-288. MUNTWYLER, E., 1972: Water and electrolyt metabolism and acid-base balance. C. V. Mosby Company, USA. NEWTON, G. L.; FONTENOT, J. P.; TUCKER, R. E.; POLAN, C.E., 1972: J. Anim. Sci. 35, 440-445. ROSE, R. J.; ARNOLD, K. S.; CHURCH, S.; PARIS, R., 1980: Equine Vet. J. 12, 19-22. SNOW, D. H.; KERR, M. G.; NIMMO, M. A.; ABROTT, E. M., 1982: Vet. Rec. 110, 377-384. SOLIMAN, M. K.; NADIM, M. A,, 1967: Zbl. Vet. Med. A 14, 53-56. SOUTHON, S.; HEATON, F. W., 1982: Comp. Biochem. Physiol. 72, 415-419. ST. OMER, V. V. E.; ROBERTS, W. K., 1967: Can. J. Anim. Sci. 47, 39-46. WEIDENHAUPT, K., 1977: Untersuchungen zum Kaliumstoffwechsel des Pferdes. Hannover, Tierarztl. 52, 155-170. S. K., 1981: Aviat Space Environ. Med. 52, 169-179. mittelkde. 51, 182-196. Hochsch., Diss. Anschrifi der Awfuren: Institut fur Tierernahrung der TiHo Hannover, Bischofsholer Danim IS, D-3000 Hannover 1. Department uf Physiology, School of Veterinary Medicine, 0-3000 Hannover 1 Retention of digesta in the gastrointestinal tract of the guinea pig By E. SAKAGUCHI, R. HELLER, G. BECKER and W. v. ENCELHARDT Receipi of Ms. 8. 5. 85 The guinea pig is a non-ruminant, strictly herbivorous animal with a voluminous caecum. Caecal contents in guinea pigs are rapidly and thoroughly mixed with the contents in the upper proximal colon; both compartments form together a common fermentation chamber (SAKAGUCHI et al. 1985). The production of short-chain fatty acids in the caecum and upper colon of guinea pigs contributes markedly to the energy gain of the animal. This energetic con- tribution is comparable to that in the rabbit (PARKER 1976; MARTY & VERNAY 1984). A particu- larity in the rabbit is the considerably longer retention time of fluid and small particles as compared to larger particles (reviewed by HORNICKE 1984). Such a separation in the large inte- stine achieves a rapid passage of the fibrous contents but sufficient microbial utilization of easier digestible smaller particles. This explains the poor fibre digestibility in the rabbit. In guinea pigs, however, organic matter and crude fibre are digested as efficiently as in horses and ponies (SLADE & HINTZ 1969). This would suggest species differences in digesta retention and in caecal functions between guinea pigs and rabbits. U.S. Copyright Clearance Center Code Statement: I. Anim. Physiol. a. Anim. Nutr. 55 (1986), 44-50 0 1986 Verlag Paul Parey, Hamburg und Berlin ISSN 0044-3565 / Intercode: ZTTFAA 0044-3565/86/5501-0044 $ 02.50/0

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Page 1: Retention of digesta in the gastrointestinal tract of the guinea pig

44

KNOCHEL, J. P.; DOTIN, L. N.; HAMBURGER, R. J., 1972: J. Clin. Invest. 51, 242-253. KOLLE, H., 1984: Uberdie Fiitterungspraxis von Hochleistungspferden sowie die Trankwasseraufnahme (mit

und ohne Salz/Glucosezusatz) bei Pferden wahrend und nach korperlicher Belastung. Hannover, Tier- .irztl. Hochsch., Diss.

E. Sakagurhi, R. Heller, G. Becker and W v. Engrlhardl

LINDEMANN, R. D., 1976: Am. J. Med. Sci. 272, 5-17. LINDNER, A,; SCHMIDT, M.; MEYER, H.; TELEB, H. M., 1984: Z. Tierphysiol., Tierernahrg. u. Futtermittelkde.

MALHOTRA, M. S.; SRIDHARAN, K.; VENKATASWAMY, Y.; RAI, R. M.; PICHAN, G.!; RADHAKRISHAN, U.; GROVER,

MANSMANN, R. A.; CARLSON, G. P.; WHITE, N. A,; MILNE, D. W., 1974: J. Am. Vet. Med. Ass. 165,265-270. MEYER, H.; WINKEL, C.; AHLSWEDE, L.; WEIDENHAUPT, C., 178: Tierarztl. Umsch. 6, 330-336. MEYER, H.; SCHMIDT, M.; LINDNER, A,; PFERDEKAMP, M., 1984: Z. Tierphysiol, Tierernihrg. u. Futter-

MuNrwYLER, E.; GRIFFIN, G. E.; ARENDS, R. L., 1953: Am. J. Physiol. 174, 283-288. MUNTWYLER, E., 1972: Water and electrolyt metabolism and acid-base balance. C. V. Mosby Company, USA. NEWTON, G. L.; FONTENOT, J. P.; TUCKER, R. E.; POLAN, C.E., 1972: J. Anim. Sci. 35, 440-445. ROSE, R. J.; ARNOLD, K. S.; CHURCH, S.; PARIS, R., 1980: Equine Vet. J. 12, 19-22. SNOW, D. H.; KERR, M. G.; NIMMO, M. A.; ABROTT, E. M., 1982: Vet. Rec. 110, 377-384. SOLIMAN, M. K.; NADIM, M. A,, 1967: Zbl. Vet. Med. A 14, 53-56. SOUTHON, S.; HEATON, F. W., 1982: Comp. Biochem. Physiol. 72, 415-419. ST. OMER, V. V. E.; ROBERTS, W. K., 1967: Can. J. Anim. Sci. 47, 39-46. WEIDENHAUPT, K., 1977: Untersuchungen zum Kaliumstoffwechsel des Pferdes. Hannover, Tierarztl.

52, 155-170.

S. K., 1981: Aviat Space Environ. Med. 52, 169-179.

mittelkde. 51, 182-196.

Hochsch., Diss.

Anschrifi der Awfuren: Institut fur Tierernahrung der TiHo Hannover, Bischofsholer Danim IS, D-3000 Hannover 1.

Department uf Physiology, School of Veterinary Medicine, 0-3000 Hannover 1

Retention of digesta in the gastrointestinal tract of the guinea pig

By E. SAKAGUCHI, R. HELLER, G. BECKER and W. v. ENCELHARDT

Receipi of Ms. 8. 5. 85

The guinea pig is a non-ruminant, strictly herbivorous animal with a voluminous caecum. Caecal contents in guinea pigs are rapidly and thoroughly mixed with the contents in the upper proximal colon; both compartments form together a common fermentation chamber (SAKAGUCHI et al. 1985). The production of short-chain fatty acids in the caecum and upper colon of guinea pigs contributes markedly to the energy gain of the animal. This energetic con- tribution is comparable to that in the rabbit (PARKER 1976; MARTY & VERNAY 1984). A particu- larity in the rabbit is the considerably longer retention time of fluid and small particles as compared to larger particles (reviewed by HORNICKE 1984). Such a separation in the large inte- stine achieves a rapid passage of the fibrous contents but sufficient microbial utilization of easier digestible smaller particles. This explains the poor fibre digestibility in the rabbit. In guinea pigs, however, organic matter and crude fibre are digested as efficiently as in horses and ponies (SLADE & HINTZ 1969). This would suggest species differences in digesta retention and in caecal functions between guinea pigs and rabbits.

U.S. Copyright Clearance Center Code Statement: I. Anim. Physiol. a. Anim. Nutr. 55 (1986), 44-50 0 1986 Verlag Paul Parey, Hamburg und Berlin ISSN 0044-3565 / Intercode: ZTTFAA

0044-3565/86/5501-0044 $ 02.50/0

Page 2: Retention of digesta in the gastrointestinal tract of the guinea pig

Retention of digesta in the guinea pig 45

In the present study, retention time of a liquid marker was estimated in various segments of the guinea pig digestive tract to evaluate the significance of the caecum for fluid retention. Furthermore, the retention times o f fluid and of particulate digesta were determined in the caecum to get informations on a possible separation mechanism for fluid and particles.

Materials and m e t h o d s

Animals and feeding

Six adult male guinea pigs (mean body weight 621 g) were used. At least three weeks prior to the experiments three of the animals were fitted with a permanent caecal cannula (inner diameter 4 mm). Throughout the experiments the animals were kept individually in wirefloor cages. A pelleted diet was fed ad libitum (Meerschweinchen-Haltungsfutter Nr. 3022, Altromin; composition: crude protein 230, crude fat 52; crude fibre 120; crude ash 83; NFE 395 g/kg diet). Water was available freely.

Experimental procedure

Administration of Juid marker per 0s. To determine the retention time of fluid in the total gastrointestinal tract (GI-tract) 1 to 1.5 ml polyethyleneglycol solution (PEG, M W 4000, 0.2 g/ml) was administered orally with a syringe and a short tube in five of the animals. The excreted faeces were collected at 2 hs intervals for the first 60 hs, at 4 hs intervals for the fol- lowing 20 hs, and at 6 hs intervals for the final 24 hs.

Injeclion ofJuid marker into the caecum. In three guinea pigs with a caecal cannula two experi- ments were done with each of the animals. PEG (0.2 g/ml) was injected into the caecum through the cannula to determine the retention time of fluid in the large intestine. Excreted faeces were collected at 2 hs intervals for 36 hs, at 4 hs intervals for the following 12 hs, and at 6 hs intervals for the final 32 hs. To determine the dilution rate of fluid in the caecal digesta 1, 3, 5, 7, and 9 hs after the injection of PEG 1 ml-samples of caecal contents were taken.

Simultaneous injection ofJuid and particle markers into the caecum. To compare the retention time of fluid with that of the particulate digesta Ce- or Cr-mordanted plant cell wall consti- tuents (CWC) were injected into the caecum of the three cannulated animals. Two experi- ments.were done with each of these guinea pigs. The C W C were prepared by grinding hay and sieving the particles. The particle sizes used were 0.08-0.2 mm. The hay-particles were pretreated with sodium-lauryl-sulphate and washed with water and acetone according to the method of U D ~ N et al. (1980). Then, the particles were labelled by incubating them in Ce- or Cr- solutions. 1 ml PEG solution (0.2 g/ml) and Ce- or Cr-mordanted C W C were injected simultaneously. Excreted faeces were collected at 2 hs intervals for 36 hs after the injection.

Analytical methods

Faeces were dried at 80°C. PEG concentrations in the faeces were determined nephelometrical- ly at 90" to the incident light ( H Y D ~ N 1955). For measuring the Ce- or Cr-concentrations in the faeces, 50 mg dried and ground faeces were irradiated for 4 hs in the reactor of the Medical High School, Hannover, and the y-activities were measured 2 weeks after irradiation using the Ge(Li)-detector of the Department of Physics, University Hohenheim, Stuttgart.

Page 3: Retention of digesta in the gastrointestinal tract of the guinea pig

46 E. Sakaguchi, R. Heller, G. Becker and W v. Engelhard

Calculations

After oral and caecal administrations the retention times were calculated using the method of COOMBE and KAY (1965): (C x, . t,) . C x,-', where x, is the quantity of marker in the collection period and t, is the time (hours) after injection of the marker. The two-compartmental system of GROVUM and WILLIAMS (1973) was fitted to time-sequence excretion data of PEG after its single oral administration. After the simultaneous injection of PEG and Ce or C r into the caecum the marker concentration rose rapidly to a maximum after the first appearance of the markers; for calculation the single volume model was applied to the excretion of the markers (BRANDT & THACKER 1958). The retention times were calculated from the marker concentra- tions in the faeces only up to 24 hs after injection to avoid a possible effect of coprophagy which could affect the values in the later periods.

The differences between the mean values were evaluated statistically by Student's t-test (SNEDECOR & COCHRAN 1967).

Results

After oral or intracaecal application of PEG the concentration in faeces increased rapidly. The decrease in faecal PEG concentration followed a straight line in a semilogarithmic graph until 24 hs after administration. Since the subsequent data did not always follow a straight line only data up to 24 hs were fitted to the two-compartmental model.

Totalgastrointestinal tract. The findings are compiled in table 1, A. From the dilution rates of PEG the rate constants (k) were calculated for the larger (1st; I lk l ) and the smaller (2nd; Ilk2) compartment applying the two-compartmental model. The mean retention time o f PEG in the larger and in the smaller compartment were 8.9 hs and 0.8 hs, respectively. The mean value o f transit time (TT) of PEG in the tubular tract was 5.6 hs, and in the total gastrointestinal tract 15.0 hs. The mean retention time (R,,,,,; table 1) calculated with the method of C ~ ~ M B E & KAY (1965) was not significantly different from those of the compartmental analysis (Sum; table 1). The rate constants estimated from the decay curves of the PEG-concentrations were similar, both in the caecum and in faeces.

Large intestine: The mean retention time of fluid estimated after the injection of PEG into the caecum is given in table 1, B. Both the values calculated from the compartmental analysis as well as from the Coombe & Kay-equation were 12 hs. The caecal retention time of PEG esti- mated from the dilution rate (]/kc) was 8.0 hs, from the rate constants of the faecal decline curve (l/kl) 9.0 hs; these values were not significantly different from each other.

Between the mean retention time of PEG and of particle markers injected simultaneously into the caecum no significant differences were seen (table 1, C). Furthermore, no difference was observed in the marker retention times in the large intestine between the two calculation methods used.

Discussion

Two major compartments where digesta are retained in the guinea pig were identified after oral administration o f the liquid marker (table 1, A). The 1st compartment (the larger one) is assumed to be the caecum together with the upper proximal colon. Data calculated from the rate constants after oral application agree closely with those gained after marker injection into the caecum as well as from PEG dilution curves in caecal contents (table 1, B).

Page 4: Retention of digesta in the gastrointestinal tract of the guinea pig

Retention of digesta in the guinea pig 47

Table 1

Mean retention time of liquid (PEG) or particle (Ce or Cr) markers in the gastrointestinal (GI) tract respectively in the large intestine of guinea pigs. All values are given in hours

Compartmental analysis

Marker R2 TT S y 9 La, K, + R , + T T . 8.9 0.8 5.6 15.0 14.3

5 5 5 5 5 n

9.0 3.0 12.0 8.0 12.0 B. Large intestine PEG 2.0 0.5 2.5 1 .o 1.4 SD

3 3 3 3 3 n+

- X

A. Total GI-tract PEG 2.6 0.9 3.1 5.4 3.9 SD

- X

9.1 3.7 12.8 C. Large intestine PEG 2.1 2.1 3.2

3 3 3

Ce-, Cr- 9.9 4.0 13.9 particles 3.5 2.1 4.7

3 3 3

12.8 - X

1.9 SD 3 n+

3.3 SD 3 n+

13.1 - X

n fi+ 5, R1 TT Sum Rl + R2 + TT - mean retention time q. K,,,., mean retention time calculated using the method of COOMBE & KAY (1965).

number of animals, one trial with each animal number of animals, two trials with each animal retention time in the first (larger) compartment ( l /k l ) retention time in the second (smaller) compartment (Ilk2) t_ransittimc through the tubular part of the GI-tract

retention time in the caecum, calculated from time course changes of marker concentration in the caecum.

The caecal contents in the guinea pig are mixed thoroughly with those in the upper proximal colon (fig. 1, shaded area), and both together form a common fermentation compart- ment comprising approximately 6.7% of the body weight (SAKAGUCHI et al. 1985). Thus, all the caecal data estimated from the findings in our experiments include the contents of the upper proximal colon (that is approximately 28 g or 2% of the body weight; SAKACUCHI et al. 1985).

Regarding the anatomy of the gastrointestinal tract of the guinea pig the smaller 2nd compartment may be the stomach. Our attemps to estimate the retention time in the stomach from the compartmental analysis were not satisfactory. The values varied considerably, and estimates were very short in all experiments (table 1, A). We therefore doubt that the stomach in guinea pigs is a well mixing compartment.

The caecal compartment in the guinea pig is the main site of the retention of digesta (60% of retention time in the total GI-tract; table 2). This is similar in the rabbit (PICKARD & STEVENS 1972, LENG et al. 1977). O n the other hand, in the equine (ARGENZIO et al. 1974) as well as in swine (CLEMENS et al. 1975) contents are retained mainly in the colon.

In our experiments the mean retention time of PEG was calculated to be 15.0 hs in the total GI-tract, mean retention time in the small intestine and in the stomach was 3.0 hs (table 2). It has been reported that gastric emptying and small intestinal transit time of fluid occurred within 4 to 8 hs after feeding in swine (CLEMENS et al. 1975) and dog (BANTA et al. 1979). The relative length o f the small intestine seems not to have great influence.

CLEMENS and STEVENS (1980) reported a mean retention time o f fluid in the total gastroin-

Page 5: Retention of digesta in the gastrointestinal tract of the guinea pig

48 E. Sakaguchi, R. Hcller, G. Becker and W. v. Engelhard!

testinal tract o f guinea pigs to be 40 hs. This value is more than twice of that calculated from our experiments. These authors fed their animals twice daily and offered feed for an one hour period only. The long retention time of fluid could be due to these feeding condi- tions. If feed is available ad libitum guinea pigs eat more or less continously in hourly intervals during day and night (HIRSCH 1973; WAIBLE 1978). Restriction of feed may result in prolonged retention times of digesta in the gastrointestinal tract as it is known from rumi- nants where retention time is increased by approximately 60% when feed intake is re- stricted (BLAXTER et al. 1956).

In a few pilot studies we measured particle size of caecal digesta in four animals by wet sieving; 25.4 Yo of total particle weight were smaller then 0.08 mm, 42.2% were 0.08- 0.2 mm, 27.2% were 0.2-0.4 mm and 5.6% were larger than 0.4 mm (unpublished observa- tions). In our experiments we labelled particles of a size between 0.08-0.2 mm with Ce or Cr

transverse colon

proxim coion

W

Fig. 1. Schema of the digestive tract of the guinea pig (modified from the figure drawn by COOPER & SCHILLER 1975). Caecal contents are mixed with those of the upper proximal colon (shaded area) as described by SAKAGUCHI et al. (1985).

so that the particle marker used may have represented the major particle size fraction of caecal contents in guinea pigs fed a pelleted diet.

Table 2

Mean retention time in the gut segments of the guinea pig

Mean retention time of PEG (hours)

b of total GI-tract

Stomach and small intestine

Caecal compartment

Distal large intestine

, Total GI-tract

3.0

9.0

3.0

15.0

20

60

20

I00

Calculated from the data in table 1, A & B Stomach and small intestine: total GI-tract - (caecal compartment + distal large intestine)

The similar retention of fluid and of particles measured in the present study is in agreement with the findings by CLEMENS & STEVENS (1980):This indicates that the caecum and the colon in guinea pigs have no mechanisms to separate fluid from particles in the large bowel. Such a separation is well described in the lemming and in the rabbit (SPERBER 1968; BJORNHAG 1972; PICKARD & STEVENS 1972; LENC et al. 1977). In the rabbit digesta particles smaller than 0.1 mm and fluid are retained in the caecum whereas particles larger than 0.1 mm pass rapidly (BJORNHAG 1972). This short retention of particles in rabbits is reflected by the rather low fibre

Page 6: Retention of digesta in the gastrointestinal tract of the guinea pig

Retention of digesta in the guinea pig 49

digestibility (FONNESBECK et al. 1974), whereas in the guinea pig crude fibre is digested as effi- ciently as in horses and ponies (SLADE & HINTZ 1969).

Coprophagy which is common in many rodents had also been observed in the guinea pig (KING 1956; B J ~ R N H A G & SJOBLOM 1977; WAIBLE 1978). Coprophagy was not prevented in our experime.nts and it is possible that a certain portion of the marker recirculated in the gastroin- testinal tract. The decrease of the faecal marker concentrations did show certain irregularities, especially 24 hs after application of the markers. W e assume that periodical variations of marker concentrations throughout the experiment might be due to the recirculation of the marker by coprophagy. For the compartmental analysis we therefore applied only data up to 24 hs after marker administration. For the total collection method, however, data from the total collection period were taken. The good agreement of the data gained from the different methods indicate that n o major portion of the marker was recirculated in these animals.

Summary

1. Polyethyleneglycol (PEG) and Ce- or Cr-mordanted plant cell wall material were used as liquid marker and particle markers, respectively.

2. The liquid marker was administered orally or injected into the caecum through a caecal cannula. In a final series of experiments the particle marker was administered simul- taneously with PEG into the caecum. Mean retention times of each marker were calcu- lated from time course changes of the marker concentrations in the caecal fluid and in the faeces.

3. Compartmental analysis of the excretion data of the markers showed that the gut of guinea pigs has two compartments.

4. The caecal compartment is the major section of the gastrointestinal tract where digesta are retained; mean retention time of fluid was 9 hours, i.e. 60% of the retention time in the total gut.

5. There was n o difference between retention time of liquid and of particle markers in the large intestine.

Zusammenfassung

Verweilzeit von Digesta im Magendarmkanal des Meerschweinchens

1. Polyathylenglycol (PEG) und Ce- oder Cr-markiertes pflanzliches Zellwandmaterial wur- den als Fliissigkeits- bzw. Partikelmarker verwendet.

2. Der Fliissigkeitsmarker wurde oral verabreicht oder durch eine Kaniile direkt ins Caecum injiziert. In weiteren Versuchen wurde der Partikelmarker gleichzeitig mit PEG ins Caecum gegeben. Die mittleren Venveilzeiten der einzelnen Marker wurden aus dem zeitlichen Ver- lauf der Markerkonzentrationen in der Caecumfliissigkeit und im Kot berechnet.

3. Die Compartment-Analysen der Markerkonzentrationen im Kot ergaben, daB im Magen- darmkanal des Meerschweinchens zwei Compartments mit verlangerten Retentionszeiten vorhanden sind.

4. Die mittleren Venveilzeiten der Fliissigkeit im Caecum betrugen 9 h (60 YO der Venveilzeit im gesamten Magendarmkanal).

5. Im Dickdarm wurde kein Unterschied zwischen den Venveilzeiten von Fliissigkeit und von Partikeln festgestellt.

Page 7: Retention of digesta in the gastrointestinal tract of the guinea pig

50 E. Sakugurhi, R. Heller, G. Becker and W v. Enplbardt

Acknowledgement

The studies were supported by a grant of the “Deutsche Forschungsgemeinschaft“ (En 65/12). The senior author was given a Research Fellowship from the “Alexander von Humboldt Foun- dation”.

The authors are extremely thankful to Dr. V. CERCASOV, Department o f Physics, University Hohenheim, Stuttgart, for his help in measuring the activity of Ce and C r after neutron activa- tion analysis. We greatly appreciate that irradiation could be done at the School of Medicine, Hannover, Dept. Nuclearmedicine, Dr. D. JUNKER. We also like to express thanks to Drs. RECH- KEMMER and WEYRETER for helpful discussions and to Miss BURMESTER and Mrs. KRAUSE for technical assistance.

References

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SLADE, L. M.; HINTZ, H. F., 1969: J. Anim Sci. 28, 842. SNEDECOR, G. W.; COCHKAN, W. G., 1967: Statistical Methods, 6th ed., Anies: Iowa State University Press. SPEKBEK, I., 1968: In: Isotope studies on the nitrogen chain, pp. 209-219, Vienna: International Atoinic

UDEN, P.; COLUCCI, P. E.; V A N SOEST, P. J., 1980: J. Sci. Food. Agric. 31, 625. WAIBLE, M., 1978: Untersuchungen zum Tagesrhythrnus der Futteraufnahme und der Coproph.igie bei

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Energy Agency.

Meerschweinchen (Zulassungsarbeit, Universitat Hohenheim).

Aulhors’ addresses: R. HELLER, G. BECKEK, W. v. ENGELHARUT: Physiologisches Institut, Tierirztliche Hoch- schule, Bischofsholer Danini 15, D-3000 Hannover 1. E. SAKAGUCHI: Department of Animal Science, Faculty of Agriculture, Okayania University, Okayaina 700, Japan.