[Studies on nitrogen metabolism in the large intestine of ruminants. 5. Metabolism of intra-cecally infused 15N-urea without and with fermentable material in heifers].
Six heifers with a live weight of 215, 227 and 238 kg (experiment 1) and 220, 227 and 233 kg, resp. (experiment 2), were supplied with ileocaecal re-entrance cannulae, jugular venous catheters and bladder catheters. The ration consisted of 4 kg maize silage and 4 kg wheat straw pellets per animal per day. Up to 3.5 kg of the straw pellets, consisting of 73% wheat straw, 10% barley, 12% molasses, NPN salts and a mineral mixture, were consumed per animal per day. In a preliminary 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 trial the re-entrance cannula was disrupted and the flowing digesta were quantitatively collected at the end of the ileum; previously collected digesta were supplemented with 15N urea and every hour over 24 h infused into the caecal part of the re-entrance cannula. Between the 24th and 30th hours the digesta were infused without 15N urea supplement. In trial 2 the digesta were also supplemented with partly hydrolysed straw meal between the 1st and 30th hours (approximately 10% straw meal DM related to digesta DM). There were no differences between trials 1 and 2 with regard to the increase of atom-% 15N excess (15N') in the plasma urea. The 15N labelling decrease of the plasma urea N shows that the half-life is 7.9 h in trial 1 and 7.0 h in trial 2. The NH3 nitrogen in faeces was distinctly higher labelled in trial 2 after the supplement of straw meal than in trial 1. The total N in faeces was also twice as highly labelled as in trial 1. Atom-% 15N' in urine was significantly higher in trial 2 than in trial 1 between the 6th and 16th hours after the beginning of 15N urea supplementation. In the decrease curve of atom-% 15N' (after the 26th hour of trial) the values in trial 1 were generally higher than in trial 2. The higher bacterial protein synthesis in the large intestine in trial 2 (after the supplement of partly hydrolysed straw meal) had the effect that 13.6% of the supplemented 15N' was excreted in faeces by the 30th hour of trial, in contrast to this only 4.7% in group 1. Up to the 4th day after the 15N urea infusion these values increased to 16.2 and 6.1%, resp., only.
Bergner
H
H
Sektion Tierproduktion und Veterinärmedizin der Humboldt-Universität zu Berlin.
Götz
K P
KP
Simon
O
O
Sommer
A
A
Ceresnáková
Z
Z
Szakacs
J
J
Chrastinova
L
L
D000821:Animal Feed; D000818:Animals; D002417:Cattle / Q000378:metabolism*; D004043:Dietary Fiber / Q000378:metabolism*; D005243:Feces / Q000032:analysis; D005260:Female; D005766:Gastrointestinal Contents; D007420:Intestine, Large / Q000378:metabolism*; D009584:Nitrogen / Q000032:analysis / Q000378:metabolism*; D014508:Urea / Q000097:blood / Q000378:metabolism*
D004043:Dietary Fiber; D014508:Urea; D009584:Nitrogen
Untersuchungen zum Stickstoffumsatz im Dickdarm von Wiederkäuern. 5. Mitteilung. Umsatz von intrazäkal infundiertem 15N-Harnstoff ohne und mit Zusatz von fermentierbarem Material bei Färsen.