Tracer studies of urea kinetics in growing pigs: II. The effect of starch infusion at the distal ileum on urea recycling and bacterial nitrogen excretion.
Six gilts, with an average BW of 70 kg, were fitted with a simple T-cannula at the distal ileum to study the effect of continuous starch infusion on urea kinetics by means of a radioisotope dilution technique. The pigs were fed twice daily 600 g of a cornstarch-based diet formulated to contain 16% CP by supplementation with isolated soy protein. Infusion of starch, compared with water, decreased (P < .05) plasma urea concentration, urea pool size, and entry, excretion, and degradation rates; urea turnover rate and urea space were not affected (P > .05). Expressed as a percentage of total entry rate, approximately 40% of urea was recycled into the digestive tract in both infusion treatments. The stimulation of microbial fermentation in the large intestine resulted in an increase (P < .05) in fecal N excretion, which was mainly due to an increased excretion of bacterial N. This increase could not be attributed to a greater secretion of urea into the large intestine and its subsequent utilization by the intestinal microflora. The increased bacterial N assimilation after starch infusion led to a reduction in ammonia absorption from the large intestine, which in turn was reflected by a reduced urinary N excretion. As a result, the overall N balance was not affected. In a second experiment, two barrows, with an average BW of 80 kg, were fed twice daily 1.4 kg of a cereal-based diet. The body urea pool of both pigs was labeled with a single injection of 1 g and 2 g of [15N]urea, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
Mosenthin
R
R
Department of Animal Science, University of Alberta, Edmonton, Canada.
Sauer
W C
WC
Henkel
H
H
Ahrens
F
F
de Lange
C F
CF
D000818:Animals; D001419:Bacteria / Q000378:metabolism; D005243:Feces / Q000737:chemistry; D005260:Female; D005285:Fermentation; D007420:Intestine, Large / Q000378:metabolism* / Q000382:microbiology; D008297:Male; D009584:Nitrogen / Q000032:analysis*; D011865:Radioisotope Dilution Technique; D013213:Starch / Q000008:administration & dosage*; D013552:Swine / Q000378:metabolism*; D014508:Urea / Q000097:blood / Q000493:pharmacokinetics*
D014508:Urea; D013213:Starch; D009584:Nitrogen