lactatingdairy cows (n=177) fed with grass and corn silage ad libitum kept in pasture, were randomly assigned to evaluate how urea nitrogen in plasma and milk can be related to their pregnancy rate. blood and milk samples were collected on the artificial insemination (ai) day to evaluate plasma urea nitrogen (pun) and milk urea nitrogen (mun) as well as progesterone levels, excluding cows with ...

the nutritional value of cereal straw can be increased using urea treatments as a source of ammonia. the conventional urea treatment process for cereal straw is a laborious and time-consuming task. it is essential to facilitate or eliminate part of the procedure with the use of machinery. this study examines the mechanical urea treatment of wheat straw and compares chemical components and diges...

in order to increase grain yield, nitrogen use efficiency (nue) and nitrogen apparent recovery fraction (narf) in wheat (triticum aestivum l.), this experiment was carried out with 5 or 6 treatments and 3 or 4 replications in 14 locations at 22 different sites in iran during the 2004-05 growing season. the experiment was designed as a completely randomized block. the effect of n sources and tim...

background: like several other parasites, teladorsagia circumcincta secretes or excretes urea, but nei-ther the rate of efflux nor the possible metabolic sources of the urea has been considered. methods: parasites were maintained by passage through sheep. urea efflux was measured using phe-nol/hypochlorite after treatment with urea aminohydrolase. the kinetics of creatine amidinohy-drolase and ...

When behavioral avoidance cannot prevent an animal from being exposed to novel environmental toxins, physiological mechanisms must cope with the toxin and its effects. We are investigating the basis of urea tolerance in populations of Drosophila melanogaster that have been selected to survive and develop in food containing 300 mmol l(-1) urea. Previous research has demonstrated that the urea-se...