animal agricultural production systems are major sources of nonpoint pollution affecting quality of water sources. nitrogen has been identified as the foremost source of nonpoint water pollution  and the potential negative impacts of n have become an area of public concern. protein degradation from feed ingredients is an important factorinfluencing aa supply to the duodenum. ruminal proteolysis...

this research was conducted to estimate the amount of microbial protein synthesis in iranian buffaloes' rumen. four male swamp buffaloes with average live body weight of 140±10 kg were used in this study. four diets of 0 (control diet, 100% forage), 15, 30 and 45% concentrate in a 4 × 4 latin square were tested. the results indicated that by increasing the concentrate level in the diet of swamp...

quantitative structure-activity relationship (qsar) models were employed for prediction the activity of p2x7 receptor antagonists. a data set consisted of 50 purine derivatives was utilized in the model construction where 40 and 10 of these compounds were in the training and test sets respectively. a suitable group of calculated molecular descriptors was selected by employing stepwise multiple ...

Five multiparous, ruminally cannulated Holstein cows (two lactating and three dry) weighing (X +/- SD) 667 +/- 35 kg were used to study the effect of abomasal purine infusion on the excretion of purine derivatives. Cows were fed corn silage four times daily at 90% of ad libitum intake (X = 9.16 kg of dry matter/d). Purines were infused into the abomasum as brewer's yeast suspensions in five inc...

Two studies were performed to evaluate the effects of dried distillers grains with solubles (DDGS) on the lactational performance of dairy cows. The intent of experiment 1 was to evaluate the effects of feeding increasing concentrations of DDGS on the feed intake and production of Holstein dairy cows. Twenty multiparous Holstein cows averaging 76 +/- 24 d in milk and 638 +/- 68 kg of body weigh...

Duodenal flow of microbial N (MN) was estimated from urinary purine derivatives to examine age-related changes in MN in male Holstein calves. In Exp. 1, endogenous purine derivatives were determined by measurement of purine derivatives in five calves fed nucleic acid-free milk replacer alone. In Exp. 2, the ratio of urinary excretion as purine derivatives to purines administered via the reticul...

Three new purine derivatives, namely, 4-caryboxy-5,6-dihydro-4H,8H-pyrimido[1,2,3-cd]purine-8,10(9H)-dione (1), 7,9-dihydro-1-(3-oxobutyl)-1H-purine-6,8-dione (2), and 7-hydro-9-(3-oxobutyl)-1H-purine-6,8-dione (3) together with six known purine and pyrimidine derivatives were isolated from the EtOH/CH(2)Cl(2) extracts of the South China Sea gorgonian Subergorgia suberosa. The structures of 1-3...

Thiopurines, Photolysis, Photooxygenation, Purine Derivatives Irradiation (A > 290 nm) of 6-thiopurine and some 9-substituted 6-thiopurines in oxygen saturated iertf-butanol leads to hypoxanthine, purine and purine-6-sulfonic acid or their substituted derivatives. Purine and hypoxanthine formation can be sensitized with dyes. The reaction of 6-thiopurine with singlet oxygen has also been perfor...

The objectives of the present study were to estimate the microbial-N flow to the small intestine and to predict the digestible organic matter intake (DOMI) in grazing Karayaka sheep based on urinary excretion of purine derivatives (xanthine, hypoxanthine, uric acid, and allantoin) by the use of spot urine sampling under field conditions. In the trial, 10 Karayaka sheep from 2 to 3 years of age ...