The aim of this study was to examine the effect of the beta2-adrenoceptor clenbuterol on food-restricted sheep. Clenbuterol was administered as a dietary admixture (4 mg/ kg diet) to a group of male Serra da Estrela sheep (n = 6). The animals were housed individually in metabolic cages and fed for 45 days at 65% of estimated requirement for energy maintenance. An untreated group with the same e...

The CERES-Maize model was developed to investigate how variations in environmental conditions, management decisions, and genetics interact to a€ect crop development and growth. A tile drainage subroutine was incorporated into CERES-Maize to improve soil-water and nitrogen leaching under subsurface tile drainage conditions. The purpose of this work was to evaluate the soil-water, soil-nitrogen, ...

Agricultural system models are tools to represent and understand major processes and their interactions in agricultural systems. We used the Root Zone Water Quality Model (RZWQM) with 26 years of data from a study near Nashua, IA to evaluate year to year crop yield, water, and N balances. The model was calibrated using data from one 0.4 ha plot and evaluated by comparing simulated values with d...

The effects of nitrogen balance on uric acid/urate, K+ and Na+ storage or mobilization were examined in the American cockroach Periplaneta americana (L.). Cockroaches on a high nitrogen diet increased in whole body uric acid/urates, K and Na+. Those on a semi-starvation diet maintained fairly constant levels of uric acid/urates, K+ and Na+. However, those on a low nitrogen diet mobilized stored...

The removal of gaseous ammonia in a system consisting of a biotrickling filter, a denitrification reactor and a polishing bioreactor for the trickling liquid was investigated. The system allowed sustained treatment of ammonia while preventing biological inhibition by accumulating nitrate and nitrite and avoiding generation of contaminated water. All bioreactors were packed with cattle bone comp...

Seasonal variations in leaf nitrogen, phosphorus and potassium concentrations were studied in a mature carob (Ceratonia siliqua L. cv "Mulata") orchard subjected to a 4-year irrigation and fertilization experiment. Three irrigation regimes (0, 50 and 100%), based on the evaporation values obtained from a class A pan, were tested in combination with two nitrogen (N) supply regimes in which 21 kg...

During the febrile stages of most acute infections both the total and the nitrogen metabolisms are found to be considerably altered. These, under ordinaryconditions of feeding, usually result in negative nitrogen balances and a breakdown of proteins attributed to the combined effect of increased calorie expenditure and to the destruction of the tissues. The ' toxic destruction of proteins' appe...

We analyzed three kinds of information to evaluate the potential of forests in the Chesapeake Bay watershed to retain the nitrogen in atmospheric deposition. Long-term (13:~) measurements of nitrogen in precipitation and stream discharge for one forested watershed in the Inner Coastal Plain showed consistently high nitrogen retention. Annual wet precipitation deposited an averagk of U.4 kg N/ha...

This study was aimed at quantifying soybean (Glycine max) nitrogen fixation under reduced tillage (RT) and conventional tillage (CT) in a tropical Ferralsol of the sub-humid zone of western Kenya, using the isotope N dilution method. Crop residue (CR) management was a superimposed treatment in soybean-maize rotation and intercropping systems. This study quantified N in abscised soybean leaves. ...