Nitrogen was recognized over 200 yr ago as an element essential for normal function of farm animals. During the first half of the 19th century, the roles of proteins and urea in N metabolism were discovered. By the middle of the 20th century, the substrates, products, and enzymes of the urea cycle were elucidated. Work since then has quantified dietary crude protein requirements for specific pr...

In ruminants excess dietary Nitrogen (N) is excreted as urea mainly through urine. Urea, the major form of urinary N is rapidly converted to ammonia after excretion. Ammonia is an important environmental pollutant that impacts the quality of human and animal life .The NRC (2001) considered ammonia emissions from concentrated animal feeding operations (CAFO) as a major air quality concern. Ammon...

The purpose of this study was to compile and evaluate relationships between feed nitrogen (N) intake, milk urea N (MUN), urinary urea N (UUN), and ammonia (NH(3)) emissions from dairy farms to aid policy development. Regression relationships between MUN, UUN, and NH(3) emissions were compiled from studies conducted in Wisconsin, California, and the Netherlands. Relative reductions in NH(3) emis...

The objective of this research, was to quantify sustainability indicators of organic dairy farms using Automatic Milking Systems (AMS), and a comparative group of organic dairy farms using conventional milking systems (CMS). Milk yield per cow was higher for AMS farms but did not result in higher net return to management. Nitrogen surplus per ha of available land was higher for AMS farms, Anima...

This experiment was conducted to evaluate the effects of processing protein meals by tannin extracted from pistachio by-product on apparent total tract digestibility, ruminal fermentation and performance of dairy cows. For tannin extraction, one kilogram of sun-dried pistachio by-products was immersed in four liters of water for 48 h. Then, pistachio by-products were removed from the water and ...

Nitrogen (N) in livestock food sources that does not end up in a product (e.g. milk or eggs) or that does not get incorporated in body tissue is excreted by the animal. Nitrogen in the urine is in the form of urea which can rapidly hydrolyse to form ammonium carbonate. The decomposition of ammonium carbonate frees up ammonium ions that can volatilise as gaseous ammonia (NH3). Hydrolysis of urea...

Five Haflinger mares were hand-milked at 0 h (pre-suckle) and 6 h (postsuckle), 12, 24, 48, 72 and 96 h after parturition. Total solids, protein, fat, lactose, calculated gross energy content, leptin and non-protein nitrogen components (urea, alpha-amino nitrogen, creatinine and allantoin) were determined. The levels of the major constituents differed significantly in pre-suckle colostrum from ...

Data from 35 trials with 482 lactating cows fed 106 diets were used to study the effects of animal and dietary factors on the relationship between milk and blood urea N and the value of milk urea N in the assessment of protein status. In two trials, urea N in whole blood and in blood plasma were closely related (r2 = 0.952); the slope was not significantly different from 1.0, and the intercept ...