Milk Urea Nitrogen as a Tool to Monitor the Protein Nutrition of Dairy Cows
Open Access
- 1 December 1997
- journal article
- Published by American Dairy Science Association in Journal of Dairy Science
- Vol. 80 (12), 3333-3340
- https://doi.org/10.3168/jds.s0022-0302(97)76309-4
Abstract
The relationship between protein nutrition and milk urea N was investigated in three experiments with a total of 125 cows. After 4 wk of pretreatment, cows received 1 of 13 diets with different ratios of protein to energy for 16 wk. Milk was sampled individually for urea analyses during pretreatment and during wk 1, 5, 10, and 15 of treatment. Results were compared with N losses estimated from rumen fermentation and with N losses of metabolic origin. The mean milk urea N concentration was 12.6 mg/100 ml of milk (range, 9.0 to 18.3 mg). For bulk samples especially, the rumen efflux of crude protein intake was the main determinant of the variation in milk urea N (r2 = 0.81; residual SD = 1.1). However, N losses from the rumen explained only about 50% of the variation in the milk urea N content of samples from individual cows. The N losses of metabolic origin, which, in these experiments, were responsible for 47 to 100% of urinary N losses, were not related to milk urea N. Results showed that regular measurement of milk urea N in bulk samples can be used to monitor N losses from rumen fermentation. However, the value does not give an indication of the efficiency with which the absorbed protein is utilized.Keywords
This publication has 9 references indexed in Scilit:
- The Dutch protein evaluation system: the DVE/OEB-systemLivestock Production Science, 1994
- Efficiency of protein utilization in dairy cowsLivestock Production Science, 1994
- Nutrition Management of Dairy Cows as a Contribution to Pollution ControlJournal of Dairy Science, 1992
- Urea concentrations in milk in relation to milk yield, live weight, lactation number and amount and composition of feed given to dairy cowsLivestock Production Science, 1985
- Urea concentrations in milk and blood as influenced by feeding varying amounts of protein and energy to dairy cowsLivestock Production Science, 1983
- Zum Einfluß eines verminderten Proteingehaltes der Ration (über Verwendung von geschütztem Protein) auf Milchleistung und einige Blutparameter als Kennzeichen der LeberbelastungZeitschrift für Tierphysiologie Tierernährung und Futtermittelkunde, 1982
- Einfluß des Rohproteinniveaus auf die Fruchtbarkeit und den Harnstoffgehalt in Körperflüssigkeiten bei HochleistungskühenArchives of Animal Nutrition, 1981
- Feed evaluation for ruminants. I. The systems in use from May 1977-onwards in The NetherlandsLivestock Production Science, 1978
- A TWO‐STAGE TECHNIQUE FOR THE IN VITRO DIGESTION OF FORAGE CROPSGrass and Forage Science, 1963