References
- Broderick, G. A., 2003. Effects of varying dietary protein and energy levels on the production of lactating dairy cows. J. Dairy Sci. 86:1370–1381.
- CPM, Cornell-Penn-Miner, 2004. CPM Dairy. Dairy cattle ration analyzer, version 3.0.6.
- Cunningham, K. D., Cecava, M.D., Johnson, T.R., Ludden, P.A., 1996. Influence of source and amount of dietary protein on milk yield by cows in early lactation. J. Dairy Sci. 79:620–630.
- Flachowsky, G. and Lebzien, P., 2006. Possibilities for reduction of Nitrogen (N) excretion from ruminants and the need for further research – a review. Landbauforschung Völkenrode 56:19–30.
- Leonardi, C., Stevenson, M., Armentano, L.E., 2003. Effect of two levels of crude protein and methionine supplementation on performance of dairy cows. J. Dairy Sci. 86:4033–4042.
- National Research Council, 2001. Nutrient Requirements of Dairy Cattle. 7th rev. ed. Natl. Acad. Sci., Washington, DC.
- Nousiainen, J., Shingfield, K.J., Huhtanen, P., 2004. Evaluation of milk urea nitrogen as a diagnostic of protein feeding. J. Dairy Sci. 87: 386–398.
- Olmos Colmenero J. J. and Broderick, G.A., 2006. Effect of dietary crude protein concentration on milk production and nitrogen utilization in lactating dairy cows. J. Dairy Sci. 89:1704–1712.
- Oltner, R. and Wiktorsson, H., 1983. Urea concentrations in milk and blood as influenced by feeding varying amounts of protein and energy to dairy cows. Livest. Prod. Sci. 10:457.
- SAS., 2000. User’s Guide: Statistics, version 6.SAS Institute Inc., Cary, NC, USA.