Location: Range and Livestock ResearchTitle: How well does the current metabolizable protein system account for protein supply and demand of beef females within extensive western grazing systems? Author
Submitted to: Joint Abstracts of the American Dairy Science and Society of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 3/15/2013
Publication Date: 6/20/2013
Citation: Waterman, R.C., Caton, J.S., Loest, C.A. 2013. How well does the current metabolizable protein system account for protein supply and demand of beef females within extensive western grazing systems? Joint Abstracts of the American Dairy Science and Society of Animal Science. Beef Species Symposium #438. Interpretive Summary:
Technical Abstract: Extensive western beef livestock production systems within the Southern and Northern Plains and Pacific West combined represent 60% (approximately 17.5 million) of total beef cows in the United States. The beef NRC is an important tool and excellent resource for both professionals and producers to use when implementing feeding practices and nutritional programs within these various production systems. Objectives of this symposium paper are to identify areas within the current beef NRC that could be refined so that future beef NRC models would have greater precision predicting protein supply and demand for beef cattle production within extensive western grazing systems. In western systems, a management protocol often implemented is strategic supplementation which may consist of supplying a prorated bolus dose of protein. An important addition to the current beef NRC model would be to allow users to describe supplement composition, and amount and frequency in which supplement is delivered. Beef NRC models would then need to be modified to account for N recycling that occurs throughout a supplementation interval and the impact that this would have on microbial efficiency and microbial protein supply. The beef NRC should also consider the role of ruminal and postruminal supply and demand of specific limiting amino acids. Additional considerations should include the partitioning effects of nutrients under different physiological production stages (e.g., lactation, pregnancy, and during periods of BW loss) and the role of metabolic modifiers or additives. Metabolic modifiers or additives can greatly influence partitioning of protein (i.e., amino acids) and redirect nutrients for different physiological needs. Our intention is that information provided by this symposium will aid in the revision of the beef NRC by providing supporting material for changes and identifying gaps in existing scientific literature where future research is needed to enhance the predictive precision and application of the beef NRC models.