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Regression equations can be used to estimate the preharvest neutral detergent fiber (NDF) concentration of alfalfa. In New York, where the stubble height of alfalfa varies due to terrain, predictive accuracy of existing equations may be reduced. Th e objectives of this experiment were to develop and evaluate alfalfa NDF equations that incorporate intended stubble height. Stands of first-cut alfalfa were sampled in producers’ fields in New York in 2007, and cut into 5-cm segments. Predictive NDF equations were developed for each segment and for the whole plant. To develop whole-plant equations, it was necessary to develop and use equations describing the change, with alfalfa height, in the contribution of each segment to the overall dry matter (DM). The r² values ranged from 0.90 to 0.93 for the individual segments and 0.93 for the whole-plant equations. The whole-plant equations performed comparably to existing models when evaluated using a dataset of 109 alfalfa samples cut at 10 cm, from 19 New York counties in 2004 and 2005. Th e derived equations were also fitted to samples collected at a range of stubble heights from New York and Minnesota in 2008. For the New York dataset, the r² values for whole-plant equations ranged from 0.86 to 0.87, compared with 0.66 to 0.68 for existing equations, which were also biased. The r² values for the Minnesota dataset were also high, but with some translational bias. The equations could be used by New York producers to obtain a more accurate estimate of preharvest NDF concentration.

Item Type:	Refereed Article
Keywords:	preharvest neutral detergent fiber concentration, NDF, alfalfa, stubble height
Research Division:	Agricultural, Veterinary and Food Sciences
Research Group:	Crop and pasture production
Research Field:	Crop and pasture production not elsewhere classified
Objective Division:	Animal Production and Animal Primary Products
Objective Group:	Livestock raising
Objective Field:	Dairy cattle
UTAS Author:	Parsons, D (Dr David Parsons)
ID Code:	53007
Year Published:	2009
Web of Science® Times Cited:	12
Deposited By:	Agricultural Science
Deposited On:	2008-10-21
Last Modified:	2012-11-13
Downloads:	1 View Download Statistics