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ARS Home » Midwest Area » Madison, Wisconsin » U.S. Dairy Forage Research Center » Dairy Forage Research » Research » Publications at this Location » Publication #259011
Title: Predicting TDN losses from heat damaged hays and haylages with NIR

Author
item YAN, RONG - University Of Wisconsin
item UNDERSANDER, DANIEL - University Of Wisconsin
item Coblentz, Wayne

Submitted to: Forage and Grazinglands
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/2/2010
Publication Date: 2/8/2011
Citation: Yan, R., Undersander, D.J., Coblentz, W.K. 2011. Predicting TDN losses from heat damaged hays and haylages with NIR. Forage and Grazinglands. Available: http://www.plantmanagementnetwork.org/fg/.

Interpretive Summary: During the storage of hay or haylage, spontaneous heating may occur and lead to losses of available protein and digestible nutrients. Recent research indicates that losses of Total Digestible Nutrients (TDN) may be more significant economically than losses of available protein. Objectives for this project were to establish a near-infrared (NIR) model to estimate losses of TDN from heated hays, test this model on 3612 producer samples obtained from commercial forage testing laboratories, and then to assess the frequency with which significant TDN (energy) losses occur across a wide range of producer samples. Samples from a previous study in which internal bale temperatures and forage quality data were measured were selected to develop the model. After model development, tests of the calibration on producer samples indicated the calibration equation was appropriate for general use. Across 3612 producer samples obtained from commercial laboratories, TDN losses exceeded 4 TDN units 50% of the time, and exceeded 8 TDN units 16% of the time. This indicates that spontaneous heating frequently affects the energy density of forages negatively. This information will help dairy nutritionists to better balance diets for dairy cows and heifers, and to properly discount the energy content of heated hays.

Technical Abstract: During the storage of hay or haylage, heating damage may occur and lead to losses of available protein and digestible nutrients. Recent research indicates that losses of TDN may be more significant economically than losses of available protein. Our objectives for this study were to establish a near-infrared (NIR) model to estimate losses of total digestible nutrients (TDN) caused by heating damage during storage, to test the model on farmer samples obtained from commercial forage testing laboratories, and then to determine the frequency with which significant losses of TDN occurred within these producer samples. Samples from a previous study in which internal bale temperatures were measured daily were selected to build into the model. The external validation coefficient of determination (R2) was 0.88, which is relatively high. The calibration was tested on three unknown sets of samples from commercial forage testing laboratories. The three sets contained spectra of 1000, 618 and 1994 forage samples submitted by producers. A very small number of samples in Sets 1, 2, and 3 exhibited H values >3 (21, 11 and 66 samples, respectively), which indicates that the developed equation was appropriate for use on the commercial samples. The predicted TDN losses from producer samples exceeded 4 TDN units 50% of the time, and exceeded 8 TDN units 16% of the time.