The future feed evaluation systems based on mechanistic digestion models require reliable estimates of forage digestible and indigestible NDF content (DNDF and INDF). The objective of this study was to examine the potential of near infrared reflectance spectroscopy (NIRS) in predicting INDF content of grass and legume silages

Hellämäki, M.

Huhtanen, P.

Nousiainen, J.

Nyholm, L.

Rinne, M.

English

University of Kentucky

University of Kentucky UKnowledge International Grassland Congress Proceedings XX International Grassland Congress Prediction of Indigestible NDF Content of Grass and Legume Silages by NIRS L. Nyholm Valio Ltd., Finland M. Rinne MTT Agrifood Research, Finland M. Hellämäki Valio Ltd., Finland P. Huhtanen MTT Agrifood Research, Finland J. Nousiainen Valio Ltd., Finland Follow this and additional works at: https://uknowledge.uky.edu/igc  Part of the Agricultural Science Commons, Agronomy and Crop Sciences Commons, Plant Biology Commons, Plant Pathology Commons, Soil Science Commons, and the Weed Science Commons This document is available at https://uknowledge.uky.edu/igc/20/satellitesymposium4/111 The XX International Grassland Congress took place in Ireland and the UK in June-July 2005. The main congress took place in Dublin from 26 June to 1 July and was followed by post congress satellite workshops in Aberystwyth, Belfast, Cork, Glasgow and Oxford. The meeting was hosted by the Irish Grassland Association and the British Grassland Society. Proceedings Editor: D. A. McGilloway Publisher: Wageningen Academic Publishers, The Netherlands © Wageningen Academic Publishers, The Netherlands, 2005 The copyright holder has granted the permission for posting the proceedings here. This Event is brought to you for free and open access by the Plant and Soil Sciences at UKnowledge. It has been accepted for inclusion in International Grassland Congress Proceedings by an authorized administrator of UKnowledge. For more information, please contact UKnowledge@lsv.uky.edu.  Silage production and utilisation 276Prediction of indigestible NDF content of grass and legume silages by NIRS L. Nyholm1, M. Rinne2, M. Hellämäki1, P. Huhtanen2 and J. Nousiainen1 1Valio Ltd. Farm Services, P.O. Box 10, FIN-00039 Valio, Finland, Email: juha.nousiainen@valio.fi, 2MTT Agrifood Research Finland, Animal Production Research, FIN-31600 Jokioinen, Finland  Keywords: NIRS, indigestible NDF, grass silage, legume silage  Introduction  The future feed evaluation systems based on mechanistic digestion models require reliable estimates of forage digestible and indigestible NDF content (DNDF and INDF). The objective of this study was to examine the potential of near infrared reflectance spectroscopy (NIRS) in predicting INDF content of grass and legume silages.  Materials and methods  The INDF content of silages was determined by 12 d ruminal incubation in nylon bags (NB; pore size 6 or 17 µm) with two dairy cows fed grass silage-based diets. After incubations, the NBs were washed with a household washing machine and the residues were analysed for NDF. INDF (g/kg DM) was expressed as ash-free NDF of NB-residues. Dried and milled samples were scanned with a NIRSystems 6500 spectrometer using a small ring cup. After treatments (math treatments 1,4,4,1 and standard normal variate and de-trending) the spectra (1100-2498 nm) were used to develop MPLS equations for INDF with WinISI II 1.50a software. The basic calibration included 52 experimental and 42 farm grass silages (Nousiainen et al., 2004), which was extended with 50 farm grass silages and 36 legume silages (Table 1). Both basic and extended calibrations were used to predict the INDF content of 50 grass and 36 legume silages (Figure 1). The majority of the samples were of Finnish origin, but some legume samples were provided by FAL (Germany), IGER (UK) and Estonian Agricultural University.  Results  The performance of calibration (all samples included) was satisfactory (SD/SECV >2.5). The prediction error (SEP) of grass silages was noticeably higher than the SECV of the basic calibration (10.0 vs. 18.0 g/kg DM, (see Nousiainen et al., 2004), but it decreased to 15.6 g/kg DM after extending the calibration with both grass and legume samples (Figure 1a). The prediction performance of legume samples was essentially improved when the basic calibration (only grass silages) was extended with legume samples (Figure 1b: SEP 49.7 vs. 17.3 g/kg DM).  YBasic = 0.94x - 1.1R2 = 0.661 SEP = 18.0 YExt = 0.86x + 4.8R2 = 0.773 SEP = 15.60204060801001201401601800 50 100 150 200PredictedObservedBasicExtendedYBasic = 1.50x - 22.1R2 = 0.624 SEP = 49.7YExt = 1.07x - 7.5R2 = 0.926 SEP = 17.3 0501001502002503000 50 100 150 200 250 300PredictedObservedBasicExtendedFigure 1 Relationship between observed and predicted INDF content of (a) grass (n = 50) and (b) legume (n = 36) silages  Conclusions  The results imply that NIRS has a great potential in predicting INDF content of silages. A general calibration both for grasses and legumes may be developed. Further work is needed to extend the INDF calibration, and to examine whether NIRS can be used to predict the potential rate of silage DNDF digestion.  References Nousiainen, J., S. Ahvenjärvi, M. Rinne, M. Hellämäki & P. Huhtanen (2004). Prediction of indigestible cell wall fraction of grass silage by near infrared reflectance spectroscopy. Animal Feed Science and Technology, 115, 295-311. Table 1  NIRS calibration statistics in predicting indigestible NDF content (g/kg DM) of grass and legume samples  Calibration Cross-validation Outliers n Mean SD SECa R2 SECVb R2 SD/SECVIncluded 180 90.0 44.69 14.88 0.889 17.56 0.847 2.5 Excluded 176 89.6 44.29 13.87 0.902 15.24 0.883 2.9 aSE of calibration, bPooled SE over cross validation sub-sets b a 

Prediction of Indigestible NDF Content of Grass and Legume Silages by NIRS

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Prediction of Indigestible NDF Content of Grass and Legume Silages by NIRS

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