Author's personal copy Animal Feed Science and Technology 170 (2011) 1–11 Contents lists available at ScienceDirect Animal Feed Science and Technology journal homepage: www.elsevier.com/locate/anifeedsci Suitability of eight techniques for estimating digestibility of herbage from continuously grazed all-day pasture S. Schneider a , K. Auerswald b , H. Schnyder b , G. Bellof a,∗ a Hochschule Weihenstephan-Triesdorf, Fachgebiet Tierernährung, Am Hofgarten 1, 85350 Freising, Germany b Technische Universität München, Lehrstuhl für Grünlandlehre, Freising, Germany a r t i c l e i n f o Article history: Received 4 May 2010 Received in revised form 28 June 2011 Accepted 25 July 2011 Keywords: Acid-insoluble ash Dairy cow Digestibility Faecal nitrogen method Pepsin-cellulase method Titanium dioxide a b s t r a c t The objective of this study was to estimate digestibility of herbage using eight different methods. Organic matter digestibility (OMD) was estimated with titanium (Ti) dioxide and acid-insoluble ash (AIA) as indigestible markers, four faecal nitrogen (N) equations, which use the same raw data, the pepsin-cellulase method (in vitro OMD) and digestibility trials with wethers (in vivo OMD). An all-day pasture with continuous stocking at 2.8 cows/ha was chosen for the comparison because it restricted selection during grazing and thus allowed comparison of in vitro- and stall feeding-based methods with methods used for pastures. A crossover experiment with eight lactating Simmental cows was conducted from May until July 2008, with two consecutive experimental periods of 28 days. The cows were divided in two similar experimental groups. Four cows were put into individual stalls and fed herbage clipped from the experimental pasture and feed intake was measured. The other four cows were put onto the fenced pasture. All cows were supplemented with 2 kg/d fresh matter of grain maize. After four weeks, the treatment groups were switched. OMD differed considerably between methods (by 20–110 g/kg). Applying the same method, OMD on pasture differed from OMD in-stall indicating that the grazing animal cannot be replaced by mowing even with high experimental effort and low opportunity for selection. It also differed over time. Only the faecal N methods were readily applicable on pasture at sufficiently high temporal resolution and – with one exception – produced similar results in-stall as the Ti method. They can in general be recommended for a large range of conditions including grazing studies but the variety of existing equations makes it difficult to select the appropriate one. This calls for the development of better defined and rigorously tested equations. © 2011 Elsevier B.V. All rights reserved. 1. Introduction The increasing costs of feed concentrates have led to increased interest in pasture-based milk production, particularly with respect to cost-effective pasture management systems. Feed intake and organic matter digestibility (OMD) ingested are the two most important components affecting the animal performance, but neither can be measured easily at pasture Abbreviations: ADF om , acid detergent fiber not assayed with a heat stable amylase and expressed exclusive of residual ash; AIA, acid-insoluble ash; BW, body weight; CP, crude protein; DM, dry matter; DDM, digestibility of dry matter; OMD, organic matter digestibility; ECM, energy-corrected milk; eIOM, enzymatic insoluble organic matter; Lignin(sa), lignin determined by solubilization of cellulose with sulphuric acid; N, nitrogen; NDF om , neutral detergent fiber not assayed with a heat stable amylase and expressed exclusive of residual ash; NFC, non-fiber carbohydrates; SD, standard deviation; Ti, titanium. ∗ Corresponding author. Tel.: +49 8161 714342; fax: +49 8161 714496. E-mail address: gerhard.bellof@hswt.de (G. Bellof). 0377-8401/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.anifeedsci.2011.07.014