Comparison of methods to quantify the number of bites in calves grazing winter oats with different sward heights

Abstract The requirement to measure the constituents of ingestive behaviour in grazing ruminants, such as the number and type of jaw movements, is essential for understanding the herbage intake process. In this experiment, three methods of recording grazing behaviour were compared: visual observation (VO; four trained observers), solid-state behaviour recorder (SSBR) and acoustic recorder (AR), in order to quantify the number of bites taken by Holstein–Friesian calves (138±11kg LW) grazing winter oat ( Avena sativa ) pastures with different sward surface heights (SSH): tall (T; 52.4±9.9cm), medium (M; 26.5±4.9cm) and short (S; 14.6±3.4cm). The number of bites was recorded on nine calves with VO, SSBR and AR during 5-min grazing sessions on each sward height. In addition, the total grazing jaw movements (GJM) and bites per GJM (PB) were calculated from the SSBR and the AR methods. The experiment was conducted on 3 days, and on each day three animals grazed on each of the three sward heights in a randomised sequence. Sound files from AR were analysed visually and aurally (Sound Forge 9.0) and recordings by SSBR were analysed using the dedicated software ‘Graze 8.0'. Data were analysed by three-way ANOVA. There were no statistical differences ( P >0.05) in the number of bites counted by the observers. The number of bites did not differ significantly between AR and VO, but were lower for SSBR ( P P P

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