Agroscope, Institute for Livestock Sciences ILS, 1725 Posieux, Switzerland

Observations about grazing: grass supply and ingestion

The aim of this study was to compare the supply of grass and the intake of three herds (test variants) over the 2012 and 2013 grazing seasons. The first herd received no supplement (control group G), whilst the other two benefited respectively from a barley (B) and whey (W) supplement. The quantity of grass offered was evaluated each week along the same marked lines with a rising plate pasture meter. The quantities of forage available to the three herds were roughly comparable in 2012 and very similar in 2013. The intake estimates, also made by measuring the height of the grass cover (entrance – exit differences), highlighted a marginally significant difference (P = 0.052) between the herds in 2012. The animals receiving a barley supplement consumed 7.7 kg DM/day (seasonal average), relative to 9.3 and 8.5 kg DM/day for the G and W groups, respectively. This substitution effect was not observed as clearly in 2013 (P = 0.149). The alkane technique (use of an indigestible marker) was also utilised over a four-day experimental period in June 2013. Although of the same order of magnitude as those obtained with the pasture meter, the values cannot be compared directly owing to differences in the methodology and

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