Sorting index of forage particle size of calves with different feeds before and after weaning.

Forty-five Holstein calves (44 ± 5.7 kg of BW and 3 ± 1.5 d of age) fed with a common pellet concentrate fed and one of following forage feeding strategies: barley straw before and after weaning (S-S), barley straw before and alfalfa hay after weaning (S-A), or alfalfa hay before and after weaning (A-A). To determine sorting activity, dry matter intake of each forage fraction was calculated as the difference between the amount of each forage fraction offered and the amount refused (actual intake). Sorting was calculated as the actual intake of each fraction expressed as a proportion of the theoretically predicted intake of that fraction. Values equal to 1 indicate no sorting, those <1 indicate selective refusals (sorting against), and those >1 indicate preferential consumption (sorting for). Both before and after weaning, calves sorted for the fraction containing long-size forage particles without differences among treatments and sorted against the short-size forage fraction.