Behavioral Observations
Results of pairwise comparisons between the 3 levels
of the factor source (i.e., STR, MS, and MC) and the 3
control treatments (i.e., MR, MR+, and HY) are shown
in Figure 2 (12 wk) and Figure 3 (22 wk).
12 wk. An interaction was found between roughage
source and amount (P = 0.008) for chewing and
7770 Webb et al.
Journal of Dairy Science Vol. 96 No. 12, 2013
rumination. Within the MS and MC treatments, calves
fed 500 g of DM/d chewed more than calves fed 250
g of DM/d (P < 0.001 and P = 0.001, respectively),
whereas chewing was similar with the 2 amounts of
STR (P = 0.18). Moreover, regardless of the amount,
calves fed STR chewed more than calves fed MS or MC,
and calves fed MS chewed more than calves fed MC
(P < 0.05). Particle size tended to affect chewing and
rumination (P = 0.088). Calves fed chopped roughage
(10.1 ± 0.76% of total scans) tended to chew more
than calves fed ground roughage (8.5 ± 0.68% of total
scans). An effect of source of roughage was found on
tongue playing (P = 0.004). Calves fed STR tongue