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Interaction Of Roughage & Co-Products Cattle Feeding
Roughages are often included at low levels (<12% of diet DM) to control acidosis and maintain intake in feedlot cattle (Stock and Britton, 1993). Since coproducts reduce the occurrence of acidosis in feedlot cattle, then perhaps roughage levels may be reduced from conventional levels in diets containing co-products. Farran et al. (2004) fed either 0 or 35% WCGF with either 0, 3.75, or 7.5% alfalfa hay at each level (i.e. treatments were factorialized with WCGF level and hay level). There was a significant interaction between WCGF and alfalfa level for feed conversion; therefore, only simple effects are presented in Table 10.With 0% WCGF, increasing alfalfa level increased ADG and DMI with no effect on feed conversion.
With 35% WCGF, increasing alfalfa hay increased ADG and DMI, but hindered (increased) feed conversion linearly. It appears that roughage can be decreased in DRC-based diets that contain 35% or more WCGF. The ADG was reduced for the 0% hay, 35% WCGF treatment, so a small amount of roughage is recommended even when WCGF is included. Similar results have been observed with SFCbased diets where alfalfa can be reduced to 2% with at least 25% WCGF (Sindt et al., 2001). Parsons et al. (2001) observed no change in feed conversion when roughage was decreased from 9 to 0% alfalfa in SFC diets with 40% Sweet Bran WCGF.
However, in their study, DMI and ADG decreased linearly. Just as with data in conventional corn-based diets, optimum amount of roughage appears to be dependent on grain processing and level of WCGF.
Source: University Of Nebraska Ag Extension
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