Whole crop wheat (WCW) appears to offer an attractive alternative forage to grass silage for dairy cows, particularly in those areas where maize silage cannot be grown. However in previous feeding trials the inclusion of WCW with grass silage has increased food intake but has not led to a corresponding increase in milk yield (Phipps et al,1993). As part of a programme to try to overcome the low efficiency of diets containing WCW, the present experiment was designed to examine the effects on feed intake and digestibility and milk production of the step-wise replacement of GS by urea-treated WCW.
Winter wheat (cv Hussar), harvested at 620g DM/kg fresh weight and preserved with 20 or 40 g urea/kg DM (WCW-2, WCW-4) was compared with first-cut perennial ryegrass silage (GS). Six multiparous Holstein-Friesian cows in mid-lactation were offered six diets over three 4-week periods in an incomplete change-over design. Diets were 6kg DM concentrates daily with forages ad lib. Treatments (DM basis) were GS alone, 2:1 GS:WCW-2 or WCW-4, 1:2 GS: WCW-2 or WCW-4, and WCW-4 alone. Feed intake and milk production were measured in weeks 3 and 4 and digestibility in week 4.