61 Effect of rapeseed inclusion in late-summer planted oat pasture on growing performance of beef steers.

摘要

The objective of this 2-yr study was to evaluate the performance of steers grazing a late summer planted oat monoculture (OAT) compared to a mixture (MIX) of oats ( ) and rapeseed ( ). The three 52 ha fields (one in yr 1 and two in yr 2) were divided into four quarters and two quarters being planted in late August with 112 kg/ha of oats and two with 56 kg/ha of oats plus 3.4 kg/ha of rapeseed at a seed cost of $62/ha for OAT and $38/ha for MIX. Crossbred beef steers, 120 in yr 1 and 240 in yr 2, were stratified by BW (280 ± 32 kg) and assigned to treatment and replicate (30 steers/13 ha quarter). Forage biomass and quality samples were taken before turning out to graze in early November. Initial forage yield did not differ (P = 0.80; SEM±635) among treatments (3,610 and 3,779 kg DM/ha for MIX and OAT, respectively). The MIX contained 73% oats and 27% rape (on DM basis). The CP (SEM±1.6) and IVOMD (SEM±0.82) content of the forage was greater ( ≤ 0.04 for the MIX (20.5%; 78.4%) than OAT (16.1%; 75.7%), respectively. Steers grazed until forage appeared to be limiting for one of the quarters, resulting in 99 d of grazing in yr 1 and 71 d in yr 2. Ending forage biomass tended ( = 0.09; SEM±119) to be greater for OAT compared to MIX at 1,741 and 1,476 kg DM/ha, respectively. There was a tendency ( = 0.07; SEM±0.03) for ADG to be greater for the MIX (0.96 kg/d) than OAT (0.88 kg/d). The lower seed costs coupled with increased gain suggests that adding rapeseed to oats may be beneficial for producers grazing growing calves in fall.