Performance of forage-finished beef cattle grazing ryegrass, rye or oats, and forage quality measured by a high-throughput procedure.

摘要

A 3-yr grazing trial was conducted with ryegrass (Lolium perenne ), rye (Secale cereale) and oats (Avena sativa) as winter pasture for forage-finished beef. Replicate 1.42-ha paddocks were established and stocked with 3 Angus x Continental crossbred steers per paddock each year in a completely randomized design. Steers had free-choice access to salt-mineral mix and water. Forage mass (FM, kg DM/ha) and nutrient composition were determined. Put-and-take steers were used to maintain forage in the vegetative stage. Average daily gain differed ( P 0.05) among years, but there was no treatment effect or animal x yr interaction. Overall mean ADG was 1.32 +/- 0.12 kg/d. In yr 1, seasonal-mean ADG (1.81 +/- 0.05 kg/d) was higher (P 0.0001) than in the other years, but ADG in yr 2 (1.05 +/- 0.05 kg/d) and yr 3 (1.11 +/- 0.05 kg/d) did not differ. There was no yr effect or yr x treatment interaction for forage concentration of NDF and ADF. Ryegrass had lower NDF (39.8% +/- 1.1) and ADF (20.6 +/- 0.6) than oats (46.0% +/- 1.1 and 24.3 +/- 0.6) and rye (46.2% +/- 1.1 and 24.4 +/- 0.6). Total gain per area differed ( P 0.05) among years and forage type, but there were no yr x treatment interactions. Animals grazing oats had a greater (P 0.05) gain per ha (504 +/- 15.4 kg/ha) than those grazing rye (425 +/- 15.4 kg/ha) or ryegrass (408 +/- 15.4 kg/ha). In conclusion, cool-season annual pastures did not differ in terms of steer ADG, but oats was superior to the rye or ryegrass pastures in total gain per area. In experiment 2, a high-throughput procedure was developed for the sequential analysis of NDF and ADF allowing a high volume of samples to be analyzed in a relatively short period of time. The fiber bag ANKOM method served as the control for evaluation of the modified water bath method (WB). A completely randomized design with a replicated 2 x 3 x 2 factorial arrangement of treatments was used. There were no differences between the methods for either NDF (31.93% WB vs 31.33% ANKOM, P = 0.29) or ADF (15.54% WB vs 15.96% ANKOM, P = 0.21). The CV were low for NDF (100% of samples with CVs below 2.8%) and for ADF (83% of samples with CVs below 5% with the highest CV at 5.9%). The WB analysis method produced repeatable results comparable to the ANKOM method and can be used to process a large number of samples in the same amount of time that 12 duplicate samples are processed using the ANKOM method.