Evaluation of cool-season binary mixtures as pasture: Herbage yield, nutritive value, and beef cattle performance

摘要

A 3-year study (2016, 2017, and 2018) was conducted to compare the effects of alfalfa (ALF; cv. Yellowhead) (Medicago falcata L.) or sainfoin (SF; cv. AAC Mountainview) (Onobrychis viciifolia Scop.) in mixtures with either Russian wildrye (RWR; cv. Tom) (Psathyrostachys junceus [Fisch.]) or hybrid bromegrass (HBG; cv. Success) (Bromus riparius Rehm & times; B. inermis Leyss) on herbage dry matter yield (DMY) and nutritive value, and beef yearlings performance at two sites: Swift Current (Brown soil zone) and Lanigan (Thin Black soil zone), Saskatchewan, Canada. In 2015, in each site, sixteen 0.7-ha (in Lanigan) or 0.8-ha (in Swift Current) paddocks were established with replicated (n = 4) ALF-HBG, ALF-RWR, SF-HBG, or SF-RWR binary mixtures. Each year in August, yearling steers (16 +/- 1 month and BW = 391 +/- 1.7 kg and 350 +/- 0.04 kg for Swift Current and Lanigan sites, respectively) were allocated to paddocks for an average 30-d grazing trial to utilize 40 & ndash;60% of available herbage. The DMY (3629 +/- 154 kg/ha) did not differ (P > 0.05) among mixtures at Swift Current. The HBG included (ALF-HBG and SF-HBG) mixtures produced 54% more (P < 0.01) DMY than RWR included (ALF-RWR and SF-RWR) mixtures (4542 vs. 2943 kg/ha, SEM = 303) at Lanigan. Legume contribution to DMY was greater at Swift Current than at Lanigan (33.1% +/- 2.1% vs. 14.0 +/- 1.7%), and ALF contributed more to DMY than SF at Lanigan (18.0 vs. 10.1%). Crude protein tended (P = 0.10) to be greater for RWR mixtures than HBG mixtures (93.5 vs. 83.4 g/kg DM for RWR and HBG mixtures, respectively) at Lanigan. The yearling steers had similar (P = 0.25) ADG (0.78 +/- 0.03 kg/d) for the treatments at Swift Current. However, at Lanigan, the animal ADG differed (P < 0.01) with 0.88 and 0.90 kg/d for ALF-RWR and SF-RWR and 0.53 and 0.63 kg/d for ALF-HBG and SF-HBG mixtures, respectively. The HBG mixtures (ALF-HBG and SF-HBG) produced approximately 10 more grazing days (GD) (AUD/ha) than the RWR (ALF-RWR and SF-RWR) mixtures at both, Swift Current (95 vs. 88 AUD/ha, SEM = 9) and Lanigan (112 vs. 101 AUD/ha, SEM = 7) sites. Sainfoin-grass mixtures produced 8 and 3 GD less (AUD/ha) than ALF-grass mixtures at Swift Current and Lanigan, respectively. Overall, these results demonstrate that all 4 binary mixtures appear to be suitable for late summer and fall grazing to provide sufficient nutritive value and beef cattle steer performance in both soil zones of Saskatchewan, Canada.