Perennial Forage Mixtures: An Integrated Approach to Investigating their Performance for Multifunctionality
Creators: Gyamfi, Hayford
Publisher: name: University of Alberta Library
Year: 2024

<p>Perennial forage mixtures are used in the feeding regimes of beef cattle producers in Alberta. This provides consistency in the supply of forage biomass and nutritive value to cover up lapses in annual forage supply, and adequately improve the performance of beef cattle. Additionally, perennial forage mixtures can potentially provide ecosystem services. However, there is skepticism regarding the correct combinations of grass and legume species to attain these benefits. Furthermore, beef cattle producers ask questions about the mixtures that can help improve their livestock-forage systems. To resolve this, a multiyear perennial forage field study was conducted at the Peace Country Beef and Forage Association, northwestern Alberta, Canada, to evaluate the performance of different forage mixtures in terms of productivity, water use efficiency, impact on soil quality, nitrogen fixation and transfer, performance of beef cattle categories on the mixtures, and to recommend some forage mixtures to producers for inclusion in their forage systems. Our findings showed that grass–legume mixtures consistently had a greater dry matter yield than monoculture grasses (by a 3.0 Mg ha–1 difference). Total digestible nutrients (only in the first year of forage production) and crude protein were higher and neutral digestible fiber was lower in grass–legume mixtures. In contrast, grass monocultures had higher total digestible nutrients (in the second and third years of production) and 48 h neutral detergent fiber digestibility, and lower acid detergent fiber (in the second and third years of production). In terms of soil quality, complex grass–legume mixtures had greater biological activity (as CO2 production) than monoculture grasses at 0–15 cm soil depth, whereas monoculture grasses had superior CO2 production at 15–30 cm layer. Surface soil infiltration (0.79 cm h–1) and compaction were improved under mixtures containing legumes. Overall, the apparent rate of soil carbon sequestration was higher under monoculture of Fleet meadow bromegrass (10 Mg C ha–1 yr–1) compared to grass–legume mixtures. Furthermore, all legumes in the simple and complex grass–legume mixtures derived most of their nitrogen use from the atmosphere (&gt;94%). However, alfalfa had a greater amount of fixed nitrogen (210.1 kg N ha–1), followed by sainfoin (52.9 kg N ha–1). Overall, more nitrogen was fixed by mixtures with more legume species and proportions, whereas a greater amount of nitrogen was transferred in mixtures with two grass species as compared to only one grass species. With regards to animal performance, grass–legume mixtures were adequate to support steers in obtaining an average daily gain (ADG) of 0.8 kg day–1 whereas monoculture grasses, grass–legume and grass-only mixtures were adequate to support gestating and lactating beef cows to obtain average daily gain of 0.10 kg day–1. In summary, perennial forage mixtures containing (i) AC Knowles hybrid bromegrass + spredor 5 alfalfa, (ii) AC Mountainview sainfoin + Veldt cicer milkvetch + spredor 5 alfalfa, (iii) AC Success hybrid bromegrass + AC Mountainview sainfoin + AC yellowhead alfalfa, (iv) AC Success hybrid bromegrass + greenleaf pubescent wheatgrass + kirk crested wheatgrass + Italian ryegrass +AC yellowhead alfalfa + rugged alfalfa + Veldt cicer milkvetch + AC Mountainview sainfoin, and (v) AC Success hybrid bromegrass + AC yellowhead alfalfa + AC Mountain sainfoin have been identified as viable options for cultivation in Alberta based on multifunctionality analysis. However, trade-offs were noticed for these treatments. AC Knowles hybrid bromegrass + spredor 5 alfalfa and AC Mountainview sainfoin + Veldt cicer milkvetch + spredor 5 alfalfa had superior dry matter yield and nutritive value but poor at enhancing soil quality indicators. In addition, AC Success hybrid bromegrass + greenleaf pubescent wheatgrass + kirk crested wheatgrass + Italian ryegrass +AC yellowhead alfalfa + rugged alfalfa + Veldt cicer milkvetch + AC Mountainview sainfoin, had high dry matter yield, nutritive value and also enhanced the soil compaction. These results may assist beef cattle producers to improve their forage livestock systems.</p>