Testing New Forage Varieties to Improve Production and Reduce Our Carbon Hoofprint

Background

New forage varieties can help improve pasture quality as well as increase animal performance and help to maximize forage production. While new varieties are tested for a number of different agronomic factors prior to registration, a limitation of new forage varieties that are currently available or in development is there is limited information on cattle digestibility and performance data available as they are not required to be registered. This study seeks to determine the effect newly developed forage varieties have on ruminal digestion and methane production by beef cattle and inform future grazing trials.

Objectives

• Determine the yield and nutritional quality of 3 new perennial grasses, one new alfalfa variety, and their grass-legume mixtures over four years
• Screen new forage varieties and mixtures for improved digestibility, ruminal fermentation profile, and low methane production using the ruminal in vitro gas production technique (batch culture)
• Evaluate the 4 treatments based on the batch culture results in a rumen simulation (Rusitec system, an in vitro semi-continuous culture which is a step closer to the animal)
• Identification of two or three forage treatments to be used in future beef cattle grazing trials that have a greater likelihood to reduce methane emissions while improving animal performance.

What they will do

Study 1: Small plot trial – Three grasses (meadow brome grass – CDC Torsion, hybrid brome grass – AAC Torque and a new salt tolerant hybrid wheatgrass -CDC Salt King) and two alfalfa cultivars (S914AF and Equinox) will be evaluated in small plot trials as monocultures and binary alfalfa-grass mixtures of each grass and each alfalfa variety, resulting in a total of 11 treatments. There will be four replications over four years. Plant height, leaf:stem, dry matter (DM) yield, and nutritive value of each plot will be evaluated when grazing maturity (late-bud to one-tenth flowering stage) has been reached.

Study 2: Rumen in vitro gas production technique (batch culture, 24 to 48 h ruminal incubations) – all 11 treatments will be incubated using a previously defined in vitro gas production technique (Mauricio et al. 1999) to evaluate the effects on potential methane production and rumen fermentation. Following incubation, samples will be dried and analyzed to determine NDF and ADF disappearance. The top 4 best performing forage treatments will be evaluated further in study 3.

Study 3: Rusitec study – a RUSITEC (rumen simulator) will be used on the top four performing treatments from study 2 to investigate ruminal digestion, fermentation, total gas and methane production and microbial protein synthesis. The fermenters mimicking rumen digestion will run for 14 days.

Implications

Developing new perennial forage varieties that yield higher and have a better nutritional value can reduce the GHG emissions of cattle on pasture and improve the environmental and economic sustainability of cow-calf and stocker operations. This study will also inform future grazing trials by identifying varieties and mixes that may have the best success in a practical setting. Understanding how new varieties perform and impact animal efficiency helps to inform producers on effective pasture rejuvenation and grazing management that benefits the cattle, the environment and the bottom line.