Sustainability of dormant season grazing: Does protein supplementation impact beef cattle performance, soil organic matter, vegetation, and residual cover for wildlife?

View the project final report

Commodities

• Additional Plants: native plants
• Animals: bovine

Practices

• Animal Production: grazing management, mineral supplements, range improvement, stockpiled forages, winter forage
• Education and Training: extension, mentoring
• Natural Resources/Environment: biodiversity, habitat enhancement, wildlife
• Production Systems: agroecosystems, holistic management
• Soil Management: organic matter

Beef cattle production on Montana farms accounted for $1.78 billion of gross income and 42% of Montana’s total agricultural sales in 2012 (USDA-NASS, 2016). Montana cattle operations are primarily cow-calf production systems that rely heavily on forages to supply nutrients for both cows and calves (Galyean and Goetsch 1993). Economic efficiency of cattle production is threatened by high feed and input costs (Meyer and Gunn 2015).  To improve profitability and transition to reduced reliance on transported harvested feeds, many cow-calf producers have adopted management strategies involving dormant season grazing (Adams et al. 1996).  Dormant range forage is deficient in nutrients and may result in decreased animal performance (Krysl and Hess 1993, Bowman et al. 1995, Mulliniks et al. 2013).  Providing supplements to grazing beef cattle during times of low forage quality may improve animal performance and provide increased economic returns (DelCurto et al. 2000).  In addition, supplementation could alter livestock grazing distribution and vegetation utilization across the landscape (Fuhlendorf and Engle 2001). Although dormant forage tends to be more tolerant of grazing pressure (Holechek et al. 2004, Petersen et al. 2014), dormant season grazing has been shown to have detrimental effects on vegetation production and residual cover when improperly managed (Willms et al. 1986, Bullock et al. 1994, Holechek et al. 2004, Petersen et al. 2014).  Removal of vegetation and litter cover reduces soil organic matter and exposes soil to direct raindrop impact, allowing for potential increases in erosion and runoff (Greene et al. 1994).  Additionally, homogeneity of vegetation structure across the landscape has been implicated in habitat degradation for many avian species (Fuhlendorf and Engle 2001).  Thus, maintaining heterogeneity of vegetation structure in rangelands is beneficial to wildlife habitat and ecological biodiversity (Fuhlendorf et al. 2006).  However, little is known about the effects of supplementation on winter grazing behavior and its potential impact on vegetation, soil, and rangeland sustainability (Judkins et al. 1985, Krysl and Hess 1993, Schauer et al. 2005).  Information relating supplementation strategies to individual grazing behavior and vegetation use on dormant forage is lacking.  Thus, the intent of the proposed research is to examine the comprehensive agroecosystem responses of dormant season grazing, with and without supplementation, on cattle performance, soil organic matter, vegetation use, and residual cover of rangelands.  Our goal is to provide insight to stakeholders concerning the ecological impacts of dormant season grazing on mixed grass rangelands, and ultimately facilitate the adoption of management strategies developed for long-term sustainability of agroecosystems in Montana.

We expect dormant season grazing by supplemented livestock to have multi-faceted effects on agroecosystems in northern mixed grass prairies.  Because supplementation affects the grazing behavior of cattle, system-level impacts are likely mediated by the provision of supplement as well as uncontrolled environmental conditions.  Our specific objectives are to evaluate how supplementation during the dormant grazing season influences:

1. Vegetation use, production, and structure, and soil organic matter. Range condition is influenced by grazing behavior (Belsky and Blumenthal 1997); thus, we expect that differences in grazing behavior will have differential effects on vegetative and structural composition of rangelands.  Data will be collected starting the summer of 2016 through 2017.
2. Cattle grazing behavior and performance. Altering an animal’s nutritional environment with the addition of supplement has a high potential to affect grazing distribution and behavior (Murden and Risenhoover 1993), as well as, weight gain and body condition.  Therefore, we expect that supplementation will have effects on distribution of pasture use, time spent grazing and distance traveled with corresponding effects on weight and body condition.  Data will be collected 2016 through 2017.

Our intentions are to further the understanding of dormant season grazing and supplementation effects on grazing behavior and rangeland condition, with the ultimate goal of facilitating the adoption of management strategies developed for long-term sustainability of agroecosystems.