- Animals: goats
- Animal Production: grazing management, grazing - rotational
- Education and Training: demonstration
Two different rotational goat browsing regimes and a control were tested in an oak savanna complex with a dense, shrubby midstory in Southwest Wisconsin using three 0.5-hectare paddocks replicated in five blocks. After two seasons under the heavy browse regime goats (1) reduced shrub cover and height though not stem density, (2) increased light at the groundlayer and (3) increased cover and richness of sun-favoring herbaceous species, without increasing soil compaction or cover of invasive species. Weight gain among kids exceeded expectations and levels of gastrointestinal nematode parasites were considered acceptable for meat production and goat health.
Management and restoration of any natural ecosystem requires a toolset that can support the goals of the land manager. In ecosystems dependent upon fire, additional tools are often needed as substitutes in situations where fire cannot be employed as an initial treatment to allow fire in the future, or as a more selective treatment between prescribed burns. Intensive rotational grazing has been explored as a vegetation management tool in the U.S. and globally, often with different species and breeds of livestock as each has its own feeding preferences. Although unmanaged grazing can cause an array of environmental problems, including soil compaction and erosion (Fleischner 1994), these impacts can be controlled when carefully managed (Papanastasis 2009, Teague et al. 2011). Intensive rotational grazing is a highly managed method in which livestock are grazed at high stocking densities for a short period of time and rotated successively through a series of small paddocks (Barnes et al. 2008). Vegetation is then allowed to recover during a resting period before livestock are rotated through the same paddocks again in order to avoid environmental impacts often arising from long-term grazing (Bailey and Brown 2011). This study explored the use of rotational goat browsing as an additional tool to restore oak savanna in the North American Upper Midwest and the viability of raising meat goat on dense midstory forage.
Oak savanna, a once-widespread, fire-dependent ecosystem having an herbaceous understory and partial oak canopy, is now categorized as critically threatened due to post-European settlement conversion to farmland and suppression of fire. In the absence of fire, the understory of surviving savannas have filled in with shade-tolerant shrub and sapling species, decreasing light at the ground layer and changing plant community composition (Nowacki and Abrams 2008). The majority of oak savanna remnants in Wisconsin are located on hillsides marginal for farming, most of which are on private land (Wisconsin Department of Natural Resources 2012). Some poorer quality remnants are restorable, but restoration methods are often time intensive with prohibitive costs. Fire is touted as the most effective restoration tool; however, private landowners often perceive fire to be a high liability with few economic benefits (Henderson 1995). In addition, fire can deter shrub colonization in oak savanna systems but can be ineffective in penetrating very dense vegetation with damp fuels (Nowacki and Abrams 2008). In similar mesic prairie systems, burning often results in the aboveground expansion of shrub and fails to kill well-established shrubs (McCarron and Knapp 2003, Heisler et al. 2004). Other methods, such as mechanical removal and herbicides, are limited by cost, slope, weather and potential damage to the herbaceous layer.
Continuous grazing practices have been destructive to ecosystems in the U.S. and globally regardless of livestock species (Auclair 1976, Fleischner 1994). Intensive, short-duration rotational browsing in which livestock are regularly rotated between paddocks may help reduce shrub cover while enhancing livestock production without the damage associated with continuous grazing (Walker et al. 2006). Rotational grazing of Scottish Highland cattle, a breed with a high browse diet, has been studied as an alternative means of shrub removal in oak savanna in Wisconsin. This breed was effective at reducing aboveground growth for specific shrub species and was observed feeding in areas where shrubs were too dense for fire to penetrate. Despite successes, the logistics of frequent transportation of such large animals required for a short duration rotational grazing regime is an obstacle (Harrington and Kathol 2009).
Meat goats have higher browse diets than the Scottish Highland cattle and are smaller and more mobile. Therefore, they may be better candidates for reducing a dense, shrubby midstory in oak savannas. Goats have been studied as agents for woody fuel reduction, invasive species management, pasture maintenance and ecosystem restoration in structurally similar ecosystems in the U.S. and globally (Batten 1979, Tsiouvaras et al. 1989, Severson and Debano 1991, Perevolotsky and Haimov 1992, Torpy et al. 1993, Popay and Field 1996, Luginbuhl et al. 1999, Valderrábano and Torrano 2000). In oak savanna, rotational goat browsing may have the potential to decrease shrub and sapling layer cover and density. Reduction of the shrub canopy in similar midwestern grassland ecosystems has resulted in more light at the herbaceous groundlayer and enhanced the available habitat for the growth of desirable sun-tolerant herbaceous species, particularly warm-season grasses (Heisler et al. 2004, Nowacki and Abrams 2008, McGranahan 2011). Additional sunlight and herbaceous growth would provide a greater, more continuous, fine fuel matrix providing opportunities for the reintroduction of fire as part of the future management plan.
In addition to the potential conservation advantages, the demand for goat meat in the U.S. is increasing, creating a potential economic incentive to raise goats for meat. The U.S. imported more than 16,000 metric tons of goat meat in 2012, up 6% from 2011 and up 45% from 2007 (Rayer 2013,). U.S. consumption of goat meat is expected to continue to increase as ethnic groups for whom goat meat is dietary staple become more prominant (Solaiman 2007). If meat goats could be raised on the forage in a shrub-infested oak savanna while simultaneously providing an ecological service this would result in a mutually advantageous situation for both livestock producers and land managers.
This study seeks to determine the extent that rotational browsing with goats can be both an effective restoration tool for reducing a dense oak savanna midstory and meet basic standards for goat meat production? If rotational goat browsing can reduce the shrub layer without negative impacts on the soil, herbaceous layer or goats, this approach has the potential to be an effective and more accessible restoration tool for ecologically important but shrub-choked open oak ecosystems.
- Reduce midstory shrub layer cover and height
Increase light availability at the groundlayer leading to an increase in the herbaceous layer
No increase in soil compaction or invasive species
Increase in goat kid weight greater than 2.7kg/month (rate of gain considered to be viable for meat production).
No significant worsening in Famacha scores