Western Rangeland Livestock Production Systems and Grazing Management

Abstract

Rangeland wildlife ecology and conservation is strongly influenced by domestic livestock systems. Domestic livestock production on rangelands in North America is dominated by ruminant livestock, with beef cattle being the largest industry. Rangeland ruminant livestock production systems are unique in that land/animal managers develop production systems that attempt to optimize the use of limited-nutrition forage bases. This involves the strategic selection of calving/lambing dates to coincide with forage resources and labor limitations. Likewise, the species, breed, and age of animal is selected to be productive in sometimes suboptimal nutrition and environmental conditions. In addition, the role of this industry in the conservation and enhancement of wildlife diversity and ecosystem services is important now and paramount in future management goals. Grazing systems that are unique to the needs of ecosystems are designed to enhance soils, vegetation, and wildlife diversity. In addition, understanding how wild and domestic animals utilize landscapes of varying topography is an ongoing area of research. Continued investigations into how animals use landscapes, grazing distribution/behavior, botanical composition of diets, and dietary strategies will be important in designing management approaches for all animals that are dependent on rangeland resources. The paradigm of sustainable management of livestock systems needs to view herbivory as a tool to manage vegetation for optimal biological integrity and resiliency. Only by the optimization of biological processes within plant communities on rangelands, will managers create systems that benefit both livestock and wildlife.

1 Western Forage-Based Livestock Production Systems

Livestock grazing is the dominant land use in areas of the western U.S. that are not suited for farming. With the exception of the Great Plains, a significant portion of the western U.S. is characterized by high elevation rangelands exceeding 1000 m (Fig. 4.1a). The Rocky Mountains are a key feature of many western states, and the associated mountain plateaus provide important summer forage resources for the domestic sheep and beef cattle industries. The region’s geological features are often characterized by shallow/rocky soils, rugged terrain, and steep slopes. Because of the dominance of high elevation regions throughout the western U.S., many areas have limited growing seasons, with the relative length of growing periods being dependent on adjacent topography, climatic patterns, and elevation.

Fig. 4.1

Topography (a) and rainfall (b) of the United States (U.S.). Color bands denote the regional elevation ranges and annual precipitation amounts. The western U.S. is dominated by areas that exceed 1000 m in elevation and less than 50 cm of rainfall

In addition, most of the western U.S. is characterized by arid and semi-arid environments with precipitation zones of less than 50 cm (20 inches; Fig. 4.1b). Therefore, western livestock producers typically operate in areas with growing seasons of less than 120 days and precipitation patterns that limit native and introduced forage production. The limited precipitation and highly variable patterns of rain/snow events often lead to seasonal shortages of forage and hay for livestock production. Furthermore, short growing seasons and irregular precipitation patterns lead to forage resources that are often limited in nutritional quality and quantity. Therefore, many livestock producers need to consider supplemental inputs to meet their animals’ nutritional needs, although the need for supplemental inputs may vary from year to year (DelCurto et al. 2000).

The western beef industry is very extensive in its land use, with optimal production being a function of the resources on each ranching unit and management’s success in matching the type of cow and production expectations to the available resources (Putman and DelCurto 2020). Successful beef producers are not necessarily the ones who wean the heaviest calves, obtain 95% conception, or provide the most optimal winter nutrition. Instead, successful producers demonstrate economic viability despite the multiple economic, environmental, and social pressures on the industry. Management practices that promote the ecological, economic and social sustainability of livestock production are paramount for the survival of the western livestock industry and rural communities that are dependent on their success.

1.1 Kinds and Classes of Livestock

The U.S. beef cattle industry. The United States is the world’s largest and most efficient beef cattle producer (pounds of beef per year). Over the past decade, the U.S. consistently produced between 24 and 27 billion pounds of beef per year, despite severe droughts that have plagued the southwest and western regions of the country during this time. The closest world competitor is Brazil, but the type of cattle differ dramatically in respect to age, breed composition, and, as a result, quality. Simply put, the United States does not have significant competition from other countries with respect to production capabilities or product quality.

The Western Beef Industry. For the purpose of this chapter, the authors discuss regions of the United States with substantial rangeland areas and ecotypes, which include the 11 western states and the Great Plains states of Texas, Oklahoma, Kansas, Nebraska, South Dakota and North Dakota (see Chap. 2). These 17 western-most states represent approximately 61% of the U.S. beef cow inventory, with approximately 19.2 million beef cows (Table 4.1). Texas is the clear leader in beef cow/calf production with approximately 4.57 million beef cows (14% of the U.S. Herd) with cash receipts for cow/calf sales generating 4.6 billion dollars annually (USDA-NASS 2019). In addition, the six Great Plains states and Montana represent almost 46% of the U.S. cow herd with all seven states in the top 10 of cow/calf production. Beef cattle productivity of this region is due in large part to the productivity of the rangeland forages reflected in the tallgrass, mixedgrass and shortgrass rangeland ecosystems. These rangelands are relatively low in elevation with continental weather patterns that yield high amounts of precipitation with most coming from April to October. In turn, this type of precipitation amount and distribution allow for greater forage production and forage quality. These rangelands often have both warm season and cool season forages, which can be strategically used to expand the window of adequate nutrition for cow/calf production particularly during lactation.

Table 4.1 Beef and sheep ranches, animal numbers, and rangeland ecotypes for the 17 western states (excluding Alaska and Hawaii)

The rangeland ecotypes of the Great Plains vary in species composition and forage production as a function of precipitation (Fig. 4.1b; Table 4.1). Generally, moving from east to west, there is a transition from tallgrass prairie to mixed grass to shortgrass prairie over a range of precipitation that ranges from 100 to 25 cm (see Chap. 2). In addition, most regions see a gradient of predominantly warm season grasses to cool season grasses with corresponding changes in overall production from east to west. The differences in vegetation and productivity result in differing beef cattle management/production strategies across the Great Plains Region. In the Tallgrass Prairie Region, a substantial stocker cattle industry exists to capture value of the predominantly warm season forages that yield substantial gains with yearlings from May thru July. This region has tremendous forage production but forage quality limits production when the warm season grasses reach advanced stages of phenological maturity. The northern and southern mixedgrass prairie is more balanced with respect to warm and cool season grasses, which results in lower rangeland productivity but greater nutritional windows of adequate nutrition. As a result, this region is dominated by cow/calf production because of the opportunity to meet beef cattle requirements during lactation and, perhaps, run yearling animals on the late spring and summer forage base. The Great Plains, which include the tallgrass, mixedgrass, and shortgrass prairies represent rangeland vegetation that has coevolved with greater herbivory (specifically American bison [Bison bison] and Rocky Mountain elk [Cervus canadensis]) than other regions of the West. As a result, these areas are generally more resilient in respect to impacts of herbivory on rangeland vegetation. Cow/calf production systems throughout the 17 western-most states often reflect the forage resources of the region that often focuses on optimizing the use of forage resources, minimizing the needs for supplemental inputs, while optimizing beef cattle production and sustainability of the forage resources.

The 10 western states (excluding Montana) are home to 15% of the U.S. beef cattle herd (4.75 million cows) yet over 40% of the U.S. land area. These states have the greatest amount of federal lands (tribal lands, USDI National Parks and Bureau of Land Management, and USDA Forest Service) and the ranching areas are primarily confined to the arid and semi-arid regions. Federal ownership of lands range from 30% in Washington to approximately 87% in Nevada. Perhaps compared to the Midwest, western beef production does not seem that important. However, beef cattle production and hay production for ruminant livestock are cornerstones of the rural economies in the western U.S. as well as Great Plains states (Tanaka et al. 2007).

Beef cattle producers in the western region are faced with many challenges. First, their ranch resources are often limited in forage quality and quantity, both of which are dynamic and dependent on climatic conditions. Thus, western ranch managers often select cattle based on their ability to thrive in environments with limited nutritional resources. Often, western beef producers select cattle with smaller frames, low to moderate milk production, and the ability to be reproductively efficient in a limited nutrition environment. These producers also tend to select calving dates that optimize beef cattle production with available forage resources. As a result, greater than 80% of western beef producers calve in the spring. Ranches that market calves at weaning tend to calve a month or two before the onset of green forage. In contrast, a growing number of producers who retain ownership or keep calves as yearlings are moving calving dates to match the onset of green forage more closely. By calving in April/May, producers try to match the cow’s nutritional requirements as closely to the forage resources as possible and minimize supplemental inputs.

Despite efforts to match cow type and production to rangeland environments, most western livestock producers are dependent on supplemental and harvested forage during portions of the year. High elevation rangelands/ranches often have extended periods of snow cover. During these periods, harvested forages are necessary. Ranches that provide feed during the December through March winter period often require a minimum of 2 tons of harvested forage per cow. While a great deal of effort is made to reduce the reliance on harvested forage, most of the alternatives such as stockpiled forage, straw, and other crop residues, are limited by nutritional quality and need substantial inputs to meet the nutritional demands of the cow/calf. Strategic supplementation is essential for these producers and often critical to their success (DelCurto et al. 2000; Kunkle et al. 2000).

The U.S. Sheep Industry. The first permanent U.S. domestic sheep flock was established in Virginia in the early 1600s (Bell 1970). From there, the American sheep industry continued to grow and eventually peaked at an estimated 56 million head in 1945 (USDA 2004). Over the last several decades, the U.S. sheep industry has contracted drastically in size, and in 2021 it was reported that there were approximately 5.17 million total sheep (USDA 2021). However, there appears to be a diminished rate of decline in recent years, suggesting that the observed exponential decay of the U.S. sheep inventory may be close to its lower asymptote.

Most recently, the U.S. was ranked 50th in the world in total sheep inventory, substantially smaller than China (1st; 163 million head), India (2nd; 74.2 million head), and Australia (3rd; 65.7 million head), to name a few of the world leaders (FAO 2017). Not surprisingly, the current number of sheep in the U.S. is small compared to swine (71.7 million head; USDA 2017b) and beef and dairy cattle (103 million head; USDA 2017c). However, the number of sheep operations across the nation (101,387) ranks only behind beef cattle (729,046), as more Americans raise sheep than dairy cattle (54,599) and hogs (66,439; USDA 2019).

Traditionally, the bulk of the U.S. sheep population has been located in the 24 states west of the Mississippi River. Today, an estimated 80% of the country’s sheep are found in the West, with Texas (1st; 730,000 head), California (2nd; 555,000 head), and Colorado (3rd; 445,000 head) being among the leaders (USDA 2021). Furthermore, the plurality of the total U.S. sheep inventory (43%) is found on large operations (> 1000 head; USDA 2012), which are more typical of the western sheep industry.

Many eastern states (MI, NY, OH, PA, VA, WI, and “Other States”) exhibited positive growth in their sheep inventory from 2001 to 2007, whereas the inventory in all but two western states (OK and MO) continued to decline during this period (NRC 2008). Despite eastern states being home to only 19% of the total U.S. inventory in 2012, they contained 39% of the nation’s sheep producers (USDA 2012). Therefore, recent trends suggest that the makeup of the U.S. sheep industry is shifting toward smaller flocks. For example, the proportion of operations with < 100 head, 100 to 999 head, and > 1000 head in 1974 was 77%, 20%, and 3%, respectively (NRC 2008), contrasted with 93%, 6%, and 1%, respectively, in 2017 (USDA 2019).

Production characteristics. Sheep have been bred to produce one or more of three products: wool, meat, and milk. The majority of the world’s dairy sheep are located in the Mediterranean countries of southern Europe and northern Africa (FAO 2017). Sheep milk is typically processed into high-quality cheeses, and Roquefort, Pecorino Romano, and Manchego styles can often be found in U.S. urban and suburban supermarkets. While the U.S. dairy sheep industry has been growing over the last several decades, it is still relatively small (Thomas et al. 2014). Therefore, the two major U.S. sheep commodities are wool and lamb.

Advances in textile technologies allow today’s wool products to range in application from next-to-skin to protective outerwear suitable in all temperatures. Wool’s durability and odor resilience are ideal for both the working class and outdoor enthusiasts. Additionally, its fire-retardant properties are capable of protecting U.S. military men and women where synthetic fibers (e.g., nylon, polyester, etc.) fail. Throughout the country and world, the western states are known for producing a high-quality wool clip (i.e., total quantity of wool shorn in an area for one year). Colorado marketed the most wool in 2020 (1.14 million kg [2.5 million lbs]), followed by Utah (1.09 million kg [2.1 million lbs]) and California (0.90 million kg [2.0 million lbs]). The heaviest average individual fleece weights came from sheep in Nevada (4.2 kg [9.2 lbs]), Montana (4.1 kg [8.9 lbs]), and Utah (4.1 kg [8.9 lbs]; USDA NASS 2021).

Sheep are shorn once per year, generally in winter or spring before pregnant ewes give birth. The highest average returns from wool on a unit basis in 2020 were garnered in Washington ($2.50/lb), Wyoming ($2.35/lb), Nevada ($2.30/lb), and Montana ($2.20 lb; USDA NASS 2017a). Therefore, the average revenue from a Montana fleece was over $19 per head in 2020. However, receipts from the sale of wool represented just 5 to 13% of the total revenue for the average U.S. sheep producer from 2010 to 2015 (LMIC 2016). Though the sale of wool is a timely income source for the extensively managed operations prevalent in the western states, the success of most sheep operations in the U.S. hinges on the value of their lamb crop.

An estimated 50% of lambs are born in April and May on operations with 500 or more breeding ewes (USDA APHIS 2014). Sheep producers benefit from the ewe’s ability to give birth to and raise multiple lambs at a time. The states with the highest lambing percentage in 2020 were Iowa (141%), Minnesota (138%), and South Dakota (132%; USDA NASS 2021). As with most commodities in agriculture, if the sheep producer wants more output (e.g., a greater lambing percentage), they need to supply more input (e.g., better genetics and increased nutrition). Therefore, the highest lambing percentages in the U.S. tend to come from Midwestern states where harvested feeds are more abundant and less expensive.

The average age and weight of lambs at weaning were 4.5 months and 33.8 kg (74.5 lbs), respectively, on western and central U.S. sheep operations in 2010. Additionally, these operations marketed their non-replacement lambs shortly after weaning at an average age and weight of 5.7 months and 42.8 kg (94.3 lbs), respectively (USDA APHIS 2012). From there, most lambs are placed in a dry lot and fed a high concentrate diet until they are finished, which was at an average live weight of 61.2 kg (135 lbs) in recent years (NRC 2008). California and Colorado have traditionally been the largest lamb feeding states, with an estimated 250,000 and 235,000 lambs on feed, respectively, in 2020 (USDA NASS 2021). Like the U.S. sheep inventory, the average per capita consumption of lamb in the U.S. has continued to decline and was below 1 pound per person in 2015 but has increased to 1 pound as of 2020. This is especially concerning considering Americans consumed an average of 34.1 kg (75.1 lbs) of poultry, 23.3 kg (51.4 lbs) of beef, and 21 kg (46.3 lbs) of pork available per person in 2015 (USDA ERS 2017). Efforts to promote American lamb, especially within the younger, more diverse U.S. population, have increased in recent years.

There are many reasons, both anecdotal and substantiated, for the contraction of the U.S. sheep industry. Throughout most of the history of domestic and international sheep production, wool was the major product, and sheep meat was, more or less, a byproduct (USDA ERS 2004). With technological advances in the 1960s, less expensive manmade fibers began to outcompete wool in the textiles market. Since then, sheep-producing nations have mostly switched their emphasis to improving lamb production while maintaining a quality wool clip. Although the U.S. is the largest meat and poultry consuming nation globally, attempts to promote lamb and increase its consumption have largely been unsuccessful. Despite these realities, sheep production in the U.S. can still be quite profitable. For example, it was estimated that the typical Wyoming region sheep operation had an average profitability of $28.11 per ewe per year from 2010 to 2015 (LMIC 2016), the equivalent of a per cow profitability of $140.56 per year.

1.2 Public Land Ownership in the Western U.S.

Western livestock industries are also dependent on the continued use of public lands for livestock grazing. Most ranches have a mosaic of pastures and rangelands (both private and public) that provide the resources for a 12-month forage resource base. Approximately 20% of the animal unit months for western livestock production are derived from public lands. While that may not seem like a large amount, when one considers that 60% of beef production is derived from ranches of 100 head of producing cows or more, approximately 1/3 of the forages for these ranches, on average, come from public lands (four months of grazing). For many areas of the West, such as the Southwest and lower elevation rangelands in the Great Basin, many ranches graze public lands for the majority of the calendar year. The greatest challenge related to public land management is managing these lands for multiple values and uses. Other values include recreation (hunting, camping, hiking, and fishing), conservation for wildlife, and the overriding desire to preserve lands for future generations.

Due to the arid to semi-arid nature of rangelands in the western U.S., these lands are often more sensitive to disturbance or overuse and, as a result, are more likely to be damaged by improper livestock use. Currently, livestock producers must be vigilant regarding public land stewardship and respect other public land values or services. Current concerns often relate to threatened and endangered species, riparian area structure and function, and differences of opinion with the public with respect to other values and ecosystem services. Other significant challenges include the fate of ranches with significant esthetic and wildlife recreational value. Numerous ranches that have changed ownership in the recent past have been purchased by investment groups for their investment and/or recreation value rather than income from beef cattle production. For these ranches, recreation and esthetic values often are prioritized over beef production goals. In addition, ranches located in desirable vacation locations (ski areas, near national parks, close to urban areas) often have property tax increases that challenge the profitability of the ranch. Many producers in these types of locations take advantage of conservation easements because of shared values and the lowering of property taxes.

Many western land grant universities and associated USDA–ARS research locations are devoting substantial resources to evaluate grazing as a tool to improve public and private land vegetation diversity and structure (Bailey et al. 2019). Specifically, studies with various species of livestock have suggested that targeted grazing could be a tool to reduce noxious weeds and, in turn, encourage more desirable vegetation. Likewise, livestock grazing is being used to control fuels to reduce the occurrence and severity of wildfires on public lands (Davies et al. 2010; Bailey et al. 2019). Perhaps, the future of public land grazing will focus more on the use of domestic herbivores to manage vegetation for more desirable outcomes.

2 Great Plains and Western Rangeland Livestock Management Techniques and Systems

Livestock managers need to provide forage resources for their animals over the 12-month production cycle (Raleigh 1970; Vavra and Raleigh 1976). Most livestock operations in the Great Plains and western U.S. utilize spring-time calving and lambing as the basis of their production cycle. For many beef cattle producers, calving one to two months before the onset of green forage is preferred because it matches cow nutrient requirements with forage resources and optimizes the weaning weights of beef calves. Some producers, however, have moved calving dates to coincide with the onset of green forage to minimize the need for nutritional inputs and closely match cow requirements with forage resources. These ranches will often retain weaned heifers/steers to capture body weight gain during the backgrounding or yearling stage of production.

Great Plains production systems are designed to optimize the use of forage resources. Most ranches implement spring calving with the greatest period of nutrient demand during lactation, coinciding with the onset of spring forage. Spring calving dates will vary from February/March to May, depending in large part on if the livestock/ranch manager plans to market calves as weaned calves or retain ownership and market as yearlings. These production systems also vary with precipitation amounts and distribution patterns, as well as vegetation characteristics. Because of the lower elevations and continental weather patterns, these regions can usually be grazed for a greater proportion of the year and, as a result, these regions have less reliance on harvested forages and hays. However, they are often challenged during the winter period with Arctic storm systems that can dramatically influence production systems in the region. In fact, weather system extremes often cause substantial problems for producers in this region and represents significant economic losses.

Great Basin, Intermountain, and Northern Mixed-grass native rangelands are often grazed in late-spring, summer, and early fall, then livestock are typically brought back to their base units before the onset of winter conditions. This allows managers to market calves during the fall/early winter period, provide supplemental feed for the winter, and manage calving/lambing at or near the ranch’s headquarters. Predators are an increasing problem for western livestock producers (see Chap. 24: Large Carnivores). Predation by wolves (Canis lupus) and grizzly bears (Ursus arctos horribilis) on cattle has expanded in the Intermountain Region, which has increased the need to manage calving and the early post-partum period to minimize risks related to predation. Likewise, the rangeland sheep industry struggles with predation due to large raptors (primarily golden eagles [Aquila chrysaetos]), black bears (U. americanus) coyotes (C. latrans), mountain lions (Puma concolor), and wolves. The timing and location of lambing are a challenge for these producers, with an increasing need for security for the animals during the most vulnerable part of their production cycle. The use of guard dogs and other security measures has increased dramatically in recent years (Mosley et al. 2020).

One of the significant management challenges for Great Plains and Western livestock producers is selecting animals that optimize production in limited nutrition environments. The ideal ewe/cow can convert forage resources to pounds of lamb/calf weaned with minimal supplemental nutrients and be reproductively successful. In addition, animals that fit the physical requirements of extensive remote rangeland sites are often preferred. Low-to-moderate milk production and moderate body sizes are often preferred with beef cattle because of the rugged terrain and limited nutrition. In the Great Plains, producers often have less challenging terrain and increased forage production, however, the quality of forage with significant warm season forage component is of lower quality compared to cool season forages, which necessitates the need for supplemental inputs. Strategic supplementation is critical in utilizing low-quality high-fiber forages during the fall and winter grazing period (DelCurto et al. 2000). Likewise, sheep breeds with greater flocking instincts and wool traits are preferred over larger carcass-based breed types. Crossbreeding to create heterosis and, as a result, increased vigor is beneficial to both livestock industries. For both sheep and cattle industries, selection for good feet and legs as well as other physical attributes for an animal that can traverse rugged terrain over several years without physical breakdown are important selection criteria.

Finally, most of the Great Plains and western livestock industry is moving to 12-month management systems that reduce the need and reliance on harvested forages (hays; Putman and DelCurto 2020). The cost of equipment and labor associated with haying are major challenges for beef producers in these regions. Moving to management systems that extend the grazing season into the late fall and winter period reduces the need for additional labor, equipment, and reliance on fossil fuels in the production system, which align with current and future trends in animal agriculture.

3 Wild and Domestic Ruminant Ecology

Ruminant animals, both wild and domestic, have co-evolved with grasslands for millions of years (Van Soest 1994). As a result, ruminants have an important function in grassland ecosystems. Most wild populations of ruminants occupy unique ecosystem niches that co-exist with other ruminants, allowing for sustainable maintenance of wildlife populations and the grassland ecosystems that are essential for their survival. Likewise, understanding how domestic ruminants co-exist with wild ruminants on rangelands is important for long-term management of both wild and domestic animal populations (McNaughton 1985).

Ruminant animals vary in respect to their ecological niche, and, as a result, so does their dietary selection strategy and associated digestive physiology (Fig. 4.2; Cheeke and Dierenfeld 2010). Generalist grazers are larger in body size (specifically ruminal-reticular size) relative to intermediate and selective grazers. In addition, grazers such as bison (Bison bison) and cattle have large muzzles, dentition adapted to optimize bite size, and large ruminal-reticular size or volume to accommodate larger fill and greater ruminal fermentation retention time (Cheeke and Dierenfeld 2010). Furthermore, larger grazers primarily exhibit diurnal grazing patterns with two to three grazing bouts per day and have a greater reliance on rumination to assist with the breakdown of high-fiber, low-quality forage resources (Van Soest 1994). These animals have a general preference for grass and “grasslike” species such as sedges even when available forbs and shrubs are of higher nutrient composition (Clark et al. 2013; Damiran et al. 2019). Simply put, these animals have evolved to consume high-fiber, low-quality forages and their ecological niche relates to the optimal use of vegetation with moderate to high levels of cellulose (Van Soest 1994).

Fig. 4.2

Ruminant dietary preference and physiologic attributes. Ruminants have co-evolved with grasslands to occupy unique ecological niches (adapted from Cheeke and Dierenfeld 2010)

In contrasts, selective and intermediate ruminants require higher quality diets and, as a result, have feeding strategies that only use grasses when young and succulent (Fig. 4.2). Rumen size relative to overall body size is smaller and their digestive physiology is adapted to more specialized diets demonstrated by smaller muzzles, increased frequency of grazing bouts, reduced reliance on rumination, and the ability to optimize the use of moderate to high quality vegetation (Van Soest 1994; Cheeke and Dierenfeld 2010). In a study evaluating mule deer (Odocoileus hemionus), Rocky Mountain elk, and cattle diets; Damiran and co-workers (2019) found that cattle primarily selected for grasses whereas mule deer and elk diets focused on forbs and shrubs when late summer grazing in mixed-conifer forest understories. In addition, estimates of dietary quality suggested that cattle selected the lowest quality diet but with greater intake rates (grams per minute) than Rocky Mountain elk (intermediate) and mule deer (selective) diets. The difference in dietary strategies suggest that these animals have minimal dietary overlap and manipulations of these ruminant populations can influence vegetation successional dynamics. In addition, the difference in dietary strategies also relate to the species tolerance or ability of ruminal microbes to break down fiber (cellulose). Understanding the distribution and use of all grazers on the landscape is important in designing management systems that optimize vegetation and wildlife diversity.

All ungulates graze selectively, so across a given landscape, there are plants grazed and those ungrazed. A large number of studies show persistent heavy grazing during the growing season decreases the competitive ability of grazed plants (Augustine and McNaughton 1998). Grazed plants may lose vigor and even die, either scenario giving ungrazed plants the competitive opportunity to increase. Consequences include a decline in palatable plant species production (Hobbs 1996) and a shift in plant community composition to unpalatable or invasive plants (Augustine and McNaughton 1998). A simultaneous decline in animal production may occur due to the lower nutritional value of the forage crop. Thus, season of use plays a vital role in the maintenance or decline of forage plants and plant communities.

Timing, duration, and intensity of grazing all interact to impact the health of forage plants. In the Intermountain West, continuous season-long grazing will negatively affect forage plants (Milchunas and Lauenroth 1993), given summer drought limits the opportunity for regrowth. However, when grazing duration is limited, there is often the opportunity for regrowth (Ganskopp et al. 2007). The amount of regrowth is probably dependent on soil moisture and plant species. However, Ganskopp et al. (2007) found no relationship between soil moisture and regrowth but did notice some species regrew better than others did. Grazing northern Great Basin grasses during vegetative, boot stage and flowering caused respective declines in fall standing crop of 34%, 42%, 58% in one year and 34%, 54%, and 100% reductions the next (Ganskopp et al. 2007). Ganskopp et al. (2004) reported similar results with boot stage-grazed Idaho fescue (Festuca idahoensis), bluebunch wheatgrass (Psuedorogeneria spicatum), and bottlebrush squirreltail (Elymus elymoides) plants. The detrimental effects of repeated boot-stage grazing of cool-season grasses are well documented. From vegetative through flowering stages, a decline in forage quality occurs, but the grazing animal’s nutritional requirements are met in most cases.

Introduced species with a tolerance for defoliation may be grazed during the growing season on native ranges deferred until after seed ripening. Crested wheatgrass (Agropyron desertorum), common in the Intermountain West, provides such an option. During the growing season, nutritional quality and palatability are adequate (Cruz and Ganskopp 1998) for livestock production. Care must be taken not to underutilize crested wheatgrass as the development of “wolfy plants” and decreased grazing efficiency of the affected pasture could occur (Ganskopp et al. 1992; Romo 1994). In a study conducted on the Zumwalt Prairie, a remnant of the Palouse Prairie, Wyffels and DelCurto (2020) reported the bunchgrass prairie contained 13% non-native species (Kentucky bluegrass [Poa pratensis], intermediate wheatgrass [Thinopyrum intermedium], and brome species (Bromus spp.)) and these species accounted for 20–50% of the botanical composition of cattle diets during the late spring early summer grazing period. The results of these studies suggest that non-native species can be used to reduce herbivory of native bunchgrasses, which would be particularly beneficial during the growing season when native bunchgrasses are most vulnerable to the negative effects of defoliation.

Once the forage plant has completed its life cycle for the year and seed has been produced, grazing has little effect on the plant’s physiological well-being unless it is overly excessive (Holechek et al. 1998). However, plant residue during dormancy plays a critical role in protecting the plant. Hyder (1953) found maintaining 200 kg/ha of residual forage maintained or improved range conditions on most sites in southeastern Oregon. Late summer, fall, and winter grazing may be practiced on ranges requiring an improvement in vigor. Unfortunately, the forage’s nutritional quality by late summer is marginal and may decline further as fall progresses. This, in turn, will result in the livestock/range manager providing supplemental inputs for optimal livestock production.

Grazing impacts may also influence seed production, establishment, and survival of young plants and longevity of older plants. Miller et al. (1994) summarized these impacts. Heavy grazing generally decreases seed production. Young plants, one to two years old, are the most susceptible to mortality caused by grazing. The longevity of plants is variable and dependent on species and grazing history. Heavy grazing effects have generally been compared to no grazing. The impacts of light to moderate grazing have not been adequately described. Given proper stocking rate control and a grazing system that provides growing season rest, these impacts can be mitigated.

Grazing bunchgrass communities during dormancy creates additional challenges for land managers and ranch managers. Grazing distribution can become problematic when riparian areas are green and upland communities are dormant (Parsons et al. 2003; DelCurto et al. 2005). Use of pastures without sensitive riparian areas is encouraged (also deferment or rest), as well as the use of management tools to move cattle away from riparian communities. These tools may include “off-stream” water (Porath et al. 2002), herding, and strategic use of supplements (Bailey et al. 2001; Tanaka et al. 2007). More recently, research efforts have focused on new technologies utilizing electronic animal identification (EID), global positioning systems and activity monitors to observe and manage livestock distribution on extensive rangeland ecosystems (DelCurto and Olson 2010; Bailey et al. 2021). Fenceless livestock systems using GPS technology have been demonstrated to be effective in managing cattle grazing in extensive environments (Ranches et al. 2021; Boyd et al. 2022). In addition, these systems have also been effective in protecting areas recently burned from grazing without the need for temporary fencing (Boyd et al. 2022).

Annual grasses, with cheatgrass (Bromus tectorum) being the most notable, are usually managed to disrupt physiological processes and prevent seed production or even kill the plants. Cheatgrass provides adequate nutrition after germination in the fall and early spring (Cook and Harris 1952), which coincides with the species sensitivity to grazing effects.

4 Grazing Systems and Season of Use

When evaluating the impact of domestic livestock on pastures and grasslands, one of the most important aspects is the management of grazing which is commonly referred to as “grazing systems.” The actual grazing management on a given ranch often incorporates multiple types of grazing system approaches. In addition, grazing systems are generally specific to a geographic area with unique vegetation communities that, in turn, have unique needs with respect to the maintenance or improvement of that plant community (Table 4.2). For more detailed information on grazing systems, outstanding reviews have been provided by numerous authors (Holechek et al. 1998; Fuhlendorf and Engle 2001; Heitschmidt and Taylor 2003; Kothmann 2009; Briske et al. 2011; Holechek et al. 2020).

Table 4.2 Summary of grazing systems utilized on rangelands with common acronyms, defining features, regions of use, unique attributes, as well as references for each system

Grazing systems have been initiated with the explicit purpose of manipulating the season of use so that periodic rest or deferment occurs during the growing season. The main goal is to allow forage plants to periodically complete their annual growth cycle and replenish nutrient reserves without being defoliated. It is generally unreasonable to expect stocking rates to be increased when moving from a season-long grazing pattern to a grazing system (Holechek et al. 1998). Typical systems used in the Intermountain West are deferred rotation and rest rotation. In some cases, other specialized systems may be used or the aforementioned modified for a specific goal such as riparian zone restoration. Specialized systems, such as intensive early stocking, have been developed with a focus of optimizing stocker cattle weight gains per acre (ha) in more productive rangelands such as the Tallgrass Prairie (Smith and Owensby 1978; Owensby and Auen 2018).

For the Great Plains Region, grazing system recommendations often differ from the more arid regions in the western U.S. Specifically, continuous grazing is often recommended for the Tallgrass Prairie and regions of the Mixed-grass Prairie (Fuhlendorf and Engle 2001; Briske et al. 2011). In general, these rangeland ecotypes usually are more homogeneous with less vegetation and topographic diversity on a landscape basis as compared to the more westerly regions of the U.S. Grazing encourages greater heterogeneity of the vegetation and, as a result, may provide more diverse habitat opportunities for wildlife. In addition, the greater precipitation and fire frequency potential for this region result in a more resilient and productive rangeland system.

For many plant species in the Intermountain West, the most critical period for detrimental grazing effects is floral initiation through the development of seed (Holechek et al. 1998). This period is critical because the plant’s demand for photosynthetic products is high, and the opportunity for regrowth is low due to declining soil moisture conditions in arid and semi-arid rangeland communities. As a result of repeated grazing at this time, the capacity of forage plants to produce both root and shoot growth the next year may be diminished, especially if the plants are heavily grazed. The development of modern grazing systems incorporates this knowledge of plant physiology, and animal behavior, so physiological damage to forage plants is minimized. Unfortunately, the best time to graze to maximize animal production is when forage plants are green and growing. Modern grazing systems incorporate use during the growing season in some years to foster animal performance and annual rest or growing season deferment during other years to allow forage plants to maintain vigor and reproduce.

Most of the western U.S. is characterized as having a short grazing history and suffers from a lack of seasonal rainfall, so forage plants are more susceptible to physiological damage from grazing (Milchunas and Lauenroth 1993). Additionally, with season-long grazing in large landscape pastures, animals have preferred grazing areas, and these patches may be heavily impacted by grazing animals while others are underutilized (Teague and Dowhower 2003). These areas typically occur near water and where forage is plentiful. Even under light stocking, these areas will receive excessive use (Holechek et al. 1998; Teague and Dowhower 2003). In contrast, the Great Plains represent vegetation communities that co-evolved with grazing ruminants (bison, elk, deer, pronghorn [Antilocapra americana], etc.). As a result, the level of use and impact of herbivory on the plants and plant communities differs from the more arid rangelands of the Intermountain West.

Deferred rotation grazing involves not grazing at least one pasture during the growing season. The simplest form is a two-pasture system where each pasture is deferred during the first half of the grazing season every other year (Holechek et al. 1998). Vegetation response under this system has been slightly better than season-long grazing on bunchgrass ranges (Skovlin et al. 1976). Under rest rotation grazing, one pasture receives a year of nonuse while grazing is distributed among the other pastures in the system (Hormay 1970). For much of the western U.S., a typical rotation system is made up of three or four pastures used during the late spring to early fall period. The rested pasture receives use after the growing season the year following rest. Rest rotation grazing resulted in Idaho fescue’s improved vigor compared to that grazed season-long (Ratliff and Reppert 1974). The development of grazing systems must include the critical economic component. Grazing systems generally involve either substantial initial investment in fences and water developments or significant annual expenditures for increased herding of livestock. The benefits of developing grazing systems must be compared to the costs of instituting these systems.

Critical to the success of a rotation grazing system is stocking rate control (Holechek et al. 1998). Depending on the number of pastures in the system, more animals are concentrated in one pasture than if the entire range was used season-long or continuously. However, most rotational grazing systems do not change stocking rate when expressed on a season long basis with the stock density increase being a function of the number of pastures. Increases in stocking rate over season-long levels may not be practical. Holechek et al. (1998) reviewed the literature and reported that stocking rates for livestock in the Intermountain West should be established, resulting in 25–40% utilization of preferred forage species. Failures of rotational grazing systems are usually related to heavy stocking rates (Holechek et al. 1998).

Rangelands dominated by annual grasses like cheatgrass require entirely different grazing systems to ensure maintenance or restoration of the perennial plant community. Mosley and Roselle (2006) provide insight into the design of a targeted grazing system for cheatgrass:

• Targeted grazing can be used to disrupt fine fuel continuity and reduce fuel loads.

• Annual invasive grasses can be suppressed when livestock grazing reduces the production of viable seeds.

• Seedheads of invasive grasses must be removed while the grasses are still green.

• It may be necessary to graze annual grasses two or three times in the spring.

• In mixed stands of annual grasses and perennial plants, livestock should be observed closely to avoid heavy grazing of any desirable perennial plants.

• Livestock perform well on annual grasses in the spring, producing weight gains similar to those from uninfested ranges.

• Targeted grazing can be integrated with prescribed fire, herbicides, and mechanical treatments to improve efficacy of control.

• Applying targeted grazing before artificial seeding can help in restoration efforts.

Targeted grazing systems designed to suppress invasive annual species should be an area of focused research because the threat to ecosystem integrity is great. Targeted grazing differs from traditional grazing management in that the goal of targeted grazing is to apply defoliation and/or trampling to achieve specific vegetation management objectives such as reduction of a noxious/invasive plant species (Bailey et al. 2019). By using specific dietary strategies of grazing ruminants, rangeland managers can exert pressure on individual plants by herbivore defoliation and, as a result, move the vegetation community towards a more desirable plant community composition (Lehnhoff et al. 2019). In addition to targeted grazing of cheatgrass, research has shown promise with targeted grazing on invasive annuals such as medusahead rye (Taeniatherum caput-medusae; DiTomaso et al. 2008; Brownsey et al. 2017). In contrast, species such as ventenata (Ventenata dubia) have been more challenging because of extremely low palatability regardless of growth stage (McCurdy et al. 2017). Other notable species would include potentially toxic rangeland plants such as larkspur (Delphinium spp.) where early sheep use has been shown to decrease the risks with subsequent cattle grazing (Pfister et al. 2010).

As mentioned previously, mixed species grazing may have management applications where multiple herbivore species with divergent dietary strategies may more uniformly use diverse vegetation communities (Walker 1997). Understanding distribution patterns of grazing ruminants as a function of season, weather extremes, and dietary strategies will be important in accounting for the impact of wild and domestic ruminants on rangeland landscapes and vegetation communities. Both domestic livestock and wildlife have been demonstrated to modify riparian vegetation which, in turn, may alter riparian hydrologic function (DelCurto et al. 2005; Averett et al. 2017). Additionally, one of the most important considerations is how ruminants modify plant communities and, in turn, how that influences fire ecology. Riggs and co-workers (2015) suggested that historical herbivory modifies future biomass and fire behavior over time. Specifically, multi-species herbivory lengthens the landscape fire-return interval for most vegetation communities. However, the effects are site-specific, and contingent on future climatic conditions and fire-suppression efforts.

5 Ruminant Animal Grazing Behavior

Most of the arid to semi-arid rangeland in the western U.S. is used as extensive pastures with ample opportunity for livestock to freely disperse over areas of diverse topography. Generally, animal use is first influenced by abiotic factors such as distance to water and slope (Coughenour 1991). Other factors are more subtle but important to predict animal distribution on the landscape. Early season use often leads beef cattle to use south-facing aspects or areas with early-maturing annual grasses (DelCurto et al. 2005). These sites are often the first areas to initiate growing and provide areas of the highest nutrient density per bite early in the grazing period. Deeper-rooted perennials such as bluebunch wheatgrass and Idaho fescue may be preferentially selected over Sandberg bluegrass (Poa secunda) due to the ability to remain green longer than the more shallow-rooted grass.

Grazing distribution patterns on diverse landscapes also indicate that cattle often prefer to do most grazing away from cool air sinks such as riparian meadows when phenology of the upland forage is vegetative (Parsons et al. 2003; DelCurto et al. 2005). In recent studies evaluating the botanical composition of diets among diverse plant communities, beef cattle showed strong preferences for grass species even though forbs and shrubs may have had a higher nutrient density (Walburger et al. 2007; Clark et al. 2013; Wyffels and DelCurto 2020). Generally, as stocking rate (use) increases and upland forages become dormant, foraging efficiency decreases (Damiran et al. 2013). The overall decrease in foraging efficiency may be due to the inability to find preferred species, resulting in increasing search time and smaller amounts consumed per bite of the preferred species. Monitoring daily grazing behavior without measuring forage intake will not provide the meaningful insight needed to understand the complex interrelationships that exist in the grazing ruminant (Krysl and Hess 1993). Krysl and Hess (1993) also state that harvesting efficiency allows further evaluation of supplementation regimens and the energetic cost of grazing, which is an essential element in understanding the effects of grazing behavior on ecosystem function.

The understanding of climate change and climatic extremes is also an important consideration for both wild domestic ruminants in rangeland ecosystems. Understanding how animals respond to drought (Roever et al. 2015) and heat stress is important, particularly in the management of cattle use near streams (DelCurto et al. 2005). Roever and coworkers (2015) indicated that cattle during drought will consolidate distribution patterns with increased reliance on riparian areas. In addition, research relative to ecological fit of domestic ruminants is important to the optimal production and use of native rangelands (Sprinkle et al. 2020). Likewise, in the interior Pacific Northwest, Intermountain West, and upper Great Plains, understanding how ruminants respond to cold stress is important for optimal management of landscape use and nutrient needs (Wyffels et al. 2019, 2020a, b; Parsons et al. 2021). When providing supplemental inputs, managers need to focus on optimizing the use of forage resources as well as encouraging optimal grazing distribution on extensive rangeland pastures or paddocks. Research in the Northern Mixed-grass Prairie has demonstrated that supplement intake patterns vary as a function of environmental extremes and are also impacted by cow age (Wyffels et al. 2020a, b; Parsons et al. 2021).

6 Other Disturbance Factors

It is difficult to evaluate wild and domestic animal interactions and impacts on vegetation diversity without discussing other disturbance factors such as fire and/or logging. Generally, fire will cause significant declines in forbs, shrubs, and trees while promoting a grass understory. Similarly, logging will open up the canopy, which encourages grasses and early successional shrubs and forbs on western Intermountain forests of North America. Combinations of logging (thinning) and understory controlled-burns have been shown to improve diets of elk and cattle early in the grazing season whereas diets in late summer and early fall were lower in quality with the treated areas (Long et al. 2008; Clark et al. 2013).

In a study evaluating overstory tree type and stand age on understory vegetation composition and quality by forage classes, Davis and coworkers (2019; Fig. 4.3) reported only limited differences due to overstory tree type and no differences due to stand age with respect to vegetation crude protein (CP) and plant fiber composition (neutral detergent fiber and acid detergent fiber). However, fibrous fractions of the vegetation were substantially lower in the understories of ponderosa pine (Pinus ponderosa) and Douglas fir (Pseudotsuga menziesii) overstories. In contrasts, graminoids and non-forested sites (meadows and grasslands) had dramatically higher fiber and lower crude protein in the late summer sampling periods. Similarly, Walburger and coworkers (2007) reported that timber harvest and previous herbivory had no effects on the quality of diets selected by cattle. In addition, cattle grazing forested rangelands in northeastern Oregon preferred a diet that was dominated by graminoids despite the fact that forbs and shrubs had higher CP and lower fiber content. However, as graminoid production and/or availability decreased, such as in heavily timbered areas, cattle increased consumption of forbs and shrubs.

Fig. 4.3

(adapted from Davis et al. 2019)

Crude protein and fiber composition of forage growth forms (graminoids, forbs, and shrubs) from May to September in diverse mixed conifer overstories, meadows, and grasslands

7 Interactive Effects with Wildlife

Domestic livestock grazing (sheep and cattle) can have both positive and negative impacts on wildlife habitat. The intensity of use plays a confounding role in analyzing effects as residual vegetation left after grazing may be a key consideration for wildlife habitat. Limiting grazing to vegetative, boot, or flowering stages may provide residual forage through regrowth (see previous discussion, Ganskopp et al. 2007). The regrowth can then provide forage and cover for various species of wildlife. During the boot stage of growth, grazing has been shown to improve the nutritional quality of forage (regrowth) available to ungulates in the fall or winter (Ganskopp et al. 2004). However, forage biomass available is less than similar ungrazed forage (Ganskopp et al. 2007).

Season of livestock grazing can also play a significant role in altering plant community composition (Severson and Urness 1994). Bitterbrush (Purshia tridentata) is a shrub species palatable to wild ungulates including mule deer, elk, and pronghorn. Ganskopp et al. (1999) reported grazing during the boot stage of bunchgrasses improved both the diameter and volume of bitterbrush plants, but grazing after the flowering of grasses resulted in an extensive use of bitterbrush. Previously, Lesperance et al. (1970) suggested that to prevent overconsumption of bitterbrush on mule deer wintering range, cattle grazing should be limited to early in the season when grasses are green and palatable. Early season grazing of meadows allows regrowth of forbs, potentially improving foraging conditions for sage-grouse (Centrocercus urophasianus; Evans 1986).

Season of use considerations can be adjusted to critical life events like bird ground-nesting and pronghorn fawning. This could include deferment to preserve habitat or grazing prior to the event to create habitat. Moderate and low stocking rates of cattle grazing during the nesting season on bunchgrass communities in northeastern Oregon caused no adverse impacts to ground-nesting songbirds (Johnson et al. 2011). These stocking rates generally provided suitable habitat for all species studied compared to the no grazing treatment. However, high stocking rates did not provide suitable habitat for ground-nesting birds. Stocking rates utilized 9.5 (elk use), 20, 32, and 46% of the available forage, respectively, for zero, low, medium, and high beef cattle stocking rates.

Domestic livestock and wildlife disease transmission is also a challenge for livestock, wildlife, and rangeland management in the future. The most commonly cited concern is pneumonia transmission from domestic sheep to bighorn sheep (Ovis canadensis; Wehausen et al. 2011; Carpenter et al. 2014). These authors provide evidence that contact between domestic and bighorn sheep may be factors in disease transmission and, in turn, a primary factor in the limited success to re-establish bighorn sheep populations throughout the West. Others argue that the direct causes of respiratory disease in wild sheep are not clearly elucidated and, despite the dramatic decline in rangeland domestic sheep numbers over the past three decades, bighorn sheep have not recovered. In addition, mortality due to pneumonia is greatest with early post-partum lambs between 1 and 3 months of age (Cassirer et al. 2013) with adult bighorn sheep demonstrated to be long-term carriers of pathogens that might cause pneumonia.

One major area of concern to wildlife in close proximity to domestic sheep is the transmission of Mycoplasma ovipneumoniae, which is thought to be the agent that predisposes bighorn sheep to pneumonia (Besser et al. 2008). Mycoplasma ovipneumoniae is a respiratory pathogen that infects animals in the Caprinae subfamily and can lead to secondary infections. While the disease has a global distribution, the prevalence in the U.S. domestic sheep population has been estimated at 88.5% of operations with at least one individual testing positive via PCR for M. ovipneumoniae (Manlove et al. 2019). While not presented as a major concern for western domestic sheep production it has been estimated that M. ovipneumoniae at current prevalence levels is associated with a 4.3% reduction in annual lamb production with lower average daily gain in lambs exposed (Manlove et al. 2019; Besser et al. 2019).

Exposure to M. ovipneumoniae is primarily the result of interactions between infected domestic sheep and wild bighorn sheep. Based on experiments that co-mingled bighorn sheep with domestic sheep free of M. ovipneumoniae and those infected, the M. ovipneumoniae negative co-mingled bighorn sheep presented a significantly higher survival rate than those that co-mingled with M. ovipneumoniae positive domestic sheep (Besser et al. 2012; Foreyt and Jessup 1982; Foreyt 1989, 1990; Lawrence et al. 2010). This led to significant restrictions on sheep grazing in bighorn sheep habitats to limit the potential for mass die-offs in bighorn sheep populations. However, M. ovipneumoniae has been reported in populations of wild Rocky Mountain goats (Oreamnos americanus) and other species outside the Caprinae subfamily such as moose (Alces alces), caribou (Rangifer tarandus), and mule deer which may also serve as transmission pools to bighorn sheep populations (Wolff et al. 2019; Highland et al. 2018).

Another concern that will certainly increase in the future will be the passive transfer of brucellosis from bison to elk to cattle relative to the Greater Yellowstone Ecosystem region (Mosley and Mundinger 2018). Brucellosis infections seem to have limited long-term impacts on bison and elk wildlife populations yet could cause considerable impacts on humans including big game hunters, ranchers, and veterinarians. Brucellosis, primarily transferred via placental and mammary fluid/tissue, was largely eradicated with the mandatory pasteurization of milk and milk products in the 1930s, as well as current “bangs” vaccination programs in the beef cattle industry. The spread of brucellosis via elk populations, however, has created considerable concern for the beef cattle industry and wildlife managers. Efforts to reduce the interaction between elk populations and cattle during the late gestational stages of elk (March through May) may be key management considerations to reduce the transmission of brucellosis. In addition, confined winter feeding of elk should be reconsidered due to the higher incidence of brucellosis in winter fed Rocky Mountain elk (Brennen et al. 2017).

8 Sustainable Livestock Systems of the Future

The Great Plains and Western U.S. rangelands have historically been managed to accommodate livestock production. However, Congress has altered the framework that governs land management with the passage of the Multiple Use Act (1968), National Environmental Policy Act (1969), Clean Water Act (1972), and the Threatened and Endangered Species Act (1973). The continued use of public and private rangelands across the western region depends on our ability to develop sustainable systems that maintain or enhance biological diversity of forages, riparian function, and wildlife. Grazing livestock nutrition and management must develop systems for economic viability that also maintain biological diversity (vegetation and wildlife) and the industry’s traditions and integrity (DelCurto and Olson 2010; Fig. 4.4). Research that is grounded in economic and ecologic sustainability should be encouraged and supported. Recent reviews evaluating the management of livestock distribution and applied management strategies for optimal distribution on arid rangelands provide a relevant background for this discussion (Bailey 2005; DelCurto et al. 2005; DelCurto and Olson 2010; Bailey et al. 2019, 2021; Holechek et al. 2020).

Fig. 4.4

Sustainable western rangeland livestock production systems will have to embrace economic viability, ecological integrity, and social values to be successful in the future (adapted from DelCurto and Olson 2010)

Future sustainable livestock production systems will need to incorporate significant management paradigm shifts to be successful. Specifically, optimal use will be a function of landscape use patterns of livestock and wildlife, where we manage the vegetation for optimization of biological processes (Vavra 2005). Specifically, there is a need to focus on the amount of vegetation needed on a landscape (post grazing) to optimize the success of that plant and plant community with a focus on photosynthetic processes, and, particularly in arid and semi-arid environments, the capture, storage and release of water. Optimal use by livestock will necessarily be related to leaving behind sufficient foliage for the plant to regenerate in the future, provide sufficient vegetation biomass to maintain or enhance soil organic matter value, and provide for enhanced soil microbial populations. Perhaps, optimal use for biological processes will hinge on vegetation remaining rather than vegetation removed by the herbivore. In addition, future management systems need to account for all herbivores, which will encompass insects to large ruminant generalist grazers, as well as livestock in respect to forage system management.

Managers need to strive for systems that promote deep-rooted perennial species that optimize nutritional opportunities for all ruminants, as well as promote healthy and stable soils for optimal production and water holding capacity. Utilizing grazing systems/principles that promote desired vegetation succession while still capturing economic value will be paramount to these efforts (Bailey et al. 2021). In turn, promoting vegetation that optimizes photosynthetic processes and water use/conservation, will be more productive and diverse (grass/forb/shrub/tree) providing greater production and nutritional opportunities for domestic livestock and wildlife. These systems, in turn, will be more resilient and adaptive to climate change processes that are especially challenging in western rangeland environments (Holechek et al. 2020). In addition, providing structure for improved habitat cover as well as improved nutrition opportunities (food) over a greater portion of the year, will benefit both wild and domestic species with respect to protection from predation, increased reproductive success and production.

Although we are faced with obvious challenges with respect to sustainable rangeland management, the integration of knowledge relative to plant responses to herbivory, herbivore ecology and grazing strategies, and dynamic grazing behavior patterns will aid in developing better and more sustainable grazing management strategies (Raynor et al. 2021). The use and application of precision technologies which will include GPS applications, virtual fencing (Boyd et al. 2022), and activity monitors that are downloaded to a cell phone or computer in “real-time” (Bailey et al. 2021) will be critical technologies of the future. Using domestic livestock to manage fuels, selectively graze undesirable plant species while minimizing impacts on desirable plants will be paramount to our success. Future systems will continue to expand the grazing season, reducing the reliance on fossil fuel and labor, while promoting less growing season use when deferred and/or rotation grazing systems are used or fewer animals are grazed in continuous grazing. Simply put, grazing to promote biological processes with respect to soils and vegetation communities will provide the most benefit to both wildlife and domestic livestock production.