Part 4: Ecosystem management using livestock: embracing diversity and respecting ecological principals

"...Livestock are an indispensable instrument in ecological management towards environmental protection, and to create and sustain the multiple circular flow of materials in the soils, water bodies and atmosphere..." - Thompson et al.

In mid-April 2023 several peer-reviewed papers were published in the Oxford University Press’ Animal Frontiers journal. This was put together following the October 2022 International Summit on the Societal Role of Meat. This special edition of Animal Frontiers was published by guest editors and authors, among the nearly 1,000 signatories of the Dublin Declaration warning that livestock systems are too precious to society to become the "victim of simplification and reductionism."

Following the initial meta-analysis in Part 2 and Part 3 which focused on meat's role in human health, ?the next couple of articles focus on livestock’s impact (including benefits) on the environment. This Part 4 summary will look at livestock’s place in the ecosystem. Livestock production is facing important challenges in the context of global change, especially related to population growth, land erosion, a decrease in biodiversity, water usage, depletion of resources, disruption of nutrient cycles and eutrophication, and climate change. Even if livestock agriculture has contributed to these issues, as other forms of human activity have done, livestock can contribute to the solution when managed well.

Key topics that will be reviewed in this article include:

1. The variability of the ecological context in which livestock systems operate, and how this can both constrain and stimulate the potential of animal production
2. The need to factor in agro-ecological principles, such as improved circularity and minimized feed-food competition; and
3. the positive ecosystem contributions of well-managed livestock and how these are affected by management strategies.

The Importance of Ecological Context and Diversity

• Livestock’s role in ecosystems has been negatively impacted when the dominant views of “nature” are landscapes devoid of human influence. As a result, many environmentalists are advocating for the intensification of human activities in areas already significantly impacted while abandoning activities in land suitable for ecological restoration – the so-called “land sparing” approach. In recent years this approach is being contested by evidence from specialized fields.
• Prior to human involvement, large herbivores classed as megafauna played an important role in ecosystems across the world consuming massive quantities of vegetation, especially through seasonal migrations. They helped in the formation of deep organic soils that are now home to some of the most productive cropping systems. They also played a role in keeping woody vegetation at bay.
• After many of these species became extinct from hunting and other pressures, woodland species had deleterious effects on the ecological functions of grassland regions. Many plant species in biodiverse pastures require considerable amounts of light to survive. As a result, hunter-gatherers used fire to control woodland areas and restore grassland biomass productivity.
• Well-managed livestock systems can provide the same functions as megafauna did, while being more suitable to fit within fragmented landscapes, livestock do not require migration, and restoring megafauna would have a higher cost of human-wildlife conflict.
• This approach of using livestock to maintain important ecosystem processes is supported by increasing evidence from ecological science and reinforces the alternative “land sharing” approach advocated for by rural development, human rights, and Indigenous peoples’ advocates.

The Need to Factor in Agroecology, Circulatory, and Feed-food Competition

• Traditionally, livestock systems were used to create nutrient rich-food from low-opportunity-cost feed material. Ruminants were tasked to create food from inedible fodder, while monogastric animals were fed undesired by-products, like potato residues or other types of food waste.
• High-productive livestock systems, however, are increasingly reliant on feed crops from arable land, creating feed-food competition.
• The agro-ecological potential of livestock systems is related to their ability to upcycle vast amounts of nonedible biomass into nutritious foods, while also recycling plant nutrients back to the land, improving soil health, and sequestering carbon.
• Most of the biomass produced annually is inedible. Wheat and corn are among the most efficient in terms of generation of material for harvest compared to nonedible above-ground biomass (e.g. straw) but the ratio remains 1:1. Other plants show even higher proportions of nonedible biomass. (Legumes are up to 2:1; rape seed is 3:1, sunflower is 4:1), In addition, processing leads to even more by-products ranging from 20% to 60% waste, generally human inedible or uneconomic.
• Additionally, nonedible biomass is created from crop rotations like clover-grass mixtures or alfalfa forage to improve soil fertility, generally every fifth year of human edible crop production.
• Ruminants also have the capacity to utilize pastures and convert nonedible biomass into human edible meats and milk. This land is often unsuitable for crop production. Globally grasslands represent 70% of the total agricultural area, but even areas with intensive arable farming have large portions of grasslands (such as 30% in Germany).
• The ratio observed in practice for nonedible biomass to edible is 4:1. Globally, it is estimated that 86% of global livestock feed does not compete with human food. There is still room for improvement within the remaining 14% in view of further reductions in food-feed competition.
• It also needs to be considered that livestock also provides a buffer for surplus crops or poorer quality crops that do not meet human-grade standards.
• Taken together, the inclusion of livestock into agricultural systems to capture the benefits of non-edible biomass consumption - while creating high-quality human food and positive effects on soils is an efficient driver of circularity. ?
• Based on this rationale, emissions, arable land use, water, energy, etc. cannot be attributed to livestock production only. Removing livestock would dissipate the generation of human food and expand the consumption of land, water, and energy to replace animal products while expanding the emissions per nutritional unit.
• Where more intensive systems are reliant on arable land, such unfavorable consequences do not justify complete abstinence. Rather the minimal environmental and climate impact of food production is in mixed systems, where livestock production is based on inevitably occurring, nonedible biomass. Enhance this further by optimizing also for climate, systems, and management perspectives to have the best impact on all sustainability indicators.

Positive Ecosystem Contribution of Well-managed Livestock and the Link with Management

• Often the discussion today on livestock’s impact on the environment centers around methane production, leading to a myopic approach to improving the environmental impact of food production.
• Often overlooked is livestock’s benefit to soil health and carbon sequestration, especially in soils with a history of mismanagement. Soil carbon sequestration has the largest potential to reduce beef emissions globally via two key mechanisms:

1. Restoration of degraded landscapes through the introduction of livestock; and
2. Use of adaptive gazing to improve ecological function.

• It is estimated 133 billion metric tons of carbon have been lost in the top 2 meters of soil globally due to agriculture. Current farming and ranching practices have aided in this loss of soil carbon due to crop rotations, synthetic inputs, and extractive practices.
• Research indicates the introduction of perennial forages, reducing tillage, and incorporating livestock, soil carbon can be restored with improved overall ecological function. ?This unique carbon benefit of livestock is rarely accounted for when compared to crop products.
• Adaptive grazing management aims to minimize soil disturbance (including overgrazing), minimize synthetic inputs, and increase plant diversity. Grazing is typically short-duration and high-intensity, leaving adequate plant residue for recovery and roost systems healthy. This management style mimics the natural behavior of grazing animals across landscapes where sporadic, but concentrated uniform forage utilization is typical.
• This maintains plants in an active state of regrowth longer, increases solar energy capture, and aids in the cycling of above-ground nutrients back into the soil via the physical trampling of plant material and urine and fecal deposition.
• Globally, grass and rangelands are under threat of conversion into marginal cropping systems or other land uses. The United States, fueled by ethanol incentives, converted approximately 3 million hectares away from rangelands between 2008 and 2012. The estimated CO2 emission release from this destruction of rangeland was estimated at 38.8 million metric tons of CO2.
• These grass and rangelands provide numerous ecosystem services, including wildlife habitat, recreation, and food production, among others. They are considered to be a long-term carbon storage mechanism.
• To optimize both environmental impact and food supply, the broad and underutilized diversity that is inherent to livestock systems should be mobilized instead of being suppressed.

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Author's takeaways: As I read and summarized this article I couldn’t help but think of the large ranch my brother and his wife manage. The property spanning roughly 2500 hectares is poorly suited to crop production with rolling hills that contain excessive rocks and less desirable soil quality. Forested areas are maintained across the ranch instead of being cleared. However, as a home to thousands of cattle, rotationally grazed, the ranch is a vibrant ecosystem that also allows an extensive variety of wildlife to thrive.

Under rotational grazing management (basically adaptive grazing management as per the summary) this ranch can sustain three times the cattle that a more traditionally, continually grazed pasture can sustain - direct evidence of the topics covered well in this article. Over the last two decades of management, soils have improved in quality and the growing season is longer, especially in drier years. The carbon-sequestering properties of good soil management are clearly apparent.

Earlier in May I toured the farm after a fire ripped through a large portion of the west side of the ranch and I wrote about the benefits of this style of management on fire protection.

The larger enterprise located at home features a typical cattle feedlot, established by the earlier generation. While female cattle are backgrounded for another year on pasture due to slower growth rates, male steers are finished earlier, leaving pasture in their first fall and grown to finished weights within the more efficient feedlot system over the winter. A Canadian winter can be harsh (and grass non-existent) so high-energy feeds are key to maintaining efficient use of feed and other resources. New technologies are being implemented across all modern feedlots to improve efficiency. As efficiency improves, so will carbon footprints.

As we land at optimal feeding systems for livestock production to minimize environmental impact, regions such as Canada will need to strike a balance between well-managed pastures and the management of more intensive confined feeding operations. I expect a heavy analysis would prove it inefficient to exclusively grass-feed or grass-finish all animals to most efficiently balance non-edible biomass circularity benefits during certain livestock growing phases.

While our industry detractors label such intensive practices as “factory farms” at times, such farms are nothing more than a well-managed, efficient way to accomplish the task. To positively affect climate and the environment, all industries need to find new ways to be ever more efficient.

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Part 5 will look deeper into quantifying livestock’s impact on the environment and alternative ways to evaluate impacts holistically. ?“Challenges for the balanced attribution of livestock’s environmental impacts: the art of conveying simple messages around complex realities" Manzano et al. 2023.

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Literature focus of Part 4:

Thompson et al. 2023 Ecosystem management using livestock: embracing diversity and respecting ecological principles ?Animal Frontiers 13(2):28-34.?https://doi.org/10.1093/af/vfac094