# Cracking the Code on Grazing Management Terminology: Animal Units, AUMs, & How to Apply Them

Does it feel like grazing management information is shrouded in acronyms and terms that boggle the mind on first glance? Do you struggle to decipher terms like animal unit equivalents? And how does one go about calculating AUMs and then applying those numbers? Be reassured, you’re not alone! There’s a lot going on when sorting through the finer points of grazing management and figuring out how to work through the many calculations.

A good starting point is defining a grazing animal in terms of how much forage it requires to meet its nutritional demands. We know that grazing animals’ forage needs differ depending on class, weight, age and stage of production. And in order to account for those differences, it’s helpful to create a baseline in order to quantify forage demand. Continue reading

# Two Methods, Four Steps for Calculating Carrying Capacity

Carrying capacity, also known as grazing capacity, is the amount of forage available for grazing animals in a specific pasture or field. Calculating the correct carrying capacity will help you determine a proper stocking rate that maintains productivity of both your animals and forage while encouraging the sustained health of the grassland resources.

 Stocking rate is the number of animals on a pasture for a specified time period and is usually expressed in Animal Unit Months (AUMs) per unit area.

One way to determine carrying capacity is to obtain past stocking rates and grazing management information and assess the condition of the pasture. But what if the historical stocking rate data is not available or you are unsure of its accuracy and reliability?

Carrying capacity can be calculated using several different techniques. All of them depend on some trial and error as they are monitored and adjusted over time. When calculating carrying capacity, it boils down to three questions:

1. How much forage is available?
2. How much of that forage can be used by grazing animals?
3. How many animals can graze on that piece of land and for how long?

The BCRC Carrying Capacity Calculator provides a road map for answering these questions using two separate methods: 1) forage estimates based on provincial guides and 2) field-based sampling, also known as the clip and weigh method. Each method contains four steps. Continue reading

# How Mother Nature Hedges Her Bets

This article written by Dr. Reynold Bergen, BCRC Science Director, originally appeared in the May 2021 issue of Canadian Cattlemen magazine and is reprinted on the BCRC Blog with permission of the publisher.

Pasture plants are generally classified as decreasers, increasers and invaders. Decreaser species are the plants you want to see and your cattle prefer to eat, so they face the most grazing pressure. Increaser plants tend to thrive when the decreaser species are challenged by overgrazing, drought or other sub-optimal conditions. Invaders (weeds) proliferate when increasers and the remaining decreasers are so weakened by overgrazing or environmental extremes that they have a hard time competing for nutrients, water and sunlight.

Healthy, productive pastures are dominated by decreasers. The composition of the decreaser community in healthy native rangelands was shaped by thousands of years of natural selection and environmental pressures. In tame pastures, humans take the wheel from Mother Nature as we seek to establish and maintain a stand of tame decreaser species that can be productive and long-lived in our particular soil and climate conditions. In both native and tame pastures, good grazing managers adjust stocking densities, grazing intensities, grazing and rest period length and frequency, etc. based on annual and seasonal variations in growing conditions to maintain pasture health and optimize long-term forage and animal productivity. Continue reading

# Carrying or Grazing Capacity

Are you managing a new-to-you pasture and you need to determine how to stock it? Perhaps it has been recently purchased or rented, or you simply don’t trust the information provided on historical stocking rates.

The first principle of pasture management is to balance the available forage supply with livestock demand. Carrying capacity (also known as grazing capacity) is the amount of forage available for grazing animals in a specific pasture or field. A substantial amount of Canada’s rangeland is in some form of public ownership (e.g. grazing leases, forest grazing allotments) and has carrying capacity data available. With privately owned or recently acquired land however, there may not be any information on historical forage production and carrying capacity.

 Carrying Capacity is defined as the average number of livestock and/or wildlife that may be sustained on a pasture that fits the management goals. Site characteristics, such as soil, water, plant, and topography of the pasture, can impact carrying capacity. Forage production and availability for grazing can also affect carrying capacity. Source: Society for Range Management, 1998.

Carrying capacity can be calculated using a variety of techniques. All of them depend more or less on trial and error as they are monitored and adjusted over time as the carrying capacity for an individual year varies from the long-term average for the pasture. The effectiveness of each method depends on the kind of grazing land, but a combination of methods is generally required. Continue reading

# Plan to Adapt When Grazing

Adaptive grazing herd management applies to grazing practices that are developed with careful consideration to the specific conditions that exist on individual farms and ranches. When it comes to adaptive grazing management, it’s all about using the resources you have available and incorporating different techniques depending on where you live, says rancher and consultant Sean McGrath. McGrath spoke about the value of being flexible but also the importance of making a plan and measuring success, during a BCRC webinar last winter.

Managing the movement of cattle through pastures or paddocks will help producers achieve energy efficiency. “Plants are solar panels and to make them efficient, we need to make sure there are solar panels there to start with,” McGrath said. He pointed out that it is much cheaper for cattle to graze than it is to manually feed them and understanding the key principles of grazing management is vital for adaptive management (skip ahead to 15:05).

Producers should manage herd movement to prevent overgrazing, which is defined as a plant being grazed before it has recovered from the previous grazing event. “We would never cut a hay field on the first of June and come back and hay it on June 10. A pasture is no different,” McGrath reasoned.

# Alfalfa is nothing to fear with simple, proper management

Editor’s note: The following is part 2 of two-part series. See part 1.

Photo supplied by Ryan Boyd

The secret — if it is a secret — to pasturing cattle on alfalfa is to follow a few simple management steps to reduce the risk of bloat, say producers from across the country, who for years claim good success by including the forage legume in pasture mixes.

Straight alfalfa stands can be managed quite well, but most producers today are favouring alfalfa/grass forage blends. They are very productive, produce excellent rates of gain on cattle, help to reduce the bloat risk, and also provide important biodiversity. Biodiversity benefits the cattle in providing a range of crops that mature at different times and can handle varying growing conditions, as well as biodiversity to benefit soil health.

The main “not to do” message is don’t turn somewhat hungry cattle into a pre-bloom high percentage stand of alfalfa and leave them to selectively graze the lush leaves. If there is a heavy dew or rain as well, it creates a perfect storm for bloat.

The key “to do” messages include making sure cattle move onto alfalfa pastures with a full gut and the forage stand is dry. Introduce them to lusher forage gradually by limiting the amount of area they have access to in a day, and force them to eat the whole plant including stems and not just leaves. Other “to do” strategies that some producers use — supply a bloat-control agent in cattle drinking water, make some dry hay available as well, as the fibre in hay reduces the risk of gas build up in the rumen, and include low-bloat forage legumes such as sainfoin in the pasture mix.

It is important to apply some basic management principles to capitalize on the benefits of having alfalfa in a grazing program. As grazing research summarized in Part 1 has confirmed over the years, not including alfalfa in pasture mixes can be like leaving money on the table.

Here is what producers from across the country had to say about how alfalfa is managed in their grazing programs: Continue reading