– Victor Shelton, Retired NRCS Agronomist/Grazing Specialist
Beware poisonous plants like perilla mint under droughty conditions.
As I write this in late September, the pastures, woodlands, cropland, yards, and gardens all appear to be settling into autumn earlier than normal. This is due primarily to prolonged dry conditions. As wet as it was earlier in the year, and with most area rainfall totals being about normal for the year, I still find myself about four inches behind on rain for the present time frame, but thankfully with rain in the forecast.
This has certainly been a good year to be a watchful grazer—but that is always a good thing! I still have both sheep and cows, and I often ask myself why. The answer is that sometimes a flerd is better. The cattle focus most of their grazing on grasses, legumes, a few random forbs, and some tree leaves within reach while the sheep most often prefer forbs and legumes over grasses.
Sheep are more selective about quality than cattle. Not to say that cattle can’t be selective, but sheep have the ability to choose individual leaves and plant pieces with their mouths, whereas cattle eat by wrapping their tongues around a good bite, tearing it off, and consuming whatever is in it. Cattle may try to consume specific plants or species they prefer, but they are more likely to take in a wider variety, especially if competing with another animal nearby.
Several years ago, I had lab work done on fecal samples collected from both cattle and sheep grazing together in the same field. If you were paying attention to their grazing and browsing, you would have quickly noticed that they were not consuming the same things. The manure samples were assessed using near-infrared (NIR) spectroscopy, a useful technique for analyzing ruminant fecal samples. It provides rapid and non-destructive assessments of the chemical composition of the samples and tests exactly what the livestock consumed—not what we thought they consumed. NIR spectroscopy can estimate the composition of fecal matter, including dry matter, crude protein, fiber and energy content.
Every time both cattle and sheep were evaluated while grazing the same field, the sheep consistently outgrazed the cattle in terms of quality. Such information can be advantageous for managing forages.
As conditions began to dry, I started getting more creative with grazing the flerd. Technically, it wasn’t a flerd—which is when a flock and herd are combined and grazed together— that was not the plan this time. The goal was to extend grazing as long as possible under dry conditions while maximizing recovery for grasses.
The cattle grazed first. The sheep followed, focusing on plants that the cattle either didn’t desire, preferred, or just missed. Sheep don’t mind leftovers and don’t complain and were moved prior to much grazing of grasses. At the same time, the sheep provide a service: besides grazing on desirable forbs (non-leguminous plants), they also browse on plants that I consider undesirable. As long as those plants are not toxic and have sufficient nutritional value, it’s a good thing!
The sheep can return to paddocks that haven’t fully recovered if there are enough desirable forbs available for grazing for a day or two. This puts extra pressure on those weeds, especially perennial weeds, gradually reducing their reserves. It might sound like the cows get the best and the sheep get the rest, but this strategy benefits both and actually allows for a longer recovery period for grasses in the paddocks before grazing them again, potentially eliminating the need for mowing or spraying.
That said, I must note that under dry conditions, especially when pastures are grazed closer than they should be, and desirable plants become scarce, you must keep an eye on the possible consumption of toxic plants. They may be green and readily available, and livestock are hungry. Try to avoid putting them in such conditions. It’s better to protect forage plants and livestock by pulling them off pasture and feeding hay.
The two main plants that come to mind right now are perilla mint and white snakeroot. Both thrive under dry conditions and are very toxic to livestock.
Perilla mint (Perilla frutescens) can be easily identified by its broad, oval-to-heart-shaped leaves with serrated edges, square stems, small tubular flowers in dense spikes (usually white or purple) and an extraordinarily strong minty aroma when crushed. It can often be found near wooded areas. Some people call this “woods mint.” You won’t forget the pungent minty smell this plant gives off; you may notice it when you’re just walking through it.
White snakeroot (Ageratina altissima) is toxic to livestock, particularly cattle and horses. It tends to grow near wooded areas, especially in normally damp conditions. I’ve been asked to examine a few sites this year where this plant was thought to be present. It is sometimes confused with similar-looking plants, especially late Eupatorium, better known as boneset. Both have white flowers in clusters that bloom in late summer and early fall and prefer similar growing conditions. Boneset leaves are tightly bound to the stem, almost wrapping, and merging on both sides of the adjacent leaf. It also has a fuzzy stem. In contrast, white snakeroot has petioles holding the leaves away from the stem, and its stem is smooth. While their flower features may be similar, they are easily distinguishable when presented side-by-side.
With the recent rains bringing moisture and new growth after a drought, there is a risk of grass tetany in the fall. It’s a good idea to ensure that you’re providing a mineral mix containing sufficient magnesium—ideally at least 10%. If possible, consider stockpiling this forage until it becomes dormant.
Remember, it is not about maximizing a grazing event but maximizing a grazing season! Be thankful for rain and keep on grazing!