There is one drawback to rotationally grazing our goats through a mix of pastures and woodland areas: a poisonous plant called White Snakeroot. This is medium-sized perennial herb native to eastern North America which prefers moist, shady areas. The plant contains a toxin called tremetol which can be passed through a dairy animal’s milk to cause a variety of serious health effects in nursing goat kids or humans, if consumed in sufficient quantities. During the 1800s, when grazing livestock in woodlands or newly cleared pastures was common, the resulting “milk fever” claimed many lives before its source was identified (many online resources repeat the claim that Snakeroot killed Abraham Lincoln’s mother). Pasteurization does not destroy the toxin.
A 1990 study, the most complete we’ve found, notes that Snakeroot has become almost forgotten as a livestock toxin due to changes in dairy agriculture. The steady decrease in pasturage (particularly in or along woodlands and marginal areas), and the concentration of larger numbers of animals and the mixing of milk from multiple farms, has mostly eliminated the ability of single animals to access enough Snakeroot to create danger. However, as the study also notes,
With resurgence of small-scale animal production, health concerns of the past are renewed…People should be informed of the potential danger of consumption of home-produced milk from cows with access to white snakeroot.
So that’s what we’re doing. We have Snakeroot on this farm, and in some of our pastures that are being reclaimed from encroaching brushy forests. We have been actively managing it since first starting dairy goats in 2008, primarily by walking all pasture paddocks prior to grazing goats to identify and pull visible Snakeroot. The plants are quite distinctive; as a perennial we feel they are best controlled by pulling the entire plant from the ground, thus removing the roots from which they can re-sprout, and disposing of the plants in an area where goats will not be grazed. We also put in an extra effort to remove plants during late summer when the plant begins to flower and set seed (it’s even more easily identifiable then due to its distinct white flowers). Over time, as we continue clearing and renovating our landscape to more open pasture, we’re seeing the Snakeroot population decline in managed areas as a response to hand weeding and because it seems to be out-competed by more sun-loving plants when the moist, shady habitats it prefers are altered.
Since 2008, we’ve seen no clinical signs of Snakeroot poisoning in the adult goats, nursing kids, or ourselves. It’s not a preferred food for the goats, though we’ve found Snakeroot plants that have been nibbled, as we do miss occasional plants when hand weeding. They seem more likely to eat it when a given pasture has been eaten well down (another reason to continually rotate their grazing areas). Leaving the kids on their mothers through the season conveniently acts as a form of early-warning system, as they will receive the highest dose of any potential toxins and show signs first. We’re comfortable with the success of our management methods for this plant, as we consume more of the milk than any off-farm customer, and also thus act as a regular safety filter for the product. However, we feel most comfortable having all consumers of our milk aware of this plant, with the option not to purchase the milk if they have concerns. This kind of openness and information-sharing is one of the core benefits of local food connections between farmers and consumers.