Hoof Nutrition Intelligence is a twice-a-month web segment that is designed to add to the education of footcare professionals when it comes to effectively feeding the hoof. The goal of this web-exclusive feature is to zero in on specific areas of hoof nutrition and avoid broad-based articles that simply look at the overall equine feeding situation.
Below you will find Part 2 of the latest question and answer installment that you can share with your footcare clients.
Q: A recent Facebook recommended starting to graze horses when grasses reach a height of 6-8 inches and slowly initiating horses to spring pasture. What about horses that are in pasture 24-7? How do you manage these horses?
By Krishona Martinson, PhD
A: Our recommendations include a slow initiation to spring pasture and not waiting to start grazing until the grasses are 6-8 inches tall. This assumes you are in a northern location with distinct growing seasons, including a winter that results in the reliance on hay.
Following these management recommendations is best achieved with facilities that have a designated dry lot, which can reduce any risk for both the pasture and horses.
From a horse perspective, it’s much riskier to not have any transition period when changing diets. For example, horses being fed hay should be slowly transitioned to spring pasture to reduce the risk of colic and laminitis. This is regardless of current housing (whether a dry lot or dormant pasture). This transition helps the gut microbes adjust, which assist with digestion. Without an adjustment period, these specialized gut microbes can die off after a rapid diet switch, which can result in the release of toxins and possible bouts of laminitis and colic. This risk might be less for fit, healthy horses, but it’s thought to increase wit holder, overweight or horses with a history of colic or laminitis.
In addition, new pasture growth (less than 2 inches) is extremely high in nonstructural carbohydrates. This might not be an issue for fit, healthy horses, but it may be an issue for overweight horses or those with a history of laminitis. Utilizing a dry lot makes managing the transition from winter hay feeding to spring grazing much easier.
From a pasture perspective, continuous grazing will eventually lead to dead spots and weed invasion, especially if there are fewer than 2 acres of pasture per horse (this recommendation reflects generalized Midwest stocking rates). All pasture grasses and legumes need an essential amount of leaf area to intercept sunlight in order to support plant growth.
If the leaf area is constantly removed by grazing, the plant utilizes root reserve to support growth. However, root reserves will eventually become depleted, and when combined with no leaf growth due to overgrazing, the plants die and weeds invade. Allowing grasses to grow 6-8 inches tall in the spring allows the root reserves to stock up after the rapid spring growth. It also allows time for the nonstructural carbohydrates to level out and become more normal. The importance of leaves to intercept sunlight to support grass growth is also why we recommend that pastures never be grazed or mowed lower than a height of 3 inches.
Krishona Martinson is an equine extension specialist specializing in improving equine forage utilization at the University of Minnesota.
Click here to read part 2 of the June 3, 2021 installment of Hoof Nutrition Intelligence: What is the connection between selenium and a healthy hoof? Click here to read more installments of Hoof Nutrition Intelligence.