It is no wonder these guys are asking to be let out onto the lush spring grass after such a long and trying winter. What horse owner could resist those molten brown eyes and soft whisper-nickers, as if saying ‘Let me out, I’ll be good…I promise!’
We work hard and do our best to provide our horses what they need; pasture seems all too natural to resist. It’s only when you understand the unique nutritional properties of early spring forage, that you can feel better about saying ‘not yet’!
If your horse survived the winter on hay, a hasty introduction to ‘rich’ spring grass can cause a shock to his digestive system. If at all possible, keep your horse off grass during the initial growth period by designating a ‘sacrifice’ area or dry lot. The size of the dry lot will depend on your available land, but generally should be large enough to allow your horse to move about freely and stretch his legs. The sacrifice area serves to protect your emerging pasture as well as allowing you an opportunity to ease your horse’s digestive tract onto new-growth grass. If he is kept in a dry lot during this time, you may consider hand walking, lunging or additional work sessions to keep him from becoming too fresh.
So what is different about spring grass that we should heed warning? As the strong spring sun warms the earth, the grass in your pasture emerges from its winter dormant state. The first few blades have a critical job of transforming sunlight into food, a process called photosynthesis, that starts the growth of the plant for the rest of the season. This food is in the form of plant sugar (fructans) and is essential for the plant to grow into a productive pasture contributor for the remainder of the season.
When overnight temperatures are cool (generally 40 degrees F) the stored energy created during the day is used to grow additional leaves and roots. Extra food not utilized overnight is stored in the plant tissues. If overnight temperatures drop below 40 degrees F, the plant will not invest in growth and the sugars will remain in the leaves. This is when the new grass is of concern for horses.
Therefore, it stands to reason that when overnight temperatures remain above 40 degrees F, it is the ideal time to start acclimating your horse to the fresh spring grass, because the level of fructans in the grass are likely to be the lowest.
The transition to pasture should be slow and gradual, starting with a period of 15-20 minutes of grazing. Gradually increase until you have reached your ideal turnout length of time; this may take the better part of a month. During this time, it is important to monitor the output of your horse; loose, unformed stools indicate digestive upset likely correlated to the increased fructans. For horses with metabolic issues prone to digestive upsets, transitions should made later in the growing cycle onto mature grasses. In addition to restricting time on pasture, a grazing muzzle can be used to further control intake.
I probably don’t need to tell you that a pasture full of healthy, green growing grass not only looks wonderful, it is an investment in your horse’s nutrition. Allowing the early grass to grow and flourish, then gradually transitioning to grazing is an investment in your overall nutrition program. Armed with this information, don’t you feel better telling him to wait?