Feeding myths and misconceptions die hard. Among the most prevalent are those related to protein. Some that refuse to die are:
• Alfalfa can cause developmental problems in young horses because it is too high in protein. Not quite.
If alfalfa is causing problems with development, it’s not because of the protein. The level of protein in alfalfa is less than that in many high quality pastures. When people get into trouble with alfalfa, it’s because of the unbalanced mineral profile.
• High protein feeds can cause development problems in young horses. Right idea, wrong reason.
It’s not the protein you’re feeding. It’s the high calories. Forcing rapid growth, excessive weight gain, and wide swings in blood sugar related to sporadic feeding of large meals, which in turn causes hormonal swings, are the culprits here.
• High protein damages the kidneys. Correct observation, wrong conclusion.
This misconception may have its roots in the observation that horses fed high levels of protein urinate more. The liver and kidneys process the wastes of protein metabolism. That’s their job. Excessive protein keeps them busy, but does not harm them.
• Adult horses need 10% protein feeds. Not even close.
The horse’s protein needs are related to its bodyweight and level of activity, and are in grams per day, not a percentage of the diet. The appropriate protein level in a grain depends entirely on how much is already present in the hay or pasture, and how much of both the horse is eating.
An 1,100-lb. horse in light work needs 820 grams of protein a day. If the horse is getting at least 18 pounds of a 10% protein hay as his base diet, he’s getting all the protein he needs from that source. If it’s an 8% protein hay, he’ll need 22 lbs./day of it to get his protein, still well within the limits of commonly fed amounts of hay.
If he’s only getting 15 lbs. of 10% protein hay a day, he’ll be short 138 grams, which he can make up with either 3 lbs. of a 10% protein grain mix, or with 1 lb. of a 30% protein-level protein/mineral supplement.
Your horse’s major source of protein and nutrients is his hay. The level of protein the horse needs in a grain mix, if any, depends on how much he is getting from his hay, his size and his level of work.
Some extra from the grain isn’t harmful, and mixed grain/hay diets show better digestibility of protein, but don’t be fooled into thinking the horse necessarily ”needs” a certain protein percentage in his grain. Most good quality hays easily meet the protein requirements without additional protein from grains, and he probably doesn’t need the extra calories either.