Question
I have had two off-the-track Thoroughbreds, both high-strung with sensitive digestive systems, develop soft manure during the winter when pasture was scarce and large quantities of hay fed. When pastures came back, the soft manure went away. I am told that this second-cut orchardgrass hay isn't preserved, but it acts like preserved hays I’ve fed in the past, staying bright green and in great shape compared to what happens to unpreserved hays during our humid summers. Can I test a hay for preservatives? I am suspicious of this nice-looking hay not providing the nutrients needed. In my experience, hay is used to help firm manure. Your thoughts?
Answer
What you have experienced with these horses is the opposite of what normally happens with the transition from pasture to hay because of the differences in water content in the two types of forage (pasture grasses are typically about 80% water, while hay is approximately 10% water). Temporary loosening of manure sometimes occurs when changing from grass to hay or changing types of hay. As the digestive system adjusts to the change, manure consistency should improve. If a horse continues to have loose manure after feeding the hay for a couple weeks, then there is something either not quite right with the horse or the hay.
Here are some possibilities specific to the horse:
1. Horses that dunk their hay (dip their hay in their water bucket before chewing it) or ones that consume more water than usual when consuming hay may have looser manure than other horses because of the high amounts of water they are consuming.
2. Horses that have an issue with absorption of water from the dorsal colon or rectum will consistently have wetter manure than normal. This does not appear to be your horse’s problem because the manure returns to normal when on pasture.
3. Food allergies can cause digestion problems. Have you tried feeding a different type of hay?
4. Horses that don’t chew hay well, such as senior horses with tooth loss, can occasionally have looser manure because the presence of coarse fiber in the gut can stimulate the thirst response, causing the horse to drink more water than normal.
5. Damage to the digestive tract from parasites can affect normal bowel function. Years of eating a low-fiber, high-starch diet, as many racehorses are fed, can cause some damage to the digestive tract. Fortunately, time usually repairs this type of damage. I would also expect that this damage would affect the horse year-round and not just when being fed hay.
The problem could be with the hay:
1. Improper or excessive use of preservatives in the harvesting and drying of hay can affect the balance of the microbiota in the hindgut. Excess propionic acid, the preservative customarily used for conserving forages, may be responsible for this microbiota upset.
2. Mycotoxin or mold contamination of hay may cause damage to the lining of the digestive tract and possibly influence fluid absorption.
Whether it is the horse or the hay, my first suggestion would be to source a different type of hay from another supplier to see if the horse experiences the same problems.
If it turns out to be a problem with the balance of the microbiota in the hindgut, you may want to consider EquiShure, which can help bring the pH in the hindgut to a level for healthy microbial balance.
