Updated: Nov 17, 2021
*The use of slow feeders has exploded in recent years due to increasing rates of obesity, rising risk of laminitis, and greater awareness of gastric ulcers. However, these tools (like all tools) can be misused.
With equine obesity rates and laminitis awareness rising in recent decades, the use of the slow feeder apparatus has exploded! Nearly every horse store (online or brick-n-mortor) sells a shocking variety of devices designed to increase the amount of time your horse spends chewing roughage, salivating, and buffering the stomach. For owners with horses at risk for laminitis, this is a blessing as the number of tools and resources available for such "easy keepers" has historically been bleak! However, with time and experience using such tools, we've learned that there are inherent dangers as well as advantages. Like most things, there are trade offs. This article brings to light six unique dangers of slow feeder devices and considers their alternatives.
1. Forage Match VS Mismatch:
I'm going to start with the not-so-obvious danger of slow feeders. It's a phenomenon that I've noticed occurring with more and more frequency; horse owners applying slow feeders when they shouldn't! You see, it's VERY important to realize WHY we are using a slow feeder before we purchase one. Slow feeders are necessary when your horse's forage does not MATCH their caloric need. Let me explain by starting with two examples.
a) A barn full of performance horses are eating alfalfa hay out of slow feed hay nets. The trainer was very proud of the homemade slow feed hay nets that had been hung from every stall. They had designed such feeders to be easily filled with several day's worth of forage, and were very happy with how clean they made the stalls. However, the same trainer was concerned with the high cost of their monthly feed store bill. The use of these slow feeders was the root of this barns feed problem! The alfalfa hay flakes were very tightly packed, so when they loaded the long, skinny hay nets with these flakes, the horses were having to work too hard to pull any hay out. The horses were losing weight fast and the barn was spending a lot of money on grain trying to keep the horses show ready. The root of the problem was not the forage or the feed, but the misapplication of the slow feeders. The horses simply were not eating enough hay on a daily basis to meet their caloric needs. I immediately called up the trainer and suggested they remove the slow feeders so that the horses could eat MORE of the appropriately matched forage.
b) A new client asked what slow feed hay net I suggested for her horse that didn't like the stemmy, mature hay being offered. In this scenario, the forage being provided to the overweight gelding in moderate work already matched the horse's caloric needs. Therefore, there was NO reason to use a slow feeder! This was especially true since the horse didn't really like the forage anyway. Introducing a slow feeder device would only further lower the horse's daily dry matter consumption, create nutrient deficiency and negative behaviors.
This hay sample appears mature (implying low calorie) and likely has low palatability. A slow feeder hay net is likely not needed in this situation, even for an obese horse, if the caloric density matches the caloric need.
It's so important that I'm going to say it again... the ideal hay for your horse should first and foremost match their caloric need. Skinny horses should eat high calorie hay, and fat horses should eat low calorie hay. This seems obvious, but without a forage analysis or nutritionist we can not know for sure. Slow feeders are great tools to limit daily dry matter/calorie intake when the primary forage does NOT match the horse's need. When the forage being provided is too high calorie for the horses' needs and we must limit intake, we can use slow feeders to decrease daily calorie intake while also increasing time chewing. This facilitates better mental health, mitigates the ulcer risk, and lowers hormone response to meals.
2. Metal Grates:
It is fairly well documented and communicated that metal grates CAN be detrimental to your horse's dental health. The metal grates wear heavily on the horse's hypsodont teeth creating uneven grinding surfaces and damage to the incisors. When slow feeders are used regularly, I do not recommend metal. I have also found from personal experience that the grates are not made with holes small enough to significantly increase chewing time. Holes that are over 1.5 inches square typically do not change the amount of time your horse spends chewing hay, so they aren't very effective anyway.
3. Getting a Shoe Caught:
Yes, slow feed hay nets that are hung too low without a safety release can be dangerous for shod horses. Most slow feed hay nets are made from very strong, unbreakable cording, so this is an important design consideration for horses that paw with shoes. There are a few options to mitigate this;
a) hang the slow feed hay net so that the lowest part of the net (when empty of hay) does not drop below the point of your horse's shoulder
b) put the slow feed hay net into another bin such as an old water trough or feeder
c) always tie the hay net to a breakable piece such as a loop of baling twine or string
4. Feeding Too High:
Feeding hay nets too high can lead to poor respiratory health. For horses with allergies or other respiratory problems, I highly suggest providing hay as low to the ground as possible. This is especially true if/when the hay is dusty. Placing slow feed devices where the horse must drop their hay to forage will help facilitate drainage from the nasal passages and lower the risk of respiratory infection.
5. Insecure Haynets:
There are reports of poorly hung hay nets leading to neck and poll soreness. Hay nets that are not properly secured can cause extreme frustration and even spinal misalignment in horses that have to twist their necks to eat from the slow feeder. I particularly cringe from hay nets hung freely from a single point. The lack of security makes it extra difficult for horses to consume hay from the net. Now, let me be clear that this has not been scientifically proven and is totally anecdotal at this point, but from experience I recommend securing hay nets from two points or at least along a wall. If you notice new negative riding behaviors soon after starting hay net use, consider changing the location and security of your slow feeder.
6. Holes are Not Small Enough:
The green hay net above is 1"x1", the blue hay net in the middle is 1.5"x1.5", and the black hay net on the right is 2.5"x2.5". They are all marketed as slow feeders.
If the holes of the slow feeder are not small enough, they will not significantly increase the amount of time your horse spends chewing their hay. Many years ago, I ran a slow feeder experiment with my own horses. I used three different "slow feeder" styles with various hole sizes and used "no slow feeder" as the control. I rotated each slow feeder style amongst each of the four horses (a proper randomized control study) and timed how long it took them to eat a 4 pound flake of hay. One of my greatest take-aways from this experiment was how small the holes had to be in order to actually length time eating! The size of the mesh holes will vary a lot between products- anywhere from 0.75 inch square holes to 2.5 inch holes. If you actually want to slow your horse down and not just make the stall tidier, I would suggest that holes be 1.25 inches or less.
Now, with all of this negativity about hay nets being stated above, I want to reconfirm the usefulness of the slow feeder device. Obesity leading to laminitis risk is a very serious problem, and slow feeders are great management tools for horses in this category. Your horse's body condition score and mental health should take priority over the dangers listed in this article. However, it is also important to be aware of the risks and try to mitigate them. It is also important to look past their popularity and consider if you even need one! Remember, slow feeders are most appropriate when the forage does not match the horse's caloric requirement. For example- when the only hay available is greater in caloric density than your horse needs at 1.5-2% of body weight (15-20 lbs of hay per day for 1,000 lb horse). Slow feed devices are great ways to lower the total amount of hay given to the horse while increasing consumption hours.
You can check out slow feeders that I recommend on OCEN's RECOMMENDED PRODUCTS page. CLICK HERE.