Calculating Hay Needs and Slow Feeder

A great online resource for a variety of slow feeders is the Paddock Paradise website. Thinking over the options, I’ve decided to go with some small hay net bags for my slow feeders. That way I can fill up the bags and set them aside, hanging them up when needed without causing a lot of delay time in the morning when hubby needs to leave to work yet horses, cats and dogs are demanding their breakfast RIGHT NOW!!

I’ll hang them off the back pipe fencing that is easy to access from the barn and house but is placed so Z and pony have to walk all the way around the barn to get water and then get back to the hay. This gives them some exercise especially as the land is sloped.

Because I don’t have a tractor and the front of the property is rather small, it will be easier for me to use square bales as opposed to round bales. I’ll buy a small portion this month to get me through the summer, and plan on buying a 6 month supply by September.

To roughly calculate hay you need to know how much your horse eats, what type he is eating, and what is his metabolism. That may sound self evident, but let me explain. Don’t worry it’s not as complicated as people want you to think.

Does your horse have access to pasture that has grass in it? If forage is provided, hay needs go down. If not, i.e. drylotted horses, hay needs go up. That is why crowding horses does not save barn owners money in the long run.

What is the growing and dormant season for your grass? During winter, when grass is dormant, hay needs increase. With this you must be careful… for example, by August, grass pastures here are usually burned from intense heat and overgrazed by the end of the summer. If so, you would need to start increasing hay then and not wait til snow hits the ground.

What is the weight of your square bales? A square bale differs greatly in size and weight. Be aware that a square bale could be anywhere from 10 to 20 lbs in weight. And it’s weight, not size, that matters.

Type of hay available really depends on your part of the country. Around here, folks will commonly state, “It’s grass hay.” Well DUH! Hay is grass, what TYPE of grass? Generally, you get a blank stare in response. Over the years, I’ve finally figured out that grass hay (in my area) simply means prairie grass that may or may not be mixed with Bermuda.

The type of grass is only important IMO in terms of discovering the calcium-phosphorus ratio as this is important in keeping your horse well. Some trainers, with horses in intense training, are more concerned about protein levels.

Your local extension agent will send off an analysis of your hay (stuffed into a plastic baggie they give you) or you can do it online through a service like Uckele. Here’s the rub though — if you board, you will need to sneak around to get samples. Barn owners (for some ungodly reason) get their panties in a wad if you test their hay.

If the barn is buying from different suppliers, your sampling will only give an average of what to expect in your area.  Sampling pays off best when you buy from the same supplier or routinely buy hay from the same geographical area. Be aware that geography may mean minerals in the soil are the same, but fertilizing or not fertilizing could effect protein, as well as when the hay was cut effects sugar levels – first cut vs. second, morning vs. evening.

Next what is your horses’ metabolism? Here are three, very different examples:

The Big Guy – 16.2 TB, senior horse (approx. 1200 lbs) with a moderate metabolism of processing food does better when he has alot of forage, and is supplemented with a senior feed that has additional fat. He’s a bit of a hayburner but not as much as a draft or Warmblood would be.

The 14.2 Appaloosa-Arabian filly at about 4 years of age, ZZ, (approx 800 lbs) eats far less forage and can get by with a carb control feed for easy keepers.

The 40″ mini-pony, over age 20, Pandora (350 lbs), needs the very bare minimum in forage and feed given only to provide supplements for her arthritis and to prevent founder. Metabolically challenged, insulin resistant possibility.

Age (such as a foal, growing horse),  pregnancy, illness, bringing back a starved horse, etc.. can also impact what you feed and how much.

Winter Stress increases hay needs dramatically. I’ve noticed that when a winter storm hits, all the horses consume hay at a greater rate. This is the same for stabled vs. pastured horses and IMO is due to the horses’ need to produce additional body heat (this is true even for blanketed horses) and the lack of the horses’ ability to move about to forage (i.e. when snow drifts or ice prevents a horse from foraging on their own).

For example, where two horses might take a week to work their way through a round bale during dry, cold, but moderate temps, during a winter storm of freezing rain and deep snow, they may demolish that same round bale in two days.

Having something constantly in front of horses when the weather changes is smart! It prevents colic and it’s why I prefer to use a combination of round bales with square bales during these winter stress times. In other seasons and weather conditions, I prefer square for feeding.


Generally,  figure about 1 pound of hay per day for every 100 pounds body weight of the horse for an easy keeper kept in average, pleasure work. This number would fluctuate depending on the amount of work the horse is doing, body condition, age, body metabolism, if bred, illness, quality of the hay being fed, and season.

For my area, I would guesstimate a year (52 weeks) at: 20 weeks of summer,  18 weeks for the transitional between-season time, and 14 weeks of winter. I know this just from years of living in this area; while Missouri might be slighly different, given a week or two fluctuation, I don’t expect it to be greatly different from here – as say if I had moved to Vermont!

Figuring a summer hay need for ZZ and Pandora (combined weight 1150 pounds) at 1 pound of hay per 100 pounds of horse weight = 11.5 pounds per day, 80.5 per week, and for 20 weeks = 1610 pounds. If 1 square bales weighs 16 pounds; 1610 divided by 16 = 100 square bales.

Transistional growing and dormant months (18 weeks) calculated 1.5 pound of hay per day for every 100 pounds of body weight = 120 pounds of hay x 18 weeks = 2174 pounds divided 16 (weight of bale) = 135 square bales.

For winter, calculated at 2 pounds of hay per 100 pounds of body weight = 160 pounds per week x 14 weeks = 2240 pounds of hay. 2240 divided 16 (weight of bale) = 140 square bales

For a year, these horses (both easy keepers in light to moderate work), with some pasture access and additional graining, would need approximately 375 square bales for the year. 375 x $6 per bale (average cost, not counting the financial spike due to winter or drought) = $2250 per year.

I could bring down that number by increasing pasture, using slow feeder methods (which keep the horse eating but at a slower pace and decreases waste), combining with round bale purchases, and buying at the best time of the year (mid summer, or pre-paying a regular supplier sometimes gets you a better deal). Another way to decrease the cost in buying hay is to buy it right out of the field, where the price runs $2-$3 per bale cheaper because you are loading it yourself.


Okay so don’t get all worked up. The only thing you really need is a tape measure to determine your horses’ weight and a pair of eyes! If you find your horse losing weight and there aren’t medical issues to account for it, then increase hay. If the horse is gaining weight, decrease grain first, and put the hay in a slow feeder.

If you board your horse, it is a smart move to tape your horse every 4-6-8 weeks to insure he/she is maintaining weight.  Weight on a horse is easy to lose – stress alone will make them drop pounds. Yet putting weight back on can be very hard if not almost impossible, especially if your horse is a senior, has illness issues, or has a nervous and high strung metabolism.

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1 Response to Calculating Hay Needs and Slow Feeder

  1. Pingback: Update: Hay in Missouri « Horse Ideology

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