Calculating Hay Needs

It’s that time of year, haying season is in full swing with the second cut underway across most of Ontario and Quebec. If you are in the parts of eastern Canada that are in a drought (which is basically 80% of the entire region east of Manitoba), you’ve probably been eyeing up your hay stockpiles. Looking at the current yields, the stress is climbing (if it’s not and you have livestock, consider yourself lucky).

Haying season and going back to work in an office are partially why it’s been crickets here at The Farming Frontiers. Almost all of my energy has gone towards finding hay and then finding ways to pay for hay. We’re definitely being impacted by the drought which I’ll have a post on soon. The first step in finding hay is figuring out how much you need. Fortunately, there is a whole country that has droughts so frequently, they have very detailed calculators on how to figure out feed requirements. Numerous Australian resources exist on meeting forage needs in a drought situation if you’re looking for more information that put I’ve put together here.

Basis for calculation

Everything in these calculations is done on a dry matter (DM) basis because no two fields of hay will have exactly the same values. This why it is very important that you get a hay analysis done on your hay so that you can optimize your feed rations and have values to track. You can use ballpark values to make an estimate but without an analysis you are guessing at best. For the purposes of all of the calculations used in this post, we are going to assume you are buying dry hay with a DM of 85%. Most of the dry hay I’ve seen has DM values ranging from 88% to 78%. You want to use the DM value for your calculation because silage bales are going to have a much higher per bale weight but the actually quantity of feed is going to be lower as there is a lot of water in silage (also called haylage, baleage).

Next, you need the dry matter intake requirement for your livestock. This is where a ration program is handy as you can figure out the exact needs per stage of production of your animals. There are several different free or paid options out there for ration programs (Montana State has one for sheep). I’ve put together a shortlist of the daily dry matter intake for various livestock for you to use if you don’t have a ration yet.

  • Sheep: 2-4% of bodyweight
  • Beef cattle: 1-3% of bodyweight
  • Goats: 3-5% of bodyweight
  • Horses: 1.5-2% of bodyweight

All of the calculations will be in imperial pounds because hay typically sells by the pound. At the time of writing, hay varied from 10 cents to 18 cents per pound. If you need to convert kilograms to pounds, multiple the kilograms by 2.205 (welcome to Canada where we use imperial and metric and remember a ton and a tonne are not the same!).

Wasted feed

If you do not already, keep track of how many bales you use in a year. This can be valuable information as you can then determine if your required hay calculation makes sense. It also helps to determine how much waste you have. Your calculations are going to need to include a percentage wasted, whether this is hay that as gone bad from insufficient storage or the animals trampled it.

Silage bales will traditionally have more waste as the smallest tears can cause significant spoilage. Different storage techniques will have different spoilage risks. Individually wrapped bales have the lowest risk factor but are also the most expensive. Bunk silos and ag bags typically work best for larger operations as you need to be able to feed at least a foot per day to keep the bag or bunk face fresh. Tube-wrapped bales work well and are cost effective but when there is a hole, odds are more than one bale will be impacted by spoilage.

Different feeding systems will also have waste factors. If you are going to be short on hay, limit feed the hay and do not just throw an entire round bale at the animals. All feed systems have some waste but some more than others. If the animals have the ability to pull feed back, you can easily be looking at a 30% waste of hay. Fenceline feeders that limit the ability for the animals to pull in feed and control how much they have access to will have much lower waste, around 3-10%. Most well-designed bale feeders have around 10-15% of waste. Some methods, like bale grazing, have calculated the return on the wasted feed for later nutrients in the soil but regardless, your hay needs calculation should include a waste and spoilage factor.


You also want to keep track of how many days you will be needing to feed hay. If you are grazing, this can vary year to year so you want to keep a buffer of days calculated. In the example, we are going to do a calculation to feed sheep from June 30th of one year to June 30th of the next year (365 days). If you are feeding silage, keep in mind that those bales need to stay wrapped for 3-5 weeks minimum before you can open them. So even if you are cutting hay the first week of June, your feed stockpile has to last into July. Having to look for hay in late May is not fun at all (been there, done that).

Following hay prices will also help you determine how much you should have on hand. Whenever possible, having extra hay on hand is never a bad thing as droughts are being more likely each decade. Normally you should aim to have all of your hay purchased before the end of September (depending on where you live, the end of the last cut). You want to avoid having to buy have between January and June as prices during those times rely a lot on the prior year’s supply. In short, buy and produce as much as you can during hay-making season.

Final Calculation

To make the final calculation you need:

  1. Daily dry matter intake requirement of your livestock (sheep, 3%)
  2. Average weight of your animal (sheep, 135lbs)
  3. Number of days you need hay for (365 days)
  4. Number of animals you intend to feed (100 sheep)
  5. Dry matter value of the hay you plan to use (85%)
  6. Waste and spoilage factor for your system (15%)

Once you have this information together, follow these steps:

  1. Daily DM intake x average weight x days on hay = DM hay needed per animal (in pounds or kilograms)
  2. DM hay requirement x number of animals = total hay needs on a dry matter basis
  3. Convert to the actual amount by taking total hay divided by DM value of hay
  4. Increase the amount by multiplying the actual amount by 1 plus the waste factor

Example using values listed above:

  1. DM hay requirement 3% x 135lbs x 365 days = 1,478lbs
  2. DM total hay requirement 1,478lbs x 100 sheep = 147,800lbs
  3. Actual hay needed 147,800lbs divided by 85% = 173,882lbs
  4. Total hay needed including potential waste = 173,882lbs x 1.15 = 199,965lbs

You can also break down your need by production stage for each animal based on your feed ration. This will give you a more precise number. Not all hay is equal so the more detailed you can get, the easier it is the control your purchasing decisions. If a seller of hay can not provide the weight of the bales or a hay analysis, proceed with caution.

Once you have the number of pounds of hay you need, you can convert that to a per bale number. Using the above example requirement, here is what that might look like:

  • 4×5 large round bales, estimated to be 850lbs each, you would need 235 bales
  • large square bales, estimated to be 1200lbs, you would need 166 bales
  • 4×4 smaller round bales, estimated to be 500lbs, you would need 399 bales

Other Considerations

The more detailed your calculation can be, the better. As you can see from the above example, the main factors impacting your buying decisions are the daily DM requirement per animal and the waste. Using rations and improving your feeding system to reduce waste will help you control how much hay you need.

When looking at hay to buy, a hay analysis and a weight per bale or simply buying by the pound will help reduce the guesswork. The hay analysis will have several values on it. Some key ones to consider:

  • Total digestible nutrients (TDN) – higher is better, straw is around 39%, look for hay over 50%
  • Crude Protein (CP) – higher is better, for comparison, straw is around 5%, look for hay over 10% unless the price reflects the lower quality. Dairy quality usually means a CP over 18%. Check the nutritional needs of your livestock to know what you need in terms of protein as it is the most expensive ingredient to replace.
  • Relative feed value (RFV) – higher is better, look for hay with a value over 90, alfalfa can easily get 130 or more while late cut grass poor quality hay will be around 60.
  • Relative forage quality (RFQ) – higher is better, straw is around 45, minimum for decent hay should be 100, lactating animals should have around 140-160.

Different stages of production have different needs which means you can try to source hay at different levels using hay analysis and rations to optimize your spending. This paper from South Dakota State University has a decent explanation of looking at hay using RFV and RFQ when making purchasing decisions.

I hope this helps you determine how much hay you will need going into winter.

Leave a Reply

Your email address will not be published. Required fields are marked *

About the author

I'm Ursina, a farmer's daughter who dreamed of one day owning her own farm and made it a reality. I love reading, big sweaters and trail riding across my farm with my horse. My mission? To help others turn their farm dreams into a reality and build their own farm business.

Agriculture Annotated

For Canadian Farmers • By A Canadian Farmer


Subscribe on Substack, never miss Studio updates!


Follow the adventures.