How much hay should you feed a cow?

Answer 1

There are a lot of factors to consider before this question can be answered. Such factors include the type of hay which is fed, its nutrient quality, moisture content, anti-quality factors such as presence of mold, as well as the weight, age, breed, class, type and gender of the cow or "cow" in question. What also matters is if you are feeding another feedstuff along with the hay or not, how much of that feedstuff is being fed to that cow per day or per feeding, whether you wish to allow it to be fed to them ad libitum (free choice) or limit-fed, and how much wastage to expect.

As a general rule of thumb, you must expect the average bovine to consume between 1.8 to 2% of their body weight in dry matter ration per day if the hay is of average quality. Let's assume we have a 1000 lb dry cow that consumes 2.0% of her body weight in dry matter (DM: all [100%] moisture from the feed is removed) per day. So for this cow, that means she consumes 1000 lbs x 0.02 = 20 lbs of DM feed, regardless of type, per day. If the hay is 20% moisture (80% DM), the amount of feed to give to that 1000 lb cow would be 20 lbs DM ration ÷ 80% DM = 25 lbs per day. That translates to (25 lbs / 1000 lbs) x 100 = 2.5% of a cow's body weight in an as-fed ration, given the hay is 20% moisture. So, if a 1000 lb cow will eat 25 lbs of hay per day as-fed, then a 1250 lb cow will consume 1250 x 0.025 = 31.25 lbs of hay per day as-fed. Or, a 1500 lb cow will consume 37.5 lbs of hay per day as-fed. A weaner steer weighing 600 lbs will consume only 15 lbs of this medium-quality hay per day as-fed, which is half of what a 1200 lb mature cow will eat.

If the hay is of higher quality, you must expect your cows to eat more: a rule of thumb to expect is between 2.5% to 3.0% of their body weight in DM ration per day. The lower the quality, the less they will eat as a percent of their body weight. Lactating cows will eat more than dry cows, and mature cows and bulls will eat more than young or growing cattle. However, forage intake as percent of body weight remains the same between growing/finishing cattle and lactating/suckler cows on excellent quality feed (which is 2.5% to 3.0% of body weight in DM ration)

So, if you have a herd of 1250 lb cows (as an average herd weight, not as an actual weight per cow) and are wondering how much hay (average-quality hay that is 20% moisture, as from above) you will need per month per cow as an average guesstimate, then the math dictates, from above, that you will need 31.25 lb/day/cow x 30.5 days/month = 953.125 lbs of hay per cow. For a 6 month winter period, that means 31.25 lb/day/cow x 183 days = 5,718.75 lbs of hay per cow, or 2.6 tons of hay per cow per winter feeding period. If you have a herd of 10 cows, that means you will need 26 tons of hay (or, if you're looking for big numbers, around 57,200 lbs of hay). If you have 200 head of 1250 lb cows, you will need 520 tons (or around 1,144,000 lbs) of hay for the winter period. If you have better (as in excellent) quality hay, expect to feed more, as in two-thirds more: as in 260 tons more hay (780 tons total = 1,716,000 lbs) for a 200-head cow herd during that winter period!

Still wondering as as to how much hay should you feed a cow? Well it is highly recommended by the author of this answer, on behalf of all cattle producers who have to feed hay during the winter or drought periods, to get your hay tested for quality before you make that mathematical conclusion and before you attempt to under- or over-estimate the amount of you will need to feed one, ten, two-hundred or more head of cattle per day, per month or during a long, 6-month winter period. Always remember, though, that it is much safer to over-estimate the amount you need for your herd than to under-estimate it, because you can never have too much hay!!