Calculating Winter Forage Needs

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We’re moving toward our winter season now as cattlemen have been testing forage for quality and supplemental needs. At this time, we can still make changes if needed. Here is a good article written by Effingham Ag Agent, Sam Ingram, on winter forage needs:

“It was my understanding that there would be no MATH!”

To begin the process of calculating the hay inventory needed for the winter, a producer does not need to do math! The first step is simple, send a forage sample in to a certified lab to determine the forage quality. The cost of this analysis is minimal and the lab does the math for you. The quality of the forage will determine the amount needed during the winter feeding period.

Once the producer receives and understands the forage quality analysis, they then can determine how much hay they will need to supplement. A simple example below shows how a producer can determine their hay needs:

A producer has 50 mature brood cows at 1,200 lbs., 2 bulls at 2,000 lbs and 10 weaned replacement heifers at 500 lbs. If we assume these animals must consume 2.5% of their bodyweight per day, we can say that:
Brood Cows will require 1500 lbs./day (= 1200 lbs X 2.5 lbs of DM/100lb of b.w. X 50 brood cows)
Bulls will require 100 lbs./day (= 2000 lbs X 2.5 lbs of DM/100lb of b.w. X 2 Bulls)
Yearling Heifers will require 125 lbs./day (= 500 lbs X 2.5 lbs of DM/100lb of b.w. X 10 Heifers)
So, daily hay required would be 1725 lbs. of dry hay (that is at 0% moisture or on a dry matter basis).

The calculation of 1725 lbs. of forage is on a dry matter basis. This means that if we bale the hay or receive hay at 85% Dry Matter (DM), 15 % is water and we do not account for that during feeding. So, a 1,000 lb. bale at 85% DM, would be 850 lbs. on a dry matter basis.

To continue on the calculation we need to estimate our feeding period. For this example we will say a producer needs to feed 120 days. So, if we multiply this number by our daily requirement we get an estimation of 120 days X 1725 lbs. = 207,000 lbs. of DM. If we assume the producer has 85% DM hay, then the as fed total would be approximately 244,000 lbs.

To account for storage loss and feeding loss (assuming barn stored and fed with a hay ring), we can conservatively add another 15% to the “as fed” total and get a total of 280,600 lbs. In this situation, for this moderate size herd, we need roughly 280 – 1,000 lb. round rolls of hay.

Now, depending on where the producer’s brood cows are in their calving season during the winter feeding period will determine if further supplementation is needed. A great option to decrease the need for stored forage or hay is to grow some high quality winter annual grasses. A cow is much more cost-effective at harvesting forages than we are with machinery and these annual grasses can save time producing and feeding hay.

In the end, producers need to think about their current hay inventory and start calculating for this coming winter. With current grain prices, a concentrate supplement may work to stretch hay more cost-effectively. Either way, a producer needs to plan their winter feeding program to avoid overpaying for any forage or supplement when supplies get tight.

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