September 16, 2019
By Denise Schwab and Katy Lippolis
A late, wet spring put a double whammy on beef producers who rely on winter feed. Most producers used up most — if not all — of their hay carryover, so are starting with no reserves.
There are many ways to approach winter feed planning, but a simple one is to calculate feed needs versus feed available. Start with an inventory of all the cattle that you plan to winter, including replacement heifers, backgrounding calves and bulls, in addition to the main cow herd.
You’ll also need approximate body weights to use in calculating feed needs. Next, inventory the feed resources available, approximate weights, dry matter and quality.
To calculate feed needs, multiply the number of animals times their weight. A general assumption is that cattle will eat 2.25% to 2.5% of their body weight in dry matter per day, so body weight times 2.5% times the number of days gives you approximately the amount of feed needed.
An example would be:
100 mature cows x 1,400 pounds = 140,000 lbs. x .025 = 3,500 lbs. DM/day x 150 days = 525,000 lbs.
20 first-calf heifers x 1,000 lbs. weight = 20,000 lbs. x .025 = 500 lbs. DM/day x 150 days = 75,000 lbs.
25 replacement heifers x 700 lbs. = 17,500 lbs. x .025 = 437.5 lbs. DM/day x 150 days = 65,625 lbs.
6 bulls x 2,000 lbs. = 12,000 lbs. x .025 = 300 lbs. DM/day x 150 days = 45,000 lbs.
65 background calves x 650 lbs. = 42,250 lbs. x .025 = 1,056 lbs. DM/day x 60 days = 63,375 lbs.
This example would need 774,000 pounds, or 387 tons, of hay on a dry matter basis. Assuming hay is 85% dry matter, 455 tons of as-fed hay is needed.
You also need to factor in some storage and feeding waste. Well-managed hay feeding with good hay bale feeders probably need to factor in 10% to 15% of waste, so now you need about 524 tons of hay for a five-month feeding period. This assumes you provide full feed of hay at all times.
A second step to forage planning is to allocate resources based on forage quality and nutrient needs for various time periods. First-cutting hay usually makes up about half of the total hay crop, but it also tends to be more mature, and therefore lower in quality. It is a good feed for midgestation cows, and maybe bulls after they are back in good condition.
Second and third cuttings tend to be higher-quality because they are less mature at harvest and are best targeted to late-gestation, calving and young stock. Grass hay tends to be a good match for weaned calves, provided it isn’t too mature.
There are many things you can do to reduce the amount of hay needed: graze crop residue or cover crops, control feed waste, substitute lower-quality forages such as corn stover, limit feeding forage and supplement with corn or corn coproducts, or feed an ionophore. But having a rough plan for feed needs provides you the opportunity to prepare for the colder months ahead.
Schwab serves as Iowa State University Extension beef specialist, and Lippolis is an ISU assistant professor of animal science.
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