How to formulate a low-cost cattle ration

Feed is the biggest bill on a cow-calf or backgrounding operation, and the cheapest ration is rarely the one built from the cheapest feed per ton. This page walks through the method and shows what it produces for six animal classes. It is arithmetic on example numbers, not feeding advice.

1. Put every feed on the same footing

Silage is about 35% dry matter, hay about 88%. Convert each feed to cost per pound of dry matter, then to cost per pound of protein and of TDN. A $55 ton of silage is about $157 per ton of dry matter, which can beat a $180 ton of hay.

2. State what the animal needs

Dry matter intake is roughly 2 to 2.5% of body weight. The ration must also hold a minimum share of crude protein and TDN in that dry matter, enough calcium and phosphorus in a ratio between about 1.5:1 and 7:1, and enough forage to keep the rumen working.

3. Let the solver trade the feeds off

Each requirement is a linear inequality in the pounds of each feed, so the cheapest ration is a linear program. The optimizer solves it, then re-solves to tell you what one more point of protein costs and the price at which a feed you are not using would start to pay.

Worked example, with the starter feeds and example prices

Animal class	Cost per head per day	30 days
Beef cow, mid-gestation	$1.84	$55.12
Beef cow, last third of gestation	$2.02	$60.61
Beef cow, lactating	$2.48	$74.25
Breeding bull, maintenance	$2.73	$81.99
Growing calf or stocker (about 600 lb)	$1.19	$35.79
Finishing steer or heifer (about 900 lb+)	$1.99	$59.63

Computed by the same solver the test suite runs. The example prices are illustrative, not quotes.

What to check before you feed it

Test your forage, replace the book values and prices, use requirements from your nutritionist or extension office, and remember what the tool does not model: trace minerals, vitamins, ionophores, urea limits, mycotoxins, water and health.

Common questions

How do you formulate the cheapest cattle ration?

Write down every feed you can buy with its price per ton as-fed, its dry matter, and its protein, energy, calcium and phosphorus on a dry-matter basis. Set the animal's dry matter intake and nutrient requirements, then find the pounds of each feed that meet them at the lowest total price. By hand you can balance two or three feeds with a Pearson square; with six or more feeds and several requirements at once, a linear program does it exactly.

Why compare feeds on a dry-matter basis?

Corn silage is about 35% dry matter and hay about 88%, so a ton of each carries very different amounts of nutrient. Price per pound of dry matter, and per pound of protein or TDN, is the fair comparison, and it is what the optimizer works with.

What does the example show?

With the example prices, cheap silage and straw set most of the cost for a dry cow, a distillers grain supplement covers protein for a lactating cow, and a finishing steer needs a large share of grain for energy. Your prices will give different answers, which is the point of running it with your own quotes.

Open the optimizer — related: the production mix optimizer and the backyard egg profit calculator.