Score every cow at weaning. The cheap time to fix a thin cow is now.

Body condition score is the one number that predicts more about next year's calf crop than anything else you can measure in the fall. A cow that calves at a BCS of 5 or better cycles sooner, breeds back earlier, and weans a heavier calf. A cow that calves at a 4 is a coin flip to be open next fall. The difference between the two is decided between now and January.

The scale

Scores run 1 to 9. A 1 is emaciated; a 9 is obese. You are looking at the ribs, the backbone, the hooks and pins, the tail head, and the brisket.

• BCS 4: ribs visible, backbone sharp, no fat over the hooks. Thin.
• BCS 5: last two or three ribs visible, backbone felt but not sharp, hooks and pins smooth. Moderate. This is the target for mature cows at calving.
• BCS 6: ribs covered, some fat over the tail head, hooks rounded. Good. This is the target for first-calf heifers at calving; they are still growing and lose more condition after calving.
• BCS 7: fat at the tail head and brisket, ribs well covered. Fleshy. Not a problem in itself, but you paid to get her there.

Montana State and UGA Extension both publish photo guides that are worth keeping in the truck. The scoring is subjective, but consistently scored by the same person it is plenty accurate for management decisions.

The 7 percent rule

One body condition score is roughly 7 percent of a cow's body weight. Moving a 1,300-pound cow from a 4 to a 5 means putting about 90 pounds on her. On a maintenance ration that takes 60 to 90 days of feeding above maintenance, which is why doing it at weaning, when she is dry, is far cheaper than in February, when she is in late gestation and needs more just to hold still.

What to do with the scores

Sort. Thin cows (4 and under) go in one group and get the better hay and some supplement. Moderate and fleshy cows get the stockpile, the stalks, or the lower-quality hay. Feeding the whole herd to bring the thin ones up over-feeds the ones that do not need it, and this year nobody has hay to waste.

Wean early on the thin ones. If a cow is a 4 in September and still has a calf on her, pulling the calf now stops the drain. Her requirement drops by a third the day the calf leaves.

First-calf heifers get their own pen. They are the youngest, thinnest, and lowest in the pecking order, and they need to be a 6 at calving. If they are running with mature cows they will be the last to the bunk and the first to be open.

Cull the 3s. A 3 in September in a drought year is not going to be a 5 by March without a lot of expensive feed, and she is telling you something about her ability to hold condition on your place.

Score again in 60 days

Scoring at weaning tells you where you are. Scoring again around Thanksgiving tells you whether the feed program is working while there is still time to change it. A thin cow discovered in January is a cow you feed hard for 60 days at the most expensive time of year, and she still might not breed back.