I believe and have evidence we can extend the productive life of cows beyond 15 years of age, thereby increasing their return on investment.

For example, I have worked with a ranch near Logan, N.M., for more than 15 years, and there are 37 cows ages 14 to 17 in one pasture that have never missed a calf. In fact, they were 81% calved out in the first 30 days of calving, in a 90-day calving season.

I have spent a lot of time with these cows looking for longevity traits. The only things I noticed were that all 37 cows have moderate-size udders and small teats; the teats were level with the ground, meaning no forward slope.

But a cow herd with longevity is developed. Here are eight thoughts about keeping old cows productive.

1. Older cows need more feed than running-age cows.

2. Put old cows with the second-calf heifers. They both need about 10% to 15% more feed than running-age cows, and the second-calf heifers need leadership.

3. Put the oldest cows with the first-calf heifers. They both need about 15% to 20% more feed than running-age cows, and the first-calf heifers need leadership.

4. Select replacement heifers, on the cow, from these "super cows" — and not in the sorting alley, where identity is lost. This applies to all replacement heifers, in my opinion.

5. Broken-mouth cows are the critical class. They can't graze properly.

6. Check teeth on all cows in the fall after about age 7.

7. Sort off all broken-mouth cows, and put them in a trap or pasture by themselves. (A large-animal practitioner who had tremendous experience with old cows once told me that a cow is in the broken-mouth stage for six to 12 months … never less, never more … before she goes into the smooth-mouth stage.) These cows will need extra attention and maybe even a little alfalfa.

Next year, a new set of broken-mouth cows go in this pasture, and the ones leaving can go with the rest of the cows.

Cattle graze new growth and regrowth. I have taken more grass samples over the last 20 years than anyone I know of. I take them with my thumb and index finger and with a sideways motion, tear the grass. And yes, I know that a cow’s pallet and gums are tougher than my fingers.

Smooth-mouth cows have no problem grazing.

8. In the fall, cull cows for body condition. Hard-looking cows go, no matter the age, and cows in good body condition stay, even if they are old enough to vote.

Remember, too, that every ranch is different and every set of cows is different.

Dan E. Gary is a ranch consultant and owner of Adobe Walls Nutrition in Amarillo, Texas.