September in West Texas can be misleading. Although the pasture still has brown grass, the cows are scattered about, and one rain may bring a bit of green to the low areas. It might look from the truck as though there is enough feed to carry on into the fall.If October remains dry, the warm-season grass will stop growing, so the cattle have to go farther to get each mouthful, and the cows begin to lose weight. Hay becomes scarce, feed cubes cost more, and the sale barn ends up with cattle from ranches affected by drought.
It is in September that you have to work out how many grazing days are left. Although the rangeland won’t give you an exact figure, you can get close enough to make decisions while still having several options.
A forage inventory will show you how much dry forage is available, how much cattle can safely be fed, what your herd requires each day, and how much you should set aside for drought conditions. The figures thus assist you in deciding whether you need to rotate your pastures, wean your calves, cull your cows, buy hay, or modify your winter arrangements.
Start With a Pasture You Can Actually Measure
You shouldn’t form your entire opinion of the ranch based on the grass you notice along the county road. You have to go through each pasture or management area, since variations in the soil, the brush, the grazing history, and the scattered summer rain can cause adjacent pastures to appear completely different from one another.
A typical clipping frame has an area of 9.6 square feet; place it in typical locations and then clip the herbage growth for the current year to the height you intend to leave after grazing. Leave out the old litter, the rocks, the woody stems, and any plants that cattle won’t eat.
In a uniform pasture, take no fewer than 10 samples, and take more if the soil, slope, or brush varies. Avoid selecting only the best grass or bare spots.
Keep the samples dry until they reach a constant weight, since even grass that appears dry can contain moisture. If you do not have the appropriate scale or drying equipment, the Extension service or the NRCS can assist.
Here is the conversion that matters:
The figure obtained by taking dry grams from one sample measuring 9.6 square feet and multiplying by 10 equals the number of pounds of dry forage per acre.
A dry sample of 90 grams is equivalent to approximately 900 pounds per acre; convert each sample and then average your figures in pounds per acre. The University of Arizona Cooperative Extension provides an example of this rangeland sampling technique.
Keep the Sample Method Consistent
Cut the grass at the same height and select a height from the leftovers that corresponds to your primary forage species and your objectives for the range.
Where possible, separate the current growth from the older material on the native range. Although weathered grass can provide roughage, it has a lower feed value. Make a record of everything that you include.
Suppose 10 samples average 900 pounds of dry forage per acre across a 640-acre pasture:
640 acres x 900 pounds per acre = 576,000 pounds of gross standing forage
That may seem like a great deal of feed, but it doesn’t mean you have 576,000 pounds worth of feed for the cattle to eat.
The estimate only shows the quantity of forage available, not its quality. Even if the grass is mature and supplies dry matter, it may still have low protein or energy levels for cows with calves. To assess quality, you should look at forage test results, the animals’ body condition, their manure, and how they graze.
Do not consider any significant new growth after the inventory date and, instead of counting the grass before it grows, check it again after it has rained.
The Grass You See Is Not the Grass Cattle Get
Cattle are not able to eat all of the grass, and you shouldn’t expect them to. Part of it gets trampled, some is spoiled by manure, and they also avoid the older stems. The fact that some grass remains helps protect the soil and keep the plants in good condition.
Harvest efficiency refers to the amount of forage actually consumed by cattle while still allowing the pasture to remain in good condition.
The example assumes 30 percent as a conservative figure, not as a rule for West Texas. In rough terrain, with water far away, thick brush, or inadequate distribution, a lower amount might be necessary. On the other hand, good distribution could allow for a higher amount.
Do not raise the figure merely to make the figures look better; instead, match it to the actual conditions of your pasture, and if you are uncertain, ask the NRCS for assistance.
These are the assumptions in our example:
Account for Wildlife Without Counting It Twice
Animals such as deer, sheep, goats, rabbits, and grasshoppers won’t read your stocking plan; instead, their numbers increase in areas where wildlife and livestock make use of the same plants or water.
You should only subtract wildlife use from harvest efficiency if you have a reasonable estimate, for example, five percent; your ranch might require a higher or lower figure.
Using 5 percent in our example:
0.05 times 576,000 pounds equals 28,800 pounds for wildlife and competing grazers.
576,000 – 28,800 = 547,200 pounds remaining
Now apply the 30 percent harvest efficiency:
0.30 times 547,200 pounds equals 164,160 pounds, which are available for cattle intake.
Do not count the losses twice. If you do not have a reliable estimate of the wildlife population, use a lower harvest-efficiency figure rather than trying to guess a wildlife percentage. If the harvest-efficiency figure you are using already accounts for heavy wildlife use, do not subtract the wildlife allowance again.
Record all the assumptions that you make and then compare the real amount of forage that has disappeared with your worksheet. Eventually, your own records will be more accurate than those based on someone else’s percentage.
Calculate What the Herd Eats Each Day
Estimate the daily dry-matter intake at 2.5 to 3 percent of body weight; we’ll go with 2.6 percent and adjust according to cattle class, forage quality, and weather conditions.
Make sure to count each class, and include the bulls, the heifers, the stockers, and the older nursing calves that eat a great deal of forage.
Suppose the pasture carries:
- 80 cows averaging 1,200 pounds
- 70 older calves averaging 500 pounds
- 4 bulls averaging 1,800 pounds
Daily demand looks like this:
- Cows: 80 x 1,200 x 0.026 = 2,496 pounds
- Calves: 70 x 500 x 0.026 = 910 pounds
- Bulls: 4 x 1,800 x 0.026 = 187 pounds
Total estimated demand = 3,593 pounds of dry matter per day
The number for calves is on the safe side for those close to weaning. Milk, creep feed, age, and forage quality all change how much pasture they eat. Separate these factors if you need a more precise estimate.
Use up-to-date weights. If you call every cow 1,000 pounds, you might underestimate how much they need. Cubes or minerals can fix a nutrient shortage, but they can’t make up for not having enough forage for the herd.
Hold Back a Drought Reserve
West Texas rainfall is too unreliable to budget every usable pound. A September shower may brighten the draws without producing enough dry matter to change carrying capacity.
In this case, we leave back 15 percent as a buffer, not as a rule to apply to all situations. The amount you set aside should be determined by soil moisture, water supply, expected weather conditions, and the level of risk you are prepared to take. You should be particularly careful if September begins dry.
Our example has 164,160 pounds available after wildlife use and harvest efficiency:
0.15 times 164,160 pounds equals 24,624 pounds reserved
164,160 – 24,624 = 139,536 pounds budgeted for planned grazing
Now divide planned forage by daily herd demand:
38.8 grazing days are obtained by dividing 139,536 by 3,593 pounds per day.
Bring it down to 38 days, not up to 39 days. Grazing budgets must always be conservative.
The herd can be brought onto the pasture until October, but not all the way through the fall.
If the 70 calves are taken away, daily demand will be down to around 2,683 pounds, so your forage will last for about 52 days, which is almost two weeks longer.
Practical Management Strategies
Put the end date on your calendar; if the herd begins grazing on September 15 and has 38 days’ feed, then circle October 22. Consider this date as the limit of your budget, not as a guarantee.
Prepare a separate budget for each pasture; otherwise, the ranch-wide average may conceal issues such as an overgrazed calving pasture or forage cattle are unable to reach in difficult terrain.
Then run at least three versions of the calculation:
- The herd as it stands today
- The herd after weaning and removing calves
- The herd is processed following pregnancy checking and the removal of any cows that are open or unsound.
The figures available to you include the possibility of moving the herd earlier, reserving a pasture for fall calving, purchasing hay in advance, or setting a date to reduce the herd if it doesn’t rain soon.
Make sure to carry out the check every two weeks in the same way. When you move the cattle, record the date and then compare the amount of forage that has disappeared with your earlier estimate. This way, you can adjust your rotation schedule before it’s too late.
Supplementation does not increase carrying capacity; it may improve digestion and lead to higher forage intake, causing grass to disappear more quickly. When there is a shortage of dry matter, other forage must be introduced, or the number of animals fed must be reduced.
Warning Signs the Forage Budget Is Running Out
The worksheet should warn you first, but cattle and grass still tell you when to look again.
Watch for herd-level changes:
- Cattle spend more hours grazing and less time resting or ruminating.
- Animals walk fences, reach under wires, or crowd gates.
- Rumen fill and body condition begin to drop.
- Calves lose bloom or fall behind expected gains.
- Manure volume falls, or manure becomes firm and stacked.
- Supplement consumption jumps without a management change.
- Cattle graze preferred plants again before those plants recover.
- Trails widen, and bare ground grows around water, shade, and gates.
One calf looking dull doesn’t always mean the pasture is short. Illness, parasites, mineral issues, or bad water can cause similar signs. If a calf is coughing, has diarrhea, has trouble breathing, has a fever, or shows sudden weakness, give it individual attention and call a vet if needed.
Watch for patterns in the herd. If cows lose body condition, calves slow down, and the best grass is gone, check the pasture again instead of just adding more feed.
A Grazing-Days Worksheet You Can Use Today
Get a pasture map, a clipping frame, clippers, paper bags, a scale, a calculator, and a notebook, and then complete those lines:
- Grazeable acres: ______
- Average dry forage: Average of converted samples = ______ lb/acre
- Gross forage: Acres x lb/acre = ______ lb
- Wildlife allocation: Gross forage x ______% = ______ lb
- Forage after wildlife: Gross forage – wildlife = ______ lb
- Harvest efficiency: Remaining forage x ______% = ______ lb
- Drought reserve: Cattle-available forage x ______% = ______ lb
- Planned grazing forage: Available forage – reserve = ______ lb
- Daily herd demand: Head x average weight x intake factor = ______ lb/day
- Estimated grazing days: Planned forage divided by daily demand = ______ days
Record the date, the amount of rainfall, the clipping height, the weights, the wildlife allowance, the harvest efficiency, and the reserve. Taking down these notes will help to explain any errors and will improve your next estimate.
The worksheet gives you the amount of forage you have, not an indication of its quality. You should use it together with body condition scoring, forage tests, and observations of your herd.
Turn Grazing Days Into Trigger Dates
It’s useful to be aware that you have 38 grazing days remaining, but that figure won’t be of any use if you leave it in your notebook; you should enter it on your calendar and establish a few trigger dates.
The recheck date is when your first date takes place. About two weeks later, go for a walk and take a sample of the pasture again. Compare the amount of forage that has disappeared with the amount your original calculation had predicted. Should the cattle be consuming it faster than expected, then adjust the remaining days rather than merely hoping the first estimate was correct.
The following is the date on which you must make your decision. Make sure you allow sufficient time to buy hay, plan the weaning process, check the cows to see if they are pregnant, or get another pasture in order. Do not wait until the final day for grazing to begin making your decisions.
The last date is when you either move the cattle or reduce the herd. This is when cattle leave the pasture or demand declines. Moving on time keeps your drought reserve from being used up as regular feed.
Using our 38-day example, the calendar might look like this:
Rain, changes in forage use, or herd adjustments might change these dates. That’s okay. The important thing is to make those changes intentionally.
A grazing-days estimate tells you what the pasture may support. Trigger dates turn that estimate into an operating plan you can use before the grass, cattle, or weather decide for you.
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