Ag Connection
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Volume 5, Number 10
October  1999


This Month in Ag Connection


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How to Determine Percent Calf Crop

Percent calf crop is based on the number of weaned calves as a percentage of those cows exposed to the bull (or artificially inseminated) during a given breeding season.

Grazing Crop Residues
Twenty Ways to Wean More Pounds of Beef
How to Determine Percent Calf Crop
Decision Software for Missouri Beef Producers

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Grazing Crop Residues

Dry weather has depleted pastures in much of Central Missouri. An alternative for fall grass pasture grazing may be to utilize crop residues where appropriate. Corn, grain sorghum (milo) and soybean residues can all be grazed.

The nutritional value of crop residue varies according to the crop, plant part and number of days between harvest and grazing. Nutritional value of corn and milo grain are very similar (table). Corn grain is much more easily digested by the rumen than a milo berry. Milo berries have a hard outer layer that makes them much more difficult to digest. However, cattle can become foundered on both milo and corn fields.

Corn leaves have less nutritional value than the grain (table) but the husk, cob and stalk have significantly less nutritional value than leaves. These values decrease as the crop weathers, the primary loss will be in energy (In vitro dry matter disappearance or IVDMD).

Milo leaves tend to be higher in protein but similar in IVDMD to corn leaves. The nutritional value of the corn and milo stalk are both poor (table). Soybean leaves are high in protein and low in IVDMD (table). The stems and pods are very similar to the leaves for IVDMD. Protein values for pods can average 6.1% and for stems 4.0%. The low energy values are due to the high lignin content of the soybean residue.


Dry Matter

Percent Crude Protein

Percent IVDMD








































































Dry weather will decrease the amount of crop residue available. Normally, 2000-2500 pounds of corn residue will remain in the field per acre. This may have to be lowered this year.

Good grazing strategy prior to turn in is to estimate the number of grazing days available, this will allow for a backup feeding strategy when the stalks run out. For grazing corn stalks we can estimate after harvest that 4% of the grain yield is down corn which amounts to 1.9 pounds of corn dry matter per day. If little mud is present and trampling is minimal this would provide .8 grazing days for calf or .4 grazing days for a cow per bushel of corn produced. (150 bu. corn/Ac x .4 = 60 days of grazing per cow per acre).

Words of caution for grazing residue this year. The dry weather has set up perfect conditions for nitrate toxicity potential. Nitrogen applications put down this spring were taken up by corn and the dry weather never gave the corn opportunities to "grow out" those accumulations. Some corn plants have had positive reactions to a nitrate test as high as the corn ear. If planning on grazing corn stubble, test the residue for nitrate. If the test is positive high up the stalk, do additional quantitative testing to develop feeding strategies. Avoid forcing the cattle to consume the stalks, the nutritional value is poor and would not contribute much toward body maintenance.

Milo stubble will remain green longer into the fall and winter. If weather conditions remain warm and we finally get fall rains with a late frost, milo can produce suckers. These suckers can be high in prussic acid that is deadly to grazing animals. If this happens cattle should not graze the stubble for at least 7 days after a hard freeze.

Cattle will selectively graze crop residue. For example in corn stalks they will go through and get the grain first, followed by the husk and leaves, then the stalk and cob. The amount of good, nutritional residue will decrease rapidly over time. It is very important to know the nutritional needs of the grazing animals.

Cattle in second period gestation should be able to maintain body condition on good corn stalk stubble. However, this is not going to be a good corn stalk stubble year. With little grain available in a lot of fields in Central Missouri cattle may need both a protein and energy supplement dependent upon conditions.

(Author: James Rogers)

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Twenty Ways to Wean More Pounds of Beef

The cow's gestation period averages 282 days but ranges from 278 to 292 days. After calving, the cow usually will not recycle for 45 to 60 days. This means she only has an average of 23 days to cycle and conceive if she is to calve every 12 months (282 + 60 + 23 = 365 days).

Your goal as a cow-calf producer is to wean a heavy calf from every cow each year. To achieve this, you must have a practical management program that will result in high fertility from your cow herd. Following these 20 management steps will help insure a higher net percent calf crop and thereby help you achieve maximum income from your herd.

  • Use an identification system and keep records. Good herd management begins with an animal identification system for record keeping. Records are important when it's time to select replacements and cull low producing animals.
  • Provide handling facilities. Adequate handling facilities are necessary for such practices as performance testing, vaccination, identification, sorting, pregnancy testing, and medical or other treatment.
  • Design a health/management program. You and your veterinarian should outline a health/management program tailor-made for your herd, locality, and market. Schedule and maintain appropriate times for vaccination, castration, controlling parasites, weighing calves, and pregnancy testing in your herd.
  • Properly use growth promoting implants. Weaning weights of steer calves can be increased as much as 30 pounds if you use growth-promoting implants during the suckling period. Bull or heifer calves kept or sold for breeding purposes should not be implanted.
  • Don't creep feed potential replacement heifers. Cows creep-fed as calves give less milk than those not creep-fed. This decreased milk production may result in lighter weaning weights of their calves each year of the cow's life. Possible exceptions to this "rule"' are when drought conditions exist or if the cows are on a fall-calving program.
  • Develop replacement heifers properly. Weaned replacement heifers should be separated from the steers. Medium-framed heifers should gain about 1 to 1.25 pounds per day and weigh about 700 pounds at 14 - 15 months. Large-framed heifers may gain 1.50 pounds per day and should weigh 800 pounds at breeding time at 14 - 15 months. Heifers managed this way should be in optimum condition to conceive early in their first breeding season.
  • Breed heifers to calve two weeks prior to the cowherd. Yearling heifers should be exposed to bulls, or AI, two weeks before breeding the cowherd. This means they will calve early their first year, allowing more individual attention at calving. Early-calving heifers also will tend to calve early throughout their lifetime.
  • Use crossbreeding. A crossbred cow will help increase total pounds of calves weaned from a herd by 10 - 20% or more. Crossbred cows usually wean both more and heavier calves than straight-bred cows. But, be aware that some cross breds require a higher management level, especially those with greater milk potential.
  • Use judgment when selecting a bull. Give consideration to the breed and type of bull used to breed yearling heifers. For AI, use semen from superior sires; for natural service, buy performance-tested bulls. Use birth weight and calving ease Expected Progeny Differences (EPD's) to guide you in bull selection.
  • Purchase bulls early. Buy a bull early when selection is the best. Select one that is physically sound, performance tested, has EPD's, and been evaluated for breeding soundness. Having the bull on your farm 45 - 60 days prior to the breeding season provides a period of adjustment, and allows him to overcome any fertility problems encountered during shipment or change in feeding program.
  • Evaluate semen and breeding soundness. Have a semen and breeding soundness evaluation performed on all bulls 60 to 14 days before the breeding season. Replace sterile bulls and those with low breeding soundness scores.
  • Provide adequate bull power. Provide one yearling bull for each 15 -20 cows and one mature bull for each 25 - 30 cows. Breeding bulls should be in good flesh condition, but not fat. If foot trimming is required, do it at least two weeks before breeding.
  • Shorten the breeding season. Shorten the breeding season each year until all your calves are born in a short period of time (60 - 75 days), resulting in a much easier to manage and more uniform calf crop. The calving season can be shortened by culling open cows and those that conceive late in the breeding season.
  • Observe breeding pastures frequently. Remove hazardous materials from the area that may cause injury to the bull. Watch for and record cows in heat; make sure that the bull is breeding these cows.
  • Pregnancy test cows. Cows can be pregnancy-tested when their calves are weaned 4 - 5 months after the start of the breeding season. With experience, pregnancy can be detected as early as 35 - 45 days after conception. Besides weaning at this time, weighing, worming, grub control, vaccination, and identification can also be done. Cost of pregnancy testing will vary, depending on number of cows and handling facilities. Remember, carrying an open cow for a year is much more costly than the few dollars spent on pregnancy testing.
  • Have cows in moderate to good body flesh condition at calving. The major reason for cows becoming thin is inadequate nutrition. During the last one third of gestation cows in average body flesh condition need 10 - 12 pounds of Total Digestible Nutrients (TDN) and 1.5 - 1.75 pounds of crude protein. Separate thin cows from the herd and feed additional TDN so that they will be in moderate condition when they calve. Also, don't forget to provide Vitamin A, salt, and a high phosphorous (8%+) mineral mix. Proper nutrition prior to calving improves calf vigor, milk production of the cow, and reduces the number of days from calving to rebreeding.
  • Separate the two-year olds. Two-year-old heifers often suffer from competition at the feed bunk if fed with mature cows. Separation from older cows also makes it easier to observe calving.
  • Be prepared and closely observe the herd at calving. Have available: clean, well-lighted maternity pens, pulling chains, disinfectant, calf respirator, disposable gloves, calf puller and halter. Observe cows at least twice while they are calving. Check with your veterinarian for advice on when to assist the cow and when to call him. You can save many calves by providing prompt assistance. Saving three more calves in a 30-cow herd is nearly equal to adding an additional 50 pounds of weaning weight to every calf in the herd.
  • Keep birth weight and calving-ease records. These records will help identify the bulls and cows responsible if problems occur. Refer to your records when selecting herd replacements as well as when selecting bulls for breeding yearling heifers.
  • Separate cows that have calved and increase their feed. Pregnant cows are easier to observe if separated from cows that have calved. Energy and protein requirements of a lactating cow are well above those of a dry, pregnant cow. A lactating cow should receive about 12 - 15 pounds of TDN and 2.0 - 2.5 pounds of protein each day. Requirements are higher for superior milk producers.

(Authors: W. L. Singleton and L. A. Nelson; Department of Animal Sciences, Purdue University)

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wpe2.jpg (3174 bytes)Decision Software for Missouri Beef Producers

Thinking about maintaining ownership of calves over the winter for spring grazing? How about purchasing calves for backgrounding this winter? Have you wondered what your breakeven price would be if you developed heifers for a Show-Me-Select sale? If you have said yes to any of these questions, your regional livestock and farm management specialists have a deal for you.

The commercial agriculture beef team has developed three spreadsheets which will help you compare different marketing options for cow/calf producers looking at retained ownership options as well as stocker/backgrounding operators. These spread sheets help you look at returns and breakeven pricing. The answers are only as good as the data used producers will need to have a good feel for livestock costs, health expense, marketing charges and cost of diet.

Your regional specialist will work with you to use the spreadsheets and if you have Microsoft Excel on a computer at home, these spreadsheets are available free of charge.

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University of Missouri ExtensionAg Connection - October 1999 -- Revised: April 20, 2004