Ag Connection
Your link to the Universities for ag extension and research information

This Month in Ag Connection
Improving Swine A.I. Performance
Do EPDs Have a Home on the Range?
Estrus Synchronization Methods for Beef Cattle
Heifer Development Program Demonstrates Use of Co-Products
Pigs and E-mail
Soil Temperatures Online
April 1997
Volume 3, Number 4

Ag Connection - Other Issues Online

Publishing Information
Ag Connection is published monthly for Central Missouri Region producers and is supported by University Extension, the Commercial Agriculture program, the Missouri Agricultural Experiment Station and the College of Agriculture, Food and Natural Resources, UM-Columbia. Editorial board: Maryann Redelfs, Managing Editor; Parman Green, James Rogers, Mark Stewart, Melvin Brees, Don Day and Ron Alexander.

MailboxComments or Suggestions?
Please send your comments and suggestions to Maryann Redelfs, Agronomy/Information Technology Specialist, University Outreach and Extension, 608 E. Spring Street, Boonville, MO 65233, call 660-882-5661, or send messages by e-mail to:

To send a message to an author, click on the author's name at the end of an article.

Improving Swine A.I. Performance

Swine researchers at North Carolina State University and the University of Georgia are just two of the groups evaluating the value of administering oxytocin to sows and gilts two to five minutes prior to breeding by artificial insemination (A.I.). This interest is in response to reports of decreased farrowing rates and smaller litter sizes after switching from natural service to A.I.

A key factor in fertilization rate and thus reproductive performance is the number of viable sperm cells that reach the oviduct of the sow or gilt. This is influenced by the number of viable sperm cells in the semen. Sperm numbers are influenced by boar management, semen processing and handling, as well as storage time.

Oxytocin causes intense contractions in the muscles of the reproductive tract and mammary system. These contractions can assist an A.I. technician by helping move sperm up the reproductive tract to the oviduct, moving eggs down the oviduct more quickly, and by reducing back flow from the uterus.

North Carolina researchers have reported an increase in reproductive performance in certain A.I. situations. These situations include using semen over 72 hours old, over extended semen and an inexperienced A.I. technician (performed 25 or less matings). Research has shown oxytocin administration increased farrowing rate from 77% to 85% and improved the number of pigs born alive by 0.8 pigs when breeding was done by an inexperienced technician. Administering oxytocin when using semen which had been extended and held more than 72 hours, improved reproductive rate from 68% to 85% and increased the number of pigs born alive by 0.7.

Georgia data looked at the oxytocin response in the university herd and in a commercial herd. The university herd did not respond to the oxytocin treatment. Oxytocin treatment did not increase farrowing rate in the commercial herd. It did increase the number of pigs born and the number of pigs born alive by 1.5 pigs.

The breeding management practices were different between the two herds in the Georgia study. The university herd was heat checked once per day and bred by A.I. at 12 and 24 hours after first detecting heat. The commercial herd was heat checked twice per day and bred at 12, 24 and 36 hours after first detecting heat. With the commercial herd, it is possible the oxytocin treatment was improving the effectiveness of the three mating systems. Additional research is needed to evaluate this.

The use of oxytocin offers potential benefits from regular use at breeding. Selective use of oxytocin at breeding seems to be the most logical approach. Oxytocin may be cost effective when:

Author: Mark Stewart, Livestock Specialist Source: G. B. Rampacek, R. V. Utley, B. Flowers, P. Ryan

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Do EPDs Have a Home on the Range?

Understanding and implementing the use of EPDs (Expected Progeny Differences) in beef cattle selection programs allows producers to have more control in developing the product they have to market. However, gaining an understanding of EPDs and how they can be successfully used is no trivial task.

An EPD is a prediction of how future progeny will perform compared to all other animals evaluated. It is based upon the concept of breeding values. A breeding value is the genetic value of an animal as a parent. Each parent gives a random half of its genes to any one offspring, so an EPD is half the animal's breeding value.

How are EPDs calculated and where do they come from? Usually twice a year, a breed association will gather all of its pedigree information and performance records and send them to one of several U.S. organizations that routinely run National Cattle Evaluations (NCE). The more of this information that is available and the more accurately it has been collected, the more reliable are the results from the NCE. The EPDs from any NCE are only comparable to other EPDs from the same evaluation.

For one reason or the other animals may be edited from the data prior to the analysis, or performance data may have just been collected after an NCE was performed. Many producers may still desire to have EPDs on those animals. Interim EPDs may be calculated by using sire and dam EPDs and contemporary group information. If no contemporary group information is available, then pedigree EPDs may be calculated. These are usually the average of the sire and dam EPDs. However, interim and pedigree EPDs are less accurate than EPDs calculated from an NCE.

An EPD is not a constant, and may change as more information is reported or refinements are made to the NCE. With each EPD is an associated accuracy value. The accuracy is a number between 0 and 1, with a value closer to 1 indicating less likelihood that the EPD will change with future evaluations. Most breed associations report a standard error with each accuracy. This simply indicates how much an EPD might change in future evaluations given some numerical degree of confidence.

An EPD should not be used as an absolute, but only compared to the EPD of another animal(s) within breed and evaluation. Remember, the EPD of each animal predicts future progeny performance compared to all other animals evaluated (relative to another animal's EPD). If sire A has a weaning weight EPD of +35 lb. and sire B has a weaning weight EPD of +20 lb. then we would expect sire A to have calves that were 15 lbs. heavier on the average (Sire A - Sire B = 35 - 20 = 15) than sire B when mated to cows of the same genetic merit and exposed to the same level of management.

If traits are heritable, measurable, and economically important, they should be considered in NCE programs. Current traits used in NCE include birth, weaning, and yearling weights, calving ease, scrotal circumference, gestation length, yearling height, carcass cutability, fat thickness, ribeye area, and marbling. Although no breed association has all, most have EPDs for birth, weaning, and yearling weight, and milk, a maternal component of weaning weight.

It is useful to know the past genetic trend and EPD averages for each trait to determine the genetic value of the sire in which you are interested compared to the rest of the breed. Most breed associations provide this information in the first pages of their sire summary. Purebred producers should know their cow herd EPD averages for each trait. Always use the most current EPDs. EPDs may change with the inclusion of new progeny data.

Most producers are interested in a multiple trait breeding program: reducing birth weights, increasing growth while maintaining or increasing milking ability of cows. A system setting independent culling levels for each trait might be useful. For example, setting EPDs with minimum or maximum values for each trait, and then only using bulls that meet those criteria.

Well established purebred breeding programs may be willing to sample unproven bulls with low accuracies. With decreased accuracy comes increased risk. Small producers or those just beginning a breeding plan may want to only use high accuracy bulls. The number of herds in which a sire has been used should also be considered. More confidence can be placed in a bull's proof if it has a high accuracy and has been used across several herds.

Commercial producers, unless using artificial insemination, are often forced to purchase non-parent, low accuracy herd sires. For yearling bulls, the current EPD may not include the animal's own performance record. Most purebred producers should be able to provide their customers with interim EPDs if such a situation occurs. If interims are not available then a combination of pedigree information and within-herd ratios may be used when evaluating performance information. However, when purchasing two-year-old bulls, the animal's own record should have been included in the analysis for traits measured through a year of age.

There has been much discussion in popular press and industry gatherings about converting EPDs so they are comparable across breeds. However, no validation of the across breed conversion methods has occurred. Conservative commercial beef cattle producers should choose the breeds of sire for their breeding program, whether terminal or rotational, based upon known breed differences and complimentarity. Then select the best bull within those breeds that meet their breeding criteria.

Numerous research studies have documented that EPDs do indeed work. However, refinements in methodology and procedures are continually being made. With technology advancements, availability of information, and the increased ability to measure economically important traits, beef cattle producers will only have increased control over their economic destiny through the use of genetic prediction methods.

For sire summary information on the World Wide Web, go to the University of Missouri Beef Page at and look under the Beef Breed Association and Genetic Evaluation Resources.

Author: William Herring, State Beef Extension

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Estrus Synchronization Methods for Beef Cattle

1-shot Method Using Prostaglandin
Days 1-6 Check heat and breed
Day 7 Inject all non-serviced females with prostaglandin
Days 8-14 Check heat and breed
2-shot Method Using Prostaglandin
Day 1 Inject all females with prostaglandin
Day 11 Give 2nd shot of prostaglandin to all females
Days 12-16 Check heat and breed
Variation of the 2-shot Method Using Prostaglandin
Day 1 Inject all females with prostaglandin
Days 2-10 Check heat and breed
Day 11 Inject all non-serviced females with a second shot of prostaglandin
Days 12-16 Check heat and breed
Synchro-Mate-B Regime
Day 0 Norgestamet Ear Implant and 2 cc. injection of norgestamet and estradiol valerate
Day 9 Remove implant
Day 10-14 Check heat and breed
MGA/Prostaglandin Regime
Day 1-14 Feed MGA (0.5 mg/hd./day)
Day 31 Inject all females with prostaglandin (17 days after MGA removal from feed)
Days 31-36 Check heat and breed
Breeding should be done according to the a.m.-p.m. rule. If detected in standing heat in the a.m., breed in the p.m. If detected in standing heat in the p.m., breed the next a.m. If females are still exhibiting standing heat as scheduled breeding, hold till the next breeding.

Other variations of these methods exist. For more information, contact your local veterinarian or University Extension Office.

Author: James Rogers, Livestock Specialist

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Heifer Development Program Demonstrates Use of Co-Products

The Missouri Beef Heifer Development Program is in its second year at Rocking 8 Cattle Company, Fayette MO. This program provides the opportunity for producers to place potential replacement heifers in a location for development, conception and return to their operation ready for production.

The 1996-97 entries more than doubled over the 1995-96 consignment, both in number of heifers and consignors. Nine consignors placed 91 head of potential replacement females on the program November 19, 1996. These heifers are being developed on a co-product ration of 50% soybean hulls, 10% cottonseed hulls, 25% wet brewers grain, 1% Moorman's RU Mineral and 14% grass hay. This is the second year co-products have been the major source for the ration in this program. Utilizing feed products like these, cattle become involved in the recycling effort for products that would otherwise be considered waste.

After 114 days on this year's program, the heifers were weighed, received the second series of immunizations, and were given a reproductive examination by Dr. Dave Hardin and Dr. Richard Randle, Veterinary Medicine, University of Missouri. The consignments gained 220 pounds and averaged in excess of 1.9 pounds per day. Heifers that received an inferior reproductive score were released from the program. This year a larger portion of the heifers received the highest rating for reproductive tract development.

Preparation for estrus synchronization began March 18, 1997 followed with artificial insemination scheduled to be initiated on April 24 1997. Consignors select the sires they want to be used on their heifers. Utilizing this method of both breed and sire selection, consignors have the opportunity to select for specific desired traits. At the conclusion of the artificial insemination period, Angus and Charolais clean up bulls will be available for a short natural service period. Pregnancy examination is scheduled to be competed on July 31, 1997. At this time the heifers will be released to be picked up by their respective consignors.

Author: Dale Watson, Livestock Specialist

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Pigs and E-mail

If you have both, we want to know. Dr. Tim Safranski, your state extension swine breeding and genetics specialist, wants to know if there are a significant number of swine producers using the Internet and/or E-mail. If so, Tim wants to use your E-mail access as a way to speed up getting information to you.

Tim has suggested forming a mail list of pork producers with E-mail addresses. He will then begin to send information out to this mail list in an ‘as it occurs' time frame. If he thinks it will be of interest, he will send it. The Pork Pages newsletter will be the first regularly occurring item sent to the mail list.

If you want to participate, send your name, what county you live in, and your E-mail address to Tim Safranski at:

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Soil Temperatures Online

Planting season is just around the corner and Commercial Agriculture/University Extension are supplying soil temperature information for several locations in Missouri. There are 16 automated weather stations in Missouri which record soil temperatures. Each station has between 1 and 4 soil temperature probes attached to it. All probes are buried under a designated surface at the 2-inch depth.

These data are now available on the Agricultural Electronic Bulletin Board (AgEBB). This Bulletin Board can be accessed by calling (573) 882-8289 with a computer/modem or on the Internet as:

Select from the menu "Missouri Agricultural Weather"; next select "Soil Temperature-Weather Stations". The soil temperature information will be updated on the bulletin board every day by 5:00 p.m.

Soil temperatures are usually the coolest between 6-8 a.m. and reach their maximum between 4-6 p.m. The concept is that if soil temperatures are suitable for crop seed germination early in the morning and throughout the day then it is likely they will be suitable for the following day.

The locations of the weather stations in Central Missouri,
and what ground cover soil temperatures are collected, are as follows:
Station/County No. of probes Bare Soil Corn Residue Wheat Residue Soybean Residue
Brunswick/Chariton 3 yes yes yes no
Auxvasse/Audrain 1 yes no no no
Columbia/Boone 1 yes no no no

Author: Pat Guinan, Extension Associate in Climatology

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University ExtensionAg Connection - April 1997 -- Revised: March 31, 1997