IN THIS ISSUE...

• Just 5 Questions

• World According To Hooter

• Hornless Fatty's Sled Ride

• Lice Fight

• The Cow Whisperer

• Them Against Us

• Trich Again

• Utilizing Snow

EDITORIALS

• TRAILS
• GAP

At present, 16 western states have testing programs to try to reduce the disease, and at least two more states are developing control/testing programs. Dr. Robert BonDurant (Veterinary Reproduction, UC-Davis) is now retired, but spent many years studying trich. “It’s not just a western problem. It was reported in Florida, Missouri and a number of Midwestern states during the 1990’s. If we look hard enough, we find it,” he says.

Idaho was the first state to require mandatory annual testing, beginning in 1989 but it took awhile before some of the other states followed suit. “We randomly sampled herds in California nearly 20 year ago and at that time we found that 16 percent of herds in our state had at least one infected bull. We tried to get California to follow Idaho’s model of required testing, but this met with resistance,” says BonDurant.

“The legislature had the authority, given to them by the California cattlemen and the California Department of Food and Agriculture—to go ahead and write legislation, but at first they were considering voluntary testing with mandatory reporting. That would have made it so nobody would want to test,” he says. The testing requirements in California were finally enacted in 2003, with a strengthening of the laws in 2007 (see sidebar).

The Disease
Tritrichomonas foetus, a one-celled protozoan, lives in the sheath of bulls and in the reproductive tract of cows, spread from animal to animal by breeding. The infection kills the developing embryo or fetus in the bred cow. She aborts during the first 4 months of gestation. After aborting, the cow becomes temporarily infertile. She returns to heat but generally does not settle if bred--until she clears the infection, which usually lasts 120 to about 150 days.

If an infected bull breeds cows, he passes the infection to them. If those cows are bred by another bull, he too will pick up the protozoa. If bulls are removed from the herd after a short breeding season (45 to 60 days), affected cows will be open because they did not have a chance to rebreed after losing their pregnancies. If bulls are left in for a long time, cows will breed back after aborting and recovering from the infection, producing late calves and a strung out calf crop the next year.

After the reproductive tract of the cow recovers, she generally has a natural immunity, which lasts about a year. A few cows may carry the disease over into the next year (if they got it toward the end of the breeding season) but bulls are the main problem in spreading trich because they tend to be carriers for a longer time.

Young bulls may spread the disease and then recover (throwing off the infection between breeding seasons), but older bulls generally remain infected for the rest of their lives. Most young bulls are merely mechanical spreaders for a short time, whereas bulls over 3 years old do not get rid of the protozoa once they are infected. These bulls carry the disease to the next season, continuing to infect cows during subsequent breedings.

The protozoa thrive in airless conditions, and live in the tiny pockets or folds that line the inner surface of the sheath. The high infection rate in older bulls is due to the fact they have more folds in which the protozoa can survive for long periods. Carrier bulls begin infecting cows at the start of the breeding season, and greatly increase the chance for large numbers of cows being exposed to the disease.

“One of the things we learned while doing our research surveys is that not all positive cultures are actually trich,” says BonDurant. “We used to think that if you cultured the bull and got something in the culture that looked like a trich and swam like a trich, it was trich. But about 10 years ago we were seeing virgin bulls come up with positive tests, and no way to have gotten trich. We learned that there are some trichomonads that are not pathogenic, so we get some false positives,” he says.

Occasionally a virgin bull will test positive on a culture, but when checked with a PCR (polymerase chain reaction) test, these organisms are found to be a different protozoan. “Fecal trich” is due to a whole family of non-pathogenic protozoa that are normal residents of the bovine digestive tract and present in manure. They can be transferred to the bull’s reproductive tract when bulls mount and try to breed one another. “These young bulls get manure in the prepuce and that’s probably how they get contaminated,” explains BonDurant. The only way to tell these kinds of protozoa apart is with an electron microscope or by using the PCR test.

A two-step testing program was therefore developed. “If your vet cultured a bull and the test is negative, fine. If it was positive and you wanted to be sure, we recommended sending it to our lab at UC-Davis for the PCR test. We worked with about a dozen diagnostic labs from western states and they sent us their positives, to run the DNA test.” Now, however, many state labs can do their own PCR tests.

Testing
Dr. Debra Lawrence (Idaho State Veterinary Medical Officer) says cattle producers in Idaho requested testing, which was begun in 1989. At the start of the program, this disease was costing the cattle industry in Idaho close to 5 million dollars annually, in calf loss and having to replace open cows.

The first testing season found 325 bulls that were positive for trich. In the years since, there has been a dramatic reduction in positive bulls, but the disease has not been eliminated. Idaho tests about 20,000 bulls a year.

All bulls in Idaho that have been used for breeding must be tested annually, and virgin bulls tagged, so people know they are part of the program. Any bulls coming into the state, no matter where they are going, must be tested before they come in.

Utah was the next state to adopt a formal testing program, similar to that of Idaho, and was followed by Oregon and Colorado. Most western states, and now Texas (as of April 2009), require some type of trich test.

There are also some grazing associations across the nation that try--through their grazing contracts--to manage the disease within their own associations. The Idaho veterinary office occasionally gets requests from various associations for information on testing, in states where there is not a mandatory program. Some of the Indian reservations have also been active in trying to prevent trich.

The only “safe” bull is a virgin bull that has never had access to cows. Any bull that has ever bred cows should be tested, to determine whether he is free of trich. To test a bull, the veterinarian collects mucus cells from the deepest portion of the sheath (using a long, small diameter rod to enter the sheath and retrieve the mucus), then cultures this material to allow the trichomonads to grow and multiply. The culture is observed for 3 to 7 days to see if there are any trichomonads growing. A heavily infected bull will have a positive culture within 3 days. If the culture is negative at that point, there is a good chance the bull is not infected, but the culture is watched for 7 days to make sure no trichomonads show up.

Any bull that tests positive should be culled and sold, but since there are a few false positives, a valuable bull that tests positive should have the culture sent to a lab that does PCR tests. For a long time, the University of California-Davis laboratory was the only one that did these tests, but now there are state labs that can run these.

Bulls testing negative should be retested a week later if there is any suspicion that trichomoniasis might be a cause of problems in that herd, since the test from a culture is not 100 percent accurate with a single sample. The test is 90 percent accurate. This means that out of 100 positively infected bulls tested, only 90 will show up on the first test as positive. If any bulls in your herd test positive, the others should be retested a week later to make sure they are actually negative.

When using cultures, you almost have to test a bull 3 times to make sure he is uninfected. If a herd is infected, retesting will be needed to be sure you are eliminating all the positive bulls. Thus the testing should be done well ahead of the breeding season, in order to have time to discover and replace infected bulls.

“The PCR test is becoming more affordable, and we can do it in our lab now, instead of having to send the samples to UC-Davis. The turnaround time is much faster,” says Lawrence. Even though a single PCR test is very accurate, Idaho regulations still require that any bull coming into the state from an unknown background must have 3 tests, 3 weeks apart.

“But in most instances, bulls are coming from seedstock producers and they are not over 2 years of age. We are now doing a lot more PCR tests, which speeds things up for people, especially if a producer wants to turn out his bulls next week. He doesn’t have to wait so many weeks for the results,” says Lawrence.

“We still encourage ranchers who are going to turn out on grazing allotments to start testing 45 days prior to turnout. Some folks have been pooling samples for the PCR test. If they have 5 bulls, for instance, they may put those samples all together for one PCR test.” If the test comes back negative, that means all the bulls are ok, and it saves money on testing. But if the pooled sample comes back positive, they have to go back and test each bull. Even though the PCR test doesn’t take a week anymore, the tests must be a week apart to make sure every bull in the bull battery is clean before they turn out.

As the methodology improves with the PCR tests, the Idaho rule may be changed to require only one test instead of three. “But at this point in time, multiple tests are still the best route, unless it’s a virgin bull and the positive result turns out to be fecal trich instead of the venereal kind. In that instance we only need one negative test,” explains Lawrence.
If the disease gets into a herd, the cows will also have to be managed (by vaccination) in order to correct the problem, so the disease cannot be spread. A veterinarian can help a producer develop an effective vaccination program.

In range states where cattle herds run together on public land, or in any states where the disease exists and you don’t know the status of your neighbor’s cattle, control of trichomoniasis can be difficult without a cooperative effort among stockmen. Even if one producer eliminates trichomoniasis in his herd, there is always risk of infection from the neighbor’s bulls unless the neighbor, too, is testing and controlling the disease. If a bull is used for two breeding seasons (spring and fall, for instance) he should be tested twice annually, ahead of each breeding season.

In herds or grazing associations that have had problems, they have been able to eventually clear it up if they diligently test all bulls, and make sure the cows have calved or are with calf by the time they are turned out in the breeding pastures. In other words, a cow that shows that she can calve is generally no longer infected and will not spread the infection to a clean bull. She will be clean for her next breeding. So most people preg check to make sure cows are pregnant by a certain date, and those cows that aren’t pregnant are culled.

Prevention
There is no treatment for trichomoniasis; prevention is the only recourse. If a person gets rid of carrier bulls and carrier cows, the disease can be eventually eliminated from a herd. The way to get rid of carrier cows is to sell all cows that are open or late calving. An extensive survey was done a few years ago in California that revealed the carrier cow syndrome. It isn’t something that occurs very often, but sometimes a cow will retain the pathogen, even if she carries a calf to term. She may still have the infection by the next breeding season, and can infect the bull that breeds her.

Trich has a way of cropping out when you least expect it, but is most likely to occur if you share a grazing pasture. “Everybody may have tested their bulls, but the biggest problem we have here in Idaho is people buying infected open cows at the sale barn,” says Lawrence. The cows may even breed and settle, but spread the disease to the bulls. “Open cows are not a bargain. If you are going to buy some, keep them home and don’t turn them out with the main herd. Another problem is the traveling bull that goes through fences.”

Oregon State University Cooperative Extension specialists list these ways to keep a herd free of trichomoniasis:

• Use only virgin bulls, or keep your bull battery as young as possible (keeping bulls for only 2 years, for instance).
• Test all bulls that have previously bred cows.
• Test all new bulls before putting them with cows, or purchase bulls from a breeder who has all bulls tested before being sold.
• Use virgin bulls on virgin heifers.
• Pregnancy test all cows and heifers 60 to 90 days after breeding and cull all those that are open. This eliminates most of the females that may have been infected and aborted and might still be infective to a bull.
• In an infected herd, consult with your veterinarian, and vaccinate all females twice the first year, 2 to 4 weeks apart (with the second vaccination 1 to 4 weeks before the breeding season starts), and revaccinate all females annually.
• Keep fences in good repair so herds don’t mingle.
• Be suspicious about buying cows, especially cull cows. You may inadvertently introduce “trich” to your herd.

One key to using vaccine in cows is timing; immunity will be highest soon after vaccination. This applies with all reproductive diseases and not just trich. Too many people vaccinate for vibriosis or lepto in the fall at preg check time. Those vaccines won’t give immunity that long.
The other key is to reduce the number of carrier animals, if possible. The goal is to reduce the challenge and raise the resistance--those two factors together help control disease. The resistance factor involves using a vaccine at the right time, in a healthy animal with a good nutritional program that bolsters the immune system.

Diligent management is crucial. Often, people go through an outbreak and work hard to get it under control, then after several years become lax on management. They may forget to test bulls one year, or decide to keep a good old cow even though she’s open, or may buy bulls that weren’t tested. These factors may allow trichomoniasis to slip back into the herd.

NOT A NEW DISEASE
Trichomoniasis was identified in cattle in the 1930’s. “The causative organism was first isolated from the GI tract and throat area in pigs,” says BonDurant. “But we don’t know how it got from pigs to cattle. Within the last 10 years it has also been isolated from the GI tract of cats with diarrhea.” Trich might have become accidentally established in cattle and found an ideal environment in the bovine reproductive tract.

Trich in cattle has existed in Europe and South and Central America for a long time. The early attention on reproductive diseases, however, was on eradication of brucellosis. After that was nearly accomplished, scientists developed a vaccine for vibriosis. Then suddenly veterinarians began seeing some of the same signs of reproductive problems, and had to start looking for something else--and realized trich was a problem.

Trich originated has probably been in cattle a long time, since it is well adapted to the bovine reproductive tract. Vibrio and trichomoniasis mimic each other. The vaccine for vibrio is very effective for that disease, if given at the right time, and the same thing is true with the vaccine for trich. When a herd is having reproductive problems, a diagnosis is extremely important. Then you’ll know whether you are dealing with vibriosis or trich.

TEXAS PROGRAM
One of the states to most recently develop regulations to control trich is Texas. After consulting with producers, market operators, veterinarians, laboratories, and animal science educators, the TAHC (Texas Animal Health Commission) developed a program to test breeding bulls.

Requirements for bulls entering Texas went into place April 1, 2009. Requirements for bulls changing hands within Texas will go into effect January 1, 2010. Trich is now a reportable disease in Texas, so the TAHC will be able to collect information on where and how much infection exists within the state.

All bulls entering Texas must now be either 24 months of age or younger and certified as virgin or test negative for trich within 30 days prior to entering the state. Non-virgin or untested bulls may enter Texas only for sale to slaughter.

A breeders certificate, with the bull’s age, ID and breeder’s signature must accompany every virgin bull, and this information must also be included on the certificate of veterinary inspection. Age can be determined by breed registry papers or by examining the animal’s teeth. If both permanent central incisor teeth are present and in wear, the animal is at least 24 months old.

Breeding bulls must be officially identified prior to entering Texas. The ID can be a brucellosis ear tag, RFID, official 840 flap or bangle tag, official individual animal breed registry brand or tattoo, or official state of origin trich tag. Any non-virgin bulls or bulls older than 24 months entering Texas must have tested negative within the 30 days prior to entry, either by one PCR test or with 3 consecutive culture tests not less than one week apart. During the testing and prior to shipment, the bulls must have no contact with female cattle.

The second phase of the program begins on January 1, 2010 and requires that any Texas bulls offered for sale, lease, or exchange within the state be certified as virgin bulls or be tested negative (unless being sold for slaughter). The delay until January was to give time to certify enough veterinarians to perform all components of the trich program and to make sure producers are familiar with the requirements.

Samples for testing must be collected by certified, accredited veterinarians and the tests run at the Texas Veterinary Medical Diagnostic Laboratory. Costs of sample collection and lab tests will be the responsibility of the stockman. Bulls that turn up positive will be restricted to movement for slaughter only, and must be sent to slaughter within 30 days of confirmation. Any other bulls in that herd will be held and isolated from female cattle until they have not less than 2 consecutive negative PCR tests or 3 consecutive negative culture tests.
“By enacting the interstate regulations now, we can address the importation of disease immediately,” says Dr. Bob Hillman, Executive Director of the TAHC. “Delaying the intrastate requirements until the first of the year will ensure that everyone can be on board to attack this disease and protect their herds.”

CALIFORNIA
The California Cattlemen’s Association and the Western United Dairymen together sponsored legislation to develop a trich control program. It was developed by the California Department of Food and Agriculture (CDFA) and went into effect September 21, 2003. CDFA approved 156 veterinarians to take the samples, and 61 labs to do the testing. Within the first 5 years 180 infected herds were diagnosed.

A new control program became effective October 5, 2007, after the cattle industry requested that the laws be strengthened. The new program consists of 12 important points:

1. Veterinarians must be approved through training (provided by CDFA), renewable every 2 years.

2. Animals require official ID and samples must be evaluated in approved labs

3. All test results, including negatives, must be reported to the district Animal Health Branch office within 30 days.

4. Positive samples must be reported to CDFA within 2 days.

5. Confirmation of positive test results by PCR may be requested but not required.

6. CDFA will investigate cases, notify owners of potentially exposed cattle, and quarantine bulls in affected and exposed herds.

7. Bulls from affected herds require 3 negative tests, at owner’s expense, at least 7 but not more than 28 days apart, to move anywhere except to slaughter.

8. Bulls from exposed herds require one negative test, at owner’s expense, before movement.

9. Bulls 18 months and older sold at public saleyards in California require a negative trich test within 60 days before sale or be consigned as slaughter only.

10. Public auction yards must post a notice to that effect.

11. Bulls 18 months and older entering California require a negative test within 60 days unless entering for slaughter, semen collection or exhibition (not commingling with other cattle)

12. Bulls moving into California on a pasture-to-pasture permit require a negative test within 12 months.