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OSU Extension BEEF Team
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Previous issues of the BEEF Cattle letter
Issue # 684
April 28, 2010
Repetitive Cattle Deworming May Cause Drug Resistant Worms - Amy Radunz, Beef Cattle Extension Specialist, UW-Madison
Dewormers have provided effective parasite control, which has resulted in returns to farmers between $20 to $200/hd. The cost of these products is reasonable when compared to potential productions gains provided. Sheep and goat farmers have long battled with drug resistant worms, however until recently there has not been evidence of this is occurring in beef cattle. In fact, some of the first evidence of worm resistance in cattle was found in Wisconsin in 2002, when a backgrounder, who acquired calves from the Southeast, experience lower than expected weight gain during the fall.
According to Dr. Shulaw, Extension Veternarian at Ohio State University, "Unlike sheep and goats, cattle tend to develop a much stronger immune response to gastronintestinal parasites after a season of grazing exposure." However, research from USDA Agriculture Research Service (ARS) and North Carolina State University (NCSU) have reported evidence of increasing resistant worm populations and decreasing efficacy of deworming drugs like avermectin pour-ons.
Dr. Gasbarre, recently retired ARS parasitologist, conducted research at the Wisconsin backgrounding operation, which used intensive grazing management and strategically timed deworming for more than 17 years. The research confirmed the decreased performance in calves was due to internal parasites still present after deworming. Research at NCSU, compared efficacy of various in anthelmintics (generic label ivermectin pour-on, brand-name ivermectin pour-on, injectable ivermectin, or drench of fenbendazole) in two different research herds. In one herd, where previously worm resistance had been identified, the only dewormer to have greater than 90% reduction in fecal egg counts, was fenbendazole. In contrast, all the anthelmintic treatments in the other herd reduced fecal counts by more than 90%. This indicates worm resistance to anthelmintics may be specific to herds and locations, therefore internal parasite control may need to be developed specifically for a farm.
Internal parasite management is no longer as simple as deworming cattle, but should include some of the following strategies:
1) Fecal Egg Count Reduction Test (FECRT) protocol, used by USDA National Animal Health Monitoring System (NAHMS), is a valuable tool to determine when animals need to be dewormed. In addition, this can be used to detect worm resistance in a group of cattle. The test can cost between $10-15 per head, but the entire herd does not need to be tested. A farmer should test at least 20 of the most susceptible animals in the herd.
2) Calves are more susceptible, shed the most eggs, and require less product to deworm than cows in the herd. Farmers could reduce cost and overuse of product by only deworming calves in the herd at the appropriate times.
3) Farmers should avoid overusing dewormers and use these products in moderation. This can occur by deworming when the drugs are most effective instead of when convenient to administer. Furthermore, the dewormers should be given using the correct dose. This requires knowing the actual individual weight or average body weight of the animal when administering the drug.
4) If resistance is detected though testing, changing drug class is recommended. Another alternative could be rotating chemicals in the deworming program.
5) Good pasture management is also critical to reduce resistance. Rotate cattle through pastures to reduce re-infections, and it is recommended to let the pastures rest for 3 to 4 weeks before re-introducing cattle.
Do You Know the Enemy? Don't Let the Brown Stomach Worm's One-two Punch Knockout Your Profits - Dr. Michele Bilderback, Extension Veterinarian, University of Kentucky
As we approach spring working of cows and calves and the growth of new pasture, it is important to understand the life cycle of cattle's most common problem parasite, the brown stomach worm (Ostertagia ostertagi). It thrives in temperate climates such as Kentucky's, especially in the moist and cool weather we usually experience in the spring. However, it is very susceptible to hot and dry conditions- a fact we can use to our advantage when choosing when to deworm.
This roundworm ("nematode") goes through a developmental process of 4 stages of larva (immature worm) and 1 egg-laying adult stage. Adult worms live in the abomasum or "true stomach" of a cow or calf for approximately 30 days where they reproduce and lay eggs. These eggs are passed out on the ground in fecal material and then go through a two week developmental stage while feeding on the manure. Larvae can survive up to a year in fecal pats, even in drought conditions or underneath snow. When the immature worm reaches the L3 stage, it must get away from the fecal pat and out on the forage to be eaten by cattle. Since the larva have no legs, they are forced to move in a film of moisture and generally move less than 1' away from the fecal pat and no more than 4" up the forage. One drop of dew may contain hundreds to thousands of immature larvae.
Once swallowed, the disease process begins. Young cattle (7-15 months old) experience "Type I Ostertagiasis" in which the larvae enter the stomach glands, grow and become adults in 3 weeks. When the adult worm leaves the gland, it tears its way out and begins feeding on the lining of the stomach. This destruction of the gastric glands makes it very difficult for the animal to digest protein which in turn causes diarrhea. Older cattle (12-20 months old) experience a "Type II Ostertagiasis". In this case, the L3 larvae migrate to the stomach glands, develop into 4th stage larvae then enter a sort of hibernation known as "hypobiosis". The immature worms remain in the stomach glands while the weather is extremely hot and dry outside, waiting for better conditions for survival of their eggs. When the weather gets cooler and wetter in the fall, all of the dormant larvae that have accumulated in the stomach glands tear out all at once, causing severe, rapid and sometimes catastrophic damage.
Control of this parasite involves treating to kill the adults, the larvae in the stomach glands as well as any new larvae ingested from the grass. Broad spectrum dewormers known as "macrolides" (Cydectin, Dectomax, Ivomec, Eprinex) are very effective and last several weeks so incoming larvae are killed before they reach the stomach glands. The "benzamidazoles" (Valbazen, Safeguard, Synanthic) are also very effective but short acting. In Kentucky, research has proven late June to early July to be the optimal time for deworming of cows and calves. All young stock under 2 years old should be dewormed again in the fall since they are most susceptible to parasite problems. Although adult cattle are often considered "immune" to worms in the stomach, these adult worms will reproduce and lay eggs during times of stress, especially at calving. Therefore deworming of all cattle is essential to decreasing pasture contamination.
In summary, control of the brown stomach worm comes from an understanding of the host-parasite-environment interaction. Bear in mind that anything done to break up manure and expose the larvae to light and heat will reduce their numbers in pasture. Avoid overgrazing that forces cattle to eat too close to manure and the ground. Strategic deworming for all cattle on the farm in late June-early July and a second round in the fall for young stock will help to eliminate parasitic disease and economic loss as well as reduce pasture contamination.
Will Cows Get Pregnant in the Coming Breeding Season? - Dr. W. Dee Whittier, Extension Veterinarian, Cattle, VA-MD Regional College of Veterinary Medicine, VA Tech
The winter of 2010 has broken a number of records. Beef cows on most farms have probably been affected to a significant degree by the winter. The seventy days of snow cover that we experienced in Blacksburg have altered cow diets for the worse while unusually cold temperatures and wind chills have markedly increased nutrient requirements.
A review of what research and experience has taught us about reproductive performance helps us predict and hopefully take steps to remedy the effects of this situation on the upcoming breeding season. Otherwise open cows and later calves may have a profound effect on future profits.
Years of research have helped to show the major factors that influence each of these main items. Here are the generally agreed on contributors:
So what's different this season than most years? Cows lost more weight in the winter and therefore calving at lower body condition scores than usual. That means that they will tend to be slower to cycle than usual. If the average cow begins cycling twenty-one days later that results in about 15% more open cows in a 65-day breeding season.
A wise producer can use the other knowledge we have of the factors that determine outcomes of beef reproduction to overcome this drawback. Here are some procedures that can be done to increase the odds that cows will become pregnant efficiently.
Having a successful breeding season this year will require that typical management be improved in many operations. Utilizing some of the above special techniques, even if they are not necessary in most breeding situations, may pay real dividends this season.
OSU Animal Sciences Hall of Fame Induction is Set
On May 19th, the Department of Animal Sciences will celebrate the achievements of those who have enhanced student education and enriched the animal sciences industry through the annual Hall of Fame ceremony. Several prestigious student awards will also be presented.
This year, the Department will induct Tim Barnes, Shropshire Breeder, Livestock Judge, and Industry Leader into the Animal Sciences Hall of Fame. Recipients of the Animal Sciences Hall of Fame have demonstrated superior skill and achieved success in the field of Animal Science for themselves and their families. They have also practiced service to others through giving their time, energy and thoughtfulness in the local community.
Barnes earned his induction into the Hall of Fame through his continued leadership in the agricultural community. Barnes, a 1972 graduate of The Ohio State University Department of Animal Sciences, has been active in the sheep industry since he first showed Shropshire Sheep at his county fair in 1959. Barnes is never too busy to talk with a producer whether it be a veteran or youth and is continually active in sheep organizations and judges in sheep shows across the State and the country.
He is a past president of the Ohio Sheep Improvement Association and the Ohio and American Shropshire Breed Associations. Last December, the OSIA awarded him with the Charles Boyles Master Shephard Award which he helped develop.
Barnes and his wife Debbie along with their two grown sons-Chad and Shane operate the family sheep farm and their family's grain operation-Scioto Farms in Delaware County.
The Hall of Fame Ceremony is set for 3:00 to 4:00 p.m., to be followed by a social hour. For more information, contact April Hayes (email@example.com) or Dr. Steve Boyles (firstname.lastname@example.org).
Weekly Roberts Agricultural Commodity Market Report - Mike Roberts, Commodity Marketing Agent, Virginia Tech
LIVE CATTLE futures on the Chicago Mercantile Exchange (CME) closed up on Monday with the exception of the deferred June 2011 contract. The APR'10LC contract finished at $99.525/cwt; up $0.300/cwt and $0.575 over a week ago. JUNE'10LC futures were up $0.675/cwt at $95.500/cwt and $1.00/cwt higher than last report. The AUG'10LC contract closed at $94.325/cwt; up $0.825/cwt and a $1.600/cwt over last Monday's close. Short covering and Friday's bullish USDA report were supportive. On Friday USDA put the April 1 feedlot cattle supply at 10.769 mi head; 96.5% compared to this time last year. The average trade expectation was for 97.1% of a year ago. March placements were put at 103% of last year at this time vs. trade estimates of 106.6%. This is the smallest supply in 6 years. No fed cattle were reported trading in the Plains states. Prices are expected to retreat to near $98/cwt amid asking prices of $100-$101/cwt. Early on Monday USDA put the 5-area average at $99.39/cwt; down $0.12/cwt from this time last week. Good wholesale beef trade was reported with USDA putting choice boxed beef at $170.34/cwt; up $1.38/cwt from Friday and $3.23/cwt over last report. Floor traders were cautious noting worries over a slowdown in beef consumption when higher priced beef get to store shelves in a few weeks. According to HedgersEdge.com, the average packer margin was raised $18.40/hd from last report to a positive $45.50/hd based on the average buy of $99.35/cwt vs. the average breakeven of $103.00/cwt. The question is, "Will the DOW continue to strengthen keeping prices good or will the government suit against Goldman Sachs result in a loss in the DOW and a fundamental way of futures trading thus lowering all commodity prices when Goldman-Sachs exits an enormous amount of long positions?" Newspapers are already comparing futures trading in crop and livestock commodities to financial derivatives trading in mortgages. If the DOW sinks, so will cattle.
FEEDER CATTLE at the CME finished up on Monday. The May'10FC contract closed up $1.175/cwt at $113.750/cwt; and $0.70/cwt higher than last week at this time. AUG'10FC futures closed at $116.950/cwt; up $1.375/cwt and $0.925/cwt over last report. Feeders followed fats higher on short-covering and profitable cattle prices goading feed yards into paying more for young cattle. Spot April and nearby May futures at discounts to the CME feeder cattle index encouraged buying. The April contract expires on Thursday. The CME feeder cattle index was placed at $112.53/lb; down $0.21/lb and $0.92/lb lower than this time last week. Cash prices were steady to firm with 12,000 head reported sold in Oklahoma City. Last Monday 7891 head were sold and this time last year 9653 made the trip. As long as fat cattle market and the DOW are in good shape feeders should remain firm.
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BEEF Cattle is a weekly publication of Ohio State University Extension in Fairfield County and the OSU Beef Team. Contributors include members of the Beef Team and other beef cattle specialists and economists from across the U.S.
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