Strategy for Managing Horn Flies

megan van emon msu extension beef specialistDr. Megan Van Emon, MSU Extension Beef Cattle Specialist

As I’m sure many of you have noticed, it’s shaping up to be another bad fly year.  Horn flies are common on beef cattle here in Montana.  Annual control costs and cattle production losses can exceed $780 million annually in the U.S.

Horn flies spend the majority of their time on animals and will move from the back to the sides of the belly during the heat of the day.  Female horn flies deposit their eggs in fresh manure and can deposit up to 500 eggs during her life.  Horn fly larvae hatch and develop in manure.  Several generations of flies occur during the summer, with adult horn fly populations typically peaking during late summer.  When temperatures decline in the fall, horn fly pupae hibernate in the soil.

Horn flies prefer larger animals (cows, steers, heifers, and bulls), and tend not to bother calves until late summer.  One horn fly can bite 20 to 30 times per day, which can result in thousands of bites per day in large populations.  Cattle that are infested with over 200 flies will begin to bunch together in an attempt to escape the flies.  Large populations of horn flies cause changes in grazing behavior and can reduce feed intake, which ultimately decreases production.  Production losses include reduced feed intake, reduced feed efficiency, decreased milk production, and decreased weight gain.

Multiple methods are available for controlling horn fly populations.  Insecticides are the primary method for horn fly control as other methods are ineffective.  Methods available for cattle on pasture include dust bags, ear tags, sprays, pour-ons, boluses, and feed additives.

Dust bags, back rubbers, and oilers are most effective when cattle must pass under them on their way to water, feed, or mineral.  Dust bags can also be placed in loafing areas where they can be used free-choice.  Ear tags contain insecticides that allow for small amounts to be released over time by traveling through the hair coat when the animal is moving or grooming.  When using animal sprays to control horn flies, complete coverage and penetration to the skin is essential.  Sprays are easily applied, but require multiple treatments throughout the summer because the control of horn flies only lasts 3 to 4 weeks.  Pour-ons are also easily used and provide effective treatment for several weeks when used properly.  However, pour-on control may vary with weather and other factors.  Feed additives and boluses may be incorporated in mineral blocks, loose mineral or tubs.  The insecticides included as a feed additive pass through to the manure and kills the fly larvae.  Feed additives are most effective when consumed in sufficient amounts all season long.

For additional information and horn fly control contact your local Extension office to request a copy of the MontGuide by Greg Johnson, MSU Veterinary Entomologist.  The article is entitled “Horn Flies on Cattle: Biology and Management” (MT200912AG) and contains additional information about horn fly biology and available insecticide products.

Tips for a Successful Bull Season – Breeding Soundness Exams

Vet Tested. Kid Approved! Image via Jennifer Nielson from Fallon during 2015 Spring Bull Testing

Vet Tested. Kid Approved! Image via Jennifer Nielson from Fallon during 2015 Spring Bull Testing

By Dr. Megan Van Emon, Montana State Beef Cattle Extension Specialist

One of the most cost efficient methods of a successful breeding program is the breeding soundness exam (BSE) conducted on bulls.  Bulls are responsible for breeding 20 to 50 cows each breeding season while cows are responsible for one calf each year.  Having a BSE conducted on the bulls is crucial to a successful breeding program.

The BSE is an exam conducted by veterinarians that includes a physical exam, semen evaluation, and an internal and external exam of the reproductive tract.  Evaluating the feet, legs, teeth, eyes, flesh cover, and scrotal circumference and shape is included in the physical exam.  The semen evaluation includes semen normality and motility.  The BSE should be conducted 30 to 60 days prior to the beginning of breeding.  It is important to note that the bull’s sperm production cycle is approximately 60 days, and if illness, injury or other issue occurs, this could negatively impact the BSE and breeding capability of the bull and may need to be re-evaluated.  An additional BSE can be conducted at the end of the breeding season to determine if bull fertility decreased throughout the breeding season.

Body condition is crucial for bulls during the breeding season.  Having adequate flesh cover during the breeding season is needed to provide the extra energy required for breeding.  Body condition can be impacted by the number of cows the bull is expected to breed, the distance traveled to breed or eat, and nutrition during the breeding season.  A body condition score 6 or sufficient body condition that the ribs appear smooth across the bull’s side is the ideal flesh cover at the start of the breeding season.

Ensuring bulls are structurally sound in their feet and legs is needed to begin the breeding season.  Bulls with unsound feet and legs will have a difficult time walking and mounting for mating if a significant distance needs to be traveled for breeding.  General health of the bull is also needed to ensure bulls have adequate semen quality and the ability to mate.  Scrotal circumference is an essential measure because it is directly related to sperm production, sperm normality, and the onset of puberty.  The external and internal reproductive tract examinations ensure there is no inflammation, abscesses, warts, or penile deviations.

The semen evaluation includes the measurement of semen motility or the percentage of sperm cells moving in a forward direction.  The bulls needs to at least have 30% sperm motility to pass the BSE.  Sperm morphology, or the proper shape, is also determined and at least 70% of the sperm cells should have a normal shape.

If all of the minimum requirements are met, the bull will be classed as “satisfactory.”  However, if a bull does not pass one of the tests, they will be classed as “classification deferred.”  If a bull is classed as “classification deferred,” the bull should be tested again after 6 weeks.  If a mature bull fails the subsequent BSEs, they will be classified as “unsatisfactory.”  A young bull may be “classification deferred,” and pass the subsequent test.  Exercise caution when making bull culling decisions based on a single BSE.

Understanding Expected Progeny Differences (EPD)

megan van emon msu extension beef specialistBy Megan Van Emon, Montana State Extension Beef Cattle Specialist

Expected progeny differences (EPDs) estimate the genetic value of one animal over another of the same breed.  EPDs are calculated using statistical equations and models and use known information on that animal that is submitted by the breeder, which can include data from the animal itself, ancestors, relatives (i.e. brothers and sisters), and progeny.  Adjustment factors are used to adjust for data such as age and sex.  Another factor that is considered when calculating EPDs is the environment from which the animal comes.  Most commonly, EPDs are used to compare bulls within the same breed.

For example:

Bull 1 has a weaning weight EPD of 30.  Bull 2 has a weaning weight EPD of 17.  If both bulls were bred to a similar group of cows, we would expect calves from Bull 1 to average 13 pounds (30 – 17 = 13) heavier than Bull 2 at weaning.

Numerous other EPDs are used to compare bulls, such as scrotal size, birth weight, ribeye area, feedlot merit, calving ease, mature daughter’s weight, milk, etc.  Numerous other EPDs are available and can vary by breed.  EPDs are calculated and reported in the same unit of measurement as the trait (i.e. birth weight in pounds; fat depth in inches).

EPDs do NOT predict the actual birth weight, weaning weight, index value, etc of an animal.  They only predict the expected difference between animals.  If you want to know the average performance for a specific trait within a breed, many breed associations have sire summaries.

An accuracy value is also included with each EPD trait.  The accuracy is used to determine the reliability of the EPD and will be reported as a number between 0 and 1.  Accuracy increases towards 1 as more data is reported for a specific animal.  It is also important to note that as the accuracy moves closer to 1, the EPD of the trait for that bull will not change significantly in the future.  Young bulls that do not have any progeny data rely on data from ancestors for accuracy, which is usually from 0.1 to 0.4.

EPDs can be compared across breeds, if the proper adjustment factors are used.  Breed adjustment factors are developed at the Roman L. Hruska U.S. Meat Animal Research Center in Nebraska and are updated each year.  The base of the comparison is to Angus EPDs.  Comparing EPDs across breeds is less accurate than comparing within the same breed.

It is important to note that EPDs do NOT guarantee a specific difference on each animal.  EPDs are constantly changing as more data is added for each bull.  As more data is added to the system for a specific bull, extreme values are averaged out.  Extreme values can occur, even in a high accuracy (high reliability) bull.

EPDs should be used as a management tool for your cow herd, but should NOT be the only tool.  Physical appearance, or phenotype, should also be a tool used when selecting bulls.

When and Why to Body Condition Score Cattle

megan van emon msu extension beef specialistBy Dr. Megan Van Emon, MSU Extension Beef Cattle Specialist

Body condition scoring is a management tool that can be used to evaluate the nutritional status of beef cattle. The tool uses a numeric score, 1 to 9, for evaluating the fleshiness, or body energy reserves, of the beef cow and does not require the gathering and working of cows. Body condition score utilizes a score from 1 to 9, with 1 being emaciated and 9 being very obese, with the ideal BCS being 5 to 6. Areas considered when evaluating body condition score include the brisket, back, tail head, hooks, pins, and ribs.

Body condition scoring should be measured throughout the year at strategic time points during the production cycle. Body condition should be evaluated at the beginning of the breeding season, 90 days prior to calving, calving, late summer, weaning, 45 days after weaning, and fall. Maintaining the optimum BCS throughout year is crucial to maintaining reproductive efficiency and cow and calf health.

Evaluating BCS 90 days prior to calving will allow those thin cows to be separated and fed accordingly to improve body condition. Late gestation adds increased stress on the cow due to the rapid growth of the calf. Having adequate body condition at calving reduces the stress on both the cow and calf. Cows at optimum body condition at calving produce healthier calves and are able to maintain peak lactation compared with thin cows.

If cows are thin at calving, the pre-calving nutrition program or weaning dates may need to be changed. It is difficult for thin cows to gain body condition immediately after calving, which requires large amounts of high quality feeds. This may not be an economically viable decision.

Maintaining adequate BCS reduces postpartum interval compared with thin cows and will improve pregnancy rates after a 90 day breeding season. A BCS 5 or 6 improves pregnancy rates drastically compared with a BCS of 4. Therefore, having cows in good body condition during the breeding season improves pregnancy rates.

Measuring BCS between breeding and weaning (late summer) allows for nutritional adjustments to be made. If cows are thin heading into weaning, early weaning can be considered to reduce the stress on the cow. Early weaning of thin cows lets those cows regain condition before heading into the winter months and the increased nutrient demands during late gestation.

Cattle Body Condition Scoring Megan Van Emon MSU Extension

Analyzing BCS at weaning allows for thin cows to be separated and fed apart from the fleshy cows. This will help the thin cows regain body condition before heading into fall. This is also a time to focus on young cows that are weaning their first calf, as they are more likely to be thin compared to the older cows.

Evaluating body condition 45 days after weaning gives you a good idea if cows are regaining condition after weaning. If thin cows are not regaining body condition, then nutritional adjustments can be made before entering the winter months.

Condition scoring cows during the fall allows for the critical evaluation of feed resources. Most years, the fall months include reduced pasture availability and quality, which makes it difficult for cows to regain condition. Those cows that are thin heading into winter can be fed separately with supplemental feeds to improve body condition.

Concerns When Feeding Sprouted Grain to Cattle

megan van emon msu extension beef specialistBy Megan Van Emon, MSU Extension Beef Specialist

Summer in Montana has been a wild ride. Because of the weather, grain harvest was delayed in many areas, and some barley and wheat have sprouted in the seed heads.  These sprouted grains, although not suitable for traditional markets, can be used as a feedstuff for livestock.

Based on the research, sprouted grains have similar feed value to non-sprouted grains.  Daily gains and feed efficiency in the feedlot are similar between cattle consuming non-sprouted or sprouted grains.  However, due to the high starch content of wheat and barley, feeding below 20% of the total ration on a dry matter basis is recommended to minimize incidences of acidosis.  For the greatest benefit of feeding wheat and barley, either sprouted or not, the kernels should be rolled or cracked, and should never be self-fed or used for creep feeding. Fine grinding of wheat and barley should be avoided.

grain cattle ranch feeding montanaMajor areas of concern when feeding sprouted grains are proper storage and the potential development of mold and mycotoxins.  Proper storage of the sprouted grains is crucial to maintaining quality and limiting mold growth.  If moisture levels are less than 13 percent, it can be stored as you would ordinarily store grain. When determining moisture levels of a field, make sure multiple samples are collected.  Moisture content may vary across the field depending on topography and wind, which would cause uneven drying the sprouted grain.  If moisture levels are greater than 13%, ensiling may be a better option for storage.  Sprouted grains can be ensiled in silos, bunkers, or storage bags.  Whole grain does not pack well, so rolling or cracking of the grain should be done prior to ensiling.  Sprouted grains, such as barley and wheat, can be layered with corn silage during silage packing to ensile the sprouted grain.

Due to high moisture of the sprouted grains and with cool weather conditions, mold may develop. If mold is seen on sprouted grains, it is recommended to collect multiple samples from the field. Proper drying of sprouted grains may occur on the outer edges and will be less susceptible to mold and mycotoxin production compared to the center of the field. Mold and mycotoxin levels should be assessed prior to feeding or harvesting because they can be hazardous to both humans and livestock. Barry Jacobsen, MSU Extension Plant Pathology, cautions that the dose of the mold or mycotoxin is very important when feeding potentially moldy feed. Jacobsen suggests that when submitting samples to labs, mold species and genus should be identified if possible. If mycotoxins are present in the sprouted grains at moderate levels, the sprouted grains should be combined with clean, non-moldy feed to reduce mycotoxin levels. For more, please contact your local Extension Office.

Introducing Dr. Megan Van Emon – Montana State Extension Beef Specialist

megan van emon msu extension beef specialistDr. Megan Van Emon began as the MSU Extension Beef Cattle Specialist located at the USDA-ARS Fort Keogh Livestock and Range Research Laboratory in Miles City, MT on August 1.

Megan grew up on a small farm in northeast Indiana, where they raised pigs and dairy steers. She was a 10-year 4-H member and showed rabbits, goats, and beef. She studied Animal Science at Purdue University and graduated with her BS in 2006. Megan continued her education at Purdue with Dr. Scott Lake, studying ruminant nutrition and graduating with her MS in 2008. Her research topic was the optimization of protein quality of dried distillers grains with solubles for ruminants.

Megan moved to Hettinger, ND in May of 2009 to begin her Ph.D. in ruminant nutrition with Drs. Chris Schauer and Kim Vonnahme. Using sheep as a model for cattle, her research focus was supplementing metabolizable protein to ewes during late gestation and determining the effects on the offspring.

While in Hettinger, she also conducted research in weaning strategies with Angus calves and ram fertility. In May of 2013 Megan graduated from North Dakota State University with her Ph.D. After graduating from NDSU, she moved to Iowa State University as a Post-Doctoral Associate with Drs. Stephanie Hansen and Dan Loy in beef feedlot nutrition. Megan’s main research focus at ISU was to determine the effects of feeding algae meal to beef steers on digestibility, preference, and performance.

Megan says, “I’m excited to be here in Miles City and I’m looking forward to getting around the state to discuss the opportunities available here in Montana. Please call, email, text, and stop by.”

Megan’s Contact Information: Megan Van Emon; Office: 406-874-8286; Cell: 701-928-1096; Fax: 406-874-8289; Email: [email protected].