Printer Friendly Version

Reproductive Diseases Can Cost You • Forage Testing Up 51 Percent in Arkansas • Comparison of Nitrogen Sources for Forage Yield • Activities of the Arkansas Milk Stabilization Board • Byproduct Feeds: Getting the Most Out of Your Feeding Program

Reproductive Diseases Can Cost You
Dr. Jeremy Powell, Assistant Professor and Veterinarian

Sometimes we don’t realize the danger that is lurking around the next corner. Just when you get through the breeding season and you’ve got all the cows settled, it hits. A major abortion storm sweeps through that wipes out next year’s calf crop, and you’re left with all the puzzling questions: What could have caused this? How can you get a diagnosis? More importantly, what can you do to prevent this from occurring next year? There are many potential causes that lead to abortion or embryonic death in cattle, but the majority of the problems are typically due to a handful of pathogens – Leptospirosis, Infectious Bovine Rhinotracheitis (IBR), Bovine Viral Diarrhea (BVD), Trichomoniasis and Vibriosis.

Leptospirosis is a disease that can affect several species, including cattle, sheep, pigs, dogs, horses, wildlife and man. This disease is caused by bacteria that are well suited for wet, moist environments. Cattle can be exposed from consuming contaminated stock ponds or by wildlife, rodents or infected domestic animals. Transmission can occur when the bacteria penetrate a mucous membrane (mouth, nose, conjunctiva, genital tract) or enter an open wound. Once an animal is infected, the organism circulates throughout the body and localizes in the kidneys, mammary glands and genital tract. Once the urogenital tract becomes infected, the bacteria can be shed in urine, uterine discharge, semen and aborted fetuses/placentas. This shedding allows other herd mates to become exposed and infected.

Abortions due to Leptospirosis typically occur in the second or third trimester of gestation. Cows do not abort the fetus when they first contract the disease, and infected cows frequently exhibit no other signs of illness. If cows are affected very late in gestation, they may give birth to weak or poorly developed calves.

IBR can lead to several forms of clinical disease. The IBR virus can cause symptoms that range from respiratory tract infections, ocular infections, abortions, genital infections and neurological infections to a generalized infection of newborn calves.

Abortion from IBR typically occurs from four months of gestation up to term. Cows aborting due to an IBR infection may experience temporary infertility from vaginitis after the abortion has occurred. Unvaccinated herds are at the highest risk for IBR abortion problems.

BVD virus can cause a wide variety of clinical syndromes in cattle, including infertility, respiratory disease (pneumonia), congenital abnormalities (eye defects, brain defects), abortion and stillbirths in calves. If a pregnant cow acquires a BVD infection, there are several possible outcomes depending on the stage of pregnancy when she is infected.

A normal calf could be born to a cow that becomes infected during late gestation (> 180 days). However, an infection during early pregnancy (< 125 days) can result in more detrimental outcomes. During this time period, possible outcomes of an infection include early embryonic death, abortion, fetal mummification or a persistently infected calf. Fetuses exposed to BVD that are at 150 days or more of gestation could be born with congenital defects. These defects may lead to poor brain development, eye abnormalities, structural malformations and stunted growth. Calves born with congenital defects usually have difficulty standing and walking and may exhibit an early death due to a poor ability to nurse the dam.

Vibriosis is caused by bacteria called Campylobacter. It typically causes infertility during the breeding season due to loss of early pregnancies. Characteristic clinical signs of this disease would include a high percentage of cows in the herd returning to heat during the breeding season. They may also show prolonged or irregular estrus periods. Then, when calving season occurs, many cows will be calving later in the season due to the repeated breeding caused by infection. Infrequently, cows may abort between four and eight months of a Campylobacter infection.

Trichomoniasis is a venereal disease of cattle caused by a protozoa organism, Tritrichomonas foetus. This disease causes very few outward signs of illness. Therefore, it can often be present in a herd for a considerable time before it is suspected and diagnosed. Infected cows will experience infertility and early embryonic death, causing the cow to return to heat and subsequently extending the breeding season. This, in turn, causes devastating losses due to poor calf crops and prolonged calving seasons.

Trichomoniasis has few adverse effects in the bull, but the bull acts as the main source of transmission for the herd. In bulls, the organism lives on the tissue lining of the penis and prepucial sheath. Younger bulls less than 4 years of age tend to clear themselves of the infection, while those 4 years and older are often infected for life.

There are many other potential causes of abortion in cattle other than the diseases covered in this article. One that is worth mentioning is Brucellosis, also known as Bang’s disease. For some time, the U.S. had been classified free of Brucellosis. However, in light of the recent outbreak in Montana, the importance of preventing this disease has been re-established. Producers should strongly consider a preventative vaccine for their replacement heifers. Replacement heifers must be vaccinated by a veterinarian or state technician for Brucellosis between 4 and 12 months of age.

Diagnosing the cause of abortion is somewhat trying, and results can be inconclusive greater than 50 percent of the time. When submitting tissues to a diagnostic laboratory, careful handling of the sample submission is essential. Always refrigerate samples as soon as possible to prevent further breakdown of tissue. When submitting samples, you should include the fetus, the placenta and a maternal blood sample. Some diseases that cause abortion in cattle can also infect humans, so always be cautious when handling aborted fetuses and tissue. If you do not plan to use the tissues for diagnostic purposes, always remember to dispose of them so that other animals in the herd do not become exposed from these contaminants.

The chart below provides an estimate of age for an aborted fetus.

Table modified from New Mexico State University Cooperative Extension Service publication B-215

Although herd health needs may vary between operations, there are a few standard vaccines that should be included to prevent problems with reproductive diseases in your herd. Among these are a 5-way viral vaccine (IBR, BVD, PI-3, BRSV), a 5-way Leptospirosis vaccine and a Vibriosis vaccine. Since vaccination needs may vary, it is important to get your veterinarian’s input when selecting vaccines for your operation.

For more information on reproductive diseases and other cattle diseases, contact your county Extension office.

Forage Testing Up 51 Percent in Arkansas
Dr. Shane Gadberry, Assistant Professor

A survey at two Arkansas Beef Improvement Program workshops this past winter revealed 92 percent of the participants fed hay at least one-third of the year. The survey also revealed that  two-thirds of the participants in the two workshops never had their hay lots analyzed for nutrient content. Although having forages analyzed for nutrient composition isn’t a common practice for livestock producers, the number of samples submitted to the University of Arkansas Diagnostics Laboratory was up during the 2007-08 hay production and feeding seasons.

Higher feed prices may be the driving force behind the 51 percent growth, compared to 2006-07, in the number of hay samples submitted to the Diagnostics Laboratory between May 2007 and April 2008. Hay analyses reached almost 1,000 samples, up from the previous nine-year average of 554 samples. Bermudagrass and mixed grass accounted for 37 percent and 35 percent of the samples, with the remaining representing fescue, johnsongrass, forage sorghums and alfalfa.

Twenty-four percent of the samples submitted requested nitrate analysis. Within this group, 34 percent contained 700 ppm (beginning level for cautionary measures) or greater nitrate-nitrogen. While higher nitrogen costs have producers talking about reducing fertilization, concerns over nitrate accumulation do not diminish, especially with certain forages (johnsongrass, sudangrass and sorghum-sudan hybrids). Fortunately, many of the county Extension offices are now equipped with qualitative nitrate test kits that can be used to screen hay samples or standing crops prior to harvest.

The protein and energy content of the hays tested in 2007-08 remained the same compared to past years. Crude protein averaged 12 percent, with 68 percent of the samples within the range of 8.2 to 15.8 percent CP. Energy content, expressed as TDN (total digestible nutrients), averaged 56.5 percent with 68 percent of the samples within the range of 51.2 to 61.8 percent TDN.

Very few of the hay samples analyzed did not have enough combined protein and energy to meet gestating cow requirements. Overall, 95 percent contained a sufficient amount of protein for late-gestation and 84 percent percent contained an adequate amount of TDN.

Due to the additional protein requirement associated with milk production, there were fewer samples that met the protein requirement for lactation; however, 79 percent still contained enough protein for cows with moderate milking ability. Total digestible nutrients, unfortunately, were almost opposite of what was observed with protein. Sixty-two percent of the hays WERE NOT adequate in TDN for lactation.

High feed prices and other input costs are causing livestock producers to re-think forage production and supplemental feed practices. Hopefully, the value of forage testing is being realized. At the writing of this article, winter corn futures were trading for $6/bu. This could keep the byproduct feed energy market in the $150 to $170/ton range or greater and supplemental energy feed costs during lactation over $0.15 per head daily, not including hauling or local feed mill markups.

Not only does forage testing help identify where nutrient shortfalls occur and the type of supplemental feed needed to compensate for deficiencies, but forage testing is also a valuable tool to help determine if pre-harvest forage management practices need adjusting so the reliance on purchased concentrate feeds can be minimized. Grass hay protein content can be correlated with the amount of nitrogen fertilization. Reducing or eliminating nitrogen fertilization rates will not only reduce hay yields but will also result in lower hay protein content, increasing the odds for needing protein supplementation. On the other hand, TDN is highly correlated with plant fiber content – the higher the fiber, the lower the digestible energy. Fiber increases as the plant matures over time. If a forage analysis returns with an undesirably low TDN content, it can be interpreted as harvest was delayed too long. To improve TDN, the forage will have to be harvested at an earlier stage of maturity.

Rainfall patterns kept many producers in Arkansas from getting in the hay fields soon enough this spring, and a lot of fescue and ryegrass were being harvested at a mature stage. Ideally, cool-season grasses are harvested at a late boot, early head stage, which means the seed heads are just beginning to emerge from the stem. Harvesting at this stage will generally result in a TDN content that is sufficient for a lactating beef cow. Because of the delayed harvest, many of the hays cut this spring will be inadequate in energy for lactation.

The additional fuel and fertilizer costs along with short hay supplies have kept hay markets 54 percent above the five-year average reported by USDA. High feed prices and the lack of storage and handling facilities will limit the adoption of replacing hay with alternative feedstuffs in a wintering diet. Until reliance on hay for wintering beef cattle is minimized by stockpiling forages in fall and establishing complimentary forage systems, forage testing will continue to be a valuable tool for making cost-effective winter feeding and harvested forage management decisions.

Comparison of Nitrogen Sources for Forage Yield
Kenny Simon, Program Associate - Forages

Declining supply and increasing cost of ammonium nitrate have put pressure on fertilizer dealers and producers to switch to urea even though it may be less efficient for topdressing pastures. Nitrogen loss inhibitors, such as Agrotain, are being used in rice fields in eastern Arkansas to reduce urea volatilization. This product may improve efficiency of urea in pastures which could reduce fertilizer costs for producers managing for optimum forage production. The University of Arkansas Cooperative Extension Service is conducting farm demonstrations comparing nitrogen sources for effect on forage production.

In February 2008, a field experiment was established in a tall fescue pasture in Fulton County to determine spring response of tall fescue to four sources of nitrogen fertilizer – ammonium nitrate, urea, urea treated with Agrotain and calcium nitrate. Each fertilizer treatment was applied at the rate of 75 lb N per acre. Application date was February 29. Recent soil test indicated P and K levels were optimum. Fertilizer treatments were compared to a non-treated check and were replicated four times. The forage was allowed to grow until May 29 when all plots were harvested. A sickle mower was used to harvest a three-foot wide strip from the center of each plot. Subsamples were dried to a constant weight for moisture correction.

Results indicate that nitrogen should be applied to maximize growth response. Mean yields from nitrogen application in late February were more than one and one-half times the yield of the untreated check 5,571 lb/acre vs. 3,249 lb/acre, respectively (Table 1). Yield was not different among nitrogen sources. Urea with Agrotain tended to have a numerically higher yield; however, the difference between it and other N sources was not statistically significant.

Table 1. Effect of nitrogen source on dry matter yield of tall fescue

^a All N sources applied at rates of 75 lb/acre N.

^b Yields are means of four replications.

^c,d Uncommon superscripts within the same column are significantly different.

With record high fertilizer cost, it is important to get the maximum return on your investment. Fertilizer sources should be compared according to the cost per pound of nutrient. Comparing sources based on price per ton will not give an accurate assessment of the true cost per acre (Table 2). For example, of the N sources listed on page 4, there are considerable differences in the price cost per ton; however, the price/lb of nutrient is similar.

Table 2. Comparing the nitrogen prices (June 2008 retail prices) of common fertilizers

Now the big question, is it cost effective to apply N fertilizer? In order to determine if fertilizing with N is cost effective, we must work through the following. If producing 4’ x 5’ bales weighing 750 lb each, 3.1 additional bales would be produced per acre with N fertilizer. The average cost to apply 75 lb of N/acre is $57.38. Therefore, the N fertilizer cost per additional bale was $18.51.

In conclusion, ammonium nitrate was the most cost effective, yielding over one and half times the yield of the check for $0.73/lb N.

Byproduct Feeds: Getting the Most Out of Your Feeding Program
Paul Beck, Associate Professor

Back to Animal Science E-News