An extensive review of research on the value of using androgenic, estrogenic and combination implants on production and meat quality in beef cattle was conducted at Mississippi State University.
Average daily gain, feed conversion efficiency and increased daily feed intake improved with estradiol implants in steers.
Trenbolone acetate-treated heifers had more efficient feed-to-gain conversion than untreated heifers.
Calves implanted with zeranol exhibited fewer signs of environmental stress. This offers the opportunity to reduce production costs by increasing the vigor of feedlot steers and reducing the incidence of stress-induced illnesses.
Implants have both beneficial and detrimental effects on carcass quality.
Carcass protein and longissimus area are increased by implants.
Carcass weight, carcass length and leg length were increased by estradiol implants, and kidney, pelvic and heart fat and conformation scores were decreased.
Anabolic implants have been suspected of causing meat quality defects since they entered mainstream use. Anabolic implants tend to reduce fat deposition, resulting in decreased marbling scores and fat thickness, as well as decreased percentages of carcasses grading Choice.
Implanted steers had greater percentage of carcasses that would be discounted because of maturity.
Implants have been shown to decrease tenderness.
The most adverse effect of implant use is the occurrence of dark cutters in cattle.
Anabolic implants consisting of estrogenic, androgenic or combinations of estrogenic and androgenic hormones benefit production by increasing rates of gain and feed efficiency.
Producers should not use implants if their herd has a history of producing dark cutters or if their cattle have a high percentage of Brahman influence, as these cattle are more prone to stress prior to slaughter and have higher incidences of producing dark cutting beef. Producers with low marbling cattle should be wary of using implants because they have been noted to reduce marbling. (Webb, et al., Mississippi State University as reported by Tom R. Troxel, Extension beef cattle specialist, section leader — Anim. Sci.)
Measuring Meat Tenderness
Scientists at the U.S. Meat Animal Research Center, Clay Center, NE, and associates in Colorado and South Dakota looked at the use and accuracy of three objective systems for identifying tender beef. The three systems — prototype of the BeefCam, colorimeter and slice shear force — were evaluated based on progressive certification of the longissimus as “tender” in 10% increments.
In Phase I, 308 carcasses (105 top Choice, 101 low Choice, and 102 Select) from two commercial plants were tested. In Phase II, 400 carcasses (200 rolled Select and 200 rolled Choice) from one commercial plant were tested.
The prototype BeefCam performed poorly in this study. The colorimeter performed inconsistently, appearing to be useful in Phase I, but not in Phase II, and was of little value when used within USDA Select.
Bottom line — in this study at least, indirect, non-invasive methods that are based primarily on measuring lean meat color to predict meat tenderness may not be sufficiently accurate to warrant their use. (J. of Anim. Sci., Dec, 2002. 80: 3315-3327.)
Sweetgrass Adaptation Trial
The Bridger, MT, Plant Materials Center (PMC) has joined forces with four neighboring PMCs to test the regional adaptation of sweetgrass — Hierochloe odorata. In spring 2002, Bridger received plants from the PMCs at Bismarck, ND; Manhattan, KS; Meeker, CO and Roselake, MI. South Dakota State University released the commercial variety, ‘Radora,’ in 1998 and it has been included in the study as the standard of comparison. In turn, Bridger sent plants to each of the PMCs for testing in their respective environments.
All plants were lined out in short rows with ample space allowed for spreading, and then sprinkler irrigated twice weekly over the summer. An initial evaluation conducted in October at Bridger looked at several performance factors including survival, vigor, establishment, rate of spread, tiller development, and leaf length. The overall ranking from best to worst was Montana, Michigan, Colorado, Kansas, North Dakota, and Radora.
Preliminary results from North Dakota showed the Colorado and Montana collections performing well. Colorado reported that the Montana entry survived a sneaky attack of glyphosate. Michigan indicated that all transplants had survived, and Kansas had poor overall survival due to the effect of an ongoing drought. The PMCs are expected to carry on their appraisal of sweetgrass through 2004.
There is a continued interest in sweetgrass as a culturally significant plant for use in religious and spiritual ceremonies, as well as in a variety of medicinal treatments. Montana is gearing up for the 2004 bicentennial celebration of the Lewis and Clark Expedition and it is anticipated that sweetgrass will play a vital role in the festivities.
Direct inquiries to Susan R. Winslow USDA-NRCS, Plant Materials Center, RR2, Box 1189, Bridger, MT 59014, 406/662-3579.
Secrets Of The Bovine Rumen
Canadian researchers are using new molecular tools to shed light on the ecology of the bovine rumen. They say this work holds the key to more efficient production, healthier livestock, less waste and higher quality meat and milk products. Agriculture and Agri-Food Canada (AAFC) researchers have long recognized the broad potential of the rumen environment but, until recent years, it's been difficult to observe, says Ron Teather of AAFC's Lethbridge, Alberta, Research Centre.
Now, with advances in science, researchers can peer into the rumen at the molecular level — giving them a much clearer picture of the organisms it contains and how they function.
“Until recently the rumen was just a black box — you'd put something in and see what comes out at the other end,” he says. “We used to think the rumen contained 30 or 40 different kinds of bacteria — now we realize it contains more than 500.”
For the first time, scientists can now follow the behavior of these microorganisms. One aspect Teather finds intriguing is how rumen bacteria actually compete with one another by producing natural antimicrobials. These natural antimicrobials play an important role in how the rumen functions.
Teather and fellow researcher Bob Forster discovered that these bacteriocins may provide an important tool for improving rumen function.
“Like some antimicrobials from other sources, bacteriocins can prevent disease, improve feed efficiency and alter the fat composition of livestock products,” Teather says. “Rumen bacteriocins are also non-toxic, digestible, leave no residue in meat or milk, and of course are natural in the rumen.”
For more information, contact Ron Teather at 403/317-2246.
Injection Site Lesions And Vaccine Response
Cattle producers often wonder if injection site swellings or lesions are an indication that treatment efforts and money have been wasted. Experiments conducted by University of Arkansas beef specialists indicate just the opposite.
The scientists compared the clostridial antibody response of eight-month-old heifers that did and did not develop visible injection-site lesions and swelling. Blood samples were collected on days 0, 28, 56, 84 and 112 after injection with a 7-way clostridial subcutaneous vaccination. The vaccinations were given in the neck with a pistol-grip syringe using the tented technique.
Heifers with lesions (64.9%) actually had elevated antibody titers for Clostridium chauvoei (blackleg) on day 28 and day 84 compared to heifers without lesions or swelling. Clostridium sordelli and Clostridium perfringens antibody titers were higher in heifers with lesions on days 28 and 56.
Consequently, the presence of an injection-site lesion or swelling following a clostridial vaccination may not have visual appeal but may have positive implications for immune response. (Troxel and co-workers. 2001 University of Arkansas Anim. Sci. Research Report.)
USDA Adds Voluntary Feedlot Report
USDA introduced a daily, voluntary feedlot report for finished steers and heifers in late February. The Central U.S. Daily Direct Feedlot Slaughter Cattle Report will supplement mandatory reports.
The information will be published each day at 3:30 p.m. (CST). Additional reports may be published during active trading days. Initially, the report will cover the Texas and Oklahoma panhandles and Nebraska. Coverage might be expanded as contacts are established and information is gathered.
The report will contain information about live, carcass-based and grid sales. It will be posted at www.ams.usda.gov/lsg/mncs
“Research Roundup” is compiled by BEEF staff. Submit contributions to [email protected]