A new feed ingredient that contains probiotics or “good bacteria” can reduce the presence of E. coli 0157:H7 in live cattle by as much as 50%, according to researchers at Texas Tech University.

In the study, which was conducted during the summer (when cattle are known to shed more E. coli), 180 steers were fed one of three diets. The control group received a standard diet of grain and roughage. The other two groups received a standard diet that also included one of two strains of Lactobacillus acidophilus, which is similar to the bacteria commonly added to yogurt.

Fecal samples from the cattle were analyzed upon arrival and every 28 days thereafter until they received probiotic supplementation. After a 60-day supplementation period began, samples were analyzed every 14 days. Researchers used the most sensitive test methods available to detect the presence of E. coli 0157:H7.

During the mid-feeding period, the number of cattle testing positive for E. coli 0157:H7 was 18% to 19%. Near slaughter, that number was less than 10%. Cattle fed the probiotics showed major reductions in the incidence of E. coli.

Besides reducing E. coli, the probiotic is extremely cost-effective. Researchers estimate the cost of feed supplementation is roughly 1¢/animal/day, which is offset by improvements in feed conversion.

Further research studies are underway and, if successful, will lead to commercial field trials aimed at affirming the benefits of this strain of Lactobacillus acidophilus.

To view this research in its entirety, visit the American Meat Industry Foundation's Web site at www.amif.org.

Cattle are a natural reservoir of the food-borne pathogen E. coli O157:H7. Because sodium chlorate is bactericidal only against nitrate-positive bacteria, it's been suggested that chlorate supplementation be used to reduce E. coli O157:H7 populations in cattle prior to harvest. In work at the Southern Plains Agricultural Research Center, College Station, TX, cattle were given access to drinking water supplemented with different levels and forms of sodium chlorate.

Results of this study indicate that treating cattle with sodium chlorate reduced E. coli O157:H7 populations at a pre-harvest critical control point.

Even though chlorate kills intestinal bacteria, those cells lacking nitrates are unaffected by sodium chlorate. Thus, the gastrointestinal fermentation profile was not altered by chlorate supplementation in this study. It appears that chlorate could be used to improve food safety, but further studies are needed to determine the most effective treatment regimen.
Journal of Animal Science 2002 80:1683-1689

Research in Georgia was designed to determine the impact of selecting sires based on yearling intramuscular (IM) fat measured by ultrasound on corresponding marbling score. Ultrasound measurements collected in purebred cooperator herds were combined with other ultrasound records collected by the American Angus Association.

Ultrasound genetic values for fat thickness, ribeye area and IM fat percentage were computed. Each year, bulls were randomly mated to commercial Angus females.

Data show that yearling Angus bulls selected for high IM fat percentage or high ultrasound IM fat percentage expected progeny difference (EPD) can be expected to produce steers with significantly higher amounts of marbling and quality grade. Apparently, marbling can be increased without corresponding increases in external fat thickness and yield grade.

This implies that ultrasound IM fat percentage should be included in genetic evaluation programs to allow producers to select animals that can influence the degree of marbling in progeny at a younger age.
Journal of Animal Science 2002 80:2017-2022

Measurement of differences in wholesale cut yields of beef carcasses at plant chain speeds is important for the application of value-based marketing. To improve the accuracy of grade assessment, Colorado researchers evaluated the ability of a commercial video image analysis system — the Computer Vision System (CVS) — to predict commercially fabricated beef subprimal yield and augment USDA yield grading.

The CVS was evaluated as a fully installed production system, operating on a full-time basis at chain speeds. This work indicates CVS (either alone or combined with some human grader estimates) more accurately predicted carcass cutout yields than did yield grades assigned by online graders.

Data indicate that predicting wholesale cut yields using CVS assessments was more accurate than whole-number yield grades assigned by online graders. The results also indicate CVS approached yield grades assigned by expert graders, and an augmentation system combining yield grade factors assigned by expert graders with cold camera ribeye area was as accurate as yield estimates made by expert graders.
Journal of Animal Science 2002 80:1195-1201

It's confirmed. Transportation is a major contributor to cattle stress. A study at the Lethbridge Research Centre in Alberta, Canada, found that after a three-hour trip, plasma cortisol concentrations and heart rates were higher in cattle than before loading. What's more, loading itself resulted in a 50% increase in heart rate.

The study is part of the center's ongoing research to lay the groundwork for stress-reduction strategies. Further studies will include developing objective means to measure stress and help build the basis for effective animal care protocols.

An objective measure of stress in cattle would help producers cut production costs and stress-associated losses by altering management to minimize stressful situations, the researchers say. Stress contributes to reduced growth and reproductive performance in cattle, as well as increased health problems and reduced carcass quality.

For more information, contact Gerry Mears at 403/327-2238 or visit www.agr.gc.ca/science/lethbridge.

Compiled by BEEF staff. To submit items for “Research Roundup,” e-mail dbarto@primediabusiness.com or fax to 952/851-4601.