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In 2019, severe spring weather included blizzards, floods and twisters that created serious management concerns for beef producers. Cattle reduced their mineral consumption because free choice minerals likely washed away, lost effectiveness due to leaching or were not provided consistently. Some producers concentrated only on moving animals to higher ground. Weather caused delays in working cattle, further disrupting supplementation and vaccination schedules. Operators also faced the challenges of locating quality, carryover hay supplies. Some provided old hay bales that had lost nutrients to UV light and inclement weather. Harsh environmental conditions potentially stress cattle, causing them to deplete essential trace minerals. Severe weather events such as these created a weather-induced mineral crisis. Roberto A. Palomares, DVM, Ph.D., Associate Professor at the University of Georgia, and Director of Group for Reproduction in Animals, Vaccinology and Infectious Diseases (GRAVID), has studied the effects of injectable trace minerals (ITMs) on cattle immunity for five years. ITMs include copper, zinc, selenium, and manganese. In a recent trial, Palomares immunized 48 one-month old dairy calves with an intranasal modified-live virus (MLV) vaccine. Half of the animals received Multimin®90 ITMs, while the remaining half received saline solution. Sixty days later, calves were assigned to four groups of 12 calves each: • One set received intranasal MLV vaccine and another dose of ITM, • One set received subcutaneous (subq) MLV vaccine and ITM, • One set received intranasal vaccine and saline solution, and • One set, subq vaccine and saline. Twelve calves served as a control group, receiving neither vaccines nor ITMs. “After 49 days, we challenged them with Bovine 64 California Cattleman July • August 2019

Viral Diarrhea Virus (BVDV) and Infectious Bovine Rhinotracheitis Virus (IBR),” Palomares recalls. “Finally, we placed an endoscope into the upper respiratory tract to determine disease protection by determining the levels of inflammation and tissue damage.” Since endoscopes are not routinely used in cattle, Palomares created a scoring system reflecting symptoms in sinus and nasal cavities, the nature of excretions, and the appearance of the larynx, trachea, and bronchi. The control group, also challenged with BVDV and IBR, displayed significant inflammation, respiratory tract ulceration, and soft tissue nodules. BVDV commonly suppresses immunity, allowing highly infectious bacteria, such as Pasteurella multocida or Mycoplasma bovis to cause secondary infections. “The two groups receiving vaccines plus ITMs had significantly lower endoscopic respiratory clinical scores,” Palomares reveals. “Although those receiving vaccine only were protected from infection compared to unprotected animals. Animals receiving ITMs with vaccine had the highest positive statistical difference, suggesting that ITMs decreased inflammation and tissue damage caused by BVDV and IBR.” Stress from inclement weather, weaning, shipping, or vaccinations may result in excessive oxidant or free radical production. These compounds damage cell DNA, nuclei, and cell membranes. Both leukocytes (white blood cells) and neutrophils (specialized white blood cells) fight infection and are especially susceptible to oxidant damage. Trace minerals, particularly copper, selenium and zinc, boost enzymes that neutralize free radicals. Zinc is also crucial for the growth of cells involved in DNA replication, such as white blood cells. Selenium also moves neutrophils to infection sites. Manganese converts cholesterol to estrogen and testosterone, which is necessary ...CONTINUED ON PAGE 66

Profile for California Cattleman

July/August 2019 California Cattleman magazine  

July/August 2019 California Cattleman magazine