Beef Management Tips

Livestock Update, September 2007

Dr. John B. Hall, Extension Beef Cattle Specialist, VA Tech

September Beef Management Calendar

Spring Calving Herds

• Test hay for nutrient content and make decisions on supplements now!
• Give pre-weaning vaccinations to calves for VQA program
• Pregnancy check cows
• Body condition score cows at weaning and separate thin cows
• Put open, old and very thin cows on cull list
• Make arrangements for backgrounding calves
• Continue feeding high Se trace mineral salt
• Continue to stockpile grass, if possible

Fall Calving Herds

• Body condition score cows; plan nutrition grazing program on BCS
• Inventory feed supplies for winter, make decisions on alternative feed supplies now!
• Make sure all calving supplies are on-hand and clean
• Move pregnant heifers and early calving cows to calving area about 2 weeks before due date
• Start calving
• Check cows 3 to 4 times per day; heifers more often – assist early if needed
• Keep calving area clean and well drained; move healthy pairs to large pastures 3 days after calving
• Ear tag all calves at birth; castrate male calves in commercial herds
• Give selenium and vitamin A & D injections to newborn calves
• Feed cows extra energy after calving especially to two-year-olds.  Cows calving at BCS < 5 should receive special nutritional attention
• Keep high quality, high Selenium, high magnesium minerals available
• Purchase estrous synchronization supplies; line-up AI tech or AI supplies

Prussic Acid Poisoning Could be a Problem in Late Summer and Early Fall

Members of the sorghum family such as grain sorghum, forage sorghum, sudex, Sudangrass and Johnsongrass may produce high level of prussic acid during times of stress.  Wild cherry, choke cherry, peach, apple and elderberry trees can also form prussic acid.  Prussic acid also known as hydrogen cyanide is extremely toxic to mammals in high amounts.  This cyanide compound quickly inhibits the animal’s ability to use oxygen and death occurs in a matter of minutes to hours.

The plants mentioned above produce sugars in the leaves and stems, which contain the cyanide ion.  Drought stressed plants produce high levels of these sugars. When the plant is damaged or chewed these sugars combine with other enzymes in the plant to produce prussic acid.   Normally, plant growth keeps the concentration of these sugars low enough that the animal can detoxify the prussic acid.  However, concentrations of prussic acid reach toxic levels in drought-stressed, frost damaged, or storm damaged plants.

To avoid prussic acid poisoning, producers should not graze cattle on drought stressed, storm damaged or frosted forages from the sorghum family.  Additionally, cattle should be kept away from wilted cherry leaves from newly cut or storm damaged trees.  The prussic acid danger in forages is reduced after several weeks of significant regrowth following a drought or one to two weeks following a killing frost.  Dried cherry leaves do not pose a danger.  Also, prussic acid content of the forage can be reduced by 50% through the hay curing or ensiling process.  So making hay or silage from these crops may be the best option.

Tests for prussic acid are available through the state diagnostic labs or other laboratories.  Forages should contain less than 50mg% on a dry basis to be safe to feed.  Pasture samples need to be taken fresh and frozen.  Remember summer annuals may also be high in nitrates.  For more information on prussic acid poisoning in livestock or sampling procedures contact your county extension agent.

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