COW/CALF CORNER The Newsletter From the Oklahoma Cooperative Extension Service October 23, 2017

COW/CALF CORNER

The Newsletter

From the Oklahoma Cooperative Extension Service

October 23, 2017

In this issue

Feedlot inventory continues to swell

Derrell S. Peel, Oklahoma State University Extension Livestock Marketing Specialist

Prussic acid and nitrate poisoning are concerns after a light frost

Glenn Selk, Oklahoma State University Emeritus Extension Animal Scientist

Feedlot inventory continues to swell

Derrell S. Peel, Oklahoma State University Extension Livestock Marketing Specialist

Counter-seasonally strong feeder cattle prices this fall indicated good demand despite growing feeder cattle supplies.  The October Cattle on Feed report confirmed that much of that demand came from feedlots.  September feedlot placements were up 13.5 percent year over year, more than generally expected ahead of the report.  Marketings were up 2.9 percent over last year.  Feedlot inventories for October 1 were pushed higher by the large placements to 5.4 percent above year ago levels.  At 10.813 million head, the October on-feed inventory is the largest October inventory since 2012. 

September placements were higher across all weight categories but largest in relative terms for the heaviest and lightest weight categories.  Placements under 600 pounds were up 17.4 percent year over year while placements over 800 pounds were up 14.4 percent compared to last year.  Placements in the 600 and 700 pound categories were up 13.3 and 8.9 percent respectively.

Quarterly on-feed estimates in the October report showed that the number of steers on-feed was up 1.6 percent year over year on October 1 while the inventory of heifers in feedlots was up 13.0 percent from one year ago.  This indicates continued growth in heifers on feed (July 1 heifers on feed were up 10.6 percent year over year).  Heifer slaughter so far this year is consistent with these inventory totals, up 12 percent year over year, and suggests that heifer slaughter will continue to grow for the foreseeable future.  These numbers suggest that heifer retention (and likely herd growth) is slowing.  However, the average ratio of steer to heifer slaughter (which peaked recently in 2016) and is adjusting down, is still at levels not seen since 1975 (prior to mid-2015).  Steer slaughter for the year to date is up 2.9 percent year over year. 

Steer and heifer carcass weights continue to run well below last year with reported carcass weights for the most recent week down 16 pounds for steers and down 15 pounds for heifers compared to the same time last year.   Average fed carcass weights are down 14.6 pounds for the year to date. Average fed carcass weights are down due to lighter steer and heifer carcasses and a growing proportion of heifers to steers in the fed slaughter mix.  USDA reports total cattle slaughter up 5.8 percent year over year so far this year with beef production up 4.2 percent for the year to date. 

Prussic acid and nitrate poisoning are concerns after a light frost

Glenn Selk, Oklahoma State University Emeritus Extension Animal Scientist

Although late October has been very warm and “summer-like”, the average first frost date for much of the Southern Plains is here.  Soon a cold front will bring near-freezing to sub-freezing nighttime temperatures

 It was discovered in the early 1900s that under certain conditions sorghums are capable of releasing hydrocyanic acid or commonly called prussic acid.  Prussic acid when ingested by cattle, is quickly absorbed into the blood stream, and blocks the animal's cells from utilizing oxygen.  Thus the animal dies from asphyxiation at the cellular level.  Animals affected by prussic acid poisoning exhibit a characteristic bright red blood just prior to and during death.  Lush young regrowth of sorghum-family plants are prone to accumulate prussic acid especially when the plants are stressed such as drought or freeze damage.  Light frosts, that stress the plant but do not kill it, are often associated with prussic acid poisonings. 

Producers should avoid grazing fields with sorghum type plants following a light frost.  The risk of prussic acid poisoning will be reduced, if grazing is delayed until at least one week after a "killing freeze".  As the plants die and the cell walls rupture, the hydrocyanic acid is released as a gas, and the amount is greatly reduced in the plants.  One can never be absolutely certain that a field of forage sorghum is 100% safe to graze.

Cattle that must be grazed on forage sorghum pastures during this time of year should be fed another type of hay before turning in on the field, and should be watched closely for the first few hours after turn in.  If signs of labored breathing, such as would be found in asphyxiation, are noted, cattle should be removed immediately.  Call your local veterinarian for immediate help for those animals that are affected.  Be certain to read OSU Fact Sheet PSS-2904 “Prussic Acid Poisoning” before turning cattle to potentially dangerous fields. 

Frosts also stress the plant before a hard freeze kills it.  Plant stress from frosts will impair the normal metabolism of the plant.  Therefore the plant continues to take up nitrates from the soil but is inefficient at converting the nitrates to protein.  Therefore nitrate accumulations may reach dangerous levels.  Testing the forage before grazing or cutting for hay will provide important knowledge about the safety or danger in the forage.  Visit with an OSU County Extension office about testing procedures and read OSU Fact Sheet PSS-2903 “Nitrate Toxicity in Livestock”.

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