 Rumen acidosis liver abscess  Polioencephalomalasia, or Polio, or PEM, or “Brainer”  Nitrate poisoning

 Acute  Laminitis, founder  Hopelessly off-feed  Sell immediately  Chronic or subacute  A little off feed, poor performers  Long term effect  Rumenitis: more problems as we have longer fed cattle – calf-feds, Holsteins, Japanese  Probably bigger problem in the PNW with barley, wheat and potato feeding  Best symptom is liver abscesses (Fusobacterium necrophorum; Actinomyces pyogenes) Its all about bunk management !!

 Acidosis symptoms  variable feed intake (symptom and cause)  feces: loose – splattering, less than 1” high, no dimpling/concentric rings  lack of cud chewing  hoof lines, abnormal hoof growth  dairy: milk fat inversion  beef: liver abscesses

Indicates rumen insultIndicates rumen insult Grows.25 inch (6 mm) / monthGrows.25 inch (6 mm) / month

O A - A A +

sbl 00

CONTROL RUMENSIN +TYLAN NO. HEAD % A % A8.4 a 3.5 b % A+20.1 a 3.5 b TOTAL36.2 a 12.4 b LAUDERT, 1990, 4 TRIAL SUMMARY ab (P<0.02)

 Classically associated with periods of rumen digestive upset ◦ irregular feed intake ◦ Consumption of moldy feed ◦ Lush highly fermentable forages – rapeseed forage  Classically considered to be thiamine deficiency ◦ Usually from presence of thiaminases ◦ Administer thiamine – oral or injectible

 Symptoms: ◦ Laminar cortical necrosis (brain damage) ◦ Blindness ◦ Staggering ◦ Down ◦ Seizures ◦ Recent understanding: high dietary sulfur is a predisposing factor: rumen bacteria convert sulfur to hydrogen sulfide, enters the blood, interferes with energy metabolism, “starves” the CNS

 Current issue is with corn byproducts – wet milling involves softening the grain with sulfuric acid ◦ Inclusion of high levels of corn gluten feed or corn distillers grain can increase risk of PEM ◦ Low rumen pH increases production and absorption of sulfide ◦ No amount of dietary thiamine can completely eliminate the risk – may reduce the incidence ◦ Formulate diets to have 0.4% Sulfur (or less)

 Ruminal conversion of nitrates in plants to nitrites (instead of ammonia to microbial protein), enters blood, binds with hemoglobin to form methemoglobin, reduces oxygen transport to cells.  Formation of methemoglobin is normally reduced (via electron donation) by protective enzyme systems: ◦ e.g., NADH methemoglobin reductase (cytochrome-b5 reductase)cytochrome-b5 reductase

 Symptoms: ◦ Respiratory distress ◦ Incoordination ◦ Weakness ◦ muscle tremors ◦ Collapse - dead ◦ Don’t stress affected cattle!

 Common feeds: ◦ Stressed crops (drought, frost, hail) ◦ Cool, overcast climate ◦ Lower portion of stem/stalks of certain plants: pigweed, sorghum, corn, Sudan grass, barley and oats ◦ High N fertilizer ◦ Immature more than mature forages

 15 to 45 g of Nitrate per 100 pounds body weight – from feed and water ◦ 1% nitrate in forage DM ◦ 1,500 mg/ml nitrate (ppm) in water  Younger cattle are more susceptible

Category NO3NO3-N KNO3Remarks 1<0.5<0.12<0.81 Generally safe for beef cattle and sheep Caution - some subclinical symptoms may appear in pregnant horses, sheep and beef cattle High nitrate problems - death losses and abortions can occur in beef cattle and sheep 4<1.23<0.28<2.00 Maximum safe level for horses. Do not feed high nitrate forages to pregnant mares.