L16. NPN and Ammoniated Feeds

Question 1

Why use NPN?

Answer 1

• GI micro-organisms convert NPN to protien if:
  
  • pH is in “acceptable” range (5.5-7)
  • DIgestible corbohydrates are available
  • THey have time to adapt
• It boosts the “protein” content of feed
• Helps maintain more neurtral rumen pH with high-grain diets
• Improves rumen mircrobial greath efficiency
• Improves hindgut fiber digestion
• Works best in ruminants
  
  • some benefit in hindgut fermenteros
  • no benefit to non-fermenting animals

Question 2

Sources

Answer 2

Urea

biuret

Ammonium sulfate

Mono Ammonium Phosphate (MAP_

Question 3

Mechanism

Answer 3

• Excessive free gas production causes bloat
• NH3 reacts with water to form ammonium hydroxide
  
  • forms a storngly basic solution ( increases pH)
  • corrosive
• Increase rumen pH promotes NH4 absorption
  
  • physiological NH4 uptake by urea cycle is overwhelmed
  • increases blood NH4
    
    • CNS effects

Question 4

Species Differences

Answer 4

Unadapted, adult ruminants are most susceptible

Hindgut fermenters have ¼ to ⅓ the capacity of ruminants to convert NPN to ammonia

need 3-4 times the NON for poisoning

Non-fermenting monogastrics are resistant to NPN poisoning

Question 5

NPN acclimation

Answer 5

NPN to protein conversion is inducible, but takes time

Promoted by adequate “feeding” of microbes

Easily digestible coarbohydrates, minerals

Requires consistnet NPN feeding

aclimation is lost in 1-2 days of low NPN

Question 6

Clinical Picture

Answer 6

First signs are “ uneasiness”, slight bloat, excessive salivation

Progresses to muscle tremors, tachypnea, tachycardia, frequent urination, stiffness, ataxia

Final stages include collapse, lateral prostration witha an inability to regain sternal recumbency, bloat, regurgitation, dyspnea, periodic tetanus-like spasms, convulstions, death

Course often rapid, aniamls simply found dead

Question 7

Rumen and Blood pH profiles

Answer 7

increase blood NH4 causes increased blood pH (up to 8)

alkalosis causes reduced oxidative phosphorilation and ATP production, cells switch to lactate produciton to meet energy needs

Lactate leaching into systemic circulaiton brings pH back to … and below … normal

Question 8

Treatment

Answer 8

Often futile if dose was high and symptoms progressed to nervous involvement

Triage may be necessary

First treat animals that are still standing

Early, aggressive intervention is needed

Large volumes of cold water and vinegar into rumen

Rumenotomy

Rumen stasis may be a lingering problem

Question 9

Diagnosis

Answer 9

• Antemortem:
  
  • characteristic signs
  • history of change in feeding practices
  • high rumen pH
  • ammonia smell
• Postmortem:
  
  • rumen and ocular content assays for ammonia (>20ppm)
    
    • placed sample in sealed container and freeze ASAP
  • Feed assays for high NPN contnet
    
    • rumen content assays unreliable due to rapid breakdown
  • Lesions associated with bloat
  • pulmonary edema and froth/fluid in trachea

Question 10

Risk Factors

Answer 10

high levels of NPN-misformulaitons

abrupt or periodic NPN intake

inadequate mixing of feed

concnetrates may contain 30-40% NPN

Poor adaptation: lack of readily available carbodydrates, inadequate phophorus, sulfur, and trace minerals

High levels of soluble protien: rapidly hydrolyzed in rumen, adds to NH4 burden

Open feed troughs: leached NPN can accumulate in water puddles

Poorly maintained fertlizers storage containers

Question 11

NPN feeding recommendations

Answer 11

Slowly acclimatize to NPN over 2-3 days

feed everyd ay

if a day or two was skipped, acclimatize agian

Feed no more that 3% total NPN

NPN should not be a more that ⅓ total nitrogen

Question 12

Ammoniated Feed:

What to do with bad hay

Answer 12

poor quality roughage, exposed to high levels of anhydrous ammonia gas, have:

increased digestibility

increased crude protien

increased palatability

Question 13

Ammoniated Feed:

Clinical Picture

Answer 13

Animals go “Bonkers” for breif periods

they spontaneously begin trembling, with rapid blinking or ear twitching, ataxia, apparent blindness, tachypnea, frothing at the mouth, urination or defectaion

then stampede wildly, running into objects, convulsions are possible,

Return to normal after a few minutes

nursing animals are affected through the milk

Recovery takes 1-3 days form removal of toxic feed

Question 14

Diagnosis

Answer 14

unique clinical signs

With a history of ammoniated feed

Recovery upon removal of ammoniated feed

Detection of 4-methylimidazole in the milk/serum

Question 15

Ammoniated feed:

Treatment

Answer 15

Remove toxic feed

prevent injuries

Prevent nursing from affected animals and discard milk from affected cows