NPN & Ammoniated Feeds Flashcards
1
Q
Why use NPN in cattle?
A
- GI micro-organisms convert NPN to protein if:
- pH is ± 5.5 - 7
- Digestible carbs are available
- Have time to adapt
2
Q
Why are NPNs used?
A
- Boosts “Protein” content of feed
- helps maintain more neutral rumen pH with high-grain diets
- Improves rumen microbial growth efficiency
- Improves hindgut fiber digestion
- Works best in ruminants
3
Q
What are the sources of NPNs
A
- Urea
- Biuret
- Ammonium sulfate
- Monoammonium phosphate (MAP)
4
Q
What is the MOA for NPN toxicity?
A
- Excessive free gas (NH3) production causes bloat
- NH3 reacts with water to form ammonium hydroxide (NH4OH)
- forms strong basic solution (⇡pH)
- Corrosive
- ⇡ Rumen pH promotes NH4 absorption
- physiological NH4 uptake by urea cycle is overwhelmed
- ⇡ blood NH4
- CNS effects
5
Q
What are the signs of NPN toxicosis?
A
- First: Uneasiness, slight bloat, excessive salivation
- Progresses to: muscle tremors, tachypnea, tachycardia, frequent urination, stiffness, ataxia
- Final: collapse, lateral prostration with an inability to regain sternal recumbency, bloat, regurgitation, dyspnea, periodic tetanus-like spasms, convulsions, death
6
Q
What is the treatment for NPN toxicity?
A
- Often futile if does was high and symptoms progressed to nervous involvement
- Early aggressive intervention is needed:
- Large volumes of cold water (20-30 L) and vinegar (2-6 L) into rumen
- Rumenotomy
- Rumen stasis may be a lingering problem
7
Q
How is NPN toxicity diagnosed antemortem?
A
- Characteristic signs
- hx of change in feeding practices
- high rumen pH
- ammonia smell
8
Q
How is NPN toxicity diagnosed postmortem?
A
- Rumen and ocular fluid content assays for ammonia (>20ppm)
- Feed assays for high NPN content
- rumen content unreliable - rapid breakdown
- Lesion s associated with bloat (bloat line)
- Pulmonary edema and froth/fluid in trachea
9
Q
What are the risk factors for NPN toxicity?
A
- High levels of NPN - mis formulations
- Abrupt or periodic NPN intake
- Inadequate mixing of feed
- concentrates may contain 30-40% NPN
- Poor adaptation
- lack of available carbs
- inadequate phosphorus, sulfur and trace minerals
- high levels of soluble protein
- hydrolyzed in rumen, adds to NH4 burden
- Open feed troughs
- NPN can accumulate in water puddles
- Poorly maintained fertilizer storage containers
10
Q
What are the feeding recommendations for NPNs?
A
- Slowly acclimatize to NPN over 2-3 days
- Feed NPN every day
- Feed no more than 3% total NPN
- NPN should NOT be more than ⅓ of total nitrogen
11
Q
What can be done with bad hay?
A
- Poor quality roughage, when exposed to high level of anhydrous ammonia gas have:
- increased digestibility
- increased crude protein
- increased palatability
12
Q
What happens when material with high sugars, or protein blocks with urea and molasses are exposed to anhydrous ammonia gas?
A
- Ammonization introduces AA which has condensation reactions with sugars
-
toxic pyrazines and imidazoles are formed
- induce intermittent abnormal nerve function and convulsions
13
Q
What are the clinical signs of Pyrazines and imidazole toxicity?
A
- Animals go “bonkers” for brief periods
- spontaneous trembling, with rapid blinking or ear twitching, ataxia, apparent blindness, tachypnea, frothing at the mouth, urination or defecation
- Stampede wildly, running into objects
- convulsions possible
- return to normal after a few minutes
14
Q
How is pyrazine and imidazole toxicity diagnosed?
A
- Unique clinical signs
- hx of ammoniated feed
- recovery upon removal of ammoniated feed
- detection of 4-methylimidazole in milk/serum
15
Q
How is pyrazine and imidazole toxicity treated?
A
- remove toxic feed
- prevent injuries
- prevent nursing from affected animals and discard milk from affected cows
