Preventing Animal Disorders
on Pasture
Patty Scharko, DVM, MPH
Livestock Disease Diagnostic Center
University of Kentucky
Animal Disorders on Pasture
Bloat
 Acute Bovine Pulmonary Emphysema
(fog fever)
 Nitrate Toxicity
 Cyanide/Prussic Acid Toxicity
 Poisonous Plants
 Mineral deficiency
Grass Tetany
Trace mineral- copper, selenium

Animal Disorders on Pasture
not covered
Blackleg
Johne’s disease
Pinkeye
Footrot
Salmonellosis
Leptospirosis
and more
Grass Tetany
Nitrate
AIP
ABPE
Fog fever
Bloat
Dec
Feb
Apr
Jun
Nitrate
Cyanide
Aug
Oct
Dec
Bloat
Bloat
What is it?

gas accumulates in the rumen

animal unable to eructate (belch up gases)

can result in sudden death
Pasture bloat
(legume)
 Legumes
favor frothy bloat;
winter wheat
 Frothy bloat
 Stable protein foam in rumen
traps gas from fermentation
 Pressure on lungs
Causes of Bloat

Animal inheritance for
susceptibility

High susceptible cattle have
larger rumen volumes and
slower passage rate
 Bloating cattle consume
18 to 25% less alfalfa than
non-bloaters
Causes of Bloat
 Adaptation
to pasture/ration
 Rumen microflora need to adapt
 Time
of day
 Dew does affect bloat
 Cattle were 2-17 times at higher risk
when fed between 7 - 8 AM
compared to 11 AM - noon
Causes of Bloat
 Plant
maturity
 Soluble protein content in plant
 Lush, young plants produce bloat
 Alfalfa < 10 inches caused bloat 2
times compared to alfalfa > 19 inches
Treatment
 Do
NOT remove from pasture at
first signs of bloat
 Continuous
grazing gives less bloat
than removal and return
Effect of feeding on incidence of
bloat on alfalfa
Grazing System
Continuous Graze 6hrs/da
-----Number of cases----
Week 1
1
25
Week 2
4
16
Total
5
41
J. Anim. Sci. 1995. 73:1493-1498
Treatment
 Foam
reducersdrench or tube
 Bloat-Pac
 Bloat treatment
 Dish
detergent: 1 oz in 1 L water
 Vegetable oil- tube only
 Beware of turpentine
Treatment
 Last
resort/ emergency
hole in rumen
left side
trochar, cannula, or knife
needs to be sutured by
veterinarian
antibiotics
Effect of feeding treatment products on
alfalfa pasture bloat
Treatment
Monensin
Rumensin
Lasolacid*
Bovatec
Polaxalene
Dose, mg/lb
0.3a
0.6
0.3
0.45b
0.6a
20a,b
Bloat Guard
* Not approved in lactating dairy cattle
a
Reduction
71
72
30
12
16
100
JAS 1983. 56:1400; b JAS 1986. 63:1246
Prevention

Bloat Guard
 Pre-mix
 Molasses-mineral block
 Ionophores
Rumensin- approved in stocker, feeder,
beef & dairy cows, dairy & beef
replacement heifers & calves; goats
Bovatec
 Must
be consumed on the same day
that bloating may occur
Prevention
1. Do NOT remove at first signs of bloat
2. Provide grass-legume mixture for
pasture
3. Do NOT turn hungry cattle on lush immature
alfalfa or clover
Acute Bovine
Pulmonary Emphysema
 Aka:
Fog Fever or
Atypical Interstitial Pneumonia
 Nutritional disorder, resulting in
sudden onset of acute respiratory
distress

Caused by formation and metabolism of
3-methylindole (3MI)
“Fog Fever”/ABPE

“Fog fever” occurs often when moving
from grazed down area to lush
succulent growth

The better quality the pasture moved to,
the greater occurrence of ABPE
 Death
may be sudden, average 30%
“Fog Fever”/ ABPE
Signs:
Open-mouth breathing
Frothing at mouth
Labored breathing with expiratory grunt
Atypical Interstitial Pneumonia
LDDC Necropsy Case Diagnosis
4
1996
1997
1998
1999
2000
2002
2003
3
2
Dec
Nov
Oct
Sep
Aug
Jul
Jun
Apr
Mar
0
Feb
1
Jan
LDDC Necropsy Cases
5
ABPE Prevention with
Rumensin (monensin) or Bovatec (lasalocid) *a
1
Clinical
Trt./Dose Signs
M 100 mg 0/4
Lung
Lesions
Deads
2
M 200 mg 0/4
0/4
0/4
3
L 100 mg
2/4
4/4
1/4
4/4
4/4
1/4
Group
4
0/4
2x
1x
2x
Control
* Boavatec is not approved in lactating dairy cattle
a
Vet Record 107:322
0/4
Effect of Bovatec (lasalocid*)
on ABPE Prevention
Group
Dose
mg/hd/da
Clinical
Signs
Deads
1
0
5/5
3/5
2
200
0/5
0/5
3
400
0/5
0/5
4
600
0/5
0/5
* Not approved in lactating dairy cattle
a
J. Anim. Sci. 60:232
Nitrate Toxicity

SIGNS:
Depression, staggering, incoordination
Excess salivation
Brownish discoloration of mucous membranes

Drought

N fertilization

Grazing &/or hay
 Sorghum, Sudan, Johnson grass
 Stable in hay
Nitrate Toxicity
LDDC Necropsy Cases
4
3
2
Dec
Nov
Oct
Sep
Aug
Jul
Jun
Apr
Mar
0
Feb
1
Jan
LDDC Necropsy Cases
5
1996
1997
1998
1999
2000
2002
2003
2004
2005
Nitrate Toxicity

Nitrite is the toxic entity; 10x more toxic
than nitrates

Nitrite combines with hemoglobin to
form methemoglobin; prevents oxygen
transport

Chocolate brown blood

Death from asphyxiation
Nitrate Toxicity (2)
 Young
cattle are more susceptible
 Hungry
 Cattle
cattle more susceptible
can adjust to higher levels given
enough time
Nitrate Toxicity (3)
 Nitrite
crosses into fetus; can lead to
abortion
Prevention
 Ensiling
reduces 40 to 60%
 Dilution
 Increase
tolerance
PPM Nitrate
dry matter
0-4,400
4,400-8,800
8,800-15,000
> 15,000
Feeding instructions
Safe to feed. Be cautious with pregnant and young
animals at upper level.
Generally safe when fed with a balanced ration
with low nitrate water. Some lowered production
problems and Vitamin A deficiency may occur.
For pregnant animals, limit to 50% of total dry
matter.
Limit to 25% of total dry ration. Fortify well with
energy, minerals, and Vitamin A. May result in
reproduction problems over period fed.
Toxic. Do not feed. Sudden death, abortion,
severe depression, difficulty breathing may occur
Cyanide (Prussic Acid)
Toxicity

SIGNS: Severe respiratory difficulty, sudden death

Sudan, sorghum-sudan, sorghum (Johnson
grass), wild cherry tree

Frost/stress

Do NOT graze frosted plants!
Wait 10-14 days after non-killing frost
Wait 48 hours after killing frost
Cyanide (Prussic Acid)
Toxicity

Ingest cyanogenic glycosides that yield
hydrocyanic (prussic) acid in rumen

Hydrocyanic acid stops cellular respiration;
death from respiratory paralysis
 Bright
red blood
Toxic Plants
Japanese
Yew (Taxus)
Oak/Acorns
Buckeye
Osage
orange (hedgeapple)
Mineral Deficiency

Magnesium

Selenium

Copper
Grass Tetany
 Hypomagnesemia,
magnesium
deficiency, grass staggers, winter tetany
 Affects
only ruminants
• Primarily in lactating beef cows in spring
• Within 60 days of calving
• Pastured on cool season grasses
 Spring grasses are high in potassium
 Heavily fertilized (nitrogen &/or potash)
Magnesium Deficiency
20
15
10
Dec
Nov
Oct
Sep
Aug
Jul
Jun
Apr
Mar
0
Feb
5
Jan
LDDC Necropsy Cases
25
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
Grass Tetany

Cows need 20 grams of Mg daily or
4 oz/day of
15% Mg mineral mix
 Consumption important, individual cows may not consume
adequate free choice minerals

For spring calving, start Dec/Jan and continue until
daytime temperatures above 60o F

PREVENT!!
Copper Deficiency
Selenium Deficiency
“white muscle disease”