1/32
Looks like no tags are added yet.
Name | Mastery | Learn | Test | Matching | Spaced |
---|
No study sessions yet.
What are the three main environmental components that can contribute to disease?
soil
atmosphere
housing
How does soil contribute to disease?
impacts on feed nutrient content
pathogen access
environmental toxins
How does soil interact with plants?
nutrient source for plants
indirect nutrient supply for animals
plant composition may be influenced by:
climate - temperature, light, precipitation
soil pH
moisture
uptake of nutrients into plant may be affected by:
amount of nutrient in soil
pH of soil affects ionization and availibity
interactions of minerals with each other and with organic material
What minerals are deficient in soil?
selenium
iodine
phosphorus
copper
cobalt
magnesium
What minerals are abundant in soil and can cause toxicities?
selenium
copper
molybdenum
iron
sulfur
fluorine
nitrates
What interactions do microbes and parasites have with soil?
body wastes - Leptospira, E. coli, Salmonella, Clostridium
dead carcasses and remains
Anthrax, Botulinum, Clostridium
spores of organisms may survive for years or decades or centuries
Invertebrates in soil may harbor pathogens
earthworm: pig lungworm
snails: intermediate host for range of parasite
parasite eggs/larvae - Hookworm, Trichostrongyles, Ascarids, Trichuris
How does excess moisture in soil impact pathogens?
movement of pathogens and contaminants can be easier
favorable for organism survival
How does insufficient soil moisture or drought affect pathogens?
increased risk for plant toxins - prussic acid, nitrates
higher potential for poisonous plant consumption
favorable for aerosol transmission of organisms
How does soil impact tissue trauma?
frozen soil can cause poor footing, leading to slippage and injuries
How does the atmosphere contribute to disease?
ambient temperature stress
aerosolized toxins, pollutants
elevation
What is the biggest environmental stress factor?
temperature
Thermoneutral zone
the environmental temperature range in which the animal does not expend energy to maintain normal body temperature
TMZ is dependent on …
species
body size
haircoat, housing, bedding, wind exposure
What kinds of animals are more tolerant to cold stress but less tolerant to heat stress?
ruminants (opposite case of nonruminants)
Are younger or older animals more susceptible to cold?
younger animals due to limited subcutaneous fat and brown adipose tissue; they can also shiver and use up all of their glucose
Lower critical temperature
temperature at which an animal must increase heat production to maintain core body temperature
cold stress
feed intake increases and heat production increases → increased energy requirements for maintenance to generate heat
The effects of cold are more severe when …
conditions are wet and windy
Deleterious effects of cold
interference with water intake (frozen water supplies)
injuries (frozen ground)
frostbite
pulmonary hypertension
death by hypothermia
Pulmonary hypertension
change in environmental temp by 40 degrees Fahrenheit or more in 24 hours can induce this
increases susceptibility to certain types of pulmonary diseases
Frostbite
worse in un-adapted animals
extremities usually affected
ears
tail
scrotum
more severe if body part is wet
newborns affected
animals grooming each other
Upper critical temperature
temperature at which an animal must expend energy to dissipate heat
heat stress
feed intake decreases and heat production increases → increased energy requirements for maintenance to dissipate heat
Heat stress
a situation in which high environmental temperature and humidity result in the body’s inability to cool itself
mild degree of hyperthermia
elevation of 1-2 degrees C in some species
rectal tempts 103-104 degrees Fahrenheit in cattle
effects include
decreased DM intake
changes in metabolism
decreased production of milk, growth, and eggs
decreased reproductive efficiency → lower conception rates and higher embryo mortality
Factors increasing heat load
increased metabolic rate
exercise
at maximal intensity, muscle energy increased 40-60 fold
high environmental temperature
high environmental humidity
competition for cardiac output
redistribute perfusion among organ systems → body is trying to get blood to the skin to dissipate heat; takes it away from other organs
may reduce radiation and conduction
may reduce GI blood flow and affect digestion and absorption
rectal temp 106 or higher represents hyperthermia in horses
Heat stroke
most extreme form of heat stress
severe hyperthermia
body temperatures 107 degrees F and above
brain damage begins at 109-110 F
medical emergency
cool safely, and as rapid as possible
if cooled too rapidly, it may result in fatal lung changes
Malignant Hyperthermia
elevated body temperature of 110 F and above
fatal in nearly every case
Porcine stress syndrome is an example
genetic trait
often associated with anesthesia
cases reported in other species including humans
How does the atmosphere impact aerosol transmission?
microbial transmission
feet to many miles
increases with relative humidity
as humidity increases, so does microbe survivability
droplet transmission
Noxious gases
may originate from many sources
manure or manure storage areas
feed storage - especially tower silos
heating devices
never enter a confined space without good ventilation support
Carbon monoxide
a noxious gas that competes with O2 for transport sites
usual source is heaters operating at a reduced efficiency (ex. farrowing facilities)
Nitrogen oxides
silo gas
forms during the fermentation process
crops high in nitrates are most at risk
heavier than air - accumulates toward the ground
causes lung pathology in humans and animals
high concentrations: immediate distress, collapse, death
lower exposure: respiratory congestion, water eyes, cough, difficulty breathing, fatigue, and nausea
safety must be exercised when entering silos and good ventilation is ideal
Ammonia
manure and urine are the usual source
>25 ppm depresses muco-ciliary apparatus
increases respiratory disease
the smell of ammonia does not equal manure odor
Manure gases
mixture of
methane
nitrogen oxides
sulfur oxides
release rate may be increased during agitation of storage areas
results in acute and chronic lung pathology
How does housing contribute to disease?
impacts from:
ventilation
sufficient space
animal management
cleanliness
dryness
appropriate lighting
allowance or normal behaviors
Factors to consider with housing
animal welfare
space requirements
adequate facilities for examination and treatment
animal physiology and behavior
dry bedding
ventilation
good footing
weather conditions
wind breaks
cold/heat stress
Lighting
adequate lighting in confined systems
chickens
pullets no more than 10 hours of light daily
laying hens → 14-16 hours of light daily to stimulate egg production
meat birds → constant low-level light