Final Flashcards
What drives the genetics at the beginning of cattle industry?
Seedstock producers
- they sell bulls and bred heifers
- control all the genetics of cattle industry
What controls the market price of bulls?
Market price of beef products
Who do the seedstock operators sell to?
Cow/calf operations
- sell weaned calves
Wear do the weaned calves go after being sold by the cow/calf operations?
Stocker/backgrounder
- take weaned calves and get them ready for the feedlot (where they will gain 3-4 lb/day)
T/F: mortality is increasing on feedlots across the country
True
-cost of antibiotics have increased dramatically as well (antibiotic usage is increasing, not just prices)
What is slide with cattle selling?
When the price per pound of meat is reduced due to the weight of the calf being more than the agreed calf weight at sale, or increased if the calf doesnt weigh as much
- usually expressed as sell price with (0.0$) slide which means 0.0 cents per 100 lb body weight
- weight at sell vs weight at delivery is how slide comes into play
T/F: value of gain of steers equals the sale price
F
- usually value of gain is between 2/3-3/4 of original sale price
T/F: The higher the value of gain, the more money a producer can make
T
What are the only 2 factors that can be controlled regarding cattle purchasing?
- type of calves purchased
- management of calves at receiving
What are the 4 categories of calves that can be purchased from a cow/calf operation?
Category 1: preconditioned calves
- ideal
Category 2: bought straight off of one farm
-no sale barn
Category 3: fresh market calves
-sold at livestock market- havent been there long
Category 4: stale calves
- have been at market for a while
What does preconditioning mean?
- calves have had their shots
- calves are home raised
- they come from a defined program with vaccination and other requirements
AKA they are vaccinated before shipping, weaned, and trained to eat and drink out of a trough
What vaccines should preconditioned calves have recieved?
- IBR-BVD type I and II, PI3-BRSV (5 way- at least 1 dose should be modified live)
- mannheimia hemolytica
- blackleg (7 way clostridial)
*should receive at least 2 weeks prior to shipping
What does “double vaccinated” mean?
-calves have received 2 sets of shots
When should cows be weaned?
Weaning: should be at least 45 days of age
- need to be eating something besides mammas milk and grass
How can you rate preconditioned cattle?
-Weaned calves, vaccinated and from one source or calves comingled prior to purchase
-Weaned calves, vaccinated, from multiple sources
- Unweaned calves, vaccinated from a single source
-Unweaned vaccinated calves from multiple sources
What should be done with category 1 calves after purchase?
Don’t need to vaccinate, can deworm+ delouse, add coccidiostat, +/- implant
What is the only reason why you would not implant calves?
If they are being marketted as “all natural”
What should you do with category 2 cattle?
Should be vaccinated within 24 hours after arrival (5 way, 7 way), dont need to use meta phylaxis, parasite control, +/- implant
What should you do with category 3 calves?
-group that is the most difficult to develop a receiving plan for
- always recommend parasite control
-plan depends on if you have more time or more money
*should remove cattle from market as soon as possible, provide fresh clean water and good quality hay immediately
What commercial cattle product contains selenium, copper zinc and manganese?
Multi-min
What should you do with category 4- aka stale calves on arrival?
-most will benefit from metaphylaxis, parasite control
What are the main bacterial pathogens involved in BRD?
-histophilus somnus
-mannheimia hemolytica
-mycoplasma bovis (much less common in beef than dairy)
-pasteurella mulocida
-bibserteinia (a lot of people like to blame this for a lot of acute deaths)
In most cases of BRDC, what bacteria are involved?
-single agent infections are the most common
-primary one is lungs is mannheimia, followed by histophilus, then pastuerella
-bibersteinia is rarely isolated as a sole agent
What is the main bacterial agent isolated from the upper respiratory tract in BRD cases?
Pasteurella followed by mannheimia
Describe the resistance overtime to ceftiofur, baytril (enro)
Ceftiofur: going up over time
Baytril: going up overtime
Nuflour: all over the place
Penicillin: increasing over time
Draxxin: all over the place
- price has gone down recently, low dose required (can use in dart gun)
Which antibiotic should you never use to treat BRD?
Oxytet- very high resistance
What ancillary treatments can be used for BRDC?
NSAIDs, antivirals, vitamin C injections
-adding in banamine is nice
What signs should you tell a producer to look out for for BRDC?
-increased respiratory effort (open mouth breathing, neck extended, head down)
-lethargy (droopy ears), not with herd
-coughing, nasal discharge
*temp will guide treatment
What are the ideal AI conception rates, bull conception rates and season long pregnancy rates in beef herds?
AI: 60-65%
Bull: 60-65%
Season long rate: 90+%
What are the 3 most important factors in having a successful reproductive program?
-successful reproductive program last year
-cow nutrition
-bull +/- AI
What are the number one things affecting return to cyclicity in beef cattle?
Days post-partum and body condition at calving
-age (after 10- consider culling based on overall physical), suckling, presence of bull and use of exogenous hormones also contribute
Why is a successful breeding program last year important to the breeding program this year?
The earlier cows calf last year the sooner they will return to cyclicity this year and get bred back
-cows calving later into calving season have a higher percentage of reproductive failure
What is a wet 2 year old?
A first lactation heifer
- has to both grow on top of lactation
- hardest group to get bred back
How long after calving ends are bulls turned out?
Around 2 months (cannot wait much longer)
- allows adequate time for uterus to involute before being bred back
- early embryonic death decreases as days post partum increases
Is it easier for spring cows or fall cows to have a good BCS at calving?
Fall cows
- harder to have them gaining weigh during breeding season
*spring cows are the opposite
T/F: For spring calving cows, mother nature takes care of the positive plane of nutrition at calving
False- this is true for fall calving cows
- for spring cows, mother nature takes care of this at breeding
Why do we care about reproductive profiling?
- important metric for determining herd repro performance (required for beef cow-calf herd economic sustainability)
-create focused herd repro health program
-assist in diagnostic strategy for suboptimal repro efficiency
-guide design of intervention strategies
What should be the focus of the repro profile?
- distributions of calvings within a calving season
- number of calves born per cow exposed
- length of calving season
What are the goals of a repro profile for a traditional bull bred herd vs a herd using timed AI with a clean up bull?
Bull bred: all cows cycling at the beginning of the season
-65% total preg in first 21 day cycle, 23% in second cycle, 8% in third cycle
- less than 4% open at end of breeding season
- front end loaded calving season
AI with clean up: 75-85% pregnant within first 30 days of breeding season
-55% pregnant in first 21 day cycle by AI (goal is to have them cycle twice in one month)
-allows maximization of front loading of calving season
What does front end loading of the calving season allow for?
- more opportunities for cows to get pregnant (reduces number of open cows at the end and increases calves to sell)
-calves born earlier will weigh more and result in increased value per calf at sale
-cows stay in the herd longer (decreases numbers of replacements needed and replacement costs)
-allows for shorter period of intensive watching/processing of calves
If 10 calves are bled for a BVD titer, and 2 had high titers, and all ear notch tests are negative, what does this mean?
At some point this group of calves were exposed to BVD
T/F: over 90% of US beef herds are now using AI in addition to a bull
False
- 90% still only using bulls
-bull is responsible for over 50% of the reproductive program in most beef herds (bull has to do his job, cow has to do hers)
What is the cost of owning a bull?
25-50$/pregnancy
What are the owners responsibilities to assess bull fertility? Veterinarians responsibility?
Owner: evaluate libido and watch for problems
Vet: Breeding soundness exam- only part of the bull evaluation
What is the ideal bull to cow ratio?
In mature bulls: 1:25-40
In yearlings: 1 cow per month of age until 30 months old
- turn out at 15-16 months
What percent less bulls do you need if you are adding in a timed AI program?
25% less bulls
-always want to have enough bull power in these herds
What is the bare minimum that cow/calf herds need to record to set up a repro profile?
BCS at beginning and end of breeding season (record weights of heifers), calving date, preg checks (extend possible calving interval 21 days on either side), udder health, general health (feet, eyes), weaning weights
What are the principles behind a good biosecurity program?
Know the source of the infection, know who is susceptible, understand the mode of transmission
What are the 3 main principles of biosecurity?
- stringent bio-exclusion
- ruthless biocontainment
- early detection/vigilant surveillance
Describe the appetite vs tolerance concept regarding risk
Appetite is the owners willingness to go above and beyond to keep disease out of their herd
-tolerance is what they are willing to accept in terms of disease prevalence
*you want to try and create an environment that encourages clients to tell you when they are having problems keeping disease out- vs them becoming tolerant
What should you do before recommending a certain program to keep a disease out of a herd?
Make sure the client understands the risk and is willing to comply
- make sure they understand the outcomes that may come of the testing
What are some cattle diseases that can be controlled (minimized) but not eradicated?
Johnes, Tritrichomonas (can minimize through AI, can test bulls, maybe test cows), Moraxella bovis, mycoplasma bovis
What are some factors that ease the eradication of disease?
-easily identifiable, produces severe disease
-rarely subclinical
-no carrier state or recrudescence
-one immunotype
-no animal reservoir
-inexpensive vaccine
If a client wants to get rid of a disease in their herd, what are the next steps you should take?
-find out whats currently present in the herd
-discuss each pathogen and its relevance (are they getting paid more for disease free cattle, is the disease affecting production-ringworm doesnt affect anything, are they trying to avoid quarantine or depopulation in the case of TB or brucella)
-determine whether the client is willing to get rid of or isolate positive cattle (client must accept that no test is 100%)
-set up testing strategy for incoming cattle (ideally prior to entry, isolate facilities after entry)
What can diagnostic tests tell you?
Pathogen detection (culture, virus isolation, PCR, ag capture elisa, IHC, mcmasters) with clinical signs= infected and likely infectious
Pathogen detection and no clinical signs- infected or carrier, may be infectious
Serology: exposed or vaccinated, may be infected or infectious depending on the pathogen
- best used for organisms without a vaccine
How does baysean analysis play into pathogen testing?
What you know prior to the test influences your interpretation of the test
What does culture/viral isolation vs PCR vs immunochem/ag capture vs serology vs skin tests tell you?
Culture/viral isolation: live organism is present
PCR: organism is present, may be dead or alive
-good at detecting low amounts of organism- can complicate interpretation however
Immunohistochem: tells you organism is present and shows where it is causing infection
Serology: IgM raises before IgG
- with some diseases, presence of titers infers infection (BLV, anaplasma)
- increases or decreases in convalescent titers suggest exposure (BVDV, IBR, lepto)
-4 fold rise= 32 times original titer
Skin test: results in a type 4 hypersensitivity in positive cases
-poor individual animal test, but its all we have
What is the difference between a screening and a diagnostic test?
Screening test: tends to be cheaper and/or faster
-may identify a preclinical phase
-rules in or rules out
-determine if pathogen is in a herd
Diagnostic or confirmatory test: confirms a diagnosis
-identify the infected animals
T/F: the same test can be a screening and a confirmatory test
True
T/F: the physical exam is a screening test
True
- guides what diagnostic tests you will do next
What are the benefits to pooling samples for PCR?
Acts as a screening tool
- can save money and only run confirmatory test on the pool that tested positive
Why is it easier to find TB in a herd vs on an individual basis?
Live animal tests better on herd basis (caudal fold test)- not good for individuals
- gold standard for individuals is PCR after necropsy
When is testing commonly done for TB?
For sales and interstate transport of purebred animals
-individual herds can do CFT testing annually or biannually to be labeled as a TB accredited free herd
T/F: the US is currently considered free of tuberculosis
True
-main risks right now are deer in Michigan and cattle from Mexico
Describe the regulation of brucella in the US currently?
-federally regulated control based on vaccination and testing
- screening tests are based on serology
- most states are free (yellowstone bison are infected and mexico still affected)
- herds can test annually and become brucella certified
Should we continue to vaccinate for brucella?
- there is a human health risk with vaccine (can be found in milk)
- people may stop vaccinating for this reason
Describe the control measures of Johnes in the US
-voluntary program which combines risk assessment and herd testing
- screen with ELISA and follow with fecal culture or PCR
- no herds are designated as free, get a herd status score (high to low risk)
Describe the clinical features of bovine leukosis
-widely prevalent in dairies, less in beef
-blood transfusion thought to be primary route of transfer
-screening and confirmatory tests by serology (AGID or ELISA)
-young cattle (<6 mo) may be positive due to antibody interference
-seropositive cattle may be less productive, cows that get leukemia and lymphosarcoma die
How is anaplasmosis transmitted?
-endemic in southern states, moving north with ticks
-can transfer via tick bites or like BLV on needles, tattoo guns, etc
-calves and yearlings are fairly resistant (can make RBCs fast enough to replace loss)
-kills native adult cattle
-serologic testing or PCR for carriers, may see marginal bodies on blood smear of acutely infected cattle
How is BVD persistent infections controlled?
-primarily through vaccination
-PI cattle can be identified through ear notch
-data is conflicting as to benefit of keeping PIs out of feedlot, good idea to keep out of breeding herd
-same test used for screening and confirmation 3 weeks apart (a small percentage of ear notch cattle may be acute infection and can clear in 3 weeks)
What cattle should be tested for tritrichomonas?
All bulls over 18 months or all non-virgin bulls
What is recommended to keep mycoplasma and staph mastitis out of a herd?
Culture cows prior to putting into herd
What is recommended to keep neospora, lepto and theleria out of herds?
Test prior to entry into herd
What is the main challenge for getting rid of IBR?
They can form a latent state in neurons
What is the national veterinary accreditation program?
A program through the USDA: federal and state veterinarians authorize veterinarians to perform certain regulatory functions
- any vet can be nationally accredited
- this is voluntary, must be authorized by each state
- goal is to increase effectiveness, credibility, and global recognition to ensure continued health and well-being of US animals (animal health and disease prevention and preparedness for future)
What do you do as a US accredited veterinarian?
-testing, vaccination and certificates (health certificates)
-conduct surveillance and monitoring for diseases of concern
What is the difference between category 1 and category 2 accreditation?
Category 1 includes all small animals
- 3 training modules per 3 year renewal period
Category 2 includes all of the category 1 animals plus farmed food/fiber animals
- 6 training modules per 3 year renewal period
What is the most important job of a USDA accredited veterinarian?
-must immediately report to the area veterinarian in charge and state animal health officials all diagnosed or suspected communicable animal diseases for which USDA control or eradication program exists or all diagnosed/suspected cases of foreign animal disease
What is the eradication program for brucella?
This is zoonotic- no treatment in cattle
- in humans, can be difficult to treat
- humans acquire from drinking from raw milk
Moving from census based to statistical sampling for slaughter to reduce the number and cost of testing
- involves slaughter sampling of blood and lab based surveillance of abortions in cattle
All states are status free
What are the rules for the brucella vaccine?
Only use in females 4-12 months of age
-have to put in tattoo on ear - RB 51
How is tuberculosis transmitted?
Through respiratory and mammary secretions
-has variable intubation period, weeks to years
-highly contagious
ZOONOTIC
What type of surveillance is most common for TB?
Slaughter surveillance followed by epi investigations of affected herds (caudal fold tuberculin testing with supplemental comparative cervical Tb test)
- retest with comparative cervical must be within 10 days of original caudal tail test (or else you have to wait 60 days and no animal can go off of that farm during that time)
T/F: BSE is contagious
False
- but the variant Creutzfeldt-Jakobs disease in humans is linked to meat consumption from positive cows
-US is currently classified as negligible risk
What are the current control efforts for BSE?
-prohibition of the slaughter of down cows
-inhibiting the feeding of mammalian meat/bone meal in animal feed
-prohibiting specified risk materials (neural from >30 m) in any product
-destroying animals showing signs or at high risk
Describe the control strategies for pseudorabies in the US
-All 50 states free but feral swine is a reservoir
-prevention with biosecurity, management - aka depopulation of infected herds
-can cross species
-there is a vaccine available- need USDA approval for use- controls spread but not infection
Describe the control of scrapie (transmissible spongiform encephalopathy) in the US
-70 year battle
-can test brain or lymphoid tissue
-remove overtime with selective depopulation
-codon testing (qq- susceptible to scrapie, qr– resistant but care needs to be taken when breeding, rr- resistant)
Surveillance- regulatory slaughter surveillance and scrapie free flock certification program
-if suspected- contact aphis and they will collect and test sample for free
Describe chronic wasting disease of cervids
-transmissible spongiform encephalopathy
-no cure of vaccine
-diagnosis: collect retropharyngeal lymph nodes and brainstem for ELISA and IHC
Control:
-voluntary herd certification of farmed herds (USDA)
-wildlife services strategic plan - usda aphis wildlife services
What are cattle fever ticks?
Rhipicephalus annulatus and microplus
- vector for babesiosis (foreign animal disease) and anaplasmosis
- eradication for babesiosis in US started in 1906
- control now confined to tx/mexico border- includes dipping and tick riders (cowboys looking for cattle crossing the border)
What agencies are involved in protecting against foreign animal diseases?
- world organization for animal health (OIE)
- food and agriculture organization (FAO)
- USDA APHIS- vet services unit
- department of homeland security
What control measures should backyard flocks use to protect against avian influenza?
-get poultry from certified disease free sources
-quarantine new birds for 21 days minimum
-limit your birds access to wild birds- bird feeders, waterers
-dont mix ducks, chickens and turkeys
-BIOSECURITY
Defend the flock - good resource for clients
How is newcastle different than avian influenza?
- very similar clinical signs to HPAI aka sudden death
- much more rarely zoonotic- causes conjunctivitis in humans (less severe)
-there is a vaccine available- doesnt stop spread but reduces effects
What are the main tools to control foot and mouth disease?
-enhanced biosecurity
-rapid diagnostics
-national movement standstill (72 hour period where any cloven hooved animals can move in the US)
-trace backward/forward
-depopulate and carcass disposal
-vaccination is available- held in stockpiles as a pre-vaccine which will produce a lot of doses very quickly (no strains of vaccine are cross-protective)
Long intubation and lots of modes of transmission make this very hard to control
Describe how FMD shows up in sheep/goats vs swine vs cattle
Sheep/goats: maintenance hosts, silent spreaders
-can carry/shed virus for up to 12 months in sheep, 4 months in goats
-limited signs
Swine: amplifying host
- produce 10^6-10^9 infective virus doses daily which are shed in all excretions
-hoof lesions, vesicles, sudden death in piglets
Cattle: host that shows the most
- often first species to show clinical signs
-can carry virus for up to 6 months- some may remain infected for up to 3.5 years
-signs: vesicles, teat lesions, foot lesions, heavy calf loss
*in all groups, babies are the ones that die
*not a zoonosis
Describe classical swine fever
-highly contagious viral disease- aka hog cholera
-once endemic in US, eradicated in 1978
-reservoir is wild boar and domestic swine
-variable virulence and clinical signs
Control: stockpile vaccines
- MLV effective but does not allow for differentiation between vaccination and exposed
*can be spread through feeding uncooked garbage (insufficiently cooked meat)
What is african swine fever?
-contagious viral disease of swine only
-spread via soft ticks, feral and domestic swine
-4 forms of disease based on virulence (signs can be insidious or severe with mortality approaching 100%)
-recently has been found in haiti and dominican republic
-no vaccines available- chinese failed with vaccines and created new strains of virus by accident
What are the 3 main goals of the FAD response?
-detect, control and contain
-eradicate- stabilize animal ag, food supply
-provide: science/risk based approaches and information
Whos in charge of FAD outbreaks?
USDA area veterinarian in charge and state animal health official
- assign a FADD (foreign animal disease diagnostician) which took a course- only person allowed to collect samples in FAD investigation
What is the center for food security and public health and how do they play a role in FAD outbreaks?
-collaboration between industry, state governments, USDA and academia
-provide guidance to livestock producers to voluntarily prepare for a FAD outbreak
What is the role of VDACS?
-state level animal disease control and prevention
- they investigate outbreaks, contain the spread, and play a role in preparedness
- they overlook CVI (certificates of veterinary inspections)
- they have oversight of livestock marketing facilities
- and they are in control of the animal disease traceability program
How long do CVIs last?
30 days
What is important to remember about statements on a CVI?
State requirements vary- some require specific statements about certain diseases
-also test requirements and permit numbers may vary per state
T/F: the dirtier the cows, the higher the SCC
True
What are the steps of the milking procedure?
- Provide a low stress environment
- adrenalin can interfere with release of oxytocin which is required for milk let down - Check foremilk and udder for mastitis
- pre-dip teats with an effective disinfectant
- steps 2 and 3 can be interchanged - Completely dry teats with a single use towel
- Attach milking unit within 120 seconds of teat stimulation
- Adjust milking units as necessary
- Shut off vacuum before removing milking unit
- Dip teats with an approved post-dip disinfectant
What is the purpose of stripping the teats?
-visually checking for mastitis into strip cup
- removing highest somatic cell count milk
- stimulating milk let down
-ideally want unit on within 60-120 seconds of stimulation of the teat to avoid milk losses
What are the ideal characteristics of pre-dip?
-something that both sanitizes and disinfects
-decreases the number of bacteria at the teat end
-must be an approved dip
-purpose is to kill any bacteria/fungi at teat end (environmental pathogens)
-must use an approved dip
-contact time is a minimum of 30 seconds
What is the mechanism of action of most teat dips?
Germicide action
- iodine oxidative is commonly used- damages all bacteria (65% of what is used)
What percent is the best you can do to reduce bacteria during milking procedure?
85%
- relative risk is better with proper hygeine prior to milking
What are the 4 hygiene scores?
1: free of dirt
2: slightly dirty
3: moderately covered with dirt
4: covered with caked on dirt
Similar scores for teat end cleanliness- due to presence of pre-dip or dirt after wiping
Why are hoses never recommended for cleaning teats?
washes all the bacteria from higher on the udder to the teat end
What type of commonly used milking system do not dry cows?
Robots
- not good for reducing bacteria
How can we make sure that milk let down is ok?
-well stimulated teat
-proper lag time (largest influence on rapid and complete milk out)
- watch milk bowl- if milk isnt filling this is a problem
What is lag time?
The time from stimulation to when the milking unit is attached
- 90 seconds is ideal
- long lag times= losing milk
-low lag times= redisposed risk of mastitis
Why may cows have a dry/blind quarter?
Usually secondary to chronic mastitis and scarring of the teat
- seen very commonly
How do you differentiate an abscessed quarter from regular mastitis?
Looks like pus- smells foul
- usually caused by trueparella
- often also have sloughing material
Treatment: open up and debride
- teat amputation
- kill quarter with 10% iodine
- utilize pain meds as needed
How should the milking unit be placed?
-one teat at a time
-try to avoid squawking- indicates improper seal
-position of liner should be up to the base of the udder (covering whole teat end)
How fast should a cow milk out/how long does milk let down last?
4-6 minutes ideal
- high milking times are a reason for culling
-milk letdown lasts 6 minutes
*milking time is the same regardless of milking volume
Describe how the milking unit should be removed?
-automatic takeoffs- when milking <0.5 L/min
- manual- when there is little milk entering the bowl
- turn off the vacuum to teat and allow unit to fall off- DO NOT PULL OFF
What would be a sign that automatic takeoffs are coming off too late?
Hyperkeratosis
- amount of milk left in the quarter- should have at least 1/4 cup left after removal
What can you measure in a parlor without any machines?
Pre-dip time, lag time, teat end scores, hygiene, residual milk, teat end cleanliness, turn times
What is the purpose of post dip?
Reducing contagious pathogens
- often contain conditioning agents
- provide bactericidal agents between milking (ideally cows should stand for a couple hours after)
Describe the different types of post dips
Bactericidal agent- 1% iodine most common
Emollients: glycerol
Barrier dips to seal off the end of teat- thicker
Powder for freezing conditions- not the best but otherwise they will freeze
How long does it take for the teat sphincter to close?
2 hours
- keep cow standing- provide feed and water
How do you know the milk line vs the vaccum line in most barn types?
Milk line- will be stainless steel
Vaccum- will be white
Long blue line- carries milk
Black line- where vacuum goes to the pulsator
What is the difference between parallel and herringbone parlors?
Parallel: can fit more cows, harder to get them in, fairly efficient
Herringbone: less space efficient, easier for cows to get in, working from side of animal vs back
What is a tandem parlor?
Cows go in horizontally
- gate closes in from the side
- takes up a lot of space
What do flowmeters measure?
-conductivity
-pounds of production
-flow for automatic takeoffs
What are the main goals of winter ventilation?
- control humidity (goal between 50-70%)
- control drafts (unwanted air movements)
- control heat
- control noxious gases (ammonia, methane, carbon monoxide)
- control disease agents
- control dust (from bedding, animals, feed)
- air exchange 5 X/hour
What happens if humidity is too high during the winter? If too low?
High:
- makes the air feel colder
- bacteria and viruses survive better
Low:
- makes it harder to breath- decreases mucociliary apparatus function
What is the main source of ammonia in the environment around dairy cows?
Feces
-contains high amounts of undegraded protein which are degraded into ammonia through bacterial breakdown
-best way to avoid high ammonia levels is to remove feces
How can you remove dust from feed?
-Add fat
-pelleted feed
Adding water not recommended- will spoil quickly
What are the main goals of summer ventilation?
-controlling heat- 50 exchanges per hour
-control gases
-control disease agents
- control dust (not as much of a problem due to higher humidity levels)
Why is production lowered through heat stress?
These animals eat less
How do animals create moisture and heat?
Moisture through sweat, urine, feces, respiration
Heat- body generates it
What does ventilation remove?
Moisture, heat, dust, gases, disease agents
T/F: pressure inside the building must equal the pressure outside the building
True
- if higher in inside - the barn would explode
- if higher outside- would implode
What are the primary principles of natural ventilation?
Hot air rises and cold air sinks
Why do hot fires burn faster?
More hot air leaving quicker= more oxygen coming in from surrounding areas
What is the purpose of a ventilated ridge on the top of modern barns?
Allows hot air to escape
From what direction is the prevailing wind in north america? How does this impact the direction we want our barns to be built in?
From southwest
Want barns to run east to west so building is either facing south or north
T/F: the deeper the slope of a roof, the slower air can travel
False- faster
What allows for airflow into a barn?
A gap between the walls and the roof
- roof always extends a foot or two beyond the wall
- allows air to flow in
Wind allows the warm air to be removed faster