Passive Transfer of Immunity Flashcards
Again, placentation of ruminants? What is the significance of this?
- Synepitheliochorial
- Hypogammaglobulinemic
Describe the neonatal immune system again
- Immunocompetent but naive
- Immature system
- Time delay for response
What is the implication of the neonatal immune system being immunocompetent but naive?
- Maternal immunologic assistance is necessary
Does ingestion of colostrum = successful passive transfer?
- NO
What is successful passive transfer of immunity?
- TIMELY INGESTION and ABSORPTION of an adequate MASS of Ig (and other factors) by the neonate
What non-Ig components are in colostrum - specifically leukocytes?
- Leukocytes (1x 10^6 cells /mL)
- T lymphocytes (alpha and Beta)
- B lymphocytes
- PMNs (primarily udder defense)
- MACs (cytokines and APCs)
What non-Ig components are in colostrum - specifically cytokines?
- IL-2, TNF, IGF-1, TGF
- Limited data
Function of colostral leukocytes
- Overall helpful but not required
- Freezing, pasteurization
- Traffic to lymph nodes and mucosal lymphoid structures
- Enhances both innate and adaptive immunity
Failure of passive transfer defined by serum IgG (Bovine)
<1000 mg/dL @ 48 hours
Failure of passive transfer defined by serum IgG (Camelid)
<800 mg/dL @ 36-48 hours of age
What are the immediate and long-term risks associated with FPT?
- Increased risk of death in the first 3 months
- In the future, decreased weight gain, future milk production, and survival past 1st lactation
What is responsible for 50% of dairy calf deaths?
- FPT
Clinical signs of FPT?
- NONE
- They can look healthy or sick
- You cannot detect this on physical exam
What are calves who have FPT at increased risk for?
- Septicemia
- Diarrhea
- Enteritis
- Omphalitis
- Respiratory disease
Are the Ig levels for FPT set in stone?
- No, they are ONLY GUIDELINES for Ig needed for protection
Other factors that play into protection of calves
- Management
- Environment
- Infection pressure
- Virulence
- Antibody specificity, etc.
What are three factors that can help determine infection vs disease?
- Animal
- pathogen
- Environment
What are the three mechanisms by which colostral Ig protect calves?
- Lactogenic
- Systemic
- Enteric
Lactogenic protection
- Ig binds and neutralizes pathogens in the gut
- This is independent of gut closure or absorption
Systemic protection by IgG
- Must be absorbed
- Goes into circulation
Enteric protection by IgG
- IgG secreted back into the gut
What are the two mechanisms that must occur for passive transfer to take place?
- Transfer of IgG from maternal serum to colostrum
2. Transfer of colostral IgG from neonate’s gut to ECF
How does IgG get from the maternal serum to colostrum?
- Active
- Selective
- Receptor mediated
Which Ig is selected to be moved from maternal serum into colostrum?
- IgG1 > IgG2, IgM, IgA
When do maternal antibodies go from the serum to the colostrum?
- 4-6 weeks prepartum
Features of absorption process of IgG to the calf
- Non-selective
- Saturable (you can screw up)
- Non-receptor mediated
- “Closure”
What is absorbed from the calf gut when it’s open?
- IgG1
- Also IgG2, IgM, IgA, albumin
- And whatever else
- You can screw this up
Factors associated with successful passive transfer
- Formation of colostrum with adequate IgG concentration by the dam
- Ingestion of an adequate mass of IgG by the neonate
- Timely absorption of IgG by the neonate
Colostral immunoglobulin concentration - what can cause variation?
- Dairy vs beef (dairy is much less concentrated)
- Breed (jersey and Holstein > Brown Swiss, Ayrshire)
- Individual
- Parity
- Nutrition, environmental factors, etc.
Colostral IgG1 in Beef vs dairy
- Dairy heifers have the lowest concentration
- Even crappy beef cow colostrum is usually better than dairy cow colostrum
What is the goal for ingestion of adequate mass of IgG1?
- 150-200g x 1gG1
Mass = concentration x volume
What can lead to a failure to ingest colostrum?
- Mothering (or lack thereof); heifers and maidens at risk
- Teat conformation
- Hard milkers
- Weak, stressed neonate
- Dummy
- Multiple neonates
When does the gut close in the neonate?
- around 24 hours
- Linear closure
- The longer you wait, the worse it is
Why does gut closure timing matter?
- Age at first feeding is crucial
What other things are transferred along with IgG?
- Cytokines, proteins, growth factors, enzymes, cofactors, other cells
Who tends to get FPT: beef or dairy?
- In beef, it’s 5% FPT
- In dairy, it’s up to 39%
What is the best way to measure passive transfer in bovine?
- Serum refractometry
Other ways to measure FPT
- SRID
- Zn sulfate
- Na sulfite
- Glutaraldehyde coagulation
- Serum refractometry
- Serum GGT
- Latex agglutination
- Enzyme immunoassay
What is often underlying cause of FPT in dairy?
- Low IgG concentration in colostrum
What is the best way to perform FPT assessment, and what’s the predictive value?
- REFRACTOMETRY
- Reasonable predictive value
What values of refractometry are normal? Which suggest FPT?
- > 5.2-5.5 suggests adequate PT
- <4.5 ish suggests FPT
- Birth = 4.5-4.9 g/dL
Sample type for measuring FPT
- Blood off the baby in the first 24-48 hours
Limitations of refractometry as a measure of FPT
- Dehydration or illness
- Acute phase proteins
Refractometry in camelids?
- CANNOT DO TO ASSESS FPT
Can you assess colostrum based on appearance?
- NO
Immunoassays to measure colostrum quality
- Good sensitivity and specificity
- Not very available
- Increased cost
Colostrometer/hydrometer for colostrum quality
- Sensitivity and specificity
- 43% of dairies use this
- Measures SG
- Low sensitivity for poor colostrum (2/3 deemed okay)
- Temperature sensitive and fragile
Optical refractometry for colostrum quality
- Decent sensitivity and specificity
- Not temperature sensitive
- Not fragile
- Frozen or fresh colostrum
What % on a Brix (optical) refractometer is adequate?
> 22% Brix = 50 g/L
Best way to measure colostrum quality in dairy cattle?
- Brix refractometer
Best colostrum practices in dairy
- Milk the cows ASAP (decreased IgG every hour)
- Measure colostrum quality
- Feed 150 g IgG1 in the first 4 hours or feed 7.5% body weight
- Feed additional 5-7.5% body weight by 12 hours
- Pasteurize if Johne’s, Salmonella, Mycoplasma, or BLV
- Avoid pooling (or pool similar quality)
- Monitor for FPT
Beef best colostrum practices
- Avoid severe dietary intake precalving 9decreases colostrum volume and increased viscosity)
- Minimize disruption of calving
- Monitor and ensure suckling within 6 hours
- Intervene if dystocia or dummy calf
What is best intervention if dystocia or dummy calf?
- Restrain dam
- Milk dam and bottle (best) or tube if needed
Which is better: bottle or tube feeding for colostruM?
Bottle
What should you do to get colostrum in an animal if its unable to nurse?
- Milk out dam or other female
- Bottle/tube 3-4 quarts in the first 2 hours, repeat in 12 hours
- Frozen colostrum (diseases to consider are Johnes, CAE, etc.)
Commercial colostrum products
- Read the label
- Substitutes vs replacers
- if they contain IgG, they are regulated by the USDA
Colostrum supplements
- Provide exogenous IgG to supplement poor quality colostrum
- Provide 25-60 g IgG
- 1 dose is inadequate
- Inadequate nutrients
Colostrum replacers
- Fed instead of maternal colostrum
- Provide minimum of 100g IgG
- Adequate nutrients
- Expensive
Which is better: colostrum supplement or colostrum replacer?
- Colostrum replacer in general
Which is better: colostrum origin or serum origin colostrum replacers?
- Colostrum origin (similar nutrients, hormones, growth factors; lack cell wall components)
- By contrast, serum origin has a different process and is only approximately 20% Ig
Canadian CR and CS
- All CR prouducts licensed through CFIA
- Plasma derived CR or CS not permitted
USA CR and CS - licensed
- Only some manufacturers licensed through USDA, CVB
- Potency, purity, efficacy, regulated
Non-licensed CR and CS
- Can’t legally claim to supply IgG or purport to be used as a CR or CS, or prevent FPT
- But often used for this purpose
How should you select CS/CR?
- Select those that undergo independent evaluation for efficacy in field studies
- Consider PT of IgG, nutritional support, health, and performance
- Consider dose of IgG
- Consider apparent efficacy of absorption
Apparent efficacy of absorption
- % fed compared to amount absorbed systemically
- IgG mass (dose)
- Manufacture methods
- Other nutrients and additives
Colostrum supplements and substitutes summary of effects and when to use
- Generally don’t raise the IgG adequately
- Insufficient quantities of Ig
- Ingredients vary
- Often labeled as colostrum replacers
- Maybe could give pre-emptively
How to treat suspected FPT
- Plasma or whole blood (20-40 ml/kg IV or IP)
Oral colostrum??? (Lactogenic but not systemic immunity)
- Supportive care (Antibiotics, NSAIDs, nutrition, environment)
