Passive Transfer of Immunity Flashcards
(67 cards)
1
Q
Again, placentation of ruminants? What is the significance of this?
A
- Synepitheliochorial
- Hypogammaglobulinemic
2
Q
Describe the neonatal immune system again
A
- Immunocompetent but naive
- Immature system
- Time delay for response
3
Q
What is the implication of the neonatal immune system being immunocompetent but naive?
A
- Maternal immunologic assistance is necessary
4
Q
Does ingestion of colostrum = successful passive transfer?
A
- NO
5
Q
What is successful passive transfer of immunity?
A
- TIMELY INGESTION and ABSORPTION of an adequate MASS of Ig (and other factors) by the neonate
6
Q
What non-Ig components are in colostrum - specifically leukocytes?
A
- Leukocytes (1x 10^6 cells /mL)
- T lymphocytes (alpha and Beta)
- B lymphocytes
- PMNs (primarily udder defense)
- MACs (cytokines and APCs)
7
Q
What non-Ig components are in colostrum - specifically cytokines?
A
- IL-2, TNF, IGF-1, TGF
- Limited data
8
Q
Function of colostral leukocytes
A
- Overall helpful but not required
- Freezing, pasteurization
- Traffic to lymph nodes and mucosal lymphoid structures
- Enhances both innate and adaptive immunity
9
Q
Failure of passive transfer defined by serum IgG (Bovine)
A
<1000 mg/dL @ 48 hours
10
Q
Failure of passive transfer defined by serum IgG (Camelid)
A
<800 mg/dL @ 36-48 hours of age
11
Q
What are the immediate and long-term risks associated with FPT?
A
- Increased risk of death in the first 3 months
- In the future, decreased weight gain, future milk production, and survival past 1st lactation
12
Q
What is responsible for 50% of dairy calf deaths?
A
- FPT
13
Q
Clinical signs of FPT?
A
- NONE
- They can look healthy or sick
- You cannot detect this on physical exam
14
Q
What are calves who have FPT at increased risk for?
A
- Septicemia
- Diarrhea
- Enteritis
- Omphalitis
- Respiratory disease
15
Q
Are the Ig levels for FPT set in stone?
A
- No, they are ONLY GUIDELINES for Ig needed for protection
16
Q
Other factors that play into protection of calves
A
- Management
- Environment
- Infection pressure
- Virulence
- Antibody specificity, etc.
17
Q
What are three factors that can help determine infection vs disease?
A
- Animal
- pathogen
- Environment
18
Q
What are the three mechanisms by which colostral Ig protect calves?
A
- Lactogenic
- Systemic
- Enteric
19
Q
Lactogenic protection
A
- Ig binds and neutralizes pathogens in the gut
- This is independent of gut closure or absorption
20
Q
Systemic protection by IgG
A
- Must be absorbed
- Goes into circulation
21
Q
Enteric protection by IgG
A
- IgG secreted back into the gut
22
Q
What are the two mechanisms that must occur for passive transfer to take place?
A
- Transfer of IgG from maternal serum to colostrum
2. Transfer of colostral IgG from neonate’s gut to ECF
23
Q
How does IgG get from the maternal serum to colostrum?
A
- Active
- Selective
- Receptor mediated
24
Q
Which Ig is selected to be moved from maternal serum into colostrum?
A
- IgG1 > IgG2, IgM, IgA
25
When do maternal antibodies go from the serum to the colostrum?
- 4-6 weeks prepartum
26
Features of absorption process of IgG to the calf
- Non-selective
- Saturable (you can screw up)
- Non-receptor mediated
- "Closure"
27
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
28
Factors associated with successful passive transfer
1. Formation of colostrum with adequate IgG concentration by the dam
2. Ingestion of an adequate mass of IgG by the neonate
3. Timely absorption of IgG by the neonate
29
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.
30
Colostral IgG1 in Beef vs dairy
- Dairy heifers have the lowest concentration
| - Even crappy beef cow colostrum is usually better than dairy cow colostrum
31
What is the goal for ingestion of adequate mass of IgG1?
- 150-200g x 1gG1
| Mass = concentration x volume
32
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
33
When does the gut close in the neonate?
- around 24 hours
- Linear closure
- The longer you wait, the worse it is
34
Why does gut closure timing matter?
- Age at first feeding is crucial
35
What other things are transferred along with IgG?
- Cytokines, proteins, growth factors, enzymes, cofactors, other cells
36
Who tends to get FPT: beef or dairy?
- In beef, it's 5% FPT
| - In dairy, it's up to 39%
37
What is the best way to measure passive transfer in bovine?
- Serum refractometry
38
Other ways to measure FPT
- SRID
- Zn sulfate
- Na sulfite
- Glutaraldehyde coagulation
- Serum refractometry
- Serum GGT
- Latex agglutination
- Enzyme immunoassay
39
What is often underlying cause of FPT in dairy?
- Low IgG concentration in colostrum
40
What is the best way to perform FPT assessment, and what's the predictive value?
- REFRACTOMETRY
| - Reasonable predictive value
41
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
42
Sample type for measuring FPT
- Blood off the baby in the first 24-48 hours
43
Limitations of refractometry as a measure of FPT
- Dehydration or illness
| - Acute phase proteins
44
Refractometry in camelids?
- CANNOT DO TO ASSESS FPT
45
Can you assess colostrum based on appearance?
- NO
46
Immunoassays to measure colostrum quality
- Good sensitivity and specificity
- Not very available
- Increased cost
47
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
48
Optical refractometry for colostrum quality
- Decent sensitivity and specificity
- Not temperature sensitive
- Not fragile
- Frozen or fresh colostrum
49
What % on a Brix (optical) refractometer is adequate?
>22% Brix = 50 g/L
50
Best way to measure colostrum quality in dairy cattle?
- Brix refractometer
51
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
52
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
53
What is best intervention if dystocia or dummy calf?
- Restrain dam
| - Milk dam and bottle (best) or tube if needed
54
Which is better: bottle or tube feeding for colostruM?
Bottle
55
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.)
56
Commercial colostrum products
- Read the label
- Substitutes vs replacers
- if they contain IgG, they are regulated by the USDA
57
Colostrum supplements
- Provide exogenous IgG to supplement poor quality colostrum
- Provide 25-60 g IgG
- 1 dose is inadequate
- Inadequate nutrients
58
Colostrum replacers
- Fed instead of maternal colostrum
- Provide minimum of 100g IgG
- Adequate nutrients
- Expensive
59
Which is better: colostrum supplement or colostrum replacer?
- Colostrum replacer in general
60
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
61
Canadian CR and CS
- All CR prouducts licensed through CFIA
| - Plasma derived CR or CS not permitted
62
USA CR and CS - licensed
- Only some manufacturers licensed through USDA, CVB
| - Potency, purity, efficacy, regulated
63
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
64
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
65
Apparent efficacy of absorption
- % fed compared to amount absorbed systemically
- IgG mass (dose)
- Manufacture methods
- Other nutrients and additives
66
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
67
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)
