PE of Neonatal Ruminants

Question 1

What is the Fetal Immune System like?

Answer 1

• All livestock species born hypogammaglobulinemic
• Neonates are immunocompetent at birth but immunologically naïve
• Acquired immunity from maternal immunoglobulin found in colostrum

Question 2

What are the major components of colostrum

Answer 2

• Colostral Fat
• Growth Factors & Hormones
• Minerals & Vitamins
• Immunity

Question 3

What is the immunoglobulin composition of colostrum?

Answer 3

• IgG 24-100 g/L (Greater than 90% IgG₁)
• IgM 3-13 g/L
• IgA 1-17 g/L

Question 4

Does colostrum provide nonimmunological benefits?

Answer 4

• Improved daily gain and feed conversion
• decreased veterinary care in preweaning period
• Increased milk production in 1st and 2nd lactation
• Enhanced development of the GI tract

Question 5

What is Passive Transfer of Immunity?

Answer 5

• The timely ingestion and absorption of an adequate mass of IgG (IgG₁) by the neonate

Question 6

How does Passive Transfer of Immunity Occur

Answer 6

• Enterocytes are non-selective for the absorption of immunoglobulins in first 24hrs
  
  • enteric absorption of immunoglobulins is time sensitive
• Adequate passive transfer in dairy calves (serum):
  
  • >1000 mg/dL (10g/L) IgG
• Administer 7.5-10% BW within 2 hrs after birth
  
  • provide a minimum of 150g of IgG
  • Excellent passive transfer min is 200g IgG
• Results in ~80% of calves having adequate passive transfer

Question 7

How is failure of passive transfer of immunity (FPT) defined?

Answer 7

Calf serum IgG < 10g/L at 24-48hrs old

Question 8

How can FPT in calves be detected?

Answer 8

• Radial immunodiffusion
• ELISA
• GGT
• Total protein
• Brix refractometry
• Zinc sulfate turbidity

Question 9

What is Serum Total Protein and how does it relate to passive immunity?

Answer 9

• STP 5.0 - 5.5 g/dL = 10 g/L IgG in serum

Question 10

What Brix refractometry results are concurrent with successful passive transfer of immunity?

Answer 10

• %Brix 8.4 = >10 g/L IgG in serum
• Underestimates real IgG values for individual samples

Question 11

What factors are associated with FPT?

Answer 11

• Failure to produce
• Failure to ingest
• Failure to absorb

Question 12

What factors affect IgG concentration in colostrum?

Answer 12

• Breed
• Parity
• Pooling of colostrum
• Time of colostrum collection
• Genetics

Question 13

What methods exist to evaluate colostrum quality?

Answer 13

• Radial Immunodiffusion (RID)
• Brix refractometry
• Colostrometer

Question 14

How good is Brix Refractometry at evaluating colostrum?

Answer 14

• %18-22 = >50 g/L IgG
• High sensitivity and specificity
• Colostrum should only be kept for storage if Brix is ≥ 18%

Question 15

How effective is a colostrometer at evaluating colostrum?

Answer 15

• Green = 50 g/L IgG
• Lower sensitivity and specificity
• Affected by total solids, fat, temperature
• tendency to overestimate IgG level

Question 16

What factors affect the ingestion of colostrum

Answer 16

• Dystocia
• Abnormal calf
• Poor mammary gland conformation

Question 17

What factors affect calf absorption of colostrum?

Answer 17

• Delayed feeding of colostrum
• Hypothermia
• Poor storage and handling of colostrum
• Bacterial contamination of colostrm

Question 18

How are FPT calves treated

Answer 18

• Plasma or Whole Blood Transfusion
  
  • 20-40 ml/kg IV
• Colostrum supplement
  
  • 25-50g IgG/dose
• Colostrum replacement
  
  • >100g IgG/dose

Question 19

What are the recommendations for improving quality of maternal colostrum?

Answer 19

• Consistent vaccination program for breeding animals
  
  • Vaccinate dams against common respiratory and centric pathogens pre parturition
• Supplement low quality maternal colostrum with colostrum replacer