Neonatal Ruminants: Initial Mgmt & Clinical Investigations (Ch 19)

Question 1

What is the immunoglobulin concentration and differential of Ig types in bovine colostrum?

What is the leukocyte concentration in bovine colostrum?

Answer 1

45 mg/ml immunoglobulin (95% of the whey protein)

• 80% IgG1
• 10% IgG2
• 7% IgA
• 5% IgM

1 million leukocytes/ml

Question 2

What type of placenta do all ruminants have?

Answer 2

Cotyledonary - multiple discrete areas of attachment

Epitheliochorial - All 6 layers retained!

Question 3

How and when do the intestines absorb colostrum and “close” after birth?

Answer 3

Enterocytes selectively absorb Ig via pinocytosis in the 1st 24 hrs

“Closure” occurs by 24 to 36 hrs postpatrum and is mediated by growth factors (IGF-1, TGF-2ß, and GH) in the colostrum causing hyperplasia of intestinal epithelium and decr crypt-to-villus ratio (shift towards mature enterocytes)

Question 4

How much colostrum should calves receive and when to achieve optimal IgG transfer?

Answer 4

7.5% to 10% of BW (minimum of 150g IgG) within 2 hours of birth

Question 5

What are the 4 major factors influencing the effectiveness of passive transfer of immunoglobulins in calves?

Answer 5

1) Concentration of immunoglobulin
2) Volume of colostrum ingested
3) Age of the calf at 1st colostral feeding
4) bacterial load of the colostrum ingested

Question 6

What are factors that affect colostrum qualtiy/concentration?

Answer 6

• **Colostral Volume/weight
• **Time from calving until milking (IgG is reabsorbed)
• No consistent breed differences
• 1st/2nd calving cows vs 3rd or greater parity
• Complete elimination of a dry period
• Clinical mastitis
• Higher in summer (unless heat stressed)