Topics:
Animal Refresher, Dairy Science
Major Immunoglobulin in Ruminant Milk
Major immunoglobulin present in human milk is IgA, but in ruminant milk the major immunoglobulin is:
- IgG — Correct Answer
- IgA
- IgM
- IgD
Explanation:
Correct Answer: IgG
The major immunoglobulin in ruminant milk (bovine colostrum) is IgG, whereas in human milk/colostrum, the major immunoglobulin is IgA.
Immunoglobulins in Bovine Colostrum (Decreasing Order)
- IgG₁ > IgG₂ > IgM > IgA
- All these are present: IgG1, IgG2, IgM, IgA
Why This Matters — Passive Immunity in Calves
- In ruminants, placental transfer of antibodies does NOT occur (syndesmochorial placenta), so the newborn calf is born without circulating antibodies.
- The calf must absorb immunoglobulins directly from colostrum through the gut wall (gut closure occurs within 24–36 hours after birth).
- IgG from colostrum enters the bloodstream and provides systemic passive immunity.
Human vs. Ruminant — Key Differences
- Human colostrum → IgA predominant (protects mucosal surfaces)
- Bovine colostrum → IgG predominant (provides systemic immunity)
📚 About this Topic — Animal Refresher
This multiple choice question is from Animal Refresher, Dairy Science. It has 4 options with a detailed explanation of the correct answer. Practice more MCQs from Animal Refresher to strengthen your preparation.
