Question

Permanent incisors in cattle start coming up at the age of

• A. 3 years
• B. 2 years
• C. 6 months
• D. 12 months

Hint:

Cattle Dentition Age Rules:
2 Years = 1st pair permanent incisors ($I_1$).
3 Years = 2nd pair ($I_2$).
4 Years = 3rd pair ($I_3$).
5 Years = Full mouth ($I_4$).

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Dentition and age determination in cattle: eruption of the first pair of permanent central incisors ($I_1$ pincers) occurs at 1.5 to 2.0 years of age.
Key Formula or Approach:
\[ \text{Cattle Dental Eruption: } I_1 \text{ (Central)} = 1.5 - 2 \text{ yrs} \mid I_2 \text{ (Middle)} = 2.5 - 3 \text{ yrs} \mid I_3 \text{ (Lateral)} = 3.5 \text{ yrs} \mid I_4 \text{ (Corners)} = 4.5 - 5 \text{ yrs} \]

Step 2: Detailed Explanation:
Aging cattle by permanent incisor eruption:
- Calves are born with temporary deciduous incisors ($D_1 - D_4$).
- Eruption of permanent incisors follows a strict chronological schedule:
1. First Pair (Central Incisors Pincers, $I_1$): Erupt and replace temporary teeth at 1.5 to 2.0 years (2 years of age) (known as 'two-tooth' stage).
2. Second Pair (First Intermediates, $I_2$): Erupt at $2.5 - 3.0\text{ years}$ (four-tooth).
3. Third Pair (Second Intermediates, $I_3$): Erupt at $3.5\text{ years}$ (six-tooth).
4. Fourth Pair (Corner Incisors, $I_4$): Erupt at $4.5 - 5.0\text{ years}$ (full mouth).

Step 3: Final Answer:
Thus, permanent incisors start erupting at the age of 2 years, matching option (B).