Question

Fetal sex determination using ultrasonography can be done in cattle between

• A. 10-30 days
• B. 60-80 days
• C. 120-140 days
• D. 160-190 days

Hint:

Bovine Ultrasound Milestones:
Pregnancy Diagnosis = Day 25--30.
Fetal Sex Determination (Genital Tubercle) = 60--80 DAYS (Ideal window).
Heartbeat detection = Day 22--24.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Transrectal real-time B-mode ultrasonographic fetal sexing in cattle identifies the anatomical migration position of the bilobed echogenic genital tubercle (GT).
Key Formula or Approach:
\[ \text{Optimal Bovine Fetal Sexing Window} = 55 - 80\text{ Days of Gestation (Ideal: 60--70 days)} \]

Step 2: Detailed Explanation:
In bovine reproductive ultrasonography (fetal gender determination):
- Fetal sexing is based on mapping the anatomical position of the Genital Tubercle (GT) (the embryonic precursor of the penis in males and clitoris in females).
- In the bovine fetus, the GT starts in an indifferent position between the hindlimbs at day 50.
- Between Day 55 and Day 80 (optimally 60 to 80 days):
1. In the Male fetus, the GT migrates cranially to position immediately caudal to the umbilical cord attachment (forming the prepuce).
2. In the Female fetus, the GT migrates caudally to position immediately ventral to the base of the tail/perineum (forming the clitoris).
- Beyond 90--100 days, the large fetus drops deep into the abdominal cavity beyond transrectal probe reach.

Step 3: Final Answer:
Thus, fetal sex determination can be done in cattle between 60-80 days, corresponding to option (B).