High EST resulted in a lower relative heart weight (0.47% of YFBM) compared with low (0.52% of YFBM) and normal EST (0.53% of YFBM) at IP, a lower relative heart weight at high EST (0.58%of YFBM) compared with low (0.69% of YFBM) and
normal EST (0.66% of YFBM) at hatch, and a lower relative heart weight at high EST (0.70% of YFBM) compared with low (0.81% of YFBM) and normal EST(0.78% of YFBM) at 12 h after hatch