It is hereby made the duty of all common carriers of freight within this state to move cars of livestock at the highest practicable speed consistent with reasonable safety and the reasonable movement of its general traffic. The burden of proof that cars of livestock are so moved shall be upon the carrier, and proof that such cars were moved according to schedule or timetable shall not be prima facie evidence that they were moved at the highest practicable speed consistent with reasonable safety.
Iowa Code § 327D.102