Final answer:
The yellow coating on newborn calves that have experienced a traumatic birth is typically made of vernix caseosa, a protective waxy coating, and meconium, a tarry substance accumulated in the fetal intestines during gestation and can stain amniotic fluid when passed.
Step-by-step explanation:
The yellow coating sometimes seen on newborn calves that have had a traumatic birth can be made of two substances: vernix caseosa and meconium. Vernix caseosa is a thick waxy coating that protects the fetus's skin from becoming chapped or irritated by amniotic fluid. Meconium is a sterile, tarry, greenish-black substance that the fetal intestines accumulate during the second half of gestation and is usually excreted by the newborn soon after birth. When it is passed into the amniotic fluid, typically during birth, it can tint the fluid yellowish or greenish. Both substances have different implications for the health of the newborn. Too much meconium can predispose the newborn and mother to infections, and care is taken to clear it from the newborn's airways to prevent complications such as neonatal sepsis. Vernix caseosa on the other hand, is generally protective in nature.