Compensatory responses of goat mothers to their impaired young

The behaviour of a mother goat towards her young normally compensates for differences between them in their vigour at birth. Weakening the first-born with drugs still does not prevent its getting equal access to the udder, though weakening the second-born may render it so much less vigorous that maternal compensation does fail. When the mother is unable to distinguish her kids by sight or smell, she is unable to modulate her responses to the kids and then the more vigorous kid always establishes priority of access to the bladder. We conjecture that this is what normally occurs under harsh environmental conditions where the mother's milk supply is occasionally inadequate for two kids.