Whenever someone else milks the goats, the goats hold milk back. The substitute milker wrings out the last drop, then I go take a turn. Figgy senses my familiar warmth against her side. I sing the milking-time song I have sung for years, and all of a sudden her teats are full of milk again. The Nigerians simply have conniption fits if anyone else tries to milk them. Goats are notoriously personal, so even large commercial herds get divided into small groups cared for by the same people. Cows also thrive on familiarity. Mothers can probably relate.
I milked a cow the other day, squeezing hard to get a steady stream into the pail. Her little calf came over and butted the other side of mama's udder. Suddenly the flow got easier, as the mother's hormones released milk to my unfamiliar hands.