The Upanishads, Part 1 (SBE01), by Max Müller, , at sacred-texts.com
1. The hiṅkâra is goats, the prastâva sheep, the udgîtha cows, the pratihâra horses, the nidhana man. These are the Revatî Sâmans, as interwoven in animals.
2. He who thus knows these Revatîs, as interwoven in animals, becomes rich in animals 2, he reaches the full life, he lives long, becomes great with children and cattle, great by fame. His rule is, 'Never complain of animals.'
31:2 Revat means rich.