Śatapatha Brāhmaṇa ("of a hundred paths") 13.2.5.4

13.2.5.4

ekādaśa daśata ālabhate ekādaśākṣarā vai triṣṭubindriyamu vai vīryaṃ triṣṭubindriyasyaiva vīryasyāvaruddhyā ekādaśa daśata ālabhate daśa vai paśoḥ prāṇā ātmaikādaśaḥ prāṇaireva paśūntsamardhayati vaiśvadevā bhavanti vaiśvadevo vā aśvo'śvasyaiva sarvatvāya bahurūpā bhavanti tasmādbahurūpāḥ paśavo nānārūpā bhavanti tasmānnānārūpāḥ paśavaḥ

Eleven decades he seizes, for the Trishtubh consists of eleven syllables, and the Trishtubh means energy, vigour: thus it is for the obtainment of energy, vigour. Eleven decades he seizes, for in an animal there are ten vital airs, and the body: (trunk) is the eleventh: he thus supplies the animals with vital airs. They belong to all the gods for the completeness of the horse (sacrifice), for the horse belongs to all the gods. They are of many forms, whence beasts are of many forms; they are of distinct forms, whence beasts are of distinct forms.