Gos or Geush meant the spirit of Living Nature, creation, in a wider sense (Geush Urvaan). Originally the Bull was a symbol for the whole of it, even including mankind, but in a narrower meaning it was used to indicated the cattle that became so all-important for the agrarian people that had settled down in Aireanem Vaeja (hence: Iran), which would later grow into the Persian Empire. The Cattle did supply the essential manure to make the earth fertile for agriculture, and of course also all the other products from the cattle became very important to the agrarian people living the Peaceful way that Zarathustra taught, instead of their previous nomad way, which nearly always included raiding neighbouring tribes. So it was very important to obtain divine protection to preserve all the livestock of the farm.

[Zarathustra said:]

 I " We sacrifice to the powerful Preserver, made by Mazda,  who keeps the Flocks in Health, the herds in Health, the grown up Cattle in Health, the young ones in Health ; who watches well from afar, with a wide-spread and long-continued Welfare,  welfare-giving Friendship ;  health-giving, powerful to stand and powerful to turn to for assistance, by the Faithful.

II To the Preserver we are offering the Haoma, the Wisdom of the Tongue,  Holy Spells : Speech, Deeds, Libations and rightly-spoken Words. 

III Do Grant me, O good Preserver, that I may bring down Abundance to the World created by Mazda ; that I may bring down Immortality to the World created by Mazda ; that I may take away both hunger and thirst,  from the World created by Mazda ; that I may take away both old age and death, from the World created by Mazda."

IV And the great Zarathustra did offer up a sacrifice to the Preserver : with Haoma, with Wisdom of the Tongue, with Holy Spells, with Speech ; with Deeds accompanied by rightly-spoken Words. V And he begged the Preserver, saying :

"O good, most beneficent Preserver ! grant me that I may think according to the Law, may speak according to the Law, and may do according to the Law ; that You may spread my Mazdean Law and make it known, and that You may bestow beautiful Praises upon my Deeds."

VI The strong Preserver,  made by Mazda, the Holy Preserver, the Maintainer, did grant him that Boon as he was invoking the Preserver, saying : 

" I bless the strength and vigor of the powerful  Preserver,  made by Mazda ! VII ASHA is the Best of All Good.  Give unto Man brightness and glory !  give him Health of body,  give him the bright, all-happy,  blissful abode of the  Preserver."

The Preserver on Guard during all of the Day

(sun on left bunch of arrows) and Night (moon on top of other arrows)