Hi! My name is ***** ***** I would be happy to help with your magnificent terracotta bull.
This a great example of a Torito de Pucara roof ornament, a decorated bull typically placed (in pairs) on the roof throughout Peru and Bolivia for good luck as well as to bring agricultural abundance and fecundity -a classic form of Peruvian folk art- configured in the typical way as a jug-like vessel with an opening in his back.
This was because its original function was as a ritual vessel used during the traditional cattle-branding ceremony. It held the chicha (non-alcoholic corn beer) that was mixed with bull's blood and drunk by the shaman conducting the ceremony.
Your Torito de Pucara is a nice large example, and probably does date to the 1930s as you mention, certainly mid-20th century, though they are hard to date as the form has changed little since the late 19th century when they first became prevalent.
As for value, this example of the same size, but probably not as old as yours, sold on line for $150 which is about representative.
I would give yours an auction or on line (eBay etc) value in the range of $150 - $200. It therefore has a full retail or replacement value of $400 for insurance purposes.
I do hope this helps!
PS. If there's anything more I can help you with on this, please don't hesitate to ask. If not, could you very kindly rate my services (with the stars or "accept" button) as this is how I get paid by JustAnswer at no extra cost to you. We can still continue to communicate here on this thread after you do. And if you have another item you'd like to ask me about, just start a new Question and put "For Robert S....." in the subject line. Thanks, R.