Talk to her ask her if she can think of a way to fix it.
Keep her in the loop if you and her can talk it out. I think she may think you are doing something to make it smell worse. Make sure she knows you are try to be a good neighbor.
Plus that you posted online ask for advise. I think she will just say, well it is what it is the smell of cows and we are in the country. Try spreading before a rain better for the ground and smell.
Like me if I burn I'm on a farm and can burn anytime but why would I burn if I know my neighbor trying to dry clothes on a line or if it is nice and there windows are all open. I look at it as be a good neighbor. Make too many mad and then they go to a township meeting and ask to change the laws. Be neighborly if you can.