Geese not raised with chickens Will they still protect?

While searching my local classifieds I found a pair of adult geese. I would like to put at least one of them with my broiler flock. The seller says the have not been raised with chickens. Will the still guard the chicks? would they attack the chickens or just do nothing?

Geese have personality so there isn't likely to be one right answer here.
We have had Muscovy ducks for years and I got a pair of geese for aerial predator protection. I found that sometimes when I first tried to let out a mom with ducklings, the Gander would chase her off. Then I built some "mini-hoops" with one end hardware cloth down to the bottom pipe, so that Heinrich could see the ducklings and they could see him, before they were large enough to be let out. This worked wonderfully, and "Uncle Heinrich" is often seen book-ending a gaggle of youngsters along with their mom. He seems to prefer the Muscovy ducklings over the Khaki ducklings but that makes sense from the evolutionary standpoint.

Are your broiler flock commercial Cornish Crosses? They're not the brightest. The main way Heinrich protects is that all the birds run to be near him if they see or hear trouble. The Broilers may not do that. If the area is small enough, aerial predators may still avoid coming down strictly due to the presence of the goose.

You wrote that the ad said "pair of adult geese" - if they're bonded, I expect you will have to put both in. At this time of year that likely won't be a problem, but I've had a few mild issues during mating season - but nothing unmanageable. They *are* noisy!

My broilers are Red Rangers. I had Cornish cross last year and theses birds a far more intelligent.

I can't speak for all geese but 6 months in to my 1 year old goose ownership experience they chose one of the chickens and nearly murdered it. They were shot for that. So, those geese were not safe guards.

Howdy!
A quick note before I dash outside to feed the poultry.
I raised my initial gaggle at the same time as my current Main Flock.
In my experience, geese are bullies, but mine don't go out of their way to chase the chickens.
It seems to be a sort of Big Sibling/Little Sibling sort of relationship. The geese will protect the chickens by looking mean and being Large Angry Birds.
The chickens will keep to themselves, for the most part, and have learned to "speak goose".

Adding adult birds to an established flock would be hard, but not impossible. Geese are smart and quickly figure out what loopholes exist and how to use them.
I would pen the geese (and keep them as a pair, geese don't do well alone and will mourn the absence of a goose they liked), and let the chickens get used to them. Then slowly introduce the geese to the flock - under supervision, starting with a few minutes and working up.
My geese are "food driven", so it's easy to shape behavior with special treats for being Good Geese.
I haven't lost a chicken to a random predator in the three years I've had the geese. They have really paid for themselves over time.

Depending on the type of goose, you may have more or less problems - they do have both a "breed personality" and individual personalities.
Meet them and see what you think. Can you work with the geese without problems? Do they like you? Will they attack you?  Why is their current owner getting rid of them?

I wish you well, and hope you make the decision that's right for you and your flock.