HI,
She is from the Working Dog class, which means she needs plenty of exercise!
Do you walk her every day, briskly, for about 45 minutes? Or, if have a back yard, go out with her, running with her for 45 mintues, every day?
People and dogs get hungry when they have been doing hard work, getting a lot of exercise. Any good dry dog food is good. Look on the package for her weight, and the amount to feed her every day.
Put her food down in the morning, give her about 30 min. to decide if she wants it, then pick it back up. Don't leave it down all day. Put it back down in the evening.
If she isn't getting a lot of exercise, she probably won't want to eat anything; cause she isn't hungry!
I highly recommend a video by Ceaser Millan, a Professional Dog Behaviorist. He rehabilitates dogs, and trains people.
He has his own TV program, the Dog Whisperer, on the NGEO (National Geographic) channel, on Friday nights mainly, but also comes on some other days. This video is available from:
Cesar Millan Center
I also ordered his new book, "Ceaser's Way", from Walmart online, around $15 US, and it's very good!
There are other good videos available on the web, but this one is really worth your attention.
If you get this TV channel, please watch just one episode; you will be amazed. It's awesome. Also covers exercise and eating. Best of luck.