Breeding a 4 year old rough female collie. How many

Normally you breed once a day every other day for perhaps 3 days of breeding. Some breed 3 days in a row once a day.
In my experience once conception has taken place the female will go out of heat and cease being receptive to the male but all the females vary.
If you have not checked the male for fertility you might want a vet to check a sample of sperm.
If you are unsure when your girl usually ovulates you might want to do a progesterone test to find out if she has ovulated or not. Its possible she is a late ovulator and that is why she is still standing for the male.
You can read about the progesterone test here
http://www.woodhavenlabs.com/dogbreeding.html
If your vet can't help you with checking the male or doing a progesterone test you might find a specialist listed here can help you
http://www.whelpwise.com/testing/veterinarian-links.html
or you may find a vet in your area who works with breeders on such testing.
Hope this helps you!

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Hi Thanks for your quick response. The male has five-week-old puppies on the ground with another breeder, and we have 4-month and 10-month-old offspring by this father. The mother has also been successfully bred three times at yearly intervals. So, I guess my question is this: should I continue to breed them until she is not interested? or should I try another male (we have his brother who is also an active producer) and risk a double-sired litter?

Before risking a double sired litter and all the expenses that go with that for DNA sorting of the pups a progesterone test to see where your girl is in her cycle and if she needs to breed more might be a good idea.
You can breed her until she says no but you are already looking at an awfully long spread for whelping dates. If that is not a problem or the DNA testing isn't an issue you can add in a second stud or use the same one until she goes out of heat.
While previous litters are a good indicator for the fertility of them both (did you chart how she behaved during the breeding for the last litters? as that might help you) males can go sterile between breedings and females can get ovarian cysts or infections which mess up breeding hormones and egg release etc.
You can try with the other male but that will still leave you needing to know if your first male has developed an issue or not.
If you have your vet take a sperm sample and just look at it under a scope to see if there are lots of live sperm that will tell you a lot about where the problem might be.
Among the variables if she has an infection prevention conception do you want another male exposed to it.
So many variables. I think a little money outlay now in testing might be the best choice.

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