I'm wondering which statistical test would be appropriate here and also whether any Bioconductor or R packages would be useful:

Let's say you think that mouse coat color (black, white or orange) might be influenced by the size of the mouse (and imagine that size is binary, i.e. either big or small). You set up 6 crosses between a big mouse and a small mouse and 10 crosses between two big mice, and you count how many black, white and orange pups are generated in each cross. 

So now you have 6 independent repetitions of 1 cross and 10 independent repetitions of the other cross and you want to know whether the ratio of the three different coat colors is different in the two types of crosses. What type of statistical test is appropriate here? I was thinking that it might be multinomial logistical regression, "multinomial" because there are three possible outcomes and "logistical" because the outcomes are categorical, but I'm grasping for straws here. Any help would be appreciated, including recommendations of Bioconductor or R packages that could be useful.

Thank you. 

Eric