My question concerns the matter of mixing meat and dairy which I understand. How does this include poultry which does not produce milk to feed its young.
There have been two very similar questions posted on the site, and I recommend you read the responses to these questions for the answers to your quesitons.
You will find them under the Category Miscellaneous, below Subcategory Beliefs & Practices.
These two topics address why one may not mix meat and milk, and why chicken/poultry is treated as meat even though it does not produce milk.
If you find you still have questions after reading these items, please feel free to submit another specific question.