Hello there,
For doing MSc in Dairy Science, you need to pass your BSc degree in any science stream, with atleast 50% aggregate, as per the eligibility criteria. Hence, you are eligible for MSc Dairy Science after your BSc in physics maths.
Now, this criteria may vary in some colleges, therefore, you should check the eligibility criteria of that particular college before applying there.

Hope this answer helps you.
Good luck!!