MBA/PGDM

It's your choice to choose MBA or M.Sc (Zoology). As an academic / career expert, I can explore you about the scope and employment opportunities of both.
MBA is PG program in Management which deals various subjects of Management, Accountancy, Business Laws, Business Ethics, Organizational Behavior and Communication, Business Maths and Statistics, etc. You can specialize either in traditional branches / electives (Finance, HR, Marketing and Systems) or can choose Sectoral programs like Hospital Management, Healthcare Administration, Project Management , Logistics and Supply Chain Management, etc.
MBA is a gateway into corporate world. With an MBA, you can touch the top most position (If you have right attitude, ability, skills, leadership qualities, etc.). There is no limit for salary in corporate world. You can draw monthly salary in lakhs and there is not any specific retirement age.
Of course M.Sc in Zoology is also a good option. Teaching is the prime employment area after M.Sc-Zoology. You have to continue your studies and have to complete M.Phil / PhD to get job as Lecturer in Colleges. Also, you need to clear tests such as NET (for teaching positions at colleges) and SET (For teaching positions in Higher Secondary / HSc).
M.Sc + BEd + SET is the required qualification for HSc / Plus Two / Senior Secondary teachers.
Now a days UGC offers attractive Salary Package for college lecturers.
Now it's your decision, Think about both careers and take right decision.