Below is the official link for you to gather more information.
Hope this helps.
TNAU tells you to score minimum 60% in your intermediate examination to be eligible for it but if you want to come in the top then you need to score maximum marks , it is difficult to predict there because it varies with person to person in each academic year , but you can have a probable idea which is approximately 90% +.
I hope you got it
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Best of luck.
let me clear your doubt.
A candidate should have ICAR score above 225 for TNAU for B.Sc (Agriculture) admission for general categoryand the minimum eligibility for the B.Sc. courses is that the candidate must have completed their Class 12th exam with minimum 60% marks in the relevant subjects .
I hope my answer will be helpful for you