Lab underweeight

Question
My 2.5 months black lab is underweight n bites too much n im not so much aware of hs diet.he is an indian n vegetarian dog.pls help

Answer
Biting is common for puppies, so that's just a training issue, and enduring while he grows up.  I am noticing from answering questions on AllExperts, that you folks in India tend to get your pups very early, much earlier than in the USA and unfortunately that is to the detriment of the puppy as staying with the litter until 8-12 weeks will teach the pup bite inhibition and will not bite the humans that much.  But no worries, the pup will grow out of it.  

As far as being underweight, I hope I did not read your post correctly.  You are NOT telling me that you are feeding a growing puppy a vegetarian diet, are you?  If that is correct, you must immediately purchase a commercially approved puppy diet that contains MEAT.  You will be hurting your pup immensely by not giving it proper nutrition during it's growth period.