my 12 week old male pup has changed

We have had Tucker from 7 weeks old, he is a delightful little guy. This week since turning 12 weeks and having his second vaccination he seems to have mellowed out a fair bit, he sleeps more and is calmer, less bitey etc. Is this normal? We have changed his food this week too Artimis (higher quality) which is poultry and fish based rather than red meat based. Any info would be appreciated, am hoping he is just growing and maybe slowly maturing hence being more relaxed... Although he has started humping!

Hi & welcome to the forum.

Please come and introduce yourself here...

https://staffy-bull-terrier.niceboard.com/f7-new-member-introductions

I don't know Artimis dog food, so I can't say whether the food has changed him or not. Maybe, though, the training is paying off? 

I would love to think so

I think staffys do everything at full throttle: play, love, work! Nana loves playing with every single dog she meets, however, she plays with so much energy that some dogs, especially not puppies, growls at her. She doesn't growl back tho.

Nana's a good girl, then! 

I'd say your training is definitely paying off

Don't know about the food but if its a good quality one then all the better. Seems like you are doing great with the training.  

good job on the training

I think training and perseverance paying off.  

Sounds like training is going great