API Youtube, how to get like and dislikes

On a website, i use API Youtube with ZendGdata for retrieve all video of a user and create webpage with the video and his informations.

Now i need to add a system for like or dislikes video on my website, and i need to retrieve the number of likes and dislikes.

(Yes, there are 2 questions here^^)

So, i retrieve for example title with $videoEntry->getVideoTitle();, number of views with $videoEntry->getVideoViewCount(); but how i can retrieve number of likes/dislikes ?

And how i can vote for a video on my website ?