From the offical website of the panda center, I get that It's forbidden to get too close or feed the pandas to avoid disorganizing Pandan's food habit and prevent the pandas being infected by any disease.

Actually, we still have chance to hold a baby panda because every year the giant pandas will spend a lot of money including their food, medical care, etc. it’s a really great financial burden to the local government. In order to solve this problem, the Panda Base has made a project. Generally speaking, there are two ways that you can get close to pandas. The 1st one is to adopt a panda. That is CNY50,000 each year and CNY500,000 for whole life of the panda you have adopted. The 2nd one is to make a donation to giant panda. That is less expensive,CNY10,000. If you only want has a chance to hold a panda, you may choose this one. Or if you want to see the panda you adopted anytime during your adoption period, you may adopt one. That is better.
Usually, you can hold giant panda anytime if the panda’s condition is great. In one word, it is all depend on pandas. I am sure you can hold panda from 9:45am to 11am and 2:30pm to 4pm. If you still have problems concerning the tour in Chengdu or holding giant pandas, you may contact me by email any time. Then I will tell you the latest development.
Vanessa

Sorry, type error! If you only want has a chance to hold a panda, that is CNY1,000. not CNY10,000.