The 12 Years a Slave star has been appointed a global elephant ambassador for conservation organisation WildAid, and she has taken a trip back to her homeland to call for an end to big game poaching.

During her travels, Nyong'o visited a national park and elephant orphanage, and the life-changing experience has inspired her to call on other animal lovers to do more to save the mammals from hunters.

She says, "It was my first time to really have an intimate experience with elephants. What struck me was how big they are, how quiet they are. It was really a breathtaking experience... I really do intend for my children to have that same experience."

The actress adds, "I am proud of my Kenyan heritage, and part of that heritage is the incredible wildlife haven that is in our care. Poaching steals from us all.

"I have come to realise that when you know more, you do more. I want to encourage people all over the world to learn more about these incredible animals...

"I ask the world to end the current elephant poaching crisis by being 'Ivory Free'. It is time to ban sales of ivory worldwide and to consign the tragedy of the ivory trade to history."

Nyong'o, who will further raise awareness of the elephants' plight in forthcoming WildAid advertisements, isn't the only celebrity to campaign for an end to the lucrative ivory trade - Sex and the City star Kristin Davis has also been a longtime advocate for ending the sale of ivory in a bid to save elephants and other animals.