"Sometimes, with some writing competitions, you assume more realistic stories will get further ahead and I have entered before with a more realistic piece, but I got nowhere so I was completely wrong in my assumptions," she said.
"I think the Commonwealth Writers seem to be very much interested in world literature and a wider variety of themes.
"Black Milk couldn't have existed without Fiona Pardington's photography, which requires us to see things in a different way. Good fiction makes us see in a different way also, so it makes me very happy that Black Milk might have achieved that."
Excited to be going to Jamaica and Calabash - "I've never been anywhere tropical before" - Makereti said she's looking forward to meeting other regional winners and doing research for her next book.
"I'm writing something at the moment where one of the characters gets shipwrecked in the Caribbean so it's perfect timing."
Makereti's first novel, Where The Rekohu Bone Sings, won the Nga Kupu Ora Aotearoa Maori Book Award for Fiction in 2014 and was longlisted for the Dublin Literary Prize.
She's also enjoyed success with short story collections. In 2012, she was Writer in Residence at the Weltkulturen Museum in Frankfurt, Germany and, two years later, Creative New Zealand Randell Cottage Writer in Residence.
Stefanie Seddon, the winner for the Canada and Europe region, grew up on a farm in New Zealand but later moved to the UK. Her story, Eel, is set in the South Island where she spent the first half of her life.
"I think you never really lose the view you grow up with and when you see it through a lens of time and distance, it can be a great source of inspiration for fiction writing."
Other regional winners were: Africa, Faraaz Mahomed (South Africa); Asia, Parashar Kulkarni (India); Caribbean, Lance Dowrich (Trinidad and Tobago)
Black Milk is now available to be read at granta.com