New Zealand Thoroughbred Racing, TAB NZ and Entain have rolled out the country's richest three-year-old "slot" race, the NZB Kiwi, as the headline for a $9 million "champions day" at Ellerslie Racecourse next March.The 1,500-metre thoroughbred race will carry prizemoney of at least $3.5m from March next year, increasing to $4.5m by 2027, making it the richest race on the southern hemisphere racing calendar for three-year-olds, according to organisers.