In the 1950s and 1960s the Department of Agriculture began research into growth rates of beef cattle at Ruakura Research Station, Hamilton, and at the nearby Whatawhata Hill Country Research Station. They found that growth rates are moderately to highly inheritable, so farmers who measured their cattle’s growth and bred them selectively could considerably improve their herds.
By the mid-1960s, commercial bull-breeders began to weigh and record animals during different stages of their growth. In 1973 Beefplan, a centralised performance recording scheme, was set up to compare animal performance – but the system was limited, as it could only compare animals run together in the same environmental conditions.
Estimated breeding values (EBVs), which predict an animal’s value as a parent compared with other potential parents, enabled scientists and breeders to compare the genetic potential of animals regardless of environmental effects. Beef breeders can now use 17 different EBVs for estimating productive traits, including fertility, growth rates and carcass quality.
Cross-breeding has been a feature of cattle breeding in New Zealand since the 1950s. One benefit is hybrid vigour, where cross-bred offspring outperform their parent breeds.
Another system of cross-breeding deliberately combines the best qualities of two or more breeds. Bulls of beef breeds are mated with dairy-breed cows, producing cross-bred cows with superior milking and reproductive ability. When these cows are mated to a suitable terminal sire (a bull that breeds animals for meat, not further breeding), they produce calves with high growth rates, which will have heavy carcasses. For instance, a Hereford bull is used with a Friesian cow to produce a cow that is then mated to a terminal sire, such as a Charolais, to breed calves that grow to heavy slaughter weights. In 2005–6, 44% of beef cattle in New Zealand were cross-bred.