8 August 1997

MATCHING BY NUMBER WITH aAa…

TRIPLE A mating, a corrective breeding package better known in the US than the UK, is now aiding the breeding decisions of an increasing numbers of dairy farmers this side of the Atlantic.

British Holstein Society aAa analyser is Lynden Bustard. He says the six digit mating system goes beyond pure linear and examines functional type. "It is the best used mating system in the world, with 11,000 US herds alone using the system."

He explains that the aAa programme, developed in the US 30 years ago, evaluates each animal on three major areas – the axial skeleton, udder and pelvis, and rear leg structure. The cow is given a code of six numbers, from one to six. One indicates a dairy cow, two is a tall cow, three an open cow, four a strong cow, five a smooth cow, and six a stylish cow.

Bulls are also rated. The difference is that numbers are assigned to bulls in the order they "sire or provide" them; cows are given numbers in the order they need them.

For example, a cow coded 123456 is a dairy cow which needs additional length of bone and angularity, a better quality udder with better ligaments and more set to her rear legs, says Mr Bustard.

A bull coded 123456 can provide these traits. The first three numbers are always the most important – in the cow revealing which traits need improving and in the bull, its strongest tendencies.n

Breeders Neil Rowe (left), and Geoff Spiby, believe that aAa breeding, available in the UK last October, is well worth using to help mate cattle.