NZ animal evaluation

New Zealand Animal Evaluation Limited (NZAEL) is an independent organisation, and is a wholly owned subsidiary of DairyNZ, that manages animal evaluation for the New Zealand dairy industry.

NZAEL aims to improve the genetic merit of the national dairy herd by identifying the animals whose progeny will be the most efficient converters of feed to farmer profit. This is expected to deliver over $3 billion in profit gains to the New Zealand dairy industry over the next 10 years.

How NZAEL works

NZAEL captures, analyses and applies real animal data to the New Zealand dairy cattle database. Both male and female cattle are evaluated for their genetic merit.

Daughters of bulls are assessed and ranked within their contemporary group for a set of important genetic traits that drive profitability. These traits are shown in the graph.

Information collected by the industry is used by NZAEL to estimate breeding values (BVs). Records utilised include: milk production, somatic cell count, liveweight, body condition, mating and calving, and removals and traits other than production (TOP).

Farmers report management, or workability traits, while trained inspectors report dairy conformation and type traits. Approved milk recording companies contribute milk production records

New Zealand animal evaluation breeding worth traits for dairy cows
Effect emphasis on BW traits. Source: NZAEL 2021

Breeding Worth (BW)

Breeding Worth ranks male and female animals for their genetic ability for breeding replacements (NZAEL).

Breeding Worth combines selected genetic traits with the economic contribution of those traits to farm profit. Trait breeding values (BV) are multiplied by economic values (EV) in the formula.


The resulting profit index is Breeding Worth (BW), measured in dollars and reported relative to a Genetic Base benchmark, which is set at zero.

E.g. A bull has BW $200 his offspring receive half of his genetic merit and are expected to earn the farmer, on average, $100 more than the genetic base cow per annum.

Breeding values

Eight main traits make up the national breeding index Breeding Worth (BW). These are categorised into production traits (protein, fat, volume and liveweight) and robustness traits (fertility, somatic cells, body condition and survival).

The traits are all relevant to dairy herds across the globe.

Economic values

Economic values (EVs) are an estimate of the value of a trait to a NZ dairy farmer. Breeding with this system helps dairy farmers improve profitable traits.  

The economic values influence the effective emphasis of each trait in BW and use the costs and income sources on farm relating to the trait.

Economic values are adjusted annually to ensure BW remains relevant in an ever-changing market environment.

BW is measured across all breeds and breed mixes in New Zealand, giving a single across-breed BW figure. Animals can be directly compared for their breeding value regardless of breed or breed mix.

The way the animals are measured across breed is unique to NZ with all other countries all comparing cows within breed.

Bulls can be compared both within and across breed groups in the bull rankings of active sire list (RAS list) on the Dairy NZ website.

Comprehensive genetic evaluation information including means, standard deviations and percentiles across the main dairy breeds at a herd, and cow or enrolled sires level is available in the Animal and Herd Averages section of the website.

LIC’s NZ cow indexes (PW & LW) are also across-breed indexes.  NZ farmers use these to directly compare the profitability of cows of differing breed mix within their own herd and farm system.

Download the Breeding Worth Explained brochure for more information on BW, PW and LW.

Genetic trends

In a successful breeding programme, the genetic merit of the population should continually improve. Called genetic gain, this improvement is both cumulative and permanent, with each generation building on the genetic merit of the previous one.

The rate of genetic gain in New Zealand is BW $10/ year, on average, as animal efficiency increases. Average per cow production has increased by 50 kg milk solids in the past 10 years, while liveweight remains relatively static. Researchers estimate 40% of this production gain is due to genetic improvement.

For more detail on genetic trends view the NZAEL website.

TOP traits

In addition to production and robustness traits, it’s desirable to see genetic gain for other important non-production traits such a temperament, udders and dairy conformation.

These traits are called Traits Other than Production (TOP) and fall into two categories – management traits and conformation traits.

Management traits include adaptability to milking, parlour temperament, milking speed, overall opinion, heifer calving difficulty and cow calving difficulty. These traits are farmer scored.

Conformation traits include dairy capacity, rump width and angle, leg, teat placement and udder related traits as well as dairy conformation. These traits are inspector scored.

Download the TOP booklet for more details.

Introducing all of these beneficial traits into herds across the globe, will contribute to longer lasting, healthy cows that will benefit the dairy farming gene pool and industry as a whole.

The Genetic Base

When ranking within a population it’s useful to have a benchmark to which everything is referenced. In animal evaluation, this reference point is called the Genetic Base – also known as the Base Cow.

The Genetic Base is made up of a group of well-recorded cows from a selected year. Their profitability is set as the reference point ‘0’ and all animals are reported in relation to this group. If the animal is more profitable than the Base Cow the BW value will be positive, if less profitable, the BW value will be negative.

The Genetic Base is updated every five years. A new group of cows used as the Genetic Base are selected from a year-group five years on from the previous base. Their BW is set as the new zero reference point, although they are genetically superior to the previous base.

The result is a national herd reset with an overall drop in BW seen each base change year due to the new Genetic Base being closer to that of the current population.

Visit the NZ Animal Evaluation website for more information

NZ animal evaluation contents

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