Herd management groups

A herd management group is a group of 5 or more cows managed in the same way on the same farm. This includes cows that receive the same types of feed, feed allocation, supplements, walk the same distances, and are run together for practical management reasons. On farm, these groups are commonly called a mob, sub-herd or herd.

Why herd management groups matter

Herd management groups help make animal evaluation more accurate by comparing individual animals with their herd mates managed under the same conditions. They show which cows were managed under the same conditions at the time of herd testing, weighing or another measurement.

This is important because management can affect performance. If one group receives extra supplements, walks further, or is grazed differently, their results may not be directly comparable with cows managed under different conditions.

Using herd management groups in animal evaluation help account for these differences by:

• Reflecting how groups are often managed on farm, such as separating lighter cows for extra feed, keeping heifers away from mature cows to reduce bullying, managing health needs, or running autumn and spring calving herds separately.
• Supporting data quality and meaningful comparisons when group information is recorded at herd testing, weighing, and other key measurement points.
• Supporting more accurate breeding and production information by separating management effects from genetic effects.
• Meeting the requirements of the revised Herd Test Standard (NZS 8100:2024).

When herd testing, your Certified Herd Tester will also record details about any in-shed feeding on farm. Including this information helps meet the revised Herd Test Standard and supports more accurate animal evaluation.

What this means for your herd records

Recording herd management groups helps ensure cows are compared with the right herd mates. This supports better decisions about breeding, culling and feeding because the information is based on fairer comparisons within your herd.

At a national level, better herd management group records also support more accurate New Zealand genetic evaluation. This helps improve breeding values, sire selection and long-term genetic gain across the dairy sector.

How this links to animal evaluation

Animal evaluation is New Zealand’s system for estimating the genetic merit of dairy cows and sires. It uses herd records, performance information and known relationships between animals to make comparisons across breeds and herds. It produces Breeding Values (BVs) for individual traits, which are combined with Economic Values (EVs) to calculate indexes such as Breeding Worth (BW) and Production Worth (PW). These helps farmers rank animals on their expected efficiency and profitability to make better breeding and selection decisions.