Liveweight targets

Liveweight at first mating and calving will have an impact on the reproductive performance and milk production potential of heifers as they come into the herd. On this page, ‘heifer’ refers to replacement youngstock before first calving, including rising one-year-old (R1) and rising two-year-old (R2) animals.

Replacement heifers should be reared to achieve their liveweight targets otherwise their first calving may be delayed, liveweight at calving light and fertility during the next mating period reduced. Well-grown heifers produce more milk in the first lactation, compete better with mature cows and survive longer in the herd compared with poorly grown heifers.

Having targets offers a measure of performance and indicates well-grown stock. Targets also establish an agreed position for farmers involved in a contract grazing relationship.

Heifer liveweight targets

30% of mature weight at 6 months of age
60% of mature weight at 15 months (mating)
90% of mature weight at 22 months (pre-calving)

Because body weight is the key driver of puberty, it is important that heifers reach key liveweight targets if they are going to reach puberty at 12 months, and get in-calf at 15 months.

Achieving the 30-60-90 percent targets is more important than the pattern of growth.

Heifer development plan

Meeting heifer weight-for-age targets should be the focus rather than a particular pattern of growth. To meet targets, heifers need to grow at appropriate rates over two years; putting a plan in place will help to achieve this.

Use this tool to set a plan for the first two years of a heifer's life. Set expectations for the animals weights, feeding levels and animal health requirements. Use with your grazier to set expectations and check your heifers' progress.

Estimating mature liveweight

There are three methods to estimate average mature liveweights for a group of heifers: liveweight breeding value, weighing a selection of mature cows (6-8 years of age), and using a breed-based average mature weight.

1. Liveweight breeding value (Lwt BV)

Obtain a 'breeding value trait report' from your herd recording provider (e.g. CRV, LIC). From this report calculate the average Lwt BV using the following equation:

Mature liveweight = 510kg* ± Lwt BV

If the BV is +20, then the average mature target liveweight for a group of heifers will be 510kg* + 20 = 530kg
If the BV is -15, then the average mature target liveweight for a group of heifers will be 510kg* - 15 = 495kg

* Based on base cow liveweight of 510kg.

Strengths	Weaknesses
Objective measure.	An on-farm study showed that 30% of animals were not matched to the correct mother. This is more important when using individual animal Lwt BVs than a herd or mob average.
Best prediction based on an animal’s genetics.	Random inheritance affects individual predictions more than the average prediction for a group.
Based on recorded liveweights from herds that weigh their in-milk cows, not only sire-proving herds.	Normal variation is -5% to +5% of the prediction.
Accounts for current breeding program targets.	The heritability of liveweight is between 35% and 65% so management has a moderate influence on the animal’s actual mature liveweight.
Majority of animals will have a Lwt BV.	Currently only available through MINDA software.

2. Mature herd average weight

Average herd liveweight can be determined by weighing a cross section of the mature herd. The following are ideal guidelines for selecting cows and standardising weighing, rather than strict cut-offs:

20–50 cows (the more you weigh the more accurate)
6-8 years of age
100-200 days in milk
BCS 4.5 (add or subtract weight if above or below)
After the morning milking

Aim for 100–200 days in milk, but cows outside this range (for example, at 250 days in milk) can still provide useful information. Record days in milk and body condition score so the results can be interpreted in context.

This information can be used to validate Lwt BVs and will be most accurate for herds with consistent breeding strategies and limited breed variation within the herd.

Strengths	Weaknesses
Representative of actual herd.	Time and yard set up required. Safe weighing facilities are needed; some farms may not have a suitable place to install scales.
Can be used for herds with overseas genetics, without relying on Lwt BVs.	Not every animal will represent 'average'.
Provides measured herd liveweights for other management decisions, such as stocking rates and weight-based animal health treatments.	Does not capture recent changes in breeding policies (e.g. increasing crossbreeding).
Captures management and environmental conditions of the farm system.	Will set targets too low if mature stock were poorly grown.

3. Average mature liveweight based on breed

Determine the average mature liveweight of your heifers based on herd composition, using the table below.

Breed	Average weight of 6-8 year old cows
Jersey	441-453 kg
Crossbred	522-533 kg
Friesian	567-580 kg

Source: New Zealand Dairy Statistics (2024-25)

As these mature weights are the average of the population, groups of heifers of a comparative breed can have targets above the average mature weight. Weight gain records and physical observations should also be used to evaluate the average mature weight when applied to a group of heifers.

Setting weight-for-age targets

Treat the 6-, 15- and 22-month liveweight targets as minimum goals. Aim for every heifer to meet the target appropriate to her expected mature liveweight. When targets are based on an average Lwt BV, use the mob average to monitor overall progress, but also check the number and proportion of animals below target.

Individual heifers differ in expected mature size, so a single mob target will not suit every animal. Where individual Lwt BVs are available, assess each heifer against her own weight-for-age target. MINDA Weights uses individual Lwt BVs rather than a mob-average BV. A mob average on target can still hide underweight animals.

Example mature liveweights and weight-for-age targets

Example weight-for-age targets for animals with mature liveweights of 400–600 kg. The key targets are 30% at 6 months, 60% at 15 months and 90% at 22 months; weights at other ages are guides. These examples are not breed averages.

Mature weight	Age	Liveweight (kg)
100%	6 - 8 yrs	400	450	500	550	600
20%	3 months	80	90	100	110	120
30%	6 months	120	135	150	165	180
40%	9 months	160	180	200	220	240
50%	12 months	200	225	250	275	300
60%	15 months	240	270	300	330	360
80%	19 months	320	360	400	440	480
90%	22 months	360	405	450	495	540

Before heifers move properties, review both the mob’s average weight and individual progress against the relevant weight-for-age targets. Document the number and proportion below target and the range of weights, and agree any follow-up actions with the grazier, particularly in contract grazing situations.

Monitoring performance

Most dairy farmers and farm advisers can recognise whether heifers are in good or poor condition, but few can judge whether heifers have actually achieved target liveweights for their particular age.

Weighing heifers on a regular basis provides an 'accurate' assessment of how well heifers are growing compared to targets. It also allows for proactive management - if heifers are under target at weighing, remedial action can be taken to get them back on track. Find out more about heifer feeding and nutrition.

There is no strict rule about how often heifers should be weighed (InCalf recommends every 3 months). The more frequently heifers are weighed the more quickly a problem will be detected. Find out more about heifer weights and weighing.

Use in farm management decisions

Establishing heifer liveweight targets and the growth required to meet them helps both the grazing farm and the home dairy farm plan. On the grazing farm, targets guide stocking rates, feed supply and the cost of growing heifers. On the home dairy farm, they help plan replacement rearing, grazing arrangements and the return of well-grown heifers before calving. The information can be used when answering a range of questions, including:

On the heifer grazing farm, if pasture production is 10 tonnes DM/ha, how many heifers can be carried while meeting their liveweight targets?
What is the most efficient nitrogen policy?
How much supplement is required, either made or purchased?
What crops would be most suitable when pasture availability is limiting?
What factors could make attaining the required heifer weight gain challenging?

Liveweight targets can give you a better understanding of what the cost of growing heifers is going to be, which can then be used to assess the costs and benefits of using land for heifer grazing, to decide whether to purchase or lease land and to negotiate a fair price. They are a valuable tool to use when reviewing heifer management. Final weights can be compared with targets to identify missed opportunities and review costs. Targets can also be used to set minimum weights, establish rejection criteria, or prompt early culling.