Heifers must be reared to achieve their liveweight targets otherwise their first calving will be delayed, liveweight at calving will be too low and fertility during the next mating period reduced. Well-grown heifers will produce more milk in the first lactation, compete better with mature cows and survive longer in the herd.
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 percentage targets is more important than the pattern of growth.
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.
Setting weight-for-age targets
Weight for age targets should be used for mobs. The average weight of a mob should meet each target weight-for-age, this will indicate that they are on track for meeting the 22 month target.
Individual heifer weights will fall either side of the weight-for-age target. It is natural to have variation in a mob, and studies have shown that some healthy heifers may be 15% lighter than their peers.
Breed average mature liveweights and weight-for-age targets
Weight-for-age targets (highlighted) for animals of different mature liveweights, with guide weights for other ages.
Mature weight | Age | Liveweight (kg) | ||||
100% | 6 - 8 yrs | 420 | 465 | 500 | 550 | 600 |
20% | 3 months | 84 | 93 | 100 | 110 | 120 |
30% | 6 months | 126 | 140 | 150 | 165 | 180 |
40% | 9 months | 168 | 186 | 200 | 220 | 240 |
50% | 12 months | 210 | 232 | 250 | 275 | 300 |
60% | 15 months | 252 | 279 | 300 | 330 | 360 |
80% | 19 months | 336 | 372 | 400 | 440 | 480 |
90% | 22 months | 378 | 419 | 450 | 495 | 540 |
Before heifers move properties, the group should meet their target weight-for age. The number of animals below target and/or the range around the target should be documented, 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.
More information
- Benefits of heifer liveweight targets
- Science behind heifer liveweight and body condition score targets
- Assessing heifer performance without weight data
- Selecting mature liveweights
- Setting weight-for-age targets
- Creating a heifer growth rate plan