For NZ Dairy Farmers
If you’re running a seasonal dairy operation in New Zealand, you already know that getting your replacement heifers and young stock to hit their target weights isn’t optional — it’s the foundation of a productive, profitable herd.
Miss those weight targets, and you’re looking at late calving, lower milk production, poor fertility, and cows that don’t last in the herd. Nearly 200,000 NZ dairy heifers were tracked across three calving periods: 92% calved for the first time at age 2, but only 76% calved a second time at 3 years, and just 61% made it to a fourth calving. That’s a lot of animals culled before they’ve paid back their rearing cost.
The good news? Most of these problems are avoidable — if you have the liveweight data to manage them.
The bad news? Getting that data regularly is a pain.
The Current Options for Weighing Dairy Cattle (And Why They’re Not Great)
Option 1: Crush and Weigh Scales
Traditional scales are accurate — but they come at a cost.
You have to yard the mob, run them through the race, handle each animal, record the weights, and then repeat the whole process in a few weeks if you want to track growth rates. Yarding stress can cause cattle to lose 2-5% of their liveweight in shrink — that’s 10-15kg on a 300kg heifer, which throws off your growth data. And gut fill can account for up to 22% of a heifer’s liveweight, so even accurate scales can give you variable results depending on time since feeding and diet type.
For heifers off-farm on contract grazing, weighing is even harder. Many graziers don’t have scales, or they’re in the wrong location, or the logistics of yarding young stock every 4-8 weeks just doesn’t happen.
Option 2: Walk-Over Weigh Systems
Automated and excellent — if you have the infrastructure and the throughput to justify it. For some dairy operations, walk-over scales work well, however only for the adult milking herd.
For most farmers, cost doesn’t equal value, it doesn’t help the critical youngstock mobs, or where heifers are spread across multiple blocks or on contract grazing.
Option 3: Weigh Bands or Visual Estimation
Cheap, portable, and sometimes better than nothing. But weigh bands can be out by 20-50kg depending on the animal’s frame, body condition, and breed. When you’re trying to hit precise mating weight targets or assess whether a mob is on track, guesswork isn’t good enough, and is staff putting arms through rails around the larger animals worth the guestimate?
Option 4: Not Weighing At All
The most common option — and the most expensive. Many heifers on New Zealand dairy farms fail to reach their target liveweight, and without regular weighing, you don’t know there’s a problem until it’s too late to fix it.
Why Liveweight Targets Matter So Much in NZ Dairy
Because almost every reproductive and production outcome on your farm comes back to whether your heifers and young stock hit their weight-for-age targets
Heifer Growth and Mating Success
Heifers need to be at 60% of their mature liveweight at mating (15 months) to optimise conception rates. Miss that target, and you’re looking at lower pregnancy rates, later calving, and reduced first-lactation milk production.
The key targets for heifer growth are 30-60-90: 30% of mature weight at 6 months, 60% at 15 months (mating), and 90% at 22 months (pre-calving). These aren’t aspirational — they’re the minimum thresholds for setting heifers up for a productive lifetime in the herd.
DairyNZ recommends weighing heifers every 3-4 months, though more frequent weighing (every 4-8 weeks) allows for earlier intervention if animals are falling behind.
Lifetime Milk Production
For every 1% increase in the percentage of target liveweight achieved at 15-17 months, heifers produced an additional ~20 litres of milk in their first lactation. Well-grown heifers don’t just survive longer in the herd — they produce more milk from day one.
Heifers that failed to record a second calving had achieved a lower percentage of target liveweight at 15-17 months compared to those that calved for a second time. In other words, missing weight targets doesn’t just cost you in year one — it costs you the entire productive life of that animal.
Body Condition Score (BCS) and Reproduction
For mature cows, body condition score is the gold standard for assessing energy reserves and reproductive readiness. DairyNZ targets are BCS 5.5 at calving for 2-year-olds and 3-year-olds, and BCS 5.0 for mature cows, with no more than 1.0 BCS loss between calving and mating.
But here’s the thing: BCS is subjective, time-consuming, and requires training to do accurately. Most people need formal training to visually score cows within 0.5 BCS units, and gut fill can give a visual impression of condition over the ribs, making hands-on assessment necessary for accuracy.
BCS cameras are great for removing subjectivity, but are limited to the milking mob.
Liveweight data can complement or replace BCS in many situations. Regular weight tracking gives you an objective, quantifiable measure of whether your cows are maintaining condition through lactation, losing too much weight post-calving, or hitting their pre-mating targets. It’s faster, more consistent, and doesn’t require hands-on handling.
Accurate Dosing for Drench, Bolus, and Medications
Getting dose rates right matters — for animal health, treatment efficacy, and cost management. Under-dose a drench and you risk treatment failure or parasite resistance. Over-dose and you’re wasting expensive product or risking toxicity, particularly in young or light animals.
Accurate liveweight data means confident, precise dosing — whether it’s anthelmintics, antibiotics, trace element boluses, or metabolic treatments. Guessing can be costly. Regular weighing takes the risk out of the equation.
Contract Grazing Accountability
If you’re sending heifers off-farm, liveweight targets are the only objective measure of whether your grazier is doing their job. Liveweight targets can be used to set minimum weights, establish rejection criteria, or prompt early culling, and they provide a clear basis for reviewing costs and performance.
Without regular weighing, you’re relying on trust and guesswork — and finding out your heifers are underweight when they come home is too late.
What If Weighing Didn’t Have to Be This Hard?
That’s where Scanabull comes in.
We’re making it easier to get the liveweight data you need to hit your production goals — regularly, accurately, and without the stress, cost, and labour of traditional weighing.
How it works:
Scanabull uses 3D vision technology on your iPhone Pro to measure cattle liveweight in seconds. Walk through the pen, scan the mob, and you have weights and images synced to your secure WeighIQ dashboard. Track growth rates, compare against targets, and share data with your grazier, vet, or farm consultant if you choose.
Why it’s built for NZ seasonal dairy:
- No crush required — works in any yard, pen, or raceway you already have. Perfect for heifers on grazing blocks where traditional scales aren’t practical.
- Low-stress for stock — no yarding stress, no handling, no weight loss from the weighing process itself.
- Fast and flexible — weigh a mob in minutes, not half a day. Check heifer growth regularly without the logistics nightmare.
- Objective and repeatable — no guesswork, no estimates. Liveweight data you can track over time and use to make real management decisions.
- Contract grazing transparency — share photographed weights and growth data with your grazier. Clear, objective accountability for both parties.
The Bottom Line
In NZ seasonal dairy, hitting your heifer liveweight targets isn’t a nice-to-have — it’s the difference between cows that calve on time, get back in calf, and produce for years, versus cows that struggle, calve late, and leave the herd early.
But getting regular, accurate liveweight data shouldn’t mean losing half a day, stressing your stock, or relying on guesswork.
Scanabull is being built to give you the weight data you need — when you need it, where you need it, without the hassle.
If that sounds like something your operation could use, we’d love to hear from you.
Keen to trial it on your heifers or young stock?
Get in touch: weighin@scanabull.com
Scanabull — Low-stress weighing. Real-time data. Built for NZ dairy farmers.
