Led by Massey University’s Dr Rebecca Hickson and hosted on Limestone Downs at Port Waikato, the project’s goal is calculate the value that can be added by using high genetic-merit Angus and Hereford bulls, versus the unrecorded animals traditionally used as “follow-up bulls”.
The project also aims to identify individual bulls that perform strongly in a dairy-beef system and analyse outcomes for both the dairy farm and finishing farm operators.
Importance of dairy sector to beef exports
The dairy sector accounts for more than two thirds of New Zealand’s export cattle.
Export cattle processing – 2016/17 forecast figures:
| Of the 2.45 million head processed | |
| Cull cows | 37% |
| Cull dairy heifers | 3% |
| Cull dairy breeding bulls | 1% |
| Dairy farm total | 41% |
| Dairy-beef steers, heifers & bulls | 28% |
| Beef cows, steers, heifers & breeding bulls | 31% |
| Sheep & beef farm total | 59% |
| Total dairy genetic origin | |
| (Dairy farm total of 41% + Dairy- beef steers, heifers & bulls 28%) | 69% |
Background to progeny test
The first year of the B+LNZ Genetics Dairy-Beef Progeny Test saw 502 cows and 224 heifers calve in spring 2016, artificially inseminated with semen from 48 bulls. The heifers were naturally mated to 12 Angus, Hereford and Jersey bulls. These bulls were then used as follow up bulls for the cow herd.
The beef bulls were selected based on specific traits: birth weight, calving ease, gestation length, 400 day and 600 day growth and carcase traits, such as marbling.
Of the 2016 calf crop, all except 75 Jersey-sired calves born from the heifers were reared and are now being finished on Limestone Downs’ adjacent sheep and beef operation.
Dr Hickson says calving went well, with 1% calving difficulties in the cows and 8% in the heifers.
“Overall, the beef sires produced valuable calves with short gestations and few calving difficulties. There was variation among sires, indicating that sire selection is key to success in a dairy-beef system.”
| 2016 Calf stats | |
| Calves born | 502 head |
| Birth weight | 37kg |
| Gestation | 282 days |
| Days to weaning | 79 days |
| Weaning weights | 85kg minimum, 90kg average |
Analysis to date
Dr Hickson says results to date show that estimated Breeding Values (EBVs) work. “You can use EBVs to get the kind of calves you want. While there is individual sire variation, when you select a team of bulls, they perform where you’d expect, based on their EBVs.
“Within breed, bulls that were in the top 10% of breed for a trait were superior to bulls that had genetics similar to an average unrecorded bull.”
| Birth weight (kg) | Gestation length (days) | Weaning age (days) | |
| Hereford | |||
| Average unrecorded | 39.0 | 284.5 | 77.5 |
| Top 50% breed | 37.8 | 282.5 | 76.4 |
| Top 10% breed | 36.5 | 281.5 | * |
| Angus | |||
| Average unrecorded | 37.5 | 281.5 | 80.8 |
| Top 50% breed | 35.6 | 279.4 | 78.0 |
| Top 10% breed | 35.4 | 279.3 | * |
[* There is no figure, because selecting for low birth weight meant none of the bulls were top 10% for 200d weight.]
PhD student Lucy Coleman says that, based on a bobby calf being worth about $30 and a weaner $500, there is approximately $300 profit to the dairy farm, after rearing costs.
Heifers: bull selection and performance
Jersey bulls were selected to be breed average for liveweight and gestation length. Angus bulls selected were in the top 5% for birth weight and direct calving ease. Hereford bulls were chosen from the top 10% for birth weight and top 15% for direct calving ease.
| Jersey | Angus | Hereford | |
| Number of calves | 72 | 72 | 66 |
| Birth weight (kg) | 29.3 | 33.7 | 35.8 |
| Assistance (%) | 0 | 4 | 12 |
| Mean calving date | 24 July | 20 July | 24 July |
| Weaning age (days) | N/A* | 79.6 | 76.0 |
* Jersey calves were not reared, so weaning age was not measured.
It is worth noting that heifer liveweights were behind target at calving – about 420kg average, compared with a target of 450 kg, and calving would likely have been easier had the heifers been bigger.
Outcomes for heifers are still being recorded – i.e. re-breeding and milk yield – but the Limestone Downs dairy farm manager likes what he is seeing and supports the trial, wholeheartedly.
On-farm perspective
Limestone Downs dairy manager Aaron Frazer says his biggest concern at the outset of the trial was around the heifers calving beef-cross calves. “You don’t want extra work on top of what’s already happening. I was quite nervous about the heifers, but now we’ve done it, I’m more than happy to do it again.”
He was surprised to see how well the beef-cross calves grew in the calf-rearing system – putting on weight easily, compared to his experience growing out Friesian calves.
What now?
The second crop of calves is due on the ground this spring, which presents an opportunity to verify results to date. Meanwhile, the steers and heifers destined for processing are being finished towards their targets of 300kg and 245kg carcass weight, respectively.
