The calves are being reared together at a property in Te Awamutu to around 13 weeks of age before being moved to a large grazing property further north. The aim is to have at least 200 high fertility and 200 low fertility heifers calving in 2017.
Calves tested
Each animal will be monitored and tests performed throughout growth, puberty and first and second lactation as researchers look to understand more clearly what drives fertility.
DairyNZ senior scientist Susanne Meier says one of the key objectives is to discover any new traits that could be measured in heifers and would be good predictors of eventual fertility.
"If we have a better understanding of the genetic drivers of fertility in our cows, then we can be more targeted in our breeding selections and achieve faster gain," she says.
This could contribute to increasing the heritability of the fertility breeding value (BV), one of seven traits which dictate Breeding Worth (BW), a selection index that ranks animals for their genetic ability to breed profitable replacements for a dairy herd.
Financial gains possible
"There's potentially a huge financial gain if we can improve reliability and breed more effectively for fertility," says Susanne.
"A good example may be if we found that the high fertility heifers displayed stronger heats. This is a trait that farmers can measure, and if it were a key driver for fertility we could use that information to improve the fertility BV."
In addition to improving genetic selection for fertility, DairyNZ senior scientist and programme leader Chris Burke says: "this purpose-bred herd will enable us to thoroughly tease out why some cows are easy to get back in calf and others are a real struggle".
"We have a group of world experts in fertility champing at the bit to use this herd to find answers," he says.
Logical choice
Holstein-friesians were used in the project rather than another breed of cow for various reasons. The project required a large number of animals to be contracted and the friesian population is much larger than jersey.
To make the model as scientifically robust as possible, researchers wanted to avoid crossbreeds.
Lastly, the success of the project depends on creating two groups of cows that are on different ends of the scale for the fertility trait. The holstein-friesian breed has greater "highs" and "lows" for this trait, so it became the logical choice.
The project, which will also help validate what is already known about fertility in heifers, is part of a wider research programme known as Pillars of a Sustainable Dairy System -- a 7-year programme funded across the dairy sector. (dairynz.co.nz/pillars)
The project is funded by DairyNZ with co-funding from the Ministry of Business, Innovation and Employment and additional funding and resources for fertility research from AgResearch, Fonterra, LIC and CRV.
The team investigating improvements to cow fertility involves leading scientists and researchers from DairyNZ, AgResearch, AbacusBio, Victoria University Wellington, Cognosco (a division of Anexa Animal Health), University of Queensland, Monash University, University of Auckland, and New Zealand Animal Evaluation.
* First published in InsideDairy
Better lifetime productivity also a focus
Improving the lifetime productivity of dairy cows is the other major focus of the Pillars of a Sustainable Dairy System project. Inefficiencies in both fertility and lifetime productivity are estimated to cost the industry more than $1 billion a year.
Little is known about the reasons for animal losses and under-performance in New Zealand dairy systems. Evidence from international studies indicates that the incidence of premature animal removal is significant. Improving these statistics represents a major opportunity for New Zealand's dairy industry.
The Lifetime Productivity project led by DairyNZ senior scientist Claire Phyn will first determine the timing, incidence and reasons for premature death, involuntary culling and health-related productivity losses in dairy cows.
During the second half of the project, potential solutions to mitigate early animal attrition and productivity losses will be investigated in animal experiments and field trials.
The final outcome will be industry recommendations on animal husbandry, nutrition and farm management practices that reduce premature mortality, increase cow lifetime productivity and improve animal health and welfare.
