Mr Wagner defines the single-calving model as having a single calving period once per annum that ideally matches seasonal feed supply. Well-executed single calving models may result in no cows being milked for a period of about 30 days.
Alternative calving systems adopted by Australian dairy farmers include:
Split calving where cows calve in two or three distinct calving periods each year, and
Year-round calving where cows calve in at least 10 months of the year. Year-round calving can also include batch calving, where cows calve in multiple batches throughout the year.
Mr Wagner said Dairy Australia research suggested that simple systems were easier to manage and implement. Simple systems (e.g. single calving) were easily replicated and could be implemented at scale. Single calving further offered the benefit of having a finite set of tasks matched to a finite set of resources.
Mr Wagner said inconsistent cash-flow and historic milk processor payment systems were two perceived barriers to the adoption of the single-calving model.
Implementing a seasonal single-calving model allowed dairy farm operators to match calving (feed demand) to the seasonal pasture growth rate curve (see Figure 1).

Mr Wagner said to monitor the success of a single-calving model, farmers needed to keep accurate records to enable calculation of some key measures (see Table 1). Table 1 includes targets that AgCap had achieved with good breeding goals and management systems.

To be able to compare reproductive performance between farms, clearly defined indicators needed to be used, he said. These were:
Six-week in-calf rate = the number of cow’s pregnancy tested in calf to the first six weeks of mating as a percentage of cows at the start of the mating period, and
End of mating not-in-calf rate = the number of cow’s pregnancy tested not in calf to the whole mating period as a percentage of cows at the start of the mating period.
Mr Wagner said the major risk of single calving was associated with low in-calf rates where the options for these not-in-calf cows were limited. In other models (e.g. split calving), not-in-calf cows were simply carried forward into the next calving period.
This carryover strategy, however, could negatively impact the long-term fertility in herds, he said. Ideally in a single-calving model the not-in-calf cows were sold as cull cows, decreasing the number of replacements bred from potentially lower fertility cows.
Mr Wagner said AgCap dairy asset management had a focus on whole farm systems and as such aimed to ensure that people, process, livestock and pastures were structured and aligned to ensure the best prospect of assets performing above average.
Successful single-calving models impacted dairy businesses in each of these business parameters, he said. These included:
People single calving allowed the on-farm management team to better allocate their limited resource of time by having a defined set of tasks (see Figure 2).

Process single calving assisted with all processes including livestock record keeping. All processes and tasks throughout an annual season are clearly defined.
Pasture seasonal single calving allowed better utilisation of the cheapest feed source, pasture. Optimising pasture grown and consumed (i.e. increasing percentage of home-grown feed in the cow’s diet) was a key driver of profit.
Livestock single calving ensured that all lactating cows are at a similar stage of their lactation at any point in time throughout the year. This virtually eliminated the need for individual feeding cows grain supplements based on production or stage of lactation. Furthermore, there were minimal groups of replacement heifers being reared, again simplifying processes.
Mr Wagner said single calving models would also impact the longer-term sustainability of dairy-farming businesses:
Greenhouse gas (GHG) emissions maintaining single calving requires a significant focus on fertility. Improving the fertility of the herd meant that cows would live longer. The consequence of increasing the longevity of cows within the herd led to a decreased requirement for replacements. This would have help reduce total GHG emissions.
Animal welfare bobby calf disposal is an increasingly important issue for the Australian dairy industry. Having a single-calving model has both positive and negative impacts on this issue. Having many bobby calves to deal with in a single-calving period increased the workload of the farm management team, however, this also presents an opportunity. Being able to focus on rearing bobby calves in one period can lead to having larger numbers of weaned bobby calves within a tight age bracket, which may appeal to more buyers looking to raise these animals.
Mr Wagner said rebuilding the Australian industry would involve more than simply having an Australian Dairy Plan, it would also involve a concerted effort to improve operating efficiencies.
AgCap believed that a seasonal single calving that matches pasture feed supply would be a major step in increasing operating efficiency, he said.
But he did acknowledge there were farmers running profitable alternative calving models and that single calving would not be suitable for all dairy farm operators.