More than 100 farmers hailing from the length and breadth of the country turned up at the Masterton event to discuss the merits and pitfalls of OAD milking systems.
Building on the success of the Lower North Island OAD milking discussion group run by Massey University Professor Emeritus Colin Holmes and senior DairyNZ consulting officer Leo Hendrikse, the group “virtually visited” nine OAD milking systems through farmer presentations.
Holmes said OAD milking systems were a perfect complement to grazing systems.
“Grazing systems naturally restrict how much a cow can eat each day, how many kilograms of drymatter a cow can eat each day, compared with a confinement or feedlot system. On the other hand, OAD milking restricts how much milk the udder is prepared to produce. You actually get a re-balancing.”
Holmes said operating under a OAD milking system led to a shift in the cow’s energy balance resulting in higher average cow condition, with fewer thinner cows. Lameness was also reduced with cows required to do less walking and generating less wear and tear on races. Both of these characteristics led to better reproductive performance with tighter calving patterns achieved – generally without intervention – and lower empty rates.
“It is more sustainable for both cows and people.”
Holmes identified the absence of OAD-proven sires as one of the key challenges facing OAD milking systems. Full season OAD milking herds are estimated to make up between 2% and 5% of the national herd although exact numbers are undetermined. The small population of cows on whole season OAD makes it difficult to justify breeding companies putting significant levels of investment into the area.
“On the other hand, I suspect that the unavailability of OAD-proven sires actually deters some farmers from going OAD. If you were going to make the transition, you would say okay, I’ll change to OAD in three years time so I will use proven OAD sires and I will generate some heifers and some cows that will suit my new OAD system. You would have more confidence in having good cows straight away.”
The general trend after transitioning to a OAD system is that per cow milk yields drop initially but trend upwards in subsequent seasons. Better reproductive performance, largely driven by improved cow condition, enables strong voluntary culling of cows that do not suit a OAD system, contributing to a lift in average herd performance.
Holmes pointed out that economic surveys showed farm profit was not closely related to milk yield per cow. Of the farmer presenters, most were achieving 300-360kg milksolids/cow/year on farms that were generally operating in an environment with some limiting factor in play – hilly terrain, difficult climate, or farm layout.
Most of the farmer presenters had compensated for the lower per cow performance by increasing their stocking rate, with most achieving above regional average per hectare milksolids production.
“But high milk yield per cow does increase feed conversion efficiency, and crucially if you can produce the amount of milk you produce with fewer cows, you are almost certain to leach less nitrogen and probably less phosphorous – fewer cows, fewer urine patches.”
Holmes said that was one of the reasons why driving improvement in cows’ genetic merit was so important in OAD systems.
‘On the other hand, I suspect that the unavailability of OAD-proven sires actually deters some farmers from going OAD.’
He also highlighted the fact that production is just one part of the equation determining profitability – low farm working expenses combined with the potential to increase livestock income also came into play. He said OAD milking systems were one of the only innovations within the dairy industry involving no extra inputs.
“In New Zealand farms more and more inputs are going in. Maybe it will come back a bit with the forecast drop in [milk] payout, but it is difficult to reverse those trends when they start.
“The ability to produce at low cost is always critical because we export everything.”
