Europe's push for a longer life for dairy cows

Sunday, March 8, 2015

Just 2.5 lactations is the average production performance for European milkers despite intensive efforts to cut culling rates. Now researchers are considering longer lactations to improve overall health and longevity in the dairy herd

by NORMAN DUNN

In the 1960s, the replacement rate in an average European dairy herd was 17 per cent. Nowadays, the figure is 43 per cent, the latest stage in a relentlessly rising culling quota where it's only the exceptional animal that lasts for more than three or four lactations. The average milking cow lasts for just 2.5 lactations despite intensive research into prolonging productive life through better health and feeding management.

Mastitis, fertility problems and lameness now send most cows down the road before they've fully paid for rearing costs. Breeding for a longer productive life – that is, for healthier cows – is ongoing everywhere. But no quick fix is in sight.

Commenting on a Dutch government target for conventional dairy farms of two extra years' cow production time before 2020, researcher Jelle Zijlstra from the country's Wageningen University Animal Sciences Group reckons at least 20 years will be needed for this to happen, and maybe many more. "This is a complex process in which we have to improve many aspects."

Certainly, the Netherlands is not treading water here. There's an appropriate research program up and running and an annual Wageningen University course planned for herd managers and farmers starting in 2015 with the title "Extending the lifespan of dairy cattle."

Sweden, Denmark and Germany are among other countries researching ways of reducing cow culling rates and thus improving economic efficiency, animal welfare and the environment. For instance, reducing cow lameness through rubber matting on walkways and parlour flooring is getting intensive attention.

Danish work at Aarhus University's Institute of Agroecology spotlights calving as the main problem area leading to reduced survival in the milking herd. So why not reduce the number of calvings during a cow's lifetime through increasing lactation length?

This appears more logical after reviewing Aarhus University surveys of commercial dairy herds, which show that 65 per cent of cow health problems occur during or around calving. So instead of inseminating cows three months after calving, the Danish researchers are waiting nine months before servicing. The result is an 18-month calving interval.  

Yield penalties? The Aarhus trial has only been running for three years but it's already clear that lifetime production is the same, or even higher, than with the conventional system. Senior researcher Troels Kristensen commented at the beginning of the trial that higher energy feed is required in order to keep the yield curve steady over an extended period. He added that calving cows every 18 months means fewer replacement heifers needed, fewer cows for the same output and therefore feed savings as well as reduced emissions of greenhouse gases.

Currently, 12 herds in Denmark follow the extended lactation approach for at least a portion of their cows. Sample results so far include one farm with 94 extended lactations completed at an average yield of 10,287 kilograms of energy corrected milk (ECM) over an average 422-day lactation (mean calving interval 15 months 10 days) and another with 466-day lactations delivering an average 15,191 kilograms ECM per cow (mean calving interval 17 months). Cows in the latter herd average 22 kilograms a day on the last recording day before drying off.

Danish farmers applying the extended lactation technique comment that getting their cows back into calf is easier because the cows tend to be well settled into regular oestrus periods. All farmers asked to comment say they've identified several advantages with the extended lactation approach and that they'll continue to use it with their cows.

At Uppsala University in Sweden, a comparison of 12- and 18-month calving intervals produced the same energy corrected milk yield per calving interval day and provided better feed efficiency, lower somatic cell counts, reduced dry periods and, of course, much lower health risk for the cows.

Further afield, in Victoria, South Australia, the State Environment Department officially recognizes extended calving intervals as approved policy in dairy herds. There, the reduction of greenhouse gas emissions from cows is a major driving force behind the development of this alternative breeding approach. And this could well be the significant factor for introducing extended calving periods in other parts of the world. BF

Norman Dunn writes about European agriculture from Germany.