Future Proofing New Zealand’s Dairy Cows

1 April 2009

AgResearch scientists have unlocked the first keys on how to improve New Zealand’s dairy cows’ milk production.

One and a half year into their research on how the mammary gland is able to respond to different environmental influences, they have now identified, what they term, an “epigenetic event”.

The Dairy Scientist leading this project is Dr Kuljeet Singh, who says it is well known that factors such as nutrition and hormones influence the number and activity of the cells within the mammary gland that secrete milk proteins, therefore influencing levels of milk production. With a lot still to be discovered about how the secretory cells respond to these external and internal influences, Dr Singh and her team’s studies suggest the potential of epigenetic regulation to manipulate mammary function.

The term epigenetics refers to changes in phenotype or gene expression caused by chemical changes to the DNA, rather than changes in the DNA sequence itself. Most epigenetic changes only occur within the course of one individual organism's lifetime, but some epigenetic changes are inherited from one generation to the next. “Consequently, our research will lead to novel approaches, such as nutritional interventions for manipulating epigenetic mechanisms. Not only will that enhance the lifetime lactation performance of dairy cows, but may also enhance the lactation performance of their calves,” she says.

Dr Singh says recent research also highlights critical mammary cell signalling or biochemical pathways that play an important role in the regulation of milk production. This leads to the possibility of developing novel intervention technologies, such as using supplements or agonists (drugs that binds to a receptor of a cell and triggers a response by the cell) to modulate specific signalling pathways to enhance the efficiency of milk production in dairy cows.

Dr Singh also envisages novel biomarkers and diagnostic tools that measure treatment regimes intended to improve lactation performance.

She points out that milk yield losses occur during the milking season and that cows produce less milk when milked once a day compared to twice a day. Understanding how the milk secreting cells respond to different influences will lead to novel intervention and gene-based technologies and ultimately the development of commercial products to enhance the efficiency of milk production in dairy cows, particularly during late lactation and also in cows milked once-daily.

This programme also involves Livestock Improvement Corporation (LIC) scientists who have large databases that include one of the largest sets of phenotypic and genetic data on cow populations world-wide. Combining the extensive knowledge that AgResearch scientists have on genes that regulate milk production with the large LIC databases on NZ cow populations, will enable further understanding of how the mammary gland responds to environmental cues for enhanced milk production.

The programme, funded by the Foundation for Research, Science and Technology (FRST), began in October 2007 and already has made exciting discoveries that if fully understood and harnessed on-farm, could significantly contribute to productivity gains in the dairy industry.

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