AFBI’s ‘genetic bank’ points to the future for dairy herd improvement

Scientists at the Agri-Food and Biosciences Institute (AFBI) have recently completed a research project in which the detailed genetic profile of all cows and replacement heifers in its Hillsborough dairy herd has been obtained. This work was part of a project funded by the Department of Agriculture and Rural Development, and involved the genetic analysis of blood samples from the herd, which has one of the highest PLI (Profitable Lifetime Index) values in the UK.

Dairy cows differ in many obvious characteristics such as size, type traits and coat markings.  Farmers of course know that cows also differ in less visible qualities such as milk yield potential, milk composition, calving difficulty and fertility.  These characteristics can be measured relatively easily and cheaply.  However, there is increasing evidence that cows also differ in other important ways that are much less easy to measure.  Examples of these are the efficiency with which they convert feed to milk, the efficiency with which they digest their food, their ability to lay down body tissue and to mobilise it when necessary, the amount of methane they produce, and their resistance to diseases.  These are only a few of the many possibilities.  While such attributes are often either impossible or too expensive to measure on commercial farms, some are precisely the ones that we need information about if we want to improve the efficiency and profitability of the dairy sector.

All of these factors have their roots in the cow’s genetics as the specific information that determines each cow’s capability is stored in its DNA.  This DNA is formed from four different building bricks (called nucleotides).  Approximately 3 billion of these are arranged in long strands in nearly every cell in the body.  It is the different sequences and combinations of these bricks that make each cow unique in terms of her appearance, and potential performance, health, fertility and efficiency.

Although extremely expensive, it is now possible to read all the DNA sequences in an individual animal.  However, scientists have now developed a technique to identify small changes (mutations) within the DNA sequence.  These are called ‘SNPs’ (Single Nucleotide Polymorphisms) and there can be about 10 million within every cell.  Research is ongoing to identify links between SNPs (and combinations of them) and characteristics such as feed efficiency or disease resistance.  By analysing a small amount of tissue, such as the ear punch of a calf at birth, scientists are increasingly able to predict how that animal will perform as an adult.  The good news is that we don’t need to identity all 10 million SNPs in order to understand the potential of the animal.  Instead, this can be done by identifying as few as 15,000-50,000 SNPs, which currently costs between about £30 to £60 per cow.  However, SNP data is only useful when the link to factors like feed efficiency have been identified.

Many of these difficult to measure characteristics are recorded on a regular basis within AFBI’s dairy research programmes at Hillsborough.  AFBI’s dairy scientists are now seeking new research funding to interrogate this new information on the SNP profile of each cow in the Hillsborough herd and identify individual SNP combinations that predict various aspects of the performance potential and disease resistance of an individual cow.  This is not as simple a task as it might at first appear, as any potential links must first be validated using the Hillsborough herd.  Nonetheless, AFBI’s ultimate goal is to develop improved predictive tools that allow farmers to select the most efficient calves to retain as dairy herd replacements.

Notes to editors: 

AFBI carries out high quality technology research and development, statutory, analytical, and diagnostic testing functions for DARD and other Government departments, public bodies and commercial companies.

AFBI's Vision is “Scientific excellence in Northern Ireland …  serving the world”.
 

All media enquiries to AFBI Press Office.

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