Hunt on for super cows

Scientists say within a year they should be able to confirm a genetic marker can clearly identify such high performing animals.

The trial is being carried out at the Westpac Taranaki Agricultural Research Station (WTARS) at Hawera in conjunction with LIC and New Zealand Trade and Enterprise with funding from the Ministry of Science and Innovation and DairyNZ.

It is being replicated in Australia under the auspices of the Department of Primary Industry in Victoria. The results of both trials will be combined to ensure sufficient scale to confirm the validity of results.

The trial started in 2008 with a special facility built at the research station. This consisted of 28 pens and feed stations for the 224 calves on the facility at any one time.

Kevin Macdonald, DairyNZ's senior scientist, has been supervising the trial.

"Initially we put calves that were between six and eight months of age through the pens for 60 days. We measured their live weight and their intake for 46 days and identified which were the most efficient and which were the least efficient. All told we put through about 1050 calves, and we've kept the 10% most efficient and the 10% that are least efficient," he says.

From the differences found between calves, LIC identified a likely set of gene markers for feed conversion efficiency (FCE). The markers were used to screen 3700 cows from commercial herds and 214 cows were bought as either efficient or inefficient.

Macdonald says they are now feeding the cows in the pens with the objective of validating the marker genes by conducting the same test. The feed intake, live weight and milk production are measured for 35 days.

The feeding regime is strictly controlled. Each cow or calf carries an electric collar or ear tag so it is recorded when it puts its head into one of the feeding stations. It instantly records how much an animal has eaten.

The animals are fed special lucerne pasture cubes imported from Australia. The cubes enable intake to be measured accurately and are closer to replicating pasture.

Unfortunately no factory in New Zealand can produce them. Another DairyNZ senior scientist, Dr Garry Waghorn says the choice of the cubes over pellets is critical to the whole trial.

"You cannot measure feed intakes from pasture because it's about 85% moisture... so we have to have dry feed," he says.

"The cubes are good because we can easily weigh and measure them. Although pellets are more readily available they are not really an option because of the very screwy results they would be likely to deliver.

"We must have a trial where the evaluation is roughly the same as in the real pasture world, the only difference is that we have to give a dry feed."

Waghorn says typically a cow eats about 17 kg/DM per day of pasture which equates to about 120kg of "wet feed".

The essence of the trial is based on the biochemistry of the cow and inheritability of genes that set