The Beef Co-operative Research Centre (CRC) study looked at the physiological responses of cattle to changed social groups.

Feedlots often draft cattle for slaughter based on different market specifications, retaining those cattle which did not meet guidelines.

Doctor Ian Colditz, from CSIRO Livestock Industries, said cattle were very social animals and separating or mixing them with unfamiliar animals could evoke a stress response.

"Their immunity decreases and they are more susceptible to disease," he said.

"The glycogen they produce breaks down quickly when cattle are stressed.

"This can affect post-mortem muscle pH levels and meat quality."

The study was conducted using two groups of Hereford and Angus steers.

They were transferred from their property of origin after weaning and backgrounded on pasture before entering the Beef CRC's 'Tullimba' feedlot on a 70-day standard ration.

Dr Colditz said meat and blood samples were collected from the cattle before slaughter and from the chilled carcasses and a range of measurements analysed.

The group of steers regrouped one week before feedlot exit showed the largest results, with significantly higher meat compression values than the control steers.