By Shannon Hicks

A great-tasting steak – that is, a tender, juicy and flavourful steak – is considered to be an end product of management, genetics, age at slaughter and post-mortem aging. Researchers at the University of Guelph’s Centre for Genetic Improvement of Livestock (CGIL), say the industry can improve genetic selection for tenderness, and they’re setting off to do something about it.

Prof. Jim Wilton, Director of CGIL, and Asst. Prof. Ira Mandell, Department of Animal and Poultry Science, are studying carcass and steak tenderness measurements to gain a better understanding of the role of genetics in beef quality.

"Preliminary evidence shows that beef tenderness is moderately heritable," says Wilton. "Our research shows genetic selection can play an important role in improving beef tenderness."

Wilton and Mandell evaluated beef tenderness in two groups of cattle. The first group of animals was made up of 208 steers sired by either Angus, Charolais, Limousin, or Simmental bulls and was managed under typical feedlot conditions in Ontario at a commercial feedlot feeding a growing and finishing ration based on corn and corn-silage. The second set of data came from 600 animals from commercial operations across the province and were from various genetic and management backgrounds.

Using genetic evaluation, they found that heredity accounts for 16 per cent of the tenderness in the longissimus (rib eye) muscle, and 23 per cent of the tenderness in the semitendinous (eye of the round) muscle.

The cattle were harvested at a commercial packing plant, and data were collected on hot carcass weights, back-fat measurements, marbling score, rib eye area, and saleable meat yield.

Standardized one-inch thick rib eye and eye of the round steaks from every animal were assigned post-mortem aging times of two, seven, 14, 21, and 28 days. Shear force tests were conducted to assess beef tenderness. The steaks were cooked to a consistent internal temperature, and then the amount of force needed to cut through the steaks was measured.

Wilton found considerable variation in shear force measurements across animals based on the days of post-mortem aging. The longer the meat was aged, the more tender the meat became. This is most likely due to the action of the calpains -- enzymes that causes changes in the meat as it ages. Wilton says that one problem with meat tenderness is in part due to faster processing of beef which leads to inadequate storage time for post-mortem aging.

This research is sponsored by the Ontario Cattlemen’s Association.