Enhancing muscle fatty acid profile by pasture finishing within a dairy-origin calf-to-steer beef production system and its potential to authenticate the dietary history of the cattle

The influence of modifying a traditional 24-mo dairy steer calf to beef production system on the fatty acid composition of the longissimus muscle and its potential to authenticate beef provenance was examined. Fifty-four male calves (n = 18 per sire breed), progeny of Holstein-Friesian cows mated with Holstein-Friesian (HF), Aberdeen Angus (AA) and Belgian Blue (BB) bulls were at pasture from March until August of their second year when they were assigned to a 3 (breed types) x 3 (finishing strategies) factorial experiment. The three finishing strategies were (i) pasture only for a further 94 d prior to slaughter (21 mo of age) (Grass), (ii) concentrates ad libitum indoors for 94 d prior to slaughter (21 mo of age) (EC) and (iii) pasture only for a further 94 d followed by concentrates ad libitum indoors for 98 d prior to slaughter (24 mo of age) (LC). Compared to EC, muscle from Grass had a lower intramuscular fat concentration and omega-6: omega-3 polyunsaturated fatty acid (PUFA) ratio and higher proportion of conjugated linoleic acid. A longer period at pasture pre-concentrate finishing increased the concentration of omega-3 PUFA which was still lower than in Grass. To maximise the omega-3 PUFA concentration, a late-maturing breed is more appropriate while to maximise conjugated linoleic acid, an early-maturing breed is more appropriate and both should be finished on grass. Chemometric analysis confirmed that the fatty acid profile can authenticate "Grass-Finished" beef per se and has potential to distinguish "Concentrate-Finished" beef based on the length of grazing prior to finishing, but not distinguish between sire breeds.