Research from Teagasc shows that outdoor finished cattle will put down more muscle than fat, compared to indoor animals on the same diet. The study was carried out at the Grange Farm in Ireland, where 24 Holstein-Friesian bulls (initial weight 233kg) were adapted to ad-lib concentrates either indoors (at a stocking rate of 2.5m2 per animal) or at pasture and fed for a period of 180 days up to slaughter.

It was shown that there was no impact on the colour of the meat depending on the two systems. It had previously been estimated that animals getting greater exercise would produce darker, more red meat but the study found this wasn’t the case.

Bulls at grass grew slightly faster and had heavier, leaner carcases at slaughter. The estimated energy intake was largely similar for both housed and outdoor bulls. The authors attributed the differences to an exercise effect.

The bulls outdoors would have had a higher rate of exercise, which appeared to cause an increased partitioning of nutrients toward muscle building and less towards fat deposition – not unlike when a human exercises.

The fact that it takes much more energy to deposit a kg of fat compared with 1kg of muscle allowed for the increased rate of daily weight gain in the outdoor animals, despite similar energy intakes.