The MLA has it’s own take on grass vs grain fed beef.
The general note here is that to be considered grain fed beef cattle need to be on a diet of grain for a minimum of 60 days. Another source indicated that although a large percentage of Australian beef cattle are finished on grain only approx 3% actually achieve the 60 day mark.
There are general comments with many sources that grain fed produces whiter fat when compared with grass fed that has a more yellow colour, however no one source suggested how much grain for how long was needed to make this change noticable.
One reasonable assumption is that all Australian grass fed beef has most likely been grain finished - unless it has a PCAS certification.
The MLA has stated that finishing cattle on grain for short periods does not increase marbling or total fat content.
In considering any study that points out any other observed differences it would appear necessary to also know the extent of time the cattle were on grain and other details of the diet. EG Japanese produced Kobe beef are finished on a diet including brewery products and renowned for the texture and marbling.
Just to confuse the issue further is whether or not the feed used either in finishing in a feed lot, or as an on property supplement, or grazed pasture crops/stubble have been herbicided, pesticided or medicinally supplemented?
Hence free range does not guarantee other qualities, some of which are not acceptable for export to some markets, but may be acceptable in the domestic market. What we don’t know?