Nutritional composition and human health implications of grass-fed beef

Ireland’s climate has encouraged the development of “grass-fed” as a point of difference for Irish beef in high-value markets in Europe and beyond. A study at Teagasc Grange asked: what is the comparative nutritional composition of Irish beef which is long term grass-fed, grass/silage plus concentrate-fed or concentrate-fed, and what are the implications of the different sources of beef for the health of the beef consumer? Project lead Aidan Moloney tells us more.

Ireland’s climate, which allows cattle to graze grass for up to 8 months of the year, has encouraged the development of “grass-fed” as a point of difference for Irish beef in high-value markets in Europe and beyond. Compared to concentrate-fed beef, grass-finished beef can have a higher concentration of many nutrients considered to be of benefit to human health.

Lifetime consumption of grass or conserved grass (silage) by cattle could increase the concentrations of these nutrients beyond those reported for beef from the more traditional grass-finished cattle i.e cattle that received some concentrates during their lifetime.

Confirmation of these suggested health benefits would assist in expanding the premium position of “grass-fed” within beef markets and potentially enhance the health of the beef consumer by encouraging selection of grass-fed beef. In Ireland, cattle may also be housed and fed a conserved grass ration supplemented with a non-grass-based energy source up to 50% of the diet, especially during the finishing phase, which decreases the concentration of beneficial nutrients.

A study at Teagasc Grange asked: what is the comparative nutritional composition of Irish beef which is long term grass-fed, grass/silage plus concentrate-fed or concentrate-fed, and what are the implications of the different sources of beef for the health of the beef consumer?

Aberdeen Angus sired weanling heifers were placed on one of three production systems namely: 1) Barley-based concentrates offered ad libitum 2), Grass/grass silage only, 3) Grass silage plus 0.45 dietary intake as concentrate. At the end of the winter phase, the concentrate group (1) remained indoors while groups 2 and 3 were turnout out to pasture.  Slaughter was based on a target carcass weight of 260 kg. Approximately 3 months before slaughter, animals in group 3 were rehoused and offered a grass silage+concentrate ration. Muscle samples were collected after slaughter for analysis. Fatty acid data were subsequently used in a modeling exercise using the National Adult Nutrition Survey database at UCD.

• Compared to concentrate-fed beef, grass-fed beef had a higher concentration of Na, Mg, P, K, Ca, Mn, Fe, Cu, Zn, Se, Vitamin E and cholesterol.
• For Se and vitamin E concentrations, grass silage/concentrate-fed beef was intermediate
• Ration type didn’t change the number of nutrients that can be labelled “source of” in concentrate-fed beef.
• Compared to concentrate-fed beef, grass-fed beef had lower concentration of total and saturated fatty acids and higher concentration of omega-3 fatty acids: but the increase was not sufficient for grass-fed beef to be labelled a “source of”.
• Grass silage/concentrate-fed beef had a “healthier” fatty acid profile, from a consumer perspective than concentrate-fed beef. This could perhaps be an opportunity to label this as “Grass-based”.

The modelling exercise indicated that consumption of grass-fed beef rather than concentrate-fed beef has the potential to improve population adherence to dietary recommendations. In an acute human intervention study, there was no significant difference in selected health measures and a medium/long term intervention study is required to define an impact of habitual grass-fed beef consumption on consumer health.

This research was funded by the DAFM Food Institutional Research Measure (RMIS-6596; Project 13/F/514) led by Dr. Aidan Moloney in collaboration with research investigators at Teagasc (Dr. Edward O’Riordan) and University College Dublin (Prof. Frank Monahan, Dr. Nigel Brunton, Prof. Helen Roche, Dr. Beige McNulty, Prof. Fiona McGillicuddy).