What is the difference between grassfed and grainfed meat?
Australian beef and lamb are predominantly pasture-fed and some may feed on grain-based diets in the last few days depending on climatic conditions and product specifications.
Ruminants convert the alpha-linolenic acid found in grasses into long chain omega-3 fatty acids and levels found in Australian beef and lamb are largely determined by the quality of the pasture.
Grassfed meat comes from animals that have only grazed on grass. They feed on a range of different types of grasses, depending on climate and region. In Australia, cattle and sheep are predominantly grassfed and account for, on average, approximately two-thirds of overall beef and sheepmeat production.
Grainfed meat comes from animals which are fed grass for most of their lives and then transition to grain-based diets for the remainder of their lives. The number of days during which they are fed a grain-based diet varies.
What grains are used to feed animals?
Animals are fed a selection of grains not suitable for human consumption, including feed-grade wheat, barley, sorghum and triticale.
Grains are combined with lupins or field peas, by-products of cottonseed or canola, and silage or hay to deliver the necessary protein, carbohydrate, fat and roughage required to ensure nutritional requirements are met. These ingredients are different to those used in the US, where soy and corn predominate.
Why is grain feeding used?
Livestock are fed grain for several reasons, including to maintain a consistent meat supply, improve eating quality, meet specific needs for niche markets (e.g. for highly marbled meat), meet the energy needs of animals when pasture is limited (such as in drought conditions) and increase animal size.
Is grainfed meat more marbled than grassfed meat?
The production systems commonly adopted by Australia’s retail meat producers means there is little difference in marbling between grassfed and grainfed cattle.
Marbling refers to the fat found inside the muscle (intramuscular fat) and increases as animals get fatter, irrespective of feed type. It’s a simple equation: the longer cattle stay on a nutrient-rich diet, the fatter they become and the higher their marbling.
Since the nutritional content of grain-based feeding regimes is prescribed and food is more easily available, growth tends to be faster in grainfed than grassfed animals, so you might expect grainfed animals to have higher marbling. However as grain feeding in Australia is usually of short duration, it has little impact on marbling.
An Australian study comparing meat from grassfed and 80-day grainfed cattle found very similar total amounts of fat (as fatty acids) in the fully trimmed muscle. However, when animals were fed grain for a longer time period (150-200 days), total fat content increased.
With limited marbling, the major determinant of fat content in Australian cattle is therefore separable fat, which is found either on the outside of meat (selvedge fat) or between muscles (intermuscular fat). When trimmed of all separable fat, fat content can be as low as 2% to less than 6% for raw beef, and 3% to less than 7% for raw lamb, depending on the cut.
Is Wagyu beef high in fat?
Wagyu is a breed of cattle famous for its highly marbled meat. However, it is not so much the type of breed, but the duration and type of feed which determines the overall fat content.
Hence, meat from Wagyu beef fed for 300 or more days on a grain-based diet will be highly marbled and higher in fat compared to meat from grassfed Wagyu, which will have levels of marbling comparable to other breeds fed similar diets.
References:
Food Standards Australia and New Zealand, NUTTAB 2010 online searchable database
Warren HE et al. Meat Science 2008;78:256-269
Ponnampalam et al. Health beneficial long chain omega-3 fatty acid levels in Australian lamb managed under extensive finishing systems. Meat Science, Volume 96, Issue 2, Part B, February 2014, pages 1104-1100
Ponnampalam EN, Mann NJ, Sinclair AJ. Effect of feeding systems on omega-3 fatty acids, conjugated linoleic acid and trans fatty acids in Australian beef cuts: potential impact on human health. Asia Pacific J Clin Nutr 2006;15(1):21-29.
Wood JD and Enser M. Factors influencing fatty acids in meat and the role of antioxidants in improving meat quality. Br J Nutr 1997; 78 (Suppl 1): S49-S60
De la Fuente J, Diaz MT, Alvarez I et al. Fatty acid and vitamin E composition of intramuscular fat in cattle reared in different production systems. Meat Sci 2009; 82:331-337
Duckett SK, Wagner DG, Yates LD et al. Effects of time on feed on beef nutrient composition. J Animal Sci 1993; 71:2079-2088
Lehaska JM, Thompson LD, Howe JC et al. Effects of conventional and grass feeding systems on nutrient composition of beef. J Anim Sci Online 2008; Jul 18
Smith SB, Gill CA, Lunt DK, Brooks MA. Regulation of fat and fatty acid composition in beef cattle Asian-Aust J Anim Sci 1997; 22 (9):1225-1233