Abstract
There is increasing interest in using grass-fed beef (GFB) by-products to augment the nutrient profile of eggs among local pasture-raising systems in the US. The objective of this study was to characterize egg yolk fatty acid and antioxidant profiles using eggs from pasture-raised hens fed a corn- and soy-free diet and supplemented with GFB suet and liver compared to eggs from pasture-raised hens fed a corn and soy layer hen feed and commercially obtained cage-free eggs. The egg yolk vitamin and mineral profile was also assessed by a commercial laboratory. Both pasture-raised groups had twice as much carotenoid content, three times as much omega-3 fatty acid content, and a 5−10 times lower omega-6:omega-3 fatty acid ratio compared to the cage-free eggs (p < 0.001). Eggs from hens fed a corn- and soy-free feed and GFB by-products had half as much omega-6 fatty acid content and five times more conjugated linoleic acid, three times more odd-chain fatty acid, and 6−70 times more branched-chain fatty acid content (p < 0.001). Feeding pasture-raised hens GFB suet and liver reduces agricultural waste while producing improved egg products for consumers, but further research is needed to quantify optimal supplementation levels and the efficacy of corn- and soy-free diets.