Effects of Multiple Grass- and Grain-Fed Production Systems on Beef Fatty Acid Contents and Their Consumer Health Implications

Abstract

Despite the perception that grass-fed beef contains healthier fats, nutritional differences between different grass-fed systems and grain-fed systems are not well explored. Therefore, the present study compares the fatty acid profiles of four different Western United States beef systems including (1) steers finished in a feedyard (120 days; CON), (2) steers grass-fed for 20 months (GF20), (3) steers grass-fed for 20 months with a 45-day grain finish (45GR), and (4) steers grass-fed for 25 months (GF25). Longissimus thoracis serving of n-3 PUFA was lowest for CON compared to all other treatments (P < 0.05). No difference in eicosapentaenoic acid or docosapentaenoic acid was observed between 45GR, GF20, and GF25 (P > 0.05). Grass-fed treatments resulted in t10-18:1:t11-18-1 ratios 15 to 24 times lower compared to CON (P < 0.05). Grass-and grain-finishing resulted in nutritional trade-offs rather than nutritional absolutes with GF25 and 45GR resulting in a more favorable fatty acid profile than GF20.

Evaluating the Shelf Life and Sensory Properties of Beef Steaks from Cattle Raised on Different Grass Feeding Systems in the Western United States

“…This is similar to other studies that also found that supplementation of grain shortly before slaughter improved the sensory quality of meat from grass-fed animals [64][65][66]. In addition to improved sensory quality, the study by Klopatek et al [86] that utilized the same animals as the current study found that the 45-day grain-finishing period resulted in a more desirable fatty acid profile compared to the 20GF group.…”

“…Many studies have reported meat from grain-fed animals to contain a higher concentration of monounsaturated fatty acids (MUFA), making them more susceptible to oxidation [ 84 , 85 ]. Utilizing the same groups as in this study, Klopatek et al [ 86 ] reported a significant difference in MUFA content, with the CON group having the highest concentration. However, they also reported the 20GF group to have the lowest concentration of MUFA.…”

Attention to the Details: How Variations in U.S. Grass-Fed Cattle-Feed Supplementation and Finishing Date Influence Human Health

“…The length of time on feed also influences the PUFA content of meat. Klopatek et al (2022) found that cattle grazing for 20 months and finished for 45 days on a high concentrate diet displayed a n−6:n−3 ratio of 2.5:1 compared to animals kept on pasture for 20 or 25 months without any concentrate displaying a n−6:n−3 ratio of 1.5:1. This was mainly due to a decrease in n−3 PUFA concentrations and it was confirmed by a n−6:n−3 ratio of 5.5:1 in animals that were fed a concentrate diet for 128 days in a feedlot.…”

“…The key FAs of interest in GFB are the PUFAs, especially n−3 and n−6 PUFAs. Significant differences in n−6 concentrations have been reported in the literature with grass-finished beef containing less n−6 PUFAs compared to grain-finished beef (Davis et al, 2022;Klopatek et al, 2022). Typically, grass-raised products have higher levels of n−3 PUFAs, leading to a more favorable n−6:n−3 ratio.…”

Fatty Acid and Micronutrient Profile of Longissimus Lumborum from Red Angus and Red Angus x Akaushi Cattle Finished on Grass or Grain

“…GFB is usually higher in CLA, n -3 PUFAs, vitamin E and beta-carotene, and has a more favorable n -6: n -3 ratio compared to conventional beef [ 1 , 13 , 14 , 15 ]. On the other hand, grain-finished beef contains more cis -monounsaturated FAs (MUFAs), especially oleic acid (C18:1 c 9) [ 16 , 17 ]. The nutritional profile of GFB may vary with different plant species, supplemental feeds, regions, and season of slaughter [ 15 , 18 , 19 ].…”