Vitamin A to E in Beef Cattle: E Series

Customer Preference

Consumers judge meat based on appearance, texture and flavor (Kropf et al., 1986; Faustman and Cassens, 1990), with a strong preference for a cherry red beef color. This preferred red color is short lived and discolored meat is minced at a reduced value, at great cost to the retailer.

Meat color (Figure 1) is driven by not only the state and quantity of myoglobin but also temperature changes and largely pH, which is driven by the level of muscle glycogen reserves. Post-harvest glycogen reserves are rapidly metabolized which reduces meat pH to ~ 5.6 at 24 hours post-harvest to facilitate the cherry red color formation when deoxymyoglobin is oxidized to oxymyoglobin. Deoxymyoglobin is a heme protein containing iron in the ferrous (Fe ⁺²) form with a bright purple hue and when oxidized (due to a rapid drop in pH after several minutes of air exposure) presents as oxymyoglobin, also a heme protein with Fe still in the ferrous form. It is oxymyoglobin that provides meat with its desirable cherry red color. After several hours or even days of air exposure, oxymyoglobin is further oxidized to metmyoglobin (providing an undesirable brown pigment) which contains Fe in the ferric (Fe ⁺³) form. During oxidation one oxygen molecule is substituted with one water molecule (contributing to the appearance of drip loss). Oxidation of oxymyoglobin to metmyoglobin is largely driven by pro-oxidant molecules such as ferric ions, reactive oxygen species such as superoxide ions, hydrogen peroxide and hydroxyl radicals (Liu et al., 1995). 

Lipid oxidation affects multiple aspects of meat quality in addition to muscle pigment oxidation.  Membrane phospholipid oxidation results in a reduction of water holding capacity (with consumers noticing more water in the meat packaging) which also affects meat tenderness. Off flavors and undesirable odors from substances such as aldehydes and ketones results from lipid oxidation, strongly affecting consumer acceptance. Additionally, cholesterol oxidation in meat has also been linked to adverse biological effects such as atherosclerosis, cytotoxicity, mutagenesis and carcinogenesis and hence adequate mitigation of this oxidation process is needed (Frankel et al., 1984). 

Figure 1. Meat Color Discoloration Resulting from Oxidation

Figure 2.Vitamin E (α-tocopherol ) incorporated into subcellular membranes.

Efficacy of Vitamin E supplementation

The dietary level of vitamin E depends on the inclusion of supplemental vitamin E (mainly supplemented as a stabilized synthetically derived dl-α-tocopherol acetate) and the consumption of mainly green fodder and oilseeds. Vitamin E in plants is produced in the RRR-isomer/all-rac with about 90% degradation when processed or stored over the duration of a few weeks. Considering the limited access to green fodder of finishing cattle and the instability of naturally derived vitamin E, cattle is commonly supplemented with a stabilized α-tocopherol product, such as Rovimix^® E-50 adsorbate.

Dr. Dan Schaefer, Emeritus Professor at the University of Wisconsin Madison, one of the pioneers in researching vitamin E supplementation to extend color case life of beef, recorded industry observations of increased muscle vitamin E content of pasture fed and vitamin E supplemented dairy cattle compared to supplemented beef. Pasture fed beef imported from New Zeeland had an extended perceived red color compared to US exported beef. Research following these observations demonstrated the relationship between vitamin E supplementation pre-harvest and the α-tocopherol concentration in muscle and the associated color display life of those samples (Table 1). Vitamin E supplementation at 500 IU for the last 142 days of the feeding resulted in α-tocopherol muscle deposition of 3µg/g fresh tissue, extending the display life of beef by 3 days compared to no Vitamin E supplementation.  A similar effect (3 days display life extension) was achieved supplementing 2000 IU Vitamin E for only the last 42 days of the feeding period (Schaefer et al., 1995b; Liu et al., 1996).

Table 1. Relationship between duration and dose of Vitamin E supplementation pre-harvest on α-tocopherol concentration in longissimus (L) and rectus capitis dorsalis major (RCDM) and color display life of longissimus samples

^{Liu et al., 1996a and b and Schaefer et al., 1995b}

The effect of long and short term feeding of vitamin E to Holsteins and crossbred steers were investigated by Arnold et al., 1992 who reported that vitamin E supplementation at either 300 IU/d for 266 d; 1,140 IU/h/d for 67 days or 1,200 IU/h/d for 38 days extended the color stability and display of steaks by 2.5 to 4.8 days.

A meta-analysis of thirteen cattle trials by Sales and Koukolova, 2011 reported an α-tocopherol concentration of 3 to 4 µg/g fresh meat can be achieved by a dietary vitamin E intake level of 500 -100 IU/h/d, reducing the TBARS measurement of meat by 30 to 40% compared to meat derived from cattle not supplemented with vitamin E. The TBARS (thiobarbituric acid reactive substances-lipid oxidation) measurement is an indicator of meat quality measuring lipid oxidation. Work by Stubbs et al., 2001 demonstrated vitamin E supplementation at the 500IU/h/d level to extend the color display life of top loin steaks stored in oxygen modified atmosphere case ready packaging system (MAP).

Economics of Vitamin E and Meat Color-Display Life Extension

The economic benefits of vitamin E supplementation to extend meat display life has been well documented (Figure 4). Westcott et al., 2000 reported a $30 to $35/carcass benefit supplementing vitamin E at 500 IU/h/d for 100 days. The benefit to cost ration for packing, fabrication, distribution and retail marketing segments of the U.S. beef industry was calculated at 10.4:1 by Williams in 1992. These calculations were based on the cost of vitamin E supplementation at the 500 IU/h/d level for 126 days to be around $ 3/head. Considering the downward trend in vitamin E commodity pricing over the last decade the cost today would be closer to $1-$1.50/h (Strategic Alliance Field Study, CSU, NCBA, D. Schaefer) Considering this reduced input cost and increased value of the meat end-product the current day return on investment is even more convincing. 

Current NASEM 2021 recommendations for vitamin E supplementation in feedlot cattle are set at 15-60 mg/kg DM for receiving cattle, increasing to 50-100 mg/kg DM for finishing cattle which relates to 500-100 IU/h/d. These levels are in line with research demonstrating vitamin E to not only extend the color display life of meat through preventing lipid peroxidation but also the implied benefits of a reduced TBARS level in terms of water holding capacity and perceived tenderness. dsm-firmenich’s OVN recommendations support a supplementation level of 500 IU Vitamin E for 100 days or alternatively 2, 000 IU supplemental vitamin E for 42-45 days on feed (typically the beta agonist ration) to achieve a muscle α-tocopherol level of 3 µg/mg fresh meat to extend color display life by an additional 3 days.

Adequate vitamin E supplementation during the finishing period is a powerful and cost-effective tool to extend the color display life of meat and protect against the detrimental affects of lipid oxidation. 

Figure 4. Rovimix® E-50 Adsorbate Color-Case Life Extension in Beef