Omega-3s and grassfed beef, UW research looks into relationship
Laramie – In a recently completed study, UW Professor of Animal Science Dan Rule looked at whether or not omega-3 fatty acid deposition can be increased in grassfed beef.
“One claim that grassfed beef producers have used in marketing their products is the marked increased in certain omega-3 fatty acids, including EPA and DHA. Typically, grassfed beef is on the lean side, so while there is an increase of some fatty acids over conventionally fed beef, grass isn’t a rich source of fat, and therefore it cannot be a rich source of those fatty acids. We wanted to see if we could increase the presence of those desirable omega-3 fatty acids in muscle tissue in grassfed beef,” explains Rule.
“This study worked on whether time on grass would have an influence on EPA and DHA fatty acid amounts in beef. Plus, we supplemented one test group with a fish-oil derived supplement, which is a rich source of longer chain omega-3 fatty acids, including EPA and DHA, which are recommended for consumption,” says Rule.
For the study, Rule separated Lowline Angus cattle into three groups of 12. Lowline Angus steers were used because, with their smaller frame size, they had a better chance of reaching mature weight in one growing season. The experiment was conducted at the James C. Hageman Sustainable Agriculture Research and Extension Center (SAREC) outside Lingle, where the cattle were put on irrigated pasture.
“One group was a control group, and they were fed a beet pulp supplement that contained some minerals, and no other supplements. The second group was a neutral fat control group, and they were also fed the beet pulp pellets, some minerals and a source of fat that was primarily saturated fats. The third group was on the fish-oil supplement,” notes Rule.
He explains that the fish-oil supplement is a calcium salt of fatty acids extracted from fish oil. It’s more commonly used in the dairy industry, and this was the first time this particular supplement was used in a beef cattle grazing study. It was chosen because the calcium salt protects the poly-unsaturated fatty acids from being saturated by bacteria in the rumen by about 60 percent.
“The reason we wanted these omega-3s protected in the rumen was because we wanted to know how high the omega-3 deposition in muscle could go,” explains Rule.
Cattle were put in stalls for two hours every Monday, Wednesday and Friday, with the supplement placed in front of them. Surgical biopsies of loin muscles were taken after 42 days, and again after another 52 days. Cattle were harvested at the UW meat lab after 180 days.
“In the muscles we compared the control group to the group of fish-oil supplemented animals, and looked at the milligrams of EPA and DHA per 100 grams of fresh meat, on the average” explains Rule.
“After 180 days on a per-100-gram basis, the concentration was 72 percent greater in the fish-oil supplemented cattle for EPA, and there was over a two-fold increase for DHA. From a chemical composition standpoint I would consider the results remarkable. I didn’t expect to see this kind of an increase,” says Rule.
“From the mock tender cut, in the shoulder taken from carcasses after harvested, there was a 60 percent increase in EPA, and about a two-fold increase over the control group in DHA. In the eye of the round cut, we saw a 55 percent increase in EPA, and about a 1.9-fold increase in DHA,” explains Rule, noting again that these levels were significantly higher than expected.
He adds that a taste test panel evaluation was also conducted to ensure taste wasn’t impacted by the increased presence of fish-oil derived omega-3s.
“There was no difference as far as palatability, on the average. By and large, there were also no changes in tenderness, and the flavor attributes were fine. Part of additional data analysis will be to look at the extremes observed in taste and compare them to extremes in intake and deposition of EPA and DHA,” notes Rule.
“There are a number of questions to answer now, including the impact of the cattle type we used and the pasture they were one. We used an irrigated pasture of bromegrass and wheat grass mixed heavily with alfalfa, which probably is not characteristic of most grass-fed beef operations in Wyoming.
“The way the supplement was fed wouldn’t be done in a real world situation, either. This was research, and we needed to collect data on consumption. I think, with some tweaking of the supplement, we could make it more palatable so it could be workable in a pasture setting. Right now, I don’t think we would get any consumption if we simply placed the supplement in the pasture in the form we fed it in this study,” comments Rule.
Another thing to consider is how cattle fed a fish-oil supplement would fit into the grassfed beef marketing structure.
“This may not be consistent with organic beef standards. I’m not sure how you can organically produce calcium salt out of fish-oil extract. But, if you want to increase the deposition of certain fatty acids, you have to put them there. It will be interesting to see how this fits in,” comments Rule.
He adds that if a producer were to feed this supplement to cattle on grass, prior to putting them in the feedlot to finish, the omega-3s gained during their time on grass will stay in the muscle.
“As you feed to a Choice grade, you’re increasing marbling and subcutaneous fat. There will be the same amount of omega-3s present per 100 grams of muscle after cattle are fed to a choice grade, but as a proportion of the total fat, it will decrease as marbling increases,” he explains.
“About a decade ago, a lot of the science regarding omega-3s came from dairy scientists and nutritionists, and that’s where gras-fed beef producers were getting their information. You can make greater progress when you’re looking at milk, because a large proportion of dietary nutrients go into the milk. You will see greater concentrations of these fatty acids in the milk rather than if you looked at their distribution over the muscle mass of growing beef animals. This study looked at the latter for the first time in grassfed cattle in our region,” notes Rule.
He says that the next step will be finding a way to better monitor forage intake.
“Being able to measure forage intake and compare that to omega-3 deposition will determine whether we’ve reached a maximum on how high we can go on the deposition of these omega-3s. There are also potential breed effects and palatability issues. We want to make this available to animals while they’re on pasture. If it’s labor intensive, or unpalatable, it will be a problem, especially if we ever want to distribute it in tub or dry, bagged form.
“The other aspect of all research is funding. There are a number of opportunities to incorporate this into projects over the next several years. But, first things first, and we have to finish all the data analysis for this study, and answer some of the more immediate questions. We also need to relate the extremes in taste panel to the extremes in deposition and see if we can go higher. The last thing I want is a piece of beef that tastes like fish,” concludes Rule with a chuckle.