Just a general question about trophic levels. Traditionally, it's thought as much as one order of magnitude of energy is lost as one moves from trophic level to trophic level. I am confused here since it seems to me the energy content of certain primary consumers is more if not equal to an equal number of producers. Take a 1 acre lot of grass vs a 1 acre lot of cows; surely the calorie content in the cows is more than that in the grass no? A one ounce cut of beef has more calories than an ounce of grass. I could imagine for plankton or insects, maybe the energy content is not as conserved since they can store less energy and eat less. So my question is whether this one order of magnitude drop is a rule or just a 'rule of thumb' or if I'm framing the whole thing wrong.

Thank you

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    $\begingroup$ 1 acre of grass will not feed 1 acre of cow. in fact 1 acre of grass feedson good grazing on average 1 cow. An acre of grass produces about 10,000lbs of grass dry matter in a year. which feeds 1000lbs of cow for the same time. $\endgroup$ – John Apr 23 at 1:09
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    $\begingroup$ To second @John, standing biomass $\neq$ to production. Grass production is $>>$ consumer production. Because grass is consumed and turned into consumer biomass (in this case, cattle), and because the cattle aren't being consumed, the standing biomass is greater in the cows than the grass. $\endgroup$ – Chris Moore Apr 24 at 17:33
  • $\begingroup$ Also equal cuts of grass and beef have about the same calories, humans just can't access most of the calories in the grass. $\endgroup$ – John Apr 24 at 22:20

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