Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!att!pacbell.com!decwrl!pa.dec.com!hollie.rdg.dec.com!psw.enet.dec.com!winalski From: winalski@psw.enet.dec.com (Paul S. Winalski) Newsgroups: sci.bio Subject: Re: Where do herbivores get their amino acids? Message-ID: <1991May11.213947.10968@hollie.rdg.dec.com> Date: 11 May 91 21:39:47 GMT References: Sender: news@hollie.rdg.dec.com (Mr News) Reply-To: winalski@psw.enet.dec.com (Paul S. Winalski) Distribution: usa Organization: Digital Equipment Corporation Lines: 27 In article , dcohen@paul.rutgers.edu (Dawn Myfanwy Cohen) writes: |>Where do herbivores (especially those like cows that only eat grass) |>get amino acids from? From the plant material that they eat. |>Is it the case that leaves have enough protein for the herbivores, |>if eaten in large enough quantities? Yes. There's no problem with plant material as a source of protein. Ask any vegetarian. |>If so, why couldn't humans |>use them as a (possibly incomplete) source of protein, too? The problem with most leaves as a source of food is the tough cell walls. Vertibrate digestive tracts can't digest cellulose. Cattle and other herbivores deal with this problem through symbiosis--their digestive tracts are filled with protozoans capable of digesting cellulose. The highly rammified digestive tracts of herbivores are their way of culturing these protozoans and giving them enough time to break down the cell walls of the ingested plant material. Humans can't do this because their digestive tracts aren't set up for it. --PSW