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Sorry if I'm a little late on this one. This should be a helpful paper. Can send the .pdf offlist if you want. Menard, C., P Duncan, G. Fleurance, J Georges & K. Lila. 2002. Comparative foraging and nutrition of horses and cattle in European wetlands. Journal of Applied Ecology 39:120-133 Oliver Brown > Date: Thu, 30 Jun 2005 20:01:24 +0200 > From: Tommy Tyrberg <[log in to unmask]> > Subject: horse feeding habits > > >I'm looking for some help in explaining possible dietary differences > >between horses and cattle/sheep. My research area is stable isotope > >analysis & I need to consider possible causes for the carbon differences > >often seen between horses and these other two grazers. Can anybody > >point me in the right direction for literature references which might > >answer questions such as: do horses graze to a different level of a > >grass (i.e. more or less close to ground level) than cattle/sheep? Do > >they have a higher water requirement, so that they might regularly graze > >closer to watercourses? Are they more likely (in a prehistoric context) > >to have been fed regularly with stored feed? Are they more/less likely > >to feed in shady conditions than cattle/sheep? (I'm particularly > >interested in that question). > > Horses have a vastly different and in most respects inferior digestive > system compared to ungulates. They require more and better-quality forage > to survive, and spend considerably more of their time grazing. Their > ability to detoxify secondary compounds is also inferior to ungulates which > affect their selection of plants to graze. Generally speaking they tend to > keep to plants that use structural rather than chemical defences (e. g. > grass) and to eat smaller quantities of a larger number of plant species > (this applies also to e. g. tapirs which have similar digestive systems). > > And, yes, horses are more likely to have received supplemental feed in a > prehistoric context. Indeed the need for high-quality fodder and the > consequent costliness of maintaining horses has probably been one of the > main reasons for their generally "aristocratic" associations through history. > > As for grazing strategies my limited experience is that sheep crop more > closely than horses which in their turn crop closer than cows. The picture > is rather complicated though. Cows greatly prefer young tender plants and > tend to crop some areas quite closely to keep the grass short there while > more or less ignoring areas with high, rank grass while horses can > apparently handle more fibrous grass and crop more evenly. > > Also note that ungulates obtain a considerable part of their nutrition "at > second hand" from the micro-organisms in their rumen. This might well > affect the stable isotope ratios. > > It might be interesting to compare with geese which are also grazers but > have even less efficient digestive systems. Generally speaking they can > only use the liquid part of the green plant material and consequently > consume surprisingly large quantities of grazing (and produce equally > surprisingly large quantities of droppings). > > This subject is treated at some length by Dale Guthrie in "Mosaics, > Allelochemics and Nutrients" in "Quaternary Extinctions a prehistoric > revolution" (P. S. Martin & R. G. Klein (eds), Arizona University Press > 1984). There are more references there. > > Tommy Tyrberg > > ---------------------------------------------------------------- This message was sent using IMP, the Internet Messaging Program.