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
> 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
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