The knowledge of the grazing behaviour of cattle on Swedish semi-natural pastures
and how this relates to the nutritional quality and quantity of the vegetation is low.
In a situation where farming is being intensified both nationally and globally, it is
important to gain more information about semi-natural pastures and how to utilise
this resource properly. The aims of this thesis was to: (1) examine the grazing,
resting and fouling behaviour of cattle on grazing areas mainly dominated by seminatural
vegetation which also includes portions of grassland affected by fertilisation;
(2) determine the nutrient content and seasonal herbage production of different
vegetation types within semi-natural pastures; (3) determine the in vivo digestibility
of forages from different vegetation types in heterogeneous semi-natural grasslands;
(4) study the division of nitrogen between faeces and urine and the enteric methane
production from cattle fed these same forages.
One field and one indoor study were carried out. The field study covered three
grazing seasons and included measurements of both cattle behaviour and of the
nutritional properties of semi-natural pasture vegetation. Cattle preferred to graze,
rest, urinate and defecate on previously fertilised areas. The vegetation in these areas
was characterised by a high energy and crude protein content and a high seasonal
herbage production. The indoor study measured in vivo digestibility, methane
production and the division of nitrogen between urine and faeces of different
forages from semi-natural grasslands fed to non-lactating cows and heifers. Forage
digestibilities were lower than what is commonly reported for cultivated forages.
Digestibilities did not differ between treatments, with the exception of a lower
digestibility in the heifer group when fed of vegetation harvested on shore meadows
compared with vegetation from naturalised cultivated grasslands. Methane
production did not differ among forages. In conclusion, cattle prefer to graze in
previously fertilised areas, but other vegetation types were also utilised by the
animals. Furthermore, in vivo digestibility of semi-natural pasture vegetation was
similar to in vitro values obtained with the standard Swedish method for estimating
the energy value of forages.