Interannual and monthly variations of herbage production and nutritive value
regarding grazing ruminants' needs and welfare were evaluated in three
grasslands (semi-mountainous, mountainous and sub-alpine) located at
different altitudes (480–900, 901–1500 and 1501–2334 m,
respectively) in northern Greece during 2015–2016. Herbage biomass was
collected from 30 experimental cages (10 per grassland), weighed, dried at
65 ∘C, milled and analyzed for crude protein (CP), neutral detergent fiber (NDF), acid
detergent fiber (ADF), lignin, calcium (Ca) and phosphorus (P) content
and in vitro dry matter digestibility (IVDMD). The sub-alpine grassland was the most
productive (1031 and 1231 kg DM ha-normal1) with the
highest mean annual herbage CP content (93 and 87 g kg-normal1
dry matter; DM) for 2015 and 2016, respectively. CP content was sufficient to meet small
ruminants' and beef cattle maintenance requirements until April and May in
the semi-mountainous and mountainous grasslands, respectively, while it
could cover the above requirements in the sub-alpine grassland until June and
August, respectively. The herbage Ca concentration was higher than the
grazing ruminants' needs, while the phosphorus concentration was
insufficient. Protein and phosphorus supplementation should be provided to
animals to cover their maintenance requirements during the whole period and
to reach high levels of welfare. Even though grazing is considered as a
welfare-friendly procedure, it is uncertain whether all the welfare
principals are satisfied in extensive production systems due to variations
of forage availability and nutritive value as well as the lack of
infrastructure in grasslands.