Forage nutrition from different grassland types at different growth stages on the northeast margin of the Qinghai–Tibet Plateau

The purpose of this study was to explore the changes in the nutritional quality of the natural mixed pasture in an alpine meadow, swampy meadow, shrubland, and mountain meadow in Maqu County, and to provide basic data for the rational feeding of grazing livestock in different periods for specific pasture types. Study by the in vitro fermentation method was used to determine the digestibility and nutrient content of natural mixed herbage at different growth stages, including the grass period, early turning green period, and withering period in Maqu County, in an alpine meadow, swamp meadow, shrubland, and mountain meadow. The results are as follows: The growth period had significant influence on the DM, CP, EE, NDF, ADF, GE, Ca, P, NDF digestibility, OM digestibility, and DM digestibility (P < 0.05), but did not significantly affect the ash (P > 0.05); the grassland types had significant effects on the digestibility of ADF, ash, GE, ADF, and the digestibility of OM in Maqu natural grasslands (P < 0.05); and the interaction between growth stages and grassland types had significant effects on DM, CP, NDF, ADF, GE, Ca, P, NDF digestibility, and OM digestibility (P < 0.05). This showed that the seasonal difference in nutritional quality of herbage in Maqu is large.