Xt 15i

All diets were given a starting dose of titanium dioxide (0.4%), which was used as an indigestible marker of nutrient apparent digestibility. In pens, feces were collected, dried, sampled, and stored at −20°C for analysis. All of the growing pigs' excrement was defrosted, blended, and then baked at 65°C for 72 h before the natural moisture was restored at room temperature for 24 h.
The estimation of crude protein content was performed by multiplying the total nitrogen content, which was measured using the Kjeltec 8400 analyzer (FOSS Analytical AB, Sweden), by a conversion factor of 6.25. Additionally, the determination of crude fat content was carried out using an automated extraction analyzer (XT 15i, Ankom Technology, USA).; the total energy content in the rations and manure samples The total energy content of the rations and manure samples was determined using an oxygen bomb calorimeter (6400, Parr Instrument, USA) according to the international standard ISO 9831:1998 method. The concentration of TiO2 in all samples (feed and fecal) was measured according to Myers et al. (7 (link)).
Nutrient apparent digestibility was calculated as follows (8 (link)): Apparent nutrient digestibility (%) = [1 – (TiO2 content in the dietary/TiO2 content in the fecal sample) × (nutrient content in the fecal sample/nutrient content in the dietary)] × 100.

Plant species were classified into the three functional groups: grasses, sedges, and forbs. Only one legume species (Astragalus polycladus) was found in the study site and it was rare, therefore, we grouped it with forbs. Because of the lower statue of alpine plants and the need to avoid the interactive effect of warming and clipping, we only collected aboveground biomass for quality measurement in a 20 cm × 20 cm subplot, therefore, the biomass was not enough to measure the CP, ADF, and EE of each functional group. As a result, the CP, ADF, and EE of the AGB mixture were measured for each plot. The CP was determined with an Automatic Kjeldahl Nitrogen Determination Apparatus (Kjeltec 8100, FOSS, Höganäs, Sweden). The ADF was determined by a sequential detergent fiber analysis (Goering and Van Soest, 1970 ), and the EE was determined by the Soxhlet extraction method (ANKOM XT15i, United States).

All diets were given a starting dose of titanium dioxide (0.4%), which was used as an indigestible marker of nutrient apparent digestibility. In the pens, feces were collected, dried, sampled, and stored at −20 °C for analysis. All of the growing pigs’ excrement was defrosted, blended, and then baked at 65 °C for 72 h before the natural moisture was restored at room temperature for 24 h. The crude protein content was estimated by multiplying the total nitrogen content measured by the Kjeltec 8400 analyzer (FOSS Analytical AB, Höganäs, Sweden) by a coefficient of 6.25. The crude fat content was measured using an automatic extraction analyzer (XT 15i, Ankom Technology, Rochester, NY, USA). The total energy content in the diet was determined by an oxygen bomb calorimeter (6400, Parr Instrument, Moline, IL, USA) according to the international standard ISO 9831:1998 [14 ] method. Nutrient apparent digestibility was calculated as follows: apparent nutrient digestibility (%) = [1 − (TiO₂ content in the dietary/TiO₂ content in the fecal sample) × (nutrient content in the fecal sample/nutrient content in the dietary)] × 100 [13 (link)]. The nutrient values of rapeseed meal, cottonseed meal, and sunflower seed meal were measured according to the methods above.