Abstract: Triticale is a highly versatile cereal forage for grazing, silage, hay or as a cover crop. In the current study, ×Triticosecale Wittmack ‘Gannong No.2’ was used to determine the best cutting period and silage additive for triticale silage in the Hezuo city of Gannan Prefecture, Gansu Province. The experiment comprised a factorial combination of silage additives [untreated control (CK) and two proprietary silage additives (Sila-Max and Sila-Mix released by Ralco Nutrition, USA)] and crop development stage when harvested [head emergence, HE; flowering, FL; grain filling, GF; ripening (milk stage), RM; ripening (wax stage), RW] derived from Lactobacillus and study was conducted during the 2016/2017 growing seasons, with planting in late September. A comprehensive evaluation of data on cutting date and additive effects on silage nutritive (crude protein, CP; neutral and acid detergent fibre, NDF and ADF; dry matter digestibility, DMD; water soluble carbohydrates, WSC) and silage quality parameters (lactic, acetic and propionic acid levels; NH₄-N∶total-N) was carried out by the Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) method to estimate the differences of nutritional value and silage quality between different cutting dates and silage additive treatments. Hay yield cut at HE was 7.76 t DM·hm^-2, rising gradually to 19.31 t DM·hm^-2 when cut at RW. With respect to crop growth stage at cutting and silage nutritive value: CP fell gradually from 14.25% cut at HE to 8.66% at RW; NDF was lowest cut at HE (48.34%) and highest at FL (54.74%) with later crop growth stages intermediate; ADF values were similar (-29%) for HE, RM and RW cuts, but rose to 37.09% at GF; WSC values ranged between 4.82%-6.93% at all growth stages except RM (14.27%); and DMD was highest (72.06%) cut at HE, falling to 63.11% cut at FL, then gradually rising to 69.28% at RW. With respect to crop growth stage at cutting and silage fermentation parameters: pH ranged from 3.98 cut at flowering to 4.42 at RW with other values intermediate; lactic acid was highest (48.27%) cut at GF and notably lower than other growth stages (28.05%) cut at RW; acetic acid was highest (13.61%) cut at HE and lowest (5.36%) at RM with other cutting dates intermediate; propionic acid was >5% for HE, FL and GF cuts, but <2% for RM and RW cuts; NH₄-N∶total-N gradually increased from 4.64% cut at HE to 5.97% at RW. Comparing silage additives; lactic acid contents averaged across cutting dates were 33.69%, 34.59% and 50.18% for CK, Sila-Mix and Sila-Max, respectively, with other parameters showing expected changes linked to the higher lactic acid content in silage with Sila-Max additive. In conclusion, in order to obtain the highest hay yield, triticale should be harvested at RW growth stage, while in order to obtain better nutritional value and silage quality without excessively compromising high hay yield, it should be cut earlier at RM.

Key words: triticale, silage quality, cutting date, additives