The interest of ensiling total mixe

The interest of ensiling total mixed ration for ruminants re-emerged in the last decades. Inmany situations, ensiled total mixed ration (ETMR) has been a sustainable alternative to efficiently handle wet by-products in ruminant diets. The purpose of this study was to assess theeffect of replacing common vetch with wet brewers’ grains (WBG) at different proportions onthe fermentation quality, nutritive value, aerobic stability, in vitro gas production kinetics anddigestibility of ETMR. Four ETMR formulations were designed according to the varied ratios onfresh weight basis: (i) 45% common vetch (Control); (ii) 35% common vetch þ10% WBG; (iii)25% common vetch þ20% WBG; (iv) 15% common vetch þ30% WBG. The laboratory silos (10 L)were opened after 70 days of ensiling, then the 70-day silages were subjected to aerobic stability for 14 days and changes in ETMR temperature were recorded. Replacing common vetch withWBG linearly increased the ratio of lactic acid to acetic acid, ethanol, water soluble carbohydratecontents and dry matter recovery, and decreased pH, volatile fatty acids and ammonia nitrogencontents. When exposed to air, no ETMR deteriorated and their temperature appeared stableduring the 14 days test. With the WBG levels increasing, the organic matter digestibility, metabolisable energy, 72-h net gas production and the average gas production rate were linearlydecreased, whereas no obvious differences were observed among the control, 10% and 20%WBG silages. Therefore, 20% WBG can be used effectively in ETMR, reducing the need for common vetch without negative effects.