Ensiled biomass of Solaris tobacco variety used as forage: chemical characteristics and effects on growth, welfare, and follow-up of Holstein heifers

This study examined the use of an innovative tobacco variety,Nicotiana tabacumL., cv.Solaris,as forage.The whole plant biomass was ensiled, and the composition of SiloSolaris from bunker-silo and mini-siloswas investigated. The effects of dietary inclusion of SiloSolaris on the growth, welfare, and nutritionalprofile of sixteen Holstein heifers, divided into two groups (n= 8), SiloSolaris (SS) and Control (CTR), wereinvestigated. Heifers were group-fed diets with a 70:30 forage to concentrate ratio (on a DM basis). Bothgroups received 16.24 kg DM of concentrate mixture daily, including corn meal, wheat middlings andsoybean meal. The CTR group was fed 39.43 kg DM of hay daily, and the SS group received 23.00 kgDM of the same hay and 12.69 kg DM SiloSolaris blended with the concentrate mixture. The feeding triallasted eighty-one days with a thirty-six day adaptation phase. Data on forty-five days of diet administra-tion are reported. At the end of the feeding trial, the plasma constituents of the heifers were studied.Moreover, heifers were monitored during a follow-up period, lasting up to 1 year after calving, for ageat first insemination, age at first calving and daily milk yield. The SiloSolaris chemical compositionshowed an average DM content of 24.1 (±0.65) g/100 g. During ensiling, a decrease in CP and an increasein ammonia nitrogen contents were observed. The lactic acid content was variable (9.00 ± 2.66 g/100 gDM), while the acetic acid concentration was stable (4.27 ± 0.21 g/100 g DM). No butyric acid wasdetected in SiloSolaris, whose ammonia nitrogen content accounted for 15.7 (±1.86)% of the total nitrogenon average, and the mean pH value was 5.02 (±0.08). The SiloSolaris diet did not affect heifer growth per-formance. No differences were detected for body condition, fecal consistency, or locomotion scores. Allthe investigated plasma constituents were within or very close to the ranges reported for heifers; how-ever, significant differences between the experimental groups were observed for triglycerides, choles-terol, albumin, and magnesium. The follow-up results did not differ between the experimental groups.These initial findings suggest thatNicotiana tabacumcv.Solarisis a promising ensiled forage for growingheifers that deserve to be further investigated.