Fermentation characteristics, energy value and concentration of β carotene in yarrow (Achillea millefolium L.) silage

The aim of the study was to obtain information on the fermentation characteristics, nutritive value and beta carotene concentration of yarrow (Achillea millefolium L.) silage harvested in summer 2010. The unwilted and wilted yarrow was ensiled in small-scale laboratory silos. Concentrations of net energy for lactation (NEL) and metabolizable energy (ME) were assessed on the basis of the amount of gas which was produced during the incubation of samples with rumen liquor in vitro. Silage from unwilted material (UW) had lower dry matter (DM) concentration than silage from wilted material (W) (278 g kg(-1) vs. 539 g kg(-1)). The concentrations of lactic acid, acetic acid and butyric acid in UW and W silages were 56.61 g kg(-1) DM, 9.06 g kg(-1) DM, 0.05 g kg(-1) DM; and 3.59 g kg(-1) DM, 1.96 g kg(-1) DM, 0.00 g kg(-1) DM, respectively. W was characterised by higher concentration of water soluble carbohydrates (WSC) (120.1 vs. 69 g kg(-1) DM), lower concentration of ammonia (21 vs. 78 g kg(-1) DM total N) and lower concentration of beta-carotene (166.5 mg kg(-1)) than UW (237.1 mg kg(-1)). The energy values of both silages were similar. It was concluded that both silages were well fermented. Wilting of yarrow prior to ensiling is favourable from the point of concentration of WSC and restriction of proteolysis during the fermentation process, whilst ensiling of unwilted material enhances beta carotene preservation.