Abstract:

In order to develop additives that improve the fermentation quality of alfalfa silage， the fermentation quality and microbial diversity of alfalfa silages prepared with addition of different Lycium barbarum by-products （LBP） were studied. Alfalfa silage was prepared without （CK） and with 40 （T₁）， 60 （T₂）， and 80 （T₃） g·kg^-1 LBP. After 60 days of fermentation， the nutrient levels， fermentation quality and microbial diversity of the silages were determined. It was found that the concentrations of acid detergent fiber in the LBP silages significantly （P<0.01） decreased， while polysaccharide significantly （P<0.01） increased as the proportion of LBP increased in the alfalfa silage. The pH value and ammonia nitrogen∶total nitrogen ratio of CK silages were 4.91 and 8.58%， respectively. As the proportion of LBP increased in the alfalfa silages， the contents of ammonia nitrogen， acetic acid and pH significantly （P<0.01） decreased， while lactic acid level and the ratio of lactic acid to acetic acid significantly （P<0.01） increased. The silage aerobic stability was improved in LBP treatments， although the addition of LBP at 80 g·kg^-1 decreased aerobic stability compared with addition of 40 and 60 g·kg^-1. The dominant alfalfa silage bacterial genera were Lactobacillus， Weissella and Pediococcus. The relative abundance of Lactobacillus in LBP treatments was lower than in the CK treatment， while the relative abundance of Weissella and Pediococcus in LBP treatments was higher than in the CK treatment. The results confirm that LBP addition can improve alfalfa silage fermentation quality and aerobic stability， and change microbial community structure. The 60 g·kg^-1 LBP treatment was more effective than other tested treatments in enhancing silage fermentation.

Key words: alfalfa, Lycium barbarum by-products, silage fermentation quality, microbial diversity