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Acta Prataculturae Sinica ›› 2020, Vol. 29 ›› Issue (12): 180-187.DOI: 10.11686/cyxb2020158

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Effects of additives on fermentation quality of alfalfa silage

Cheng ZONG1(), Jian ZHANG2, Tao SHAO1, Zhi-hao DONG1, Jun-feng LI1, Lu TANG2, Qi-fan RAN2, Qin-hua LIU1()   

  1. 1.College of Agro-grassland Science,Nanjing Agricultural University,Nanjing 210095,China
    2.Chongqing Academy of Animal Science,Institute of Prataculture,Chongqing 402460,China
  • Received:2020-04-07 Revised:2020-05-07 Online:2020-12-20 Published:2020-12-28
  • Contact: Qin-hua LIU

Abstract:

The objective of this study was to improve fermentation quality and inhibit the loss of unsaturated fatty acids from alfalfa silage. Alfalfa was ensiled without additives (control), or with sodium benzoate, sodium caseinate, hexadecanoic acid, molasses, or propionic acid. After ensiling for 65 days, the fermentation quality and fatty acid contents of the various silages were evaluated. For the control silage, the pH was lower than 4.50, the lactic acid content was 54.25 g?kg-1 DM, and the butyric acid content was lower than 5.00 g?kg-1 DM. The Flieg score of the control silage was 64.33, indicative of good fermentation quality. Compared with the alfalfa material before ensiling, the silages showed significantly increased contents of linoleic acid (C18:2n6) and linolenic acid (C18:3n3) (P<0.05). Compared with the control silage, silages fermented with hexadecanoic acid and sodium caseinate showed non-significant (P>0.05) and significant (P<0.05) reductions in lactic acid content, respectively; and silage fermented with sodium caseinate showed a significantly increased (P<0.05) butyric acid content. The silages fermented with hexadecanoic acid and sodium caseinate had Flieg scores lower than 50.00, indicative of poor fermentation quality. Compared with control silage, the silages fermented with sodium benzoate, propionic acid, and molasses showed increased lactic acid contents, decreased pH, and lower contents of ammonia nitrogen and acid detergent fiber. The Flieg scores were 70.33 for sodium benzoate-treated silage, 74.33 for propionic acid-treated silage, and 67.67 for molasses-treated silage, indicative of better fermentation quality than that of the control. Compared with the control silage, silages fermented with sodium benzoate and propionic acid showed increased C18:2n6 or C18:3n3 contents, while silage fermented with molasses had decreased contents of C18:2n6 and C18:3n3 (P<0.05). In summary, sodium benzoate and propionic acid are suitable additives to produce high-quality alfalfa silage.

Key words: additive, alfalfa silage, fermentation quality, fatty acid