Effects of the use of acetic acid as the conservant in lucerne ensiling

Abstract

The influence of acetic acid as the chemical conservant in three doses (4, 6 8 g/kg green mass) on the intensity of fermentation and proteolysis in lucerne silage was investigated. On the basis of chemical analysis, it was found that with the increase of conservant dose the pH value decreased aminogenesis and nitrogen solubility was limited. In silages treated the absolute and relative domination of acetic acid was found in total acid content. The increase of free and bonded acetic acid was discovered with the increase of conservant dose. Free butyric acid was not detected, while bonded butyric acid was present in negligible concentration, without effect on silage quality. Compared to control silage (III quality class according to DLG and Zelter method), a significant increase of acetic acid in silages resulted in the decline of their quality, and they were ranked as not useful (V quality class according to DLG method), or on the margin of usefulness (IV quality class according to Zelter method). In spite of some foreign references, domestic experiences show that acetic acid is not an effective conservant and it is not recommended for that use for lucerne that is not simple to ensile.

U eksperimentu je ispitivan uticaj sirćetne kiseline, korišćene u svojstvu hemijskog konzervansa u tri doze (4, 6 i 8 g/kg zelene mase) na intenzitet fermentacije i proteolize u silažama lucerke. Na osnovu rezultata hemijskih analiza utvrđeno je da je sa porastom doze konzervansa došlo do snižavanja pH vrednosti, ograničavanja aminogeneze i rastvorljivosti azotnih materija. U tretiranim silažama utvrdjena je apsolutna i relativna dominacija sirćetne kiseline u ukupnom sadržaju kiselina. Pri dodavanju konzervansa došlo je do porasta količine slobodne i vezane sirćetne kiseline. Slobodna buterna kiselina nije utvrđena u silažama dok je prisustvo buterne kiseline u vezanom obliku bilo zanemarljivo i bez uticaja na kvalitet silaža. U odnosu na kontrolnu silažu (III klasa kvaliteta po DLG i Zelter-ovoj metodi) značajno povećanje zastupljenosti sirćetne kiseline u tretiranim silažama doprinelo je pogoršanju njihovog kvaliteta, pa su ocenjene kao neupotrebljive (V klasa kvaliteta prema DLG metodi), odnosno, na granici upotrebljivosti (IV klasa kvaliteta po Zelter-ovoj metodi). I pored nekih stranih preporuka, iskustva iz domaćih istraživanja ukazuju da sirćetna kiselina nije efikasan konzervans, i ne preporučuje se za teže silirajuća hraniva, kakva je i lucerka.