Effects of Temperature and Moisture Levels on Vitamin A in Total Mixed Ration Silage

Abstract

The aim of this study was to evaluate the effects of temperature and moisture levels on vitamin A in the total mixed ration (TMR) silage. The moisture levels of TMR were adjusted to 450 g/kg, 525 g/kg and 600 g/kg. Each moisture level had three replications and fermented at 15 °C, 30 °C and 40 °C, respectively. The TMR was sampled after 0, 7, 14, 28 and 56 days of ensiling. The fermentation quality, chemical composition and vitamin A content were analyzed. Correlations between vitamin A and individual fermentation quality, chemical composition and microbial composition in TMR silages at different moisture levels and different temperatures were also analyzed separately. The results showed that the loss of vitamin A in TMR under different fermentation conditions differed significantly (p < 0.05). The increase in moisture level and temperature led to an increase in vitamin A loss, with the greatest loss of up to 68.5% when the moisture level of TMR was 600 g/kg and the storage temperature was 40 °C. In addition, there was a significant correlation (p < 0.05) between lactic acid bacteria (LAB) and aerobic bacteria and vitamin A content throughout the fermentation process, thus LAB and aerobic bacteria were associated with vitamin A loss. Thus, a coupling effect of LAB and aerobic bacteria lead to the loss of vitamin A in TMR silage under acidic conditions.