Evaluation of lime treatment in reducing tannin content and enhancing nutrient utilization of mangrove fruits (Sonneratia alba) as an animal feed ingredient

The use of lime water is thought to be able to increase the nutritional value of feed by reducing the tannin content. This study examined the effects of soaking with lime water (calcium hydroxide) on the nutritional quality of mangrove fruits ( Sonneratia alba ) as a ruminant feed ingredient. A factorial experimental design was employed, with mangrove fruits treated with various concentrations of lime water solution (1%, 3%, 5%, and 7%) and soaked for different durations (10, 20, and 30 minutes). The study measured several parameters, including proximate composition, fiber fraction, tannin content, nutrient digestibility, and rumen fermentation characteristics. The results showed a significant reduction ( P < 0.05) in tannin content with lime water treatment (5%), which demonstrated the most striking effect in enhancing feed quality metrics. Lime water soaking did not alter the pH of the rumen fluid. There was a significantly higher digestibility of dry matter, organic matter, and crude protein in feeds treated with 5% lime water ( P < 0.05), which was consistent with the higher VFA and NH3 levels ( P < 0.05), showing enhanced microbial fermentation. Also, the feed treated with 5% lime water had significantly higher ( P < 0.05) digestible NDF, ADF, cellulose, and hemicellulose characteristics compared to the others. Treatment with 20 minutes of soaking time showed that the digestibility of feed ingredients and rumen fermentation was more optimal than 30 minutes of soaking time. However, the 30 minutes of soaking time treatment reduced methane gas production the most. Thus, the best treatment is 5% lime water and 20 minutes of soaking time. This study proves that carbonation as a cheap technological solution can convert mangrove fruit into a high-value material for livestock in an affordable and environmentally friendly.