Sustainable Use of Pennisetum sinese: Effect on Nutritional Components and Fermentation Quality of Stylosanthes guianensis in Tropics

Abstract

Mixed ensiling of Stylosanthes guianensis and Pennisetum sinese is an alternative method to improve the nutrient composition of feeds for healthy and green ruminant production in the tropics. This study examined the fermentation quality, nutritional composition, and microbial population in silage to select the most suitable ratio of mixed silage containing different proportions of S. guianensis and P. sinese. It was completely randomized and consisted of four treatments with five replications based on fresh weight as follows: S0, 100% P. sinese; S15, 85% P. sinese + 15% S. guianensis; S30, 70% P. sinese + 30% S. guianensis; and S45, 55% P. sinese + 45% S. guianensis. The silage samples were opened and detected after ensiling for 30 days. The results showed that the content of dry matter and crude protein in mixed silage increased with the increase in S. guianensis, while the content of acid detergent fiber decreased significantly, and the maximum or minimum value appeared in the S45 group. As the proportion of S. guianensis increased, the pH, ammonia nitrogen, and acetic acid in mixed silage gradually increased, but the lactic acid content decreased. In addition, the content of lactic acid bacteria and yeast showed a significant downward trend. Further study showed that there was a complex correlation between nutrient compositions, fermentation characteristics, and microbial numbers in mixed silage, especially dry matter, crude protein, and lactic acid bacteria. From the sensory evaluation of silage, S30 was excellent and exhibited an aromatic smell, a hazel color, and the loosest texture. However, from the results of the proportion of organic acids in mixed silage fermentation and further principal component analysis, the highest comprehensive score was in the S15 group. Considering the nutritional compositions and fermentation quality, the optimum ratio of mixed fermentation between S. guianensis and P. sinese in this experiment was 30:70.