Influence of Chitosan on the Physico-chemical and Nutritional Characteristics of Para Grass (Brachiaria mutica) Silage

ABSTRACT

In Bangladesh, the availability of good quality green fodder is seasonal and the shortage of adequate feed supply, especially during the dry season, is one of the major constraints to livestock production. Silage production is a well-established method of preserving green forage as nutritious feed for ruminants throughout the year. Based on the above, the present study was carried out to evaluate the physico-chemical and nutritional characteristics of Para grass (Brachiaria mutica) silage under different levels of chitosan supplementation. This experiment was conducted under laboratory conditions following a Completely Randomized Design (CRD) with four treatments and three replications. The treatments were T₀ (control, no chitosan), T₁ (5 g chitosan kg⁻¹ fresh forage), T₂ (10 g chitosan kg⁻¹ fresh forage) and T₃ (15 g chitosan kg⁻¹ fresh forage). Fresh Para grass was harvested, wilted under natural sunlight, mechanically chopped into 2–3 cm pieces and ensiled in sealed polyethylene plastic bags under anaerobic conditions for a fermentation period of 45 days. Physical and chemical properties of the silage were determined after ensiling by standard analytical methods. Dry Matter (DM), Crude Protein (CP), Crude Fiber (CF), Ether Extract (EE), Ash, Nitrogen Free Extract (NFE), pH, lactic acid, acetic acid, ammonia nitrogen (NH₃-N), dry matter loss and dry matter recovery were determined. IBM SPSS Statistics 26 was used to analyze the data. The results showed that supplementation of chitosan had significant effects (P<0.05) on the nutritional and fermentation properties of Para grass silage. The crude protein (CP), crude fiber (CF), nitrogen free extract (NFE), dry matter (DM), pH, acetic acid, lactic acid, ammonia nitrogen (NH₃-N), dry matter recovery and dry matter loss were all significantly different among the treatments, while ether extract (EE) and ash content were not significantly affected. T₂ showed the highest CP (8.87%) and lactic acid (5.86%) content with the lowest CF (33.97%) and pH (4.12), indicating superior fermentation quality and nutrient preservation. Conversely, the highest pH (4.91%), acetic acid (3.11%) and ammonia nitrogen (0.446%) were recorded in T₃. Dry matter recovery improved progressively with increasing chitosan level, reaching the highest value in T₃ (96.75%) and the lowest in T₀ (95.06%), while dry matter loss decreased correspondingly from 4.94% in T₀ to 3.25% in T₃. Physical examination showed that the silages treated with chitosan had desirable properties including light green to bright golden-green color, pleasant acidic to sweet-acidic smell, compact to dense texture and no fungal or mold growth. Flieg score analysis classified T₂ as excellent quality silage, while T₀, T₁ and T₃ were rated as good quality silage. T₂ gave the best overall fermentation quality and nutrient preservation among all treatments. In conclusion, moderate chitosan supplementation at 10 g kg⁻¹ fresh forage has the potential to be used as an eco-friendly and effective silage additive to improve the fermentation quality, nutritional value and preservation efficiency of Para grass silage for sustainable livestock feed management in Bangladesh.

Keywords: Brachiaria mutica, Chitosan, Silage, Fermentation quality, Nutritional composition, Dry matter recovery

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