In vitro Gas production and rumen fermentation for rations containing increasing levels of Panicum maximum cv. Mombasa with or without Spirulina

Abstract

<title>Abstract</title> This study aimed to evaluate the impact of replacing alfalfa hay with Panicum maximum hay, with or without ascending levels of Spirulina supplementation on in-vitro gas production and fermentation parameters. Isocaloric and isonitrogenous experimental diets were formulated to contain 40% roughage + 60 % concentrate, ascending replacement with Panicum maximum hay at levels 0, 25%, 50%, 75%, and 100% take place in rations R1, R2, R3, R4, and R5, respectively. Each ration supplemented with incremental levels 0, 0.5, 1.5, 2, 2.5, and 3kg spirulina per Ton of feed. Results indicated that the potential of gas production after 24 h was linearly increased by increasing the level of Spirulina. The control group (R1) recorded the highest values of gas production, while it was the lowest at (R5) (p&lt;.0001). In vitro degradability of dry and organic matter was negatively affected by the increment of Panicum maximum and Spirulina levels and vice versa, until 2 kg/ton of Spirulina (p&lt;.0001). The addition of Spirulina significantly (p&lt;.0001) increased total volatile fatty acids (TVFA) and N-NH3 concentration, until 2Kg/ton, while the addition of Panicum maximum hay significantly increased N-NH3 concentration, until it reached at (R4). As a result, the best mixing ratio between Alfalfa and Panicum maximum hays was recorded at R2. In conclusion, the substitution of alfalfa hay with 25% Panicum maximum hay (R2) and incorporation of Spirulina as feed additive (2Kg/ton) could offer a good solution in dry periods to improve the quality of Panicum maximum and can be used to maximize degradability and ruminal fermentation parameters.