Effects of Chitosan Supplementation in Diets with Different Concentrate to Forage Ratios on Methane Production,and Fermentation Characteristics of in Vitro Ruminal Fermentation

This experiment was conducted to investigate the effects of chitosan supplementation in diets with different concentrate to forage ratios on methane production,and fermentation characteristics of in vitro ruminal fermentation using long-term artificial rumen system-Rusitec system. A 2 × 2 two factors experimental design was adopted. The two factors were dietary concentrate to forage ratios [30 ∶ 70( lowconcentrate diet) and70 ∶30( high concentrate diet) ],and with or without chitosan supplementation( 0 and 1 500 mg / tank). Four groups with four replicates were composed. The results showed as follows: compared with the lowconcentrate diet,high concentrate diet significantly decreased methane production,neutral detergent fiber and crude protein degradation rates,as well as acetic acid and butyric acid contents,acetic acid to acrylic acid ratio and ammonia nitrogen concentration of fermentation fluid( P 0. 05),and significantly increased total gas production and propionic acid content( P 0. 05); the supplementation of chitosan significantly decreased methane and total gas production,crude protein degradation rate,as well as acetic acid and butyric acid contents,acetic acid to acrylic acid ratio and ammonia nitrogen concentration of fermentation fluid( P 0. 05),and significantly increased propionic acid content( P 0.05); there were interaction effects between concentrate to forage ratio and chitosan on methane and total gas production,crude protein degradation rate,ammonia nitrogen concentration of fermentation fluid at 0 and 6 h and acetic acid to acrylic acid ratio of fermentation fluid at 0 and 12 h( P 0.05),methane and total gas production,crude protein degradation rate and ammonia nitrogen concentration of fermentation fluid were decreased by the supplementation of chitosan in high concentrate diet at a bigger range than that in lowconcentrate diet,while total volatile fatty acid concentration and acetic acid to acrylic acid ratio were decreased by the supplementation of chitosan in high concentrate diet at a lower range than that in lowconcentrate diet. In conclusion,changing of dietary concentrate to forage ratio and chitosan supplementation both can modify ruminal fermentation pattern,there is an interaction between the two factors,and the effects of chitosan supplementation in diets with 70∶30 of concentrate to forage ratio are better than those with30 ∶70.