Effects of Chitosan on Enteric Methane Production and Nutrient Digestibility of Beef Heifers

A study was conducted to evaluate the effects of chitosan on enteric methane (CH4) and total tract nutrient digestibility of beef heifers consuming either a high-concentrate (HC; 85% concentrate) or a low-concentrate (LC; 36% concentrate) diet. Heifers were provided their respective diets ad libitum along with one of three dietary inclusion rates of chitosan: 1) CTRL=0.0% of chitosan in the diet dry matter (DM); 2) CHI-0.5=0.5% of chitosan in the diet DM; and 3) CHI-1=1.0% of chitosan in the diet DM. Twenty-four crossbred heifers were housed in the University of Florida Feed Efficiency Facility (FEF) at the North Florida Research and Education Center (NFREC) for two 22-d periods where daily intake was monitored using the GrowSafe system. Neither chitosan nor diet had any effect on dry matter intake (DMI). Average daily gain (ADG) was not affected by chitosan; however, as expected, heifers consuming HC had greater gains compared to those consuming LC. Enteric CH4 production was similar among chitosan treatments. When comparing CH4 production between HC and LC, heifers consuming LC produced nearly three times as much CH4 per day compared to HC. There was a chitosan × diet interaction for digestibility of DM, organic matter (OM), neutral detergent fiber (NDF) and acid detergent fiber (ADF). Heifers consuming LC with CHI-1 had greater digestibility of DM, OM and ADF with a tendency for enhanced digestibility of NDF. Chitosan did not have an effect on enteric production of CH4; however, total tract digestibility of nutrients was improved when heifers received 1.0% of chitosan in the diet DM along with a high-roughage diet.