Feed samples were collected weekly during each experiment. Digesta samples in Exp. 1 were thawed, homogenized within animal and diet, lyophilized in a vacuum-freeze dryer (Tofflon Freezing Drying Systems, Shanghai, China), and ground through a 1-mm screen. In Exp. 2 from d 26–28, approximately 100 g of feces was collected from each pen for 3 d and the fecal samples were stored at −20◦C prior to being oven dried. The 3 d collection of feces was pooled by pen and then dried at 65◦C for 72 h. All samples were ground to pass through a 1-mm screen (40 mesh) before analysis.