Influence of particle size of cottonseed hulls and bermudagrass hay on intake, sorting behavior, and rumen fluid parameters of feedlot lambs

Effects of particle size (PS) of cottonseed hulls (CSH) and bermudagrass hay (BGH) in females Rambouillet lambs (n = 40) feedlot diets on intake, sorting behavior, ruminal fluid parameters, serum urea nitrogen (SUN), and in vitro dry matter digestibility (IVDMD) were evaluated. Lambs were individually fed a total mixed ration (TMR) with 800 g/kg concentrate and 200 g/kg roughage (CSH or BGH) during two feedlot experiments of 25 and 21 days, respectively, following a completely randomized design with 10 replications. The roughages were ground using a hammer mill with 9.52 mm (coarse), 6.35 mm (medium), or 4.76 mm (fine) screen while the control treatment diets used unground CSH or chopped BGH. Increasing PS of CSH quadratically decreased (P < 0.001) the rejection for particles retained in the sieve of 1.18 mm and tended (P = 0.07) to linearly increase preference for particles retained in the sieve of 8 mm. Increasing PS of BGH linearly increased (P