Four ruminallycannulated Holstein steers averaging 259 kg of body weight were randomly assignedto a 4x4 Latin square to study the effects of replacing elephantgrass silagewith cottonseed hulls on intake and apparent ruminal, intestinal, and totaltract digestibilities of dry matter (DM), organic matter (OM), ether extract(EE), crude protein (CP), neutral detergent fiber corrected to ash and protein(NDFap), and corrected non-fiber carbohydrates (NFCap). Intake of total digestiblenutrients (TDN) and ruminal degradabilities of cottonseed hulls, elephantgrasssilage, sorghum, and soybean meal also were evaluated. Treatments (60% of forage)contained on DM basis: 0, 10, 20 or 30% of cottonseed hulls that partially replacedelephantgrass silage in the diet. Digestibilities were obtained using indigestibleacid detergent fiber as an internal marker. To determine ruminal degradabilityof the feeds two steers were used and the following incubation times were adopted:zero, three, six, 12, 24, 48, 72, 96 and 144 hours. Daily intake of all nutrientsexpressed either as an amount or as percentage of body weight, increased linearlyby partially replacing elephantgrass silage with cottonseed hulls. No effectsof increasing levels of cottonseed hulls were observed for apparent ruminal,intestinal, and total tract digestibilities of nutrients in the current trial.Consequently, contents of dietary TDN did not differ and averaged 59.53% acrossdiets. In addition, calculated TDN was 55.52% for cottonseed hulls. EffectiveDM degradation, assuming a passage rate of 5.06%/h, was 38.65; 41.13; 68.58,and 77.56% for cottonseed hulls, elephantgrass silage, sorghum, and soybeanmeal, respectively. It can be concluded that cottonseed hulls is a good foragealternative to elephantgrass silage and may supply up to 30% of the total DMin diets of dairy steers.
