Chizzotti et al., 2005. Rev. Bras. Zootec., 34 (6): 2093-2102

A total of 4 ruminally cannulated Holstein steers with an average body weight of 259 kg were randomly assigned to a 4*4 Latin square to study the effects of replacing elephant grass silage with cottonseed hulls on the intake and apparent ruminal, intestinal and total tract digestibilities of dry matter (DM), organic matter (OM), ether extract (EE), crude protein (CP), neutral detergent fibre corrected to ash and protein (NDFap) and corrected non-fibre carbohydrates (NFCap). The intake of total digestible nutrients (TDN) and ruminal degradabilities of cottonseed hulls, elephant grass silage, sorghum and soyabean meal were also evaluated. Treatments (60% of forage) contained on DM basis 0, 10, 20 or 30% of cottonseed hulls that partially replaced elephant grass silage in the diet. Digestibilities were obtained using indigestible acid detergent fibre as an internal marker. To determine the ruminal degradability of the feeds, 2 steers were used and different incubation times were adopted (0, 3, 6, 12, 24, 48, 72, 96 and 144 h). The daily intake of all nutrients expressed either as an amount or as percentage of body weight, increased linearly by partially replacing elephant grass silage with cottonseed hulls. No effects of increasing the levels of cottonseed hulls were observed for apparent ruminal, intestinal and total tract digestibilities of nutrients in the current trial. The contents of dietary TDN did not differ and averaged 59.53% across diets. Moreover, calculated TDN was 55.52% for cottonseed hulls. Effective DM degradation values, assuming a passage rate of 5.06%/h, were 38.65, 41.13, 68.58 and 77.56% for cottonseed hulls, elephant grass silage, sorghum and soyabean meal, respectively. It was concluded that cottonseed hull was a good forage alternative to elephant grass silage and might supply up to 30% of the total DM in diets of dairy steers