FEEDING VALUE OF COTTONSEED MEAL FOR FEEDLOT CATTLE

One hundred twenty crossbred steers (294 kg, initially) were used in a 141-d finishing trial. Four concentrations (8, 16, 24, and 32% of die t DM) of cottonseed meal (CSM, prepressed solvent-extracted) replaced steam-flaked corn in a corn-based finishing diet. Increasing level of CSM decreased ADG (linear component, P < .10), feed efficiency (linear component, P < .01), and dietary NE (linear component, P < .01). Obse rved dietary NE was 99% of expected at 8 and 16% CSM but 95% of expect ed at higher levels of inclusion (linear component, P < .05). Level of CSM did not influence (P > .10) dressing percentage, longissimus area , fat thickness, or retail yield. Eight Holstein steers (285 kg) were used in a replicated 4 x 4 Latin square design to evaluate treatment e ffects on characteristics of digestion. Ruminal digestibility of OM de creased (linear component, P < .05) as CSM increased, although ruminal digestibility of starch and feed N were not affected (P > .10). Rumin al escape protein from CSM was 58%. Total tract starch digestion was n ot altered (P > .10), but total tract digestibility of OM and GE decre ased (linear component, P < .05) and digestion of N increased (linear component, P < .01) as CSM replaced steam-flaked corn. The ratio of ob served to expected DE value of the diets was similar across CSM levels , averaging .99. Thus, comparative DE value of CSM was not affected by level of inclusion, averaging 3.32 Mcal/kg. We conclude that the NEm and NEg values of CSM are 1.88 and 1.24 Mcal/kg, respectively, and in close agreement with tabular values. However, CSM should not exceed 16 % of DMI, because higher levels may depress cattle performance and rep lacement value of CSM.