Feeding value of cottonseed meal for feedlot cattle.

Abstract

One hundred twenty crossbred steers (294 kg, initially) were used in a 141-d finishing trial. Four concentrations (8, 16, 24, and 32% of diet 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). Observed dietary NE was 99% of expected at 8 and 16% CSM but 95% of expected 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 effects on characteristics of digestion. Ruminal digestibility of OM decreased (linear component, P < .05) as CSM increased, although ruminal digestibility of starch and feed N were not affected (P > .10). Ruminal escape protein from CSM was 58%. Total tract starch digestion was not altered (P > .10), but total tract digestibility of OM and GE decreased (linear component, P < .05) and digestion of N increased (linear component, P < .01) as CSM replaced steam-flaked corn. The ratio of observed 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 replacement value of CSM.