Abstract #T187

# T187
Nutritive value of mechanically pressed cottonseed cake compared with soybean meal for lactating dairy cows.
N. Webb1, J. K. Bernard*1, S. Tao1, 1University of Georgia, Tifton, GA.

Forty-eight lactating Holstein cows were used in a randomized block trial to evaluate the nutritive value of mechanically pressed cottonseed cake (CSC) compared with solvent extracted (SBM) or expeller soybean meal (ESM). The CSC was produced by dry extruding whole cottonseed at 121 to 149°C for 12–20 s. The resulting CSC contains approximately 33% CP with 40% RDP and 60% RUP (DM basis). All cows were fed a control diet during the first 3 wk and data collected were used as a covariate in the statistical analysis. At the end of the preliminary period, cows were fed experimental diets for the following 8 wk. Treatments included: 1) control diet supplemented with SBM and ESM (CONT); 2) CSC substituted for SBM (CSBM); and 3) CSC substituted for ESM (CESM). No differences (P > 0.10) were observed in DMI (27.2, 28.1, and 28.1 kg/d), milk yield (33.0, 32.8, 33.4 kg/d), milk fat (3.96, 3.96, and 4.00%), lactose (4.67, 4.67, and 4.69%), solids-not-fat (8.62, 8.52, and 8.57%) or ECM (35.1, 34.7, and 35.7 kg/d) among CONT, CSBM, or CESM, respectively. Milk protein percentage was lower (P = 0.0418) for CSBM compared with CONT but not different to CESM (2.96, 2.84, and 2.90% for CONT, CSBM and CESM, respectively). Milk urea nitrogen concentrations were lower (P = 0.0003) for CSBM compared with CONT and CESM: 8.56, 7.58, and 9.27 mg/dL for CONT, CSBM, and CESM, respectively. No difference (P > 0.10) were observed in BW change (31.7, 32.5, and 28.1 kg for CONT, CSBM, and CESB, respectively). The lower MUN observed for CSBM suggest that substituting the CSC for SBM may have limited degradable nitrogen. The results of this trial indicate that the CSC can be substituted for soybean meal or expeller soybean meal without affecting intake, milk yield or composition.

Key Words: mechanically pressed cottonseed cake, soybean meal, expeller soybean meal