Abstract #T235

# T235
Effect of source and pelleting on protein degradation of dried distillers grains with solubles.
A. Carpenter*1,2, J. F. Rivera1,3, C. Ylioja1, K. Herrick4, B. Bradford1, 1Kansas State University, Department of Animal Sciences and Industry, Manhattan, KS, 2University of Guelph, Department of Animal Biosciences, Ridgetown, ON, Canada, 3Universidad Zamorano, Francisco Morazan, Honduras, 4POET Nutrition, Sioux Falls, SD.

Two experiments were performed to determine whether source of dried distillers grains with solubles (DDGS) or pelleting of DDGS impact ruminal and intestinal digestibility of CP and DM. In Experiment 1, treatments consisted of unprocessed Dakota Gold DDGS (DAK; POET Nutrition, Sioux Falls, SD) or commodity DDGS (CON). In Experiment 2, treatments consisted of DAK subjected to various pelleting parameters, and statistical contrasts were used to test differences within each phase. Phase 1 evaluated pelleting at 49 or 82°C; phase 2 treatments were pelleted at 66°C, either using a 4- × 22.5-mm die or a 19- × 114.3-mm die; and phase 3 evaluated pelleting at a feeder rate of 1,360 or 3,175 kg/h. Approximately 0.5 g of dried and ground (2mm) substrate was sealed into Dacron bags and suspended in the rumens of 4 heifers for 0 (washout), 2, 8, 16, 24, or 48 h, with 4 replicates per time point by heifer. A subset of each treatment was exposed to 16 h of in situ rumen degradation followed by the Three-Step Procedure of Calsamiglia and Stern (1995) to estimate intestinal digestibility. In Experiment 1, DAK had decreased soluble N (15.5 vs. 33.2 ± 4.3%) and a tendency for increased N residue after 48 h of ruminal incubation (5.8 vs. 3.5 ± 0.7%). Using an estimated passage rate of 10%/h and observed intestinal digestibility, digestible RUP (dRUP) was greater for DAK than CON (43.4 vs. 34.8 ± 2.0% of CP). In Experiment 2, pelleting of DAK increased DM and N solubility and tended to increase intestinal digestibility compared with unpelleted DAK, resulting in an increase in RDP and a decrease in dRUP (17.9 vs. 27.2 ± 1.7%). Dry matter solubility was increased (65.9 vs. 63.0 ± 0.7%; P < 0.01) and there was a tendency for greater N solubility (72.9 vs. 66.5 ± 3.4%; P < 0.10) when the larger die size was used. Additionally, increased feeder rate tended to increase DM solubility (P < 0.10). No other treatment effects were observed. In conclusion, unprocessed DAK provided more dRUP than CON, whereas pelleting of DDGS shifted protein digestion to the rumen, with minimal effects of pelleting protocol except for die size.

Key Words: protein, distillers grains, digestion