Ruminal and intestinal degradability of distillers grains plus solubles varies by source.

Currently in the dairy industry, there is a concern about the variability in the nutrient content among sources of distillers grains plus solubles (DG), but little research has evaluated the variability in metabolizable AA among sources. The ruminal degradability of crude protein (CP) in soybean meal (SBM), dried DG from 5 sources (DG1, DG2, DG3, DG4, and DG5), and 1 source of wet DG (WDG) were determined using 2 lactating ruminally cannulated Holstein cows. Feeds were incubated in the rumen for 3, 6, 12, 18, 24, and 36 h. Intestinal CP digestibility via pepsin and pancreatin and AA profiles were measured on residue from 12-h ruminal incubation of feeds. Ruminal undegradable protein (RUP) was less for SBM (46.4%) than for DG. The WDG (53.6%) had less RUP than dried DG. The RUP concentrations of DG3 (59.1%) and DG5 (60.3%) were lower than DG1 (71.7%) and DG4 (67.5%), with DG1 having more than DG2 (63.7%) and DG4. Intestinal digestibility of RUP was greater for SBM (86.7%) than DG. The DG2 (76.8%) and DG3 (74.2%) had greater intestinal digestibility compared with DG1 (59.2%), DG4 (63.0%), and DG5 (68.1%). The intestinal digestibility in WDG (65.8%) was similar to all other DG except for DG1, which was lower. Total digestibility of CP was greater in SBM (93.9%) compared with DG. Among the DG sources, the CP in DG2 (85.3%) and DG3 (84.9%) was more digestible compared with DG1 (70.7%), DG4 (74.9%), and DG5 (80.8%) but not WDG (81.9%). Based on the milk protein score (MPS), which is an estimate of the proportion of milk protein that a protein source can sustain until the first limiting AA is depleted, Met was the first limiting AA in SBM and Lys in DG. The concentrations of essential AA in the RUP were not different among DG sources, but the greater MPS in WDG (0.306) compared with the dried DG (0.240) sources indicated that WDG may have been the more ideal RUP source; but, the MPS of the metabolizable protein indicated that the protein quality of WDG was similar to that in DG2, DG3, and DG5. In conclusion, protein degradability and digestibility differed greatly among DG sources, but these differences were actually not as prominent in the concentrations of metabolizable AA and MPS among these sources.

[1]  C. H. Gordon,et al.  Analytical Estimates of Nitrogen Digestibility in Heat Damaged Forages , 1972 .

[2]  J. W. Thomas,et al.  Estimation of the extent of heat damage in alfalfa haylage by laboratory measurement , 1976 .

[3]  E. R. Ørskov,et al.  The estimation of protein degradability in the rumen from incubation measurements weighted according to rate of passage , 1979, The Journal of Agricultural Science.

[4]  W. Horwitz Official Methods of Analysis , 1980 .

[5]  W. P. T. James,et al.  The Analysis of dietary fiber in food , 1981 .

[6]  I. McDonald A revised model for the estimation of protein degradability in the rumen , 1981, The Journal of Agricultural Science.

[7]  M. F. Finner,et al.  Proposed Use of Adjusted Intake Based on Forage Particle Length for Calculation of Roughage Indexes , 1983 .

[8]  L. L. Berger,et al.  Ruminal Nitrogen Degradability and Escape of Wet and Dry Distillers Grains and Wet and Dry Corn Gluten Feeds , 1984 .

[9]  T. Klopfenstein,et al.  Evaluation of Laboratory Techniques for Predicting Ruminal Protein Degradation , 1985 .

[10]  B. Crooker,et al.  Supplying the protein needs of dairy cattle from by-product feeds. , 1987, Journal of dairy science.

[11]  W. Weiss,et al.  Barley distillers grains as a protein supplement for dairy cows. , 1989, Journal of dairy science.

[12]  P. V. Soest,et al.  Methods for dietary fiber, neutral detergent fiber, and nonstarch polysaccharides in relation to animal nutrition. , 1991, Journal of dairy science.

[13]  J. H. Clark,et al.  Microbial protein synthesis and flows of nitrogen fractions to the duodenum of dairy cows. , 1992, Journal of dairy science.

[14]  P. V. Soest,et al.  A net carbohydrate and protein system for evaluating cattle diets: II. Carbohydrate and protein availability. , 1992, Journal of animal science.

[15]  G. Cromwell,et al.  Physical, chemical, and nutritional characteristics of distillers dried grains with solubles for chicks and pigs. , 1993, Journal of animal science.

[16]  G. Varga,et al.  Evaluation of chemical and physical properties of feeds that affect protein metabolism in the rumen. , 1994, Journal of Dairy Science.

[17]  T. Klopfenstein,et al.  Evaluation of acid detergent insoluble nitrogen as an indicator of protein quality in nonforage proteins. , 1994, Journal of animal science.

[18]  Net energy for lactation and ruminal degradability of wet corn distillers grains. , 1994 .

[19]  A. Chesson,et al.  Biotechnology in animal feeds and animal feeding. , 1995 .

[20]  S. Calsamiglia,et al.  A three-step in vitro procedure for estimating intestinal digestion of protein in ruminants. , 1995, Journal of animal science.

[21]  D. Schingoethe Balancing the amino acid needs of the dairy cow , 1996 .

[22]  Giuseppe Licitra,et al.  Standardization of procedures for nitrogen fractionation of ruminant feeds , 1996 .

[23]  D. Schingoethe,et al.  Ruminal degradation, amino acid composition, and intestinal digestibility of the residual components of five protein supplements. , 1996, Journal of dairy science.

[24]  D. Schingoethe,et al.  Evaluation of corn distillers grains and ruminally protected lysine and methionine for lactating dairy cows. , 1998, Journal of dairy science.

[25]  D. Schingoethe,et al.  Corn distillers grains versus a blend of protein supplements with or without ruminally protected amino acids for lactating cows. , 2000, Journal of dairy science.

[26]  G. Shurson,et al.  Nutrient database for distiller's dried grains with solubles produced from new ethanol plants in Minnesota and South Dakota. , 2002, Journal of animal science.

[27]  D. Schingoethe,et al.  Evaluation of various sources of corn dried distillers grains plus solubles for lactating dairy cattle. , 2006, Journal of dairy science.

[28]  J. L. Anderson,et al.  Evaluation of dried and wet distillers grains included at two concentrations in the diets of lactating dairy cows. , 2006, Journal of dairy science.

[29]  C. Schwab Protected proteins and amino acids for ruminants. , 2007 .