The main objective of this project was to investigate the effects of the type of dried distillers grains with solubles (wheat DDGS, corn DDGS, and blend DDGS (eg. wheat:corn = 70:30)) and bio-ethanol plant origin on the nutrient variation and availability in ruminants. In addition, DDGS products were studied as opposed to their parental grains. The project was divided into the several following studies. In Study 1, we studied the nutritive value of DDGS products in terms of (1) chemical profiles, (2) protein and carbohydrate sub-fractions associated with different degradation rates, and (3) digestible component nutrients and energy values using the NRC 2001-chemical approach and the in situ assay-biological approach. Also, we tested the validity of acid detergent insoluble crude protein (ADICP) and acid detergent lignin (ADL) to predict the potential degradability of DDGS. Due to starch fermentation in the ethanol process, the chemical components in DDGS became approximately threefold more concentrated than in feedstock grains. Slowly degraded protein (PB3) and unavailable protein (PC) increased in DDGS, indicating a decrease in the overall protein degradability in the rumen. Intermediately degraded protein (PB2) was higher for corn DDGS than for wheat DDGS and blend DDGS (54.2 vs. 27.7 vs. 30.8 %CP), while PB3 was higher for wheat DDGS and blend DDGS (29.9 vs. 51.2 vs. 53.2 %CP). Mainly as a result of differing heat conditions, PC differed significantly between wheat DDGS originated at different bio-ethanol plants (0.7 vs. 7.6 %CP). The prediction of truly digestible CP (tdCP) and NDF (tdNDF) differed between the NRC 2001-chemical approach and the in situ assay-biological approach; however, both approaches reported similar energy values. These values were the highest for corn DDGS (DE3X: 3.9 Mcal kg-1), followed by blend DDGS (DE3X: 3.6 Mcal kg-1), and wheat DDGS (DE3X: 3.4 Mcal kg-1). Corn DDGS was superior to corn, wheat DDGS was similar to wheat and corn, and blend DDGS was similar to corn. No significant differences in energy values were reported between bio-ethanol plants. ADICP was not an accurate indicator of the potential degradability of protein in DDGS samples, while ADL seemed to be an acceptable indicator of the potential degradability of DM (r = -0.87; P<0.01), CP (r = -0.89; P<0.01), and NDF (r = -0.82; P<0.01) in wheat DDGS samples incubated in rumen during 48 h.<p> In Study 2, we studied the ruminal and intestinal digestion profiles and the hourly effective rumen degradation ratios between nitrogen (N) and energy. The results showed a reduction in the effective degradability of DM (EDDM), OM (EDOM) and CP (EDCP) of wheat DDGS relative to wheat; however, corn DDGS remained the same as corn. The effective degradability of NDF (EDNDF) did not vary between the DDGS samples and feedstock grains. Among DDGS types, EDDM ranged from 52.4 to 57.7 %, EDOM from 46.4 to 53.5 %DM, and EDCP from 34.0 to 45.6 %CP, being higher as the proportion of wheat in feedstock increased. No significant differences in EDDM, EDOM, EDCP and EDNDF for wheat DDGS were detected between the different bio-ethanol plants. The hourly effective degradability ratios between N and energy indicated a potential excess of N in rumen when DDGS samples were evaluated as single ingredient. This excess increased as the proportion of wheat in feedstock increased. Estimated intestinal digestibility of rumen bypass protein (IDP) was similar between wheat and wheat DDGS, but higher in corn DDGS than in corn. Blend DDGS had the highest IDP (93.9 %RUP). Due to the significantly different PC sub-fraction found in wheat DDGS originated at the different bio-ethanol plants, a large but numerical difference was detected in IDP (89.4 vs. 75.9 %RUP).<p> In Study 3, we used both the DVE/OEB System and the NRC 2001 Model to reveal the metabolic characteristics of DDGS protein and predict the protein supply to dairy cattle. The two models showed higher protein values (DVE or MP) for DDGS samples than for feedstock grains. The higher IDP for blend DDGS largely contributed to the higher protein value relative to wheat DDGS and corn DDGS (MP: 277 vs. 242 vs. 250 g kg-1 DM). Similarly, protein values differed significantly between the bio-ethanol plants mainly as a result of the numerical but large difference in IDP (MP: 272 vs. 223 g kg-1 DM). According to the two models, the degraded protein balance for DDGS products was higher than in the parental grains. Wheat DDGS showed the highest potential N excess (DBPNRC: 78 g kg-1 DM). For corn DDGS, however, the DVE/OEB System suggested a potential N excess (11 g kg-1 DM) while the NRC 2001 Model exhibited a potential N deficiency (-12 g kg-1 DM). The degraded protein balance for wheat DDGS was similar between the different bio-ethanol plants.<p> In conclusion, the chemical and biological characteristics of DDGS varied among types and between wheat DDGS samples manufactured at the different bio-ethanol plants. Thus, it is inappropriate to assume fixed values for the nutritive value of DDGS without considering factors such as type of grain used and bio-ethanol plant origin. Further research with higher number of samples will help to clarify the use of the chemical profile to predict energy values and the potential degradability of DDGS.

The main objective of this project was to investigate the effects of the type of dried distillers grains with solubles (wheat DDGS, corn DDGS, and blend DDGS (eg. wheat:corn = 70:30)) and bio-ethanol plant origin on the nutrient variation and availability in ruminants. In addition, DDGS products were studied as opposed to their parental grains. The project was divided into the several following studies. In Study 1, we studied the nutritive value of DDGS products in terms of (1) chemical profiles, (2) protein and carbohydrate sub-fractions associated with different degradation rates, and (3) digestible component nutrients and energy values using the NRC 2001-chemical approach and the in situ assay-biological approach. Also, we tested the validity of acid detergent insoluble crude protein (ADICP) and acid detergent lignin (ADL) to predict the potential degradability of DDGS. Due to starch fermentation in the ethanol process, the chemical components in DDGS became approximately threefold more concentrated than in feedstock grains. Slowly degraded protein (PB3) and unavailable protein (PC) increased in DDGS, indicating a decrease in the overall protein degradability in the rumen. Intermediately degraded protein (PB2) was higher for corn DDGS than for wheat DDGS and blend DDGS (54.2 vs. 27.7 vs. 30.8 %CP), while PB3 was higher for wheat DDGS and blend DDGS (29.9 vs. 51.2 vs. 53.2 %CP). Mainly as a result of differing heat conditions, PC differed significantly between wheat DDGS originated at different bio-ethanol plants (0.7 vs. 7.6 %CP). The prediction of truly digestible CP (tdCP) and NDF (tdNDF) differed between the NRC 2001-chemical approach and the in situ assay-biological approach; however, both approaches reported similar energy values. These values were the highest for corn DDGS (DE3X: 3.9 Mcal kg-1), followed by blend DDGS (DE3X: 3.6 Mcal kg-1), and wheat DDGS (DE3X: 3.4 Mcal kg-1). Corn DDGS was superior to corn, wheat DDGS was similar to wheat and corn, and blend DDGS was similar to corn. No significant differences in energy values were reported between bio-ethanol plants. ADICP was not an accurate indicator of the potential degradability of protein in DDGS samples, while ADL seemed to be an acceptable indicator of the potential degradability of DM (r = -0.87; P<0.01), CP (r = -0.89; P<0.01), and NDF (r = -0.82; P<0.01) in wheat DDGS samples incubated in rumen during 48 h.<p> In Study 2, we studied the ruminal and intestinal digestion profiles and the hourly effective rumen degradation ratios between nitrogen (N) and energy. The results showed a reduction in the effective degradability of DM (EDDM), OM (EDOM) and CP (EDCP) of wheat DDGS relative to wheat; however, corn DDGS remained the same as corn. The effective degradability of NDF (EDNDF) did not vary between the DDGS samples and feedstock grains. Among DDGS types, EDDM ranged from 52.4 to 57.7 %, EDOM from 46.4 to 53.5 %DM, and EDCP from 34.0 to 45.6 %CP, being higher as the proportion of wheat in feedstock increased. No significant differences in EDDM, EDOM, EDCP and EDNDF for wheat DDGS were detected between the different bio-ethanol plants. The hourly effective degradability ratios between N and energy indicated a potential excess of N in rumen when DDGS samples were evaluated as single ingredient. This excess increased as the proportion of wheat in feedstock increased. Estimated intestinal digestibility of rumen bypass protein (IDP) was similar between wheat and wheat DDGS, but higher in corn DDGS than in corn. Blend DDGS had the highest IDP (93.9 %RUP). Due to the significantly different PC sub-fraction found in wheat DDGS originated at the different bio-ethanol plants, a large but numerical difference was detected in IDP (89.4 vs. 75.9 %RUP).<p> In Study 3, we used both the DVE/OEB System and the NRC 2001 Model to reveal the metabolic characteristics of DDGS protein and predict the protein supply to dairy cattle. The two models showed higher protein values (DVE or MP) for DDGS samples than for feedstock grains. The higher IDP for blend DDGS largely contributed to the higher protein value relative to wheat DDGS and corn DDGS (MP: 277 vs. 242 vs. 250 g kg-1 DM). Similarly, protein values differed significantly between the bio-ethanol plants mainly as a result of the numerical but large difference in IDP (MP: 272 vs. 223 g kg-1 DM). According to the two models, the degraded protein balance for DDGS products was higher than in the parental grains. Wheat DDGS showed the highest potential N excess (DBPNRC: 78 g kg-1 DM). For corn DDGS, however, the DVE/OEB System suggested a potential N excess (11 g kg-1 DM) while the NRC 2001 Model exhibited a potential N deficiency (-12 g kg-1 DM). The degraded protein balance for wheat DDGS was similar between the different bio-ethanol plants.<p> In conclusion, the chemical and biological characteristics of DDGS varied among types and between wheat DDGS samples manufactured at the different bio-ethanol plants. Thus, it is inappropriate to assume fixed values for the nutritive value of DDGS without considering factors such as type of grain used and bio-ethanol plant origin. Further research with higher number of samples will help to clarify the use of the chemical profile to predict energy values and the potential degradability of DDGS.