Ruminal and Intestinal Degradability of Distillers Grains plus Solubles Varies by Source

Abstract

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.

Evaluation of protein fractionation and ruminal and intestinal digestibility of corn milling co-products

“…The protein fractions reported for the co-products in this study are comparable to values determined by Kleinschmit et al (2007) on 5 DDGS produced at various ethanol plants. In their study, values ranged from 5.2 to 9.8, 0.1 to 1.8, 40.9 to 51.1, 22.7 to 41.4, and 7.5 to 23.1% CP for fractions A, B 1 , B 2 , B 3 , and C, respectively.…”

“…The only co-product that was higher in RUP than HPDDG was DDGS2, which may be due to heat-damaged protein as indicated by its low soluble protein content (16.6% of CP), high ADIN content (25.0% of CP), and corresponding high protein fraction C (27.9% of CP). In addition, co-products with higher C fractions also had correspondingly elevated ADF contents likely caused by excessive heating (Kleinschmit et al, 2007).…”

Effects of chemical composition variation on the dynamics of ruminal fermentation and biological value of corn milling (co)products

“…Consistently, the DM ruminal digestibility using passage rates (kp) of CPM Dairy ) cows indicated that GERM would have the greatest ruminal degradability; BRAN and BPX would have similar values, but HP-DDG would be the corn milling (co)product with the lowest ruminal degradability (Table 2). Kleinschmit et al (2007) evaluated ruminal degradation and intestinal digestion of DDGS and reported differences in RUP among 5 different sources of DDGS. As shown in Table 2, CPM Dairy simulations predicted that the DM ruminal degradation varied from 78.1 to 82.3% for dry cows (kp = 0.04 h ), and 64.3 to 70.1% (kp = 0.08 h −1 ) for high-producing lactating cows based on the fractional rate of fermentation of the intact feed.…”

In situ ruminal degradation of amino acids and in vitro protein digestibility of undegraded CP of dried distillers’ grains with solubles from European ethanol plants

“…Hence, the AA composition of UDP and its intestinal digestibility (ID) are further important characteristics of the protein value of a feedstuff (Weisbjerg et al, 1996). Unlike the well-balanced AA profile supplied by the microbial protein, AAs coming from the UDP largely reflect the AA pattern of the original feed (Kleinschmit et al, 2007;Mjoun et al, 2010;Li et al, 2012). However, AAs of the UDP sometimes do not match the AA needs of the cow in terms of concentration and digestibility.…”

“…This may become especially relevant if the UDP content of a feedstuff is high and one AA is particularly low, as is the case for lysine in DDGS. Knowledge about whether or not the AA composition of DDGS and UDP fraction of DDGS are similar is important for ration formulation and has been reported so far (Kleinschmit et al, 2007;Mjoun et al, 2010;Li et al, 2012). However, these experiments only considered a maximum of five samples of DDGS mainly originating from corn and did not consider blend-DDGS or DDGS originating from a wide variety of grains or mixtures like those produced under European conditions.…”