Biofuel co-products as livestock feed - Opportunities and challenges

Feeding biofuels co-products to pigs 191TABLE 11Effects of including maize dried distillers grain withsolubles (DDGS) in diets fed to growing-finishing pigsParameternResponse to dietary maize DDGSIncreased Reduced UnchangedAverage Daily Gain 25 1 6 18ADFI 23 2 6 15Gain:Feed (G:F) 25 4 5 16Dressing percentage 18 0 8 10Backfat (mm) 15 0 1 14Lean meat (%) 14 0 1 13Loin depth (cm) 14 0 2 12Belly thickness (cm) 4 0 2 2Belly firmness 3 0 3 0Iodine value 8 7 0 1Notes: ADFI = Average daily feed intake. Based on experiments (n isnumber of trials involved) published after 2000 and where a maximumof 30% DDGS was included in the diets. The primary source was Steinand Shurson, 2009, whose data derived from experiments by Gralapp etal., 2002; Fu et al., 2004; Cook, Paton and Gibson, 2005; DeDecker et al.,2005; Whitney et al., 2006; McEwen, 2006, 2008; Gaines et al., 2007a, b;Gowans et al.,2007; Hinson et al., 2007; Jenkin et al., 2007; White et al.,2007; Widyaratne and Zijlstra, 2007; Xu et al., 2010a, b; Augspurger etal., 2008; Drescher et al., 2008; Duttlinger et al., 2008b; Hill et al., 2008a;Linneen et al., 2008; Stender and Honeyman, 2008; Weimer et al., 2008;and Widmer et al., 2008.would be acceptable for maintaining growth performance,but performance was reduced if 40 percent was used(Cromwell et al., 1983). Average daily gain was improvedin one experiment, reduced in six experiments, and notaffected by DDGS level in 18 experiments when up to20 percent maize DDGS was added to diets adequately fortifiedwith amino acids (McEwen, 2006, 2008; Augspurgeret al., 2008; Drescher et al., 2008; Duttlinger et al., 2008b;Widmer et al., 2008) and studies where up to 30 percentmaize DDGS was added (Cook, Paton and Gibson, 2005;DeDecker et al., 2005). In contrast, data from other experimentsin which 10, 20 or 30 percent maize DDGS wasincluded in diets fed to growing-finishing pigs showed alinear reduction in ADG (Fu et al., 2004; Whitney et al.,2006; Linneen et al., 2008; Weimer et al., 2008). A linearreduction in ADFI was also observed in two of theseexperiments (Fu et al., 2004; Linneen et al., 2008). Xu etal. (2010b) showed that ADG was not affected, but ADFIwas reduced and G:F was linearly improved in pigs feddiets containing 0, 10, 20 or 30 percent DDGS. Resultsfrom two additional experiments in which performance offinishing pigs fed diets containing 0 or 30 percent DDGSwere compared showed no differences in ADG and ADFI,but G:F was reduced in pigs fed the DDGS-containing diets(Gaines et al., 2007a, b). The reduction in G:F in the latterexperiments and the increase in G:F in the experiment byXu et al. (2010b) suggests that the energy concentrationmay have varied among the sources of DDGS used in theseexperiments.A linear increase in ADG and G:F was also observedwhen a barley-wheat-field pea-based diet was fortifiedwith 0, 5, 10, 15, 20 or 25 percent maize DDGS andfed to growing-finishing pigs (Gowans et al., 2007).However, inclusion of 25 percent DDGS in a wheat-fieldpea-based diet reduced ADG and ADFI compared withresults obtained for pigs fed a diet containing no DDGS(Widyaratne and Zijlstra, 2007).Data for ADFI were reported only in 23 experiments:increasing in two experiments, decreasing in sixexperiments, and unaffected by dietary DDGS inclusionin 15 experiments. G:F was improved in 4 experiments,reduced in 5 experiments and unaffected by dietarytreatments in 16 experiments.Based on the data provided from these 25 experiments,it is not possible to determine the reasons why pigperformance was maintained in most, but not in all,experiments in which DDGS was included in the diets. Itis possible that the maize DDGS used in the experimentsin which performance was reduced may have been of apoorer quality (lower nutrient digestibility) than expected.In some of the experiments in which performance wasreduced by feeding increasing levels of maize DDGS,dietary CP levels were also increased. In such diets,DDGS inclusion rate is confounded by CP level and it isnot possible to determine if the reduced performance iscaused by the increase in maize DDGS concentration orby the increase in CP concentration. However, in most ofthe experiments in which ADG was reduced, a reductionin ADFI was also observed. It is therefore possible that thepoorer performance was due to reduced palatability of themaize DDGS used in those diets. It has been demonstratedthat, if given a choice, pigs prefer to consume dietscontaining no maize DDGS (Hastad et al., 2005; Seaboltet al., 2008).Results from the eight experiments in which sorghumDDGS was included in diets fed to growing-finishingpigs demonstrated that if sorghum DDGS is used atconcentrations of 30 percent or less, no differences inpig performance are observed (Senne et al., 1995, 1996).However, if greater dietary inclusion rates are used, ADGwill be reduced (Senne et al., 1996; 1998; Feoli et al.,2007b, c; 2008a, b, c). Likewise, G:F is not affected if theinclusion of sorghum DDGS is limited to 30 percent (Senneet al., 1995; 1996), but G:F may be reduced if 40 percentis used (Senne et al., 1998; Feoli et al., 2008a), althoughthis is not always the case (Feoli et al., 2007c, 2008b, c).Average daily feed intake is not affected by sorghum DDGSif 30 percent or less is included in the diet (Senne et al.,1995), but ADFI may be reduced at greater inclusion levels(Senne et al., 1996; Feoli et al., 2007c, 2008b).Inclusion of 25 percent wheat DDGS in a wheat-fieldpea-based diet fed to growing-finishing pigs did not affectADG or G:F (Widyaratne and Zijlstra, 2007), but adding upto 25 percent wheat DDGS in wheat-soybean meal-based