Biofuel co-products as livestock feed - Opportunities and challenges

82Biofuel co-products as livestock feed – Opportunities and challengesTABLE 5Performance measurements for cattle fed increasing levels of modified distillers grains with solubles (MDGS) as percentageof diet DMControl diet 10% MDGS 20% MDGS 30% MDGS 40% MDGSDMI (kg/day) (1) 11.0 11.4 11.6 11.5 11.3ADG (kg) (1) 1.68 1.79 1.85 1.85 1.81G:F (2) 0.152 0.156 0.160 0.162 0.16212th rib fat (cm) 1.30 1.45 1.52 1.52 1.47Marbling score (3) 559 554 550 545 540Notes: (1) Quadratic response to level of MDGS in the diet (P < 0.01). (2) Quadratic response to level of MDGS in the diet (P = 0.07). (3) Marbling score:400 = Slight, 500 = Small, 600 = Modest. ADG = average daily gain; G:F = gain-to-feed ratio. Source: Adapted from Bremer et al., 2011.TABLE 6.Performance measurements for cattle fed increasing levels of dried distillers grains with solubles (DDGS), as a percentageof diet DMControl diet 10% DDGS 20% DDGS 30% DDGS 40% DDGSDMI (kg/day) (1) 11.0 11.5 11.8 11.9 11.9ADG (kg) (2) 1.57 1.63 1.69 1.75 1.80G:F (2) 0.141 0.143 0.145 0.147 0.14812th Rib fat, cm 1.12 1.24 1.30 1.30 1.22Marbling score (3) 569 569 569 569 569Notes: (1) Quadratic response to level of DDGS in the diet (P = 0.03). (2) Linear response to level of DDGS in the diet (P < 0.01). (3) Marbling score: 400= Slight, 500 = Small, 600 = Modest. Source: Adapted from Bremer et al., 2011.cattle performance changes for MDGS were not as greatas with WDGS.Another meta-analysis that summarized DDGS in fourtrials also resulted in a quadratic effect for DMI, as optimuminclusion was between 20 and 40 percent of dietDM (Table 6). Linear relationships were observed for ADGand G:F, as optimum inclusion was 40 percent DDGS. Thisresulted in a 13 percent improvement in feeding valuewhen feeding DDGS compared with maize. A quadraticrelationship resulted for 12th rib fat thickness, while noeffect was observed for marbling score due to feedingDDGS compared with maize. This improvement in cattleperformance was not as great as MDGS, suggesting thatdrying DGS decreases its feeding value.Although all of these meta-analysis summaries have alarge amount of data to support the results and are representativeover many experiments, the three types werenever fed in the same experiment, until recently. Nuttelmanet al. (2010b) fed WDGS, MDGS, and DDGS in the sametrial at 0, 20, 30 and 40 percent dietary DM inclusions. Nointeractions between co-product level (20, 30 or 40 percent)and type (WDGS, MDGS and DDGS) were observed.Therefore, only the main effects of co-product level (Table 7)and co-product type (Table 8) were summarized. Optimuminclusion of DGS was 40 percent for ADG and G:F. A linearincrease was observed for fat depth, with marbling scoreunchanged, as DGS inclusion increased. Therefore, thesedata suggest that cattle performance is enhanced the mostwith increasing levels of DGS up to 40 percent, similar tothe conclusions drawn from the meta-analyses.Within co-product type, no differences were observed forADG, but DMI was greatest for DDGS, least for WDGS, andTABLE 7Performance measurements for cattle fed increasing levelsof distillers grains with solubles (DGS) as percentage of dietDM (1) 0% DGS 20% DGS 30% DGS 40% DGSDMI (kg/day) 11.2 12.0 11.8 12.0ADG (kg) 1.63 1.85 1.84 1.90G:F (2) 0.146 0.156 0.157 0.161Carcass characteristicsHCW (kg) 378 400 398 405Marbling score (3) 607 609 599 60312th rib fat (cm) 1.27 1.57 1.57 1.65Notes: DMI = dry matter intake; ADG = average daily gain; HCW = hotcarcass weight; G:F = gain-to-feed ratio. (1) Overall main effect forlevel of DGS, including WDGS, MDGS and DDGS. (2) Linear response tolevel of DGS in the diet (P