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Journal of Animal Science - Animal Genetics

Efficacy of commercial enzymes in diets containing various concentrations and sources of dried distillers grains with solubles for nursery pigs12

 

This article in JAS

  1. Vol. 88 No. 6, p. 2084-2091
     
    Received: May 05, 2009
    Accepted: Jan 27, 2010
    Published: December 4, 2014


    3 Corresponding author(s): goodband@ksu.edu
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doi:10.2527/jas.2009-2109
  1. C. K. Jones*,
  2. J. R. Bergstrom*,
  3. M. D. Tokach*,
  4. J. M. DeRouchey*,
  5. R. D. Goodband 3,
  6. J. L. Nelssen* and
  7. S. S. Dritz
  1. Department of Animal Sciences and Industry, College of Agriculture; and
    Food Animal Health and Management Center, College of Veterinary Medicine, Kansas State University, Manhattan 66506-0201

ABSTRACT

In 2 experiments, 530 pigs were used to evaluate the effects of adding commercial enzymes to diets containing dried distillers grains with solubles (DDGS) on pig growth performance. In the first experiment, 180 pigs (9.0 kg initial BW) were fed a corn-soybean meal-based control diet, a diet containing 30% corn DDGS, or the 30% DDGS diet with 0.05% of enzyme A, B, or C. There were 6 pigs per pen and 6 pens per treatment. Overall (d 0 to 27), neither DDGS nor enzyme addition increased ADG and G:F. Pigs fed enzyme B had decreased (P < 0.05) ADG as a result of a tendency (P ≤ 0.10) for decreased ADFI compared with control pigs or pigs fed DDGS without added enzyme. In Exp. 2, 350 pigs (11.0 kg initial BW) were fed 1 of 10 dietary treatments. Pigs were fed a control corn-soybean meal-based diet or the control diet containing 15 or 30% DDGS from 3 sources (corn, sorghum 1, or sorghum 2). Diets containing 30% DDGS were fed with or without the same enzyme (enzyme A) as Exp. 1. There were 5 pigs per pen and 7 pens per treatment. Overall (d 7 to 28), there were no (P > 0.10) enzyme × DDGS source interactions observed. Corn DDGS did not influence (P > 0.10) ADG, ADFI, or G:F. Sorghum DDGS reduced (P = 0.003) G:F, with no difference (P > 0.10) between sorghum DDGS sources. Adding the commercial enzyme to the 30% DDGS diets did not improve performance. In summary, feeding diets with sorghum DDGS resulted in poorer G:F with no change in ADG compared with feeding the control diet or diets containing corn DDGS. Adding the enzymes used in this study to corn-soybean meal-based diets containing 30% DDGS did not improve growth performance.



INTRODUCTION

Increased ethanol production has prompted the swine industry to increase its use of biofuel coproducts. Dried distillers grains with solubles (DDGS) is one such coproduct that is widely used (Stein and Shurson, 2009). Studies show that 30% DDGS can replace the cereal grain source in nursery pig diets without affecting growth performance (Gaines et al., 2006; Spencer et al., 2007; Burkey et al., 2008). Little information on the impact of feeding sorghum-based DDGS is available in the nursery phase. Variability in DDGS nutrient content, specifically in Lys concentration and digestibility, has been reported (Stein and Shurson, 2009; Urriola et al., 2009). One source of this variability is likely due to the variety of carbohydrate sources used in ethanol production (corn, sorghum, or wheat).

Because the majority of the starch fraction is removed by fermentation, other components, such as fiber, increase in concentration. This fiber fraction contains nonstarch polysaccharides that the pig is unable to digest because of its lack of specific digestive enzymes. Supplemental enzymes have been developed for use in swine diets to assist in digestion of nonstarch polysaccharides. These enzymes have been successful in increasing the digestibility of European swine diets, which are typically formulated with starch sources that have a large crude fiber component, such as barley, wheat, or rye (Omogbenigun et al., 2004). These commercial enzymes, such as various carbohydrases, are used to improve feed utilization and decrease the cost of BW gain (Partridge, 2001). Because corn is highly digestible and has a low fiber content, enzymes have not consistently shown improvements in growth performance when used in corn-based diets (Hahn et al., 1995; Partridge, 2001). Therefore, we speculate that enzymes may be more beneficial in diets containing DDGS than in corn-soybean meal-based diets. The objective of these experiments was to evaluate the effects of different commercial enzymes in diets containing various concentrations and sources of DDGS on nursery pig growth performance.


MATERIALS AND METHODS

All experimental procedures were approved by the Kansas State University Institutional Animal Care and Use Committee.

Samples of the corn and sorghum DDGS were collected before diet formulation and subjected to proximate analysis, and analyzed for NDF and ADF, AA, and nonstarch polysaccharides contents (Englyst and Cummings, 1984; AOAC, 2000; Table 1). All enzymes were commercially available, and inclusion amounts were chosen based on manufacturers’ recommendations and guaranteed analysis (Table 2).

Table 1.

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Table 2.

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Exp. 1

A total of 180 pigs (TR4 × 1050, PIC, Hendersonville, TN; 9.0 kg initial BW) were used in a 27-d growth trial to evaluate the effects of 3 different commercial enzymes in diets containing corn DDGS on nursery pig performance. Pigs were blocked by BW and allotted to 1 of 5 dietary treatments. There were 6 pigs per pen and 6 pens per treatment. Each pen (1.2 m2) contained 1 self-feeder and 1 nipple waterer to provide ad libitum access to feed and water. Pigs were housed in the Kansas State University Swine Research and Teaching Center in Manhattan.

A common pelleted starter diet was fed from weaning until the start of the experiment (d 7). The 5 dietary treatments were 1) positive control, corn-soybean meal diet, 2) negative control, corn-soybean meal diet with 30% corn DDGS (Chief Ethanol Fuels, Hasting, NE), and the negative control diet with 3) 0.05% enzyme A (Easyzyme Mixer 1, Archer Daniels Midland Company, Decatur, IL), 4) 0.05% enzyme B (Hemicell-W, ChemGen, Gaithersburg, MD), or 5) 0.05% enzyme C (Porzyme 93010, Danisco Animal Nutrition Marlborough, UK; Table 3). For the diets containing DDGS (with or without enzyme), a single batch of feed was manufactured, then divided into subsamples. Diet samples were collected and analyzed for chemical composition including ADF and NDF (Table 4). Enzymes were added to the individual subsamples, and the respective diets were mixed again. Published mean standardized ileal digestible (SID) values for corn DDGS were used in diet formulation (Stein et al., 2006). Also, the ME value of the grains (3,420 kcal of ME/kg for corn and 3,340 kcal of ME/kg for sorghum; NRC, 1998) were used for their respective DDGS in diet formulation. Treatment diets were fed in meal form for 27 d. Average daily gain, ADFI, and G:F were determined by weighing pigs and measuring feed disappearance on d 7, 14, and 27 of the trial.

Table 3.

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Table 4.

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Exp. 2

A total of 350 pigs (PIC C22 × 1050, PIC; 11.0 kg initial BW) were used in a 21-d growth trial to evaluate the effects of a commercial enzyme in diets containing corn or sorghum DDGS on nursery pig performance. Pigs were blocked by BW and allotted to 1 of 10 dietary treatments. There were 5 pigs per pen and 7 pens per treatment. Each pen (1.5 m2) contained a 4-hole dry self-feeder and 1 cup waterer to provide ad libitum access to feed and water. The study was conducted at the Kansas State University Segregated Early Weaning Facility in Manhattan.

The 10 experimental treatments were 1) positive control, corn-soybean meal diet, 2) 15% corn DDGS (Chief Ethanol Fuels, Hastings, NE, same batch as Exp. 1), 3) 30% corn DDGS, 4) 30% corn DDGS + 0.05% enzyme A, 5) 15% sorghum DDGS from source 1 (Kansas Ethanol, Lyons, KS), 6) 30% sorghum DDGS from source 1, 7) 30% sorghum DDGS from source 1 + 0.05% enzyme A, 8) 15% sorghum DDGS from source 2 (US Energy Partners, Russell, KS), 9) 30% sorghum DDGS from source 2, and 10) 30% sorghum DDGS from source 2 + 0.05% enzyme A (Table 5). Like Exp. 1, for the diets containing 30% DDGS (with or without enzyme), a single batch of feed was manufactured, then divided into subsamples and then the enzymes added to the subsample and the respective diets were mixed again. Enzyme A was selected for use in the experiment because it contained a broader range of enzyme activities than enzymes B or C. Diet samples were collected and analyzed for chemical composition including ADF and NDF (Table 6). Sources of DDGS were analyzed for proximate analysis and AA concentrations (AOAC, 2000). Analyzed total AA concentrations for DDGS sources were used to calculate SID AA concentrations, which were used in diet formulation (Stein et al., 2006; Table 6). Treatment diets were fed for 21 d. All diets were in meal form. Average daily gain, ADFI, and G:F were determined by weighing pigs and measuring feed disappearance on d 7, 14, and 21 of the trial.

Table 5.

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Table 6.

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Statistical Analysis

Data were analyzed as a randomized complete block design with the pen as the experimental unit. Data were analyzed using the MIXED procedure (SAS Inst. Inc., Cary, NC) with treatment as a fixed effect and block as a random effect. Protected by significant F-tests for treatment, the PDIFF option of the LSMEANS statement in SAS was used to evaluate differences among treatments in Exp 1. Differences in Exp. 2 were evaluated using preplanned contrasts. Linear and quadratic effects of increasing corn or sorghum DDGS were made with the corn-soy control treatment being used as the first dosage level in both comparisons. Other contrasts included 1) all treatments containing corn DDGS vs. all treatments containing sorghum DDGS, 2) all treatments containing sorghum DDGS from source 1 vs. source 2, 3) all treatments containing 30% DDGS without enzyme vs. with enzyme, and 4) enzyme and DDGS source (corn and sorghum) interaction. Differences in means were considered significant if P-values were ≤0.05 and trends if P-values were >0.05 but ≤0.10.


RESULTS

Exp. 1

Overall (d 0 to 27), pigs fed the positive and negative control diets had greater (P < 0.05) ADG and tended to have greater (P < 0.10) ADFI than pigs fed diets containing enzyme B (Table 7). Also, pigs fed the positive control diet had greater (P < 0.05) ADG than pigs fed diets containing enzyme A. There were no overall differences in G:F among treatment diets.

Table 7.

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Exp. 2

Overall (d 7 to 28), there were no sorghum source or enzyme × DDGS source interactions (Tables 8 and 9). Increasing dietary corn DDGS did not affect ADG, ADFI, or G:F. Increasing dietary sorghum DDGS did not affect ADG or ADFI but decreased (linear, P = 0.003) G:F. Feeding sorghum DDGS rather than corn DDGS did not affect ADG but tended to increase (P = 0.06) ADFI and decreased (P = 0.05) G:F. Enzyme addition did not influence ADG, ADFI, or G:F.

Table 8.

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Table 9.

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DISCUSSION

The results of this study agree with previous research demonstrating that 30% corn DDGS can be used in nursery pig diets (Gaines et al., 2006). Also, the data of the current study show that pigs fed increasing amounts of sorghum DDGS had decreased G:F, which is in agreement with data by Feoli et al. (2008), who observed that inclusion of 30% sorghum DDGS decreased weanling pig ADG and G:F compared with a control diet without DDGS (670 vs. 548 g/d ADG and 689 vs. 585 g/kg G:F). Variability likely plays a role in the growth response to dietary DDGS. Stein and Shurson (2009) reported that the Lys concentration and its digestibility in DDGS can vary greatly. Pigs fed corn DDGS had improved G:F compared with those fed sorghum DDGS, likely because of a difference in energy density between the diets. The energy value of corn is 3,420 kcal of ME/kg, whereas that of sorghum is 3,340 kcal of ME/kg (NRC, 1998). Thus, we would expect sorghum DDGS to have a decreased energy content compared with that of corn DDGS (Feoli et al., 2007).

Each of the commercial enzyme blends was analyzed by its respective manufacturer and found to contain greater concentrations of the specific enzymes than the guarantee of the manufacturers. Addition of these commercial enzymes to diets has been reported to improve G:F and nutrient digestibility in poultry and in pigs (Bedford, 2000; Acamovic, 2001; Pettey et al., 2002; Cowieson and Adeola, 2005). These enzymes are widely used in pig diets in Europe, where feedstuffs with high fiber concentrations are the primary source of carbohydrates. Many cereal grains used in Europe have a greater proportion of nonstarch polysaccharides such as (1–3), (1–4)-β-d-glucans (barley and oats) and arabinoxylans (wheat, rye, and triticale; Bach Knudsen, 1997). Soybean meal, however, has increased β-galactomannans and α-1,6-galactosides, even after processing (Rackis, 1981; Hartwig et al., 1997). Carbohydrases such as α-galactosidase, β-1,4-mannanase, β-glucanase, and xylanase help break down some of these insoluble bonds that the nonruminant animal is otherwise unable to digest (Sugimoto and Van Buren, 1970; McGhee et al., 1978). Because corn is highly digestible and low in fiber, enzymes have not consistently shown improvements in growth performance (Partridge, 2001). Likewise, the current experiments demonstrate that the enzymes tested did not improve weanling pig performance when added to diets containing 30% DDGS compared with a corn-soybean meal positive control diet. We have no explanation why the addition of enzyme B had a negative effect on ADG in Exp. 1. Hahn et al. (1995) observed a 3% improvement in G:F in one study but no response in a second with addition of the same enzyme complex as enzyme B. Pettey et al. (2002), using the same enzyme complex, observed poorer ADG and G:F in simple diets in phase I of a 3-phase study, but not for the overall test period.

Because the distillation process increases the proportion of nonstarch polysaccharides in cereal grains, it is theorized that dietary enzymes may be more effective when DDGS is included in the diet. However, both of our studies indicate that adding these enzymes had no effect on nursery pig performance whether DDGS was included in the diet or not.

In our diet formulation, we did not add fat. Our justification was that any improvement in ADG or G:F, as a result of enzyme addition, might be better observed with a diet without added fat. Pettey et al. (2002) observed improvement in G:F of pigs fed diets with Hemicell (enzyme B in the Exp. 1), similar to the addition of 2% added fat, or an increase in the energy content of the diet by 100 kcal of DE/kg. If the dietary enzymes result in an energy release, SID lysine concentrations would be above the requirement estimate of the pig so as not to limit the potential BW gain (Schneider et al., 2006a,b).

Little is known regarding the mode of action of carbohydrases (Bedford, 1993). The effect of breaking these β-1,4 glycosidic bonds seems to differ between poultry and swine (Bedford, 2000). In poultry, carbohydrases appear to affect the viscosity of dietary ingredients within the gastrointestinal tract (GIT). Almirall et al. (1995) found that decreasing digesta viscosity in the GIT with carbohydrases may increase nutrient retention and utilization in high-fiber diets in poultry. However, Johansen et al. (1997) and Lindberg et al. (2003) suggested that altering GIT viscosity in swine by including carbohydrases does not improve the nutrient utilization in pigs because the majority of β-glucans are broken down before the terminal ileum. This is similar to the conclusions of Thacker et al. (1992), who suggested that an increase in the digestibility of nutrients by swine is due to an increase in enzymatic degradation, not by a change in GIT viscosity.

The ratio of NDF to ADF in the corn DDGS in our study is consistent with that reported by Stein and Shurson (2009). This ratio is relatively wide in corn DDGS samples, indicating increased concentration of hemicellulose. In contrast, the NDF:ADF ratio is much less in the sorghum source 1 and 2 DDGS, which is similar to that observed by Urriola et al. (2009). Therefore, the relatively large xylanase activity of all 3 enzyme sources should have had a greater impact on the corn DDGS sample than sorghum DDGS. Mannose and galactose concentrations in all of the DDGS samples were small; therefore, the galactomannanase would not be expected to lead to large effects on pig growth or G:F as a result of directly increasing energy availability.

The increase in enzymatic degradation (e.g., β-glucans) may allow the pig to utilize the sugars from nonstarch polysaccharides for energy (Kim et al., 2003). This may be the reason for increased performance observed in some studies by adding carbohydrases (Pettey et al., 2002; Kim et al., 2003). Also, dietary carbohydrases increase the sugar release in a diet and thus also increase lactobacilli growth (Axelsson, 1998). Höberg and Lindberg (2004) reported that supplementing high-fiber diets with fiber-degrading enzymes results in a shift in the molar proportion of organic acids from acetic to lactic. Therefore, the increase in lactobacilli activity, rather than gastrointestinal viscosity, may be the reason for the increase in digestibility when pigs were fed diets containing carbohydrases.

The data of the current study indicate that the enzymes evaluated, when included at manufacturer suggested amounts, did not improve growth performance. Also, adding different enzymes to diets containing 30% DDGS did not improve performance in a corn-soybean meal-based diet or a corn-soybean meal-based diet with 30% added DDGS. Feeding diets containing sorghum DDGS resulted in poorer feed efficiency.

 

References

Footnotes


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