J. Anim Sci. 2008. 86:112-118. doi:10.2527/jas.2006-381
© 2008 American Society of Animal Science
Utilization of distillers dried grains with solubles and phytase in sow lactation diets to meet the phosphorus requirement of the sow and reduce fecal phosphorus concentration1
G. M. Hill*,2,
J. E. Link*,
M. J. Rincker*,3,
D. L. Kirkpatrick*,4,
M. L. Gibson
and
K. Karges
* Michigan State University, East Lansing 48824; and and
Dakota Gold Research Association, Sioux Falls 57059
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Abstract
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Two experiments were completed to determine the potential for using distillers dried grains with solubles (DDGS) in diets with or without phytase to provide available P, energy, and protein to highly productive lactating sows without increasing their fecal P. In Exp. 1, the dietary treatments were as follows: (1) corn and soybean meal with 5% beet pulp (BP) or (2) corn and soybean meal with 15% DDGS (DDGS). Besides containing similar amounts of fiber, diets were isonitrogenous (21% CP, 1.2% Lys) and isophosphorus (0.8% P). Sixty-one sows were allotted to dietary treatments at approximately 110 d of gestation (when they were placed in farrowing crates) based on genetics, parity, and date of farrowing. Sows were gradually transitioned to their lactation diet. On d 2 of lactation, litters were cross-fostered to achieve 11 pigs/litter. Sows and litters were weighed on d 2 and 18. Fecal grab samples were collected on d 7, 14, and 18 of lactation. Dietary treatment did not affect the number of pigs weaned (10.9 vs. 10.8) or litter weaning weight. On d 14, DDGS sows had less fecal P concentration than BP sows (28.3 vs. 32.8 mg/g; P = 0.04). Fecal Ca of sows fed DDGS decreased for d 7, 14, and 18 (55.6, 51.4, and 47.1 mg/g of DM, respectively; P = 0.05) but not for BP sows. In Exp. 2, the dietary treatments were as follows: (1) corn and soybean meal (CON), (2) CON + 500 phytase units of Natuphos/kg diet, as fed (CON + PHY), (3) corn and soybean meal with 15% DDGS and no phytase (DDGS), or (4) DDGS + 500 FTU of Natuphos/kg of diet, as fed (DDGS + PHY). Sows (n = 87) were managed as described for Exp 1. Litter BW gain (46.0, 46.3, 42.1, and 42.2 kg; P = 0.25) and sow BW loss (8.1, 7.2, 7.4, and 6.3 kg for CON, CON + PHY, DDGS, and DDGS + PHY, respectively; P = 0.97) were not affected by dietary treatment. Fecal P concentration did not differ among dietary treatments but was reduced at d 14 and 18 compared with d 7 (P = 0.001). However, fecal phytate P concentration was decreased by the addition of DDGS when DDGS and DDGS + PHY were compared with the CON sows except on d 7 (P < 0.05). Sows fed CON diet had greater fecal phytate P than sows fed DDGS, and sows fed DDGS + PHY had less fecal phytate P than sows fed DDGS with no phytase (P = 0.001). Although these experiments were only carried out for 1 lactation, these results indicate that highly productive sows can sustain lactation performance with reduced fecal phytate P when fed DDGS and phytase in lactation diets.
Key Words: distillers dried grains with solubles • lactation • phosphorus excretion • phytase • sow
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INTRODUCTION
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The highly productive lactating sow has high nutritional needs. Her suggested dietary requirements are second highest in Ca, P, and CP and first for daily total calories for any age or physiological state of swine (NRC, 1998
). To maximize lactation performance and reduce BW loss, most commercial producers find it necessary to provide sows with greater dietary concentrations of Ca, P, CP, and Lys than suggested by NRC (1998). The high-quality distillers dried grains with solubles (DDGS) currently produced by the ethanol industry is estimated to contain approximately 27% protein, 9% fat, 22% NDF, 18% ADF, and 0.75% P, of which 65 to 70% is associated with the phytate molecule (Noureddini et al., 2006). Fastinger and Mahan (2006) noted that the lighter yellow product, typical of the good products of today, have greater Lys content and digestibility than the darker DDGS, which is similar to that produced in the early 1990s. Matsui (2002) has suggested that fermentation of soybean meal with Aspergillus usamii almost completely degrades the phytate molecule. Thus, the reported high bioavailability of DDGS vs. corn (Allee, 2004) is assumed to be due to the fermentation process in DDGS production. Although P and fiber are greater in DDGS than in cereal grains, it has been successfully fed to growing-finishing pigs at 15 to 20% of the diet without compromising performance (Allee, 2004; Goodband, 2004; Shurson et al., 2004).
Although DDGS might be useful in gestation diets due to its high fiber content, sows have reduced dietary needs during gestation for energy, P, and CP, and not all producers will continue its use from gestation into lactation diets. There are no published reports on the use of DDGS in lactation diets in which DDGS was not fed during gestation. Our objectives were to determine if (1) DDGS could be fed to highly productive sows during lactation and maintain sow productivity and (2) phytase could be fed with DDGS to increase P utilization.
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MATERIALS AND METHODS
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Animals and Dietary Treatments
These experiments were approved by the All University Committee on Animal Care and Use at Michigan State University. Sixty-one sows in Exp. 1 and 87 sows in Exp. 2 were allotted to treatments based on genetics, parity, and date of farrowing. When sows entered the farrowing room at approximately 110 d of gestation, they were placed in individual farrowing crates (1.25 m2 and hardened steel rod construction; Delphi Products Co., Delphi, IN), which were located in the center of farrowing pens. The 4 farrowing rooms contained 12 farrowing pens each (space/pen = 3.25 m2). Pens contained hardened steel rod flooring (Nooyen Manufacturing Inc., Mt. Sterling, KY) located over a manure collection pit. Two solid cement aisles ran the length of each room both at the back and front of the farrowing pens. Zone heating was provided to the piglets by an 85-W heat pad (0.45 m2 of space; Osborne Industries Inc., Osborne, KS) placed on the floor on 1 side of the farrowing pen.
Sows’ experimental diets were gradually introduced into their corn-soybean meal gestation diet, which met NRC (1998) recommendations, until approximately 1.36 kg of their respective diet was being fed. At farrowing, a step-up regimen was followed to achieve ad libitum feed intake of the respective dietary treatments of the sows. Therefore, sows were fed 5 to 8 kg/d, depending on litter size, genetics, and parity. Appetite was not depressed by their respective diets before farrowing or as lactation advanced.
The sows’ genetics were Yorkshire or Yorkshire x Landrace. In Exp. 1, the number of sows was 18, 19, 11, 6, 5, 1, 0, and 1 for parity 1 to 8, respectively. In Exp. 2, the number of sows was 15, 20, 17, 20, 8, 5, and 2 for parity 1 to 7, respectively. Experiment 1 was conducted from mid-July to late September, and Exp. 2 was conducted from mid-March to mid-June. Room temperatures throughout the studies ranged from 21 to 32°C. Ventilation fans in the rooms were thermostatically controlled with a set temperature of 21°C.
For both experiments, pigs were processed [ear-notched, tails docked, needle teeth clipped, and injected i.m. with 200 mg of Fe from Fe dextran (Phoenix Pharmaceutical Inc., St. Joseph, MO)] within 24 h of birth. On d 2 of lactation, pigs were cross-fostered from nonexperimental sows in the contemporary farrowing group to achieve 11 pigs/litter. The lactation period was 18 d, and sows and litters were weighed on d 2 and 18. Fresh grab samples of feces were collected from 12 randomly selected sows per treatment (13 sows on the CON treatment in Exp. 2) on d 7, 14, and 18 of lactation. Most fecal samples (collected by gloved hand as they fell from the anus) were collected when the sows defecated as they got up to eat during the early morning or late afternoon. Some d-18 samples were collected when the sows walked to the scales. No fecal samples were collected from the floor. In Exp. 1, a limited number of sows were fed a food coloring (F.D. & C. #1, C3-041 Blue color, Kraus and Co. Inc., Walled Lake, MI) to distinguish the beginning and end of a 3-d fecal collection period to determine the approximate daily fecal volume and P balance.
Because the objectives of these experiments were to determine the adequacy of nutrients from DDGS in highly productive sows, rather than determination of nutrient bioavailability, nutrients were provided to meet or exceed NRC (1998) recommendations, including appropriate ratios such as Ca:P. The dietary treatments (Table 1) in Exp. 1 were as follows: (1) corn-soybean meal + 5% beet pulp (BP) or (2) corn-soybean meal + 15% DDGS (DDGS). Because DDGS is high in dietary fiber, beet pulp was selected as a fiber source to be included in a corn-soybean diet for comparison with DDGS. Beet pulp is low in P, palatable to pigs, and commercially available. In Exp. 2, the dietary treatments (Table 1) were as follows: (1) corn-soybean meal (CON), (2) CON + 500 phytase units (FTU) of Natuphos/kg diet, as fed (CON + PHY), (3) corn-soybean meal + 15% DDGS (DDGS), or (4) DDGS + 500 FTU of Na-tuphos/kg, as fed (DDGS + PHY). A FTU is defined as the activity of the phytase enzyme that yields 1 µmol of inorganic P per minute when excess phytate is provided at a pH = 5.5 and 37°C.
The DDGS used for the 2 experiments was obtained from the same plant (Michigan Ethanol, Caro, MI). All lots were bright yellow or gold, similar to the high-quality feedstuff from this source, as described by Roberson et al. (2005) and Kalbfleisch and Roberson (2005). The DDGS was analyzed for Zn (72 mg/kg), Ca (0.008%), and P (0.75%). Little product variation was observed (data not shown).
Laboratory Analysis
Fecal grab samples (Creech et al., 2004) were oven-dried (Fisher Isotemp, Fisher Scientific, St. Louis, MO) in acid-washed glass dishes before being ground in a sample mill (Cyclotec 1093 sample mill, Foss, Eden Prairie, MN) equipped with a 1-mm screen. Samples were microwave-digested (MARS-5, CEM Corp., Matthews, NC), as described by Shaw et al. (2002). Calcium (Exp. 1 and 2) and Zn (Exp. 2) concentrations were determined by atomic absorption spectroscopy (Unicam 989, Thermo Electron Corp., Franklin, MA) and P concentrations by the spectrophotometric (DU 7400, Beckman-Coulter, Fullerton, CA) method of Gomori (1942). To ensure the accuracy of mineral analysis, a standard reference material, bovine liver standard (1577b, National Institute of Standards and Technology, Gaitherburg, MD), was digested and analyzed with the samples against the same inorganic standards for each element (atomic absorption standards: CertiPUR, EMD Chemicals Inc., Gibbstown, NJ; P standard: LabChem Inc., Pittsburgh, PA). Phytate P concentration was determined as described by Latta and Eskin (1980) with the Ca salt of phytic acid, Ca salt with 23.98% P (P9539, Sigma-Aldrich, St. Louis, MO), used to prepare the standard curve. Feed samples were ground, digested, and analyzed for Ca, P, phytate P, and Zn as described previously.
Statistical Analysis
In Exp. 1 and 2, sow and pig performance data were analyzed using the MIXED procedure of SAS (SAS Inst. Inc., Cary, NC). The model contained the effects of treatment, parity, and the treatment x parity interaction. In Exp. 2, differences among treatments were determined using orthogonal contrasts. In both experiments, fecal collections were analyzed using the MIXED procedure of SAS for analysis of repeated measures. The experimental unit was individual sow, with repeated collections on d 7, 14, and 18 of lactation. Differences between means were considered significant at P < 0.05.
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RESULTS AND DISCUSSION
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Experiment 1
Diets contained concentrations of Lys, CP (calculated), Ca, and P (analyzed; Table 1
) greater than those suggested by NRC (1998) and match more closely the concentrations being fed to the genetically superior productive sows utilized in the swine industry today. Diets contained similar amounts of fiber (Table 1) so that the primary difference between the diets was the source of P. Monocalcium phosphate was decreased in the DDGS diet, and the P in DDGS is considered to be 80% available (Allee, 2004; Shurson et al., 2004).
Dietary treatment did not affect lactation performance (Table 2). Sows fed both dietary treatments had similar BW at d 2 and 18 and lost 6.2 kg (BP) and 8.0 kg (DDGS) during the lactation period (P = 0.42). This was a smaller BW loss than that reported by Young et al. (2004) for productive sows in a commercial setting but was similar to BW loss of sows fed up to 80% DDGS (old-type DDGS) reported by Monegue and Cromwell (1995) when sows weaned 8.1 to 9.7 pigs/litter. Litter weight gain did not differ (P = 0.50) for the BP and DDGS diets, and sows weaned a similar number of pigs (P = 0.50; Table 2). Wilson et al. (2003) fed DDGS at 50% of the diet in gestation and 20% in lactation to first-parity sows and showed no effect on the number of pigs weaned or litter weight. However, they showed that sows fed a corn-soybean meal control diet weaned fewer pigs/litter in parity 2 than sows fed diets containing DDGS. Similar to our results, Monegue and Cromwell (1995) reported that weaning weight and pigs weaned/litter were not affected by dietary treatment. In the current experiment, multiparous sows lost less BW than primiparous sows (P = 0.001), but their litter weight gain and number of pigs weaned/litter did not differ (Table 3). Young et al. (2004) reported that first-parity sows lost 29.4 kg and second- and third-parity sows lost 24.6 and 25.5 kg, respectively, in a commercial setting while weaning a similar number of pigs. Our primiparous sows were lighter at farrowing than those used by Young et al. (2004; 187.5 vs. 215.7 kg), which is probably attributable to genetic differences between the 2 studies.
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Table 2. Effect of added dietary beet pulp vs. dried distillers grains with solubles on sow and litter performance during lactation (Exp. 1)1
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There was a tendency for DDGS-fed sows to have reduced fecal phytate P (P = 0.07) compared with sows fed BP (Table 4). However, total fecal P was not different, even though the DDGS sows were fed 14% less monocalcium phosphate than the BP sows. These data indicate that the P from DDGS is available to the sow and that perhaps the inositol ring has been altered by the processing procedures during the manufacturing of DDGS. Allee (2004) noted similar results with finishing pigs, and P excretion was 11.35 g/d with 20% DDGS and 10.29 g/d with 0% DDGS in a corn-soybean meal diet. We observed from our limited collections that the sows fed both diets were in positive P balance and excreted 60 to 80 g/d of dry fecal material (data not shown).
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Table 4. Effect of added dietary beet pulp vs. distillers dried grains with solubles on fecal phytate P, total P, and Ca concentrations in lactating sows (Exp. 1)1
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Fecal Ca concentration did not differ between treatments (Table 4; P = 0.19). However, there was a day effect (P < 0.02) with no treatment x time interaction in fecal Ca concentration (P = 0.20). Fecal Ca decreased by 8.5 mg/g from d 7 to 18 of lactation for sows fed the DDGS diet, whereas fecal Ca did not decrease for sows fed BP. This decrease with DDGS could be related to Ca needs over time, or it may be due to changes in large intestine microflora adapting to the fiber provided by the DDGS, because some fiber sources are known to bind dietary Ca. As noted by Groff et al. (1995), both fiber and phytate may decrease Ca absorption. This may be the result of decreased transit time by nonfermentable fiber sources, which reduces time available for absorption, or the increase in microbes with fermentable fibers that bind the Ca and make it unavailable for absorption. Phytates bind cations, including Ca, and make them less available for absorption. In growing pigs, 50% of BP has been shown to be degraded in the large intestine (Graham et al., 1986), which may alter the ability of BP to affect Ca excretion over time.
Experiment 2
The average sow BW in each treatment group did not differ at d 2 (P = 0.52) or d 18 (P = 0.56; Table 5) of lactation. As expected, BW loss during lactation was not different among treatment groups (P = 0.97). Monegue and Cromwell (1995) reported BW loss of 10 and 8 kg when diets contained 40 or 80% DDGS (the old type), respectively, during a 28-d lactation in sows consuming 5.2 or 5.3 kg diet/d. Wilson et al. (2003) fed DDGS at 0 or 50% of the diet during gestation and 0 or 20% during lactation, but BW loss was not reported. In our experiment, primiparous sows, regardless of dietary treatment, weighed less than multiparous sows (P = 0.001) on d 2 of lactation (Table 6). As expected, this trend continued at d 18 (P = 0.001), resulting in a greater BW loss (P = 0.02) for primiparous sows during the lactation period.
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Table 5. Effect of added dietary distillers dried grains with solubles with or without phytase on sow and litter performance during lactation (Exp. 2)1
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With litters balanced to 11 pigs at d 2, litter weights did not differ among treatments at d 2 or 18 of lactation (Table 5; P = 0.16 and 0.19, respectively). Number of pigs weaned/litter was similar for all treatments (P = 0.78). Average gain/pig during the lactation period did not differ due to dietary treatment (P = 0.25). Wilson et al. (2003) reported that sows fed 50% DDGS during gestation and 20% DDGS during lactation weaned fewer pigs during their second parity. Similar to our experiment, Monegue and Cromwell (1995) reported that sows fed 40 or 80% DDGS in their lactation diet did not have different litter weaning weights. As expected, the litters of primiparous sows were lighter at weaning than multiparous sows (P = 0.01; Table 6).
Total fecal P concentration on d 14 and 18 was 9 to 22% less than that on d 7 (P < 0.05), regardless of dietary treatment (Table 7). Perhaps this reduction in P excretion was due to the microbial population in the cecum or large intestine adjusting to the lactation diet of the sow and releasing more P from the phytate molecule for use by the sow. Urine was not collected to determine if this reduction in fecal P resulted in increased urinary P. Within the same day, treatment did not alter fecal P excretion, but fecal phytate P was less for sows fed DDGS + PHY than for sows fed any other treatment on any day (P < 0.05). He and Honeycutt (2001) estimated that 39% of the P in pig manure was phytate P. More recently, Baxter et al. (2003) reported that phytate P was 15.5% of total P in fresh manure of pigs fed a corn-soybean meal diet, and this percentage decreased to 9.8% when phytase was added to the corn-soybean meal diet. In our experiment, when phytase and DDGS were included in the lactation diet, fecal phytate P was only 7% of the total P. Sows are known to have an active microbial population in the cecum, which may account for the decrease in phytate P compared with the 14-kg pigs utilized by Baxter et al. (2003). Thus, our data support their conclusion that fecal phytate P is influenced by feed composition and utilization by the animal.
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Table 7. Effect of added dietary distillers dried grains with solubles with or without phytase on fecal phytate P, total P, Ca, and Zn concentrations in lactating sows (Exp. 2)1
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Fecal Ca concentration was decreased in both diets without phytase (CON and DDGS) on d 14 and 18 compared with d 7 (P < 0.05; Table 7). This is interesting, because fecal Ca was decreased in sows fed DDGS with or without phytase regardless of day of collection (P < 0.05). These data indicate that phytase is not as important in increasing the Ca available for absorption as source and time, because the DDGS diets contained less monocalcium phosphate and more limestone than the CON diets to balance Ca and P among all diets. Both limestone and monocalcium phosphate are considered to be highly available sources of Ca (Baker, 2001).
Fecal Zn excretion did not follow a specific pattern (Table 7). Parity did not influence the excretion of fecal P, Ca, Zn, or phytate P (Table 8). Multiparous sows excreted less Ca, P, and Zn on d 7 but more Ca, P, and Zn on d 14 and more Ca and Zn on d 18 than primiparous sows (day x parity, P = 0.001). There is no information in the literature about fecal excretion of sows over time for these nutrients.
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Table 8. Effect of day of collection and parity on sow fecal mineral concentrations during lactation, DM basis (Exp. 2)1
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Although P balance and bone stores of P were not evaluated in these studies, these limited data imply that DDGS can be utilized at 15% of sow lactation diets to provide protein, energy, and P to highly productive sows. With the addition of phytase to DDGS diets, the concentration of fecal phytate P can be reduced compared with corn-soybean meal diets.
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Footnotes
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1 Partially funded by Dakota Gold Research Association (Sioux Falls, SD), Michigan Agricultural Experiment Station, College of Agriculture and Natural Resources, Michigan State University (East Lansing, MI), and National Center on Manure and Animal Waste Management, North Carolina State University (Raleigh). 
3 Present address: DPI Global, 17565 Avenue 168, Porterville, CA 93257.
4 Present address: AR Extension, #15 Courthouse, 25 W. Walnut, Paris, AR 72855.
2 Corresponding author: hillgre{at}msu.edu
Received for publication June 13, 2006.
Accepted for publication September 11, 2007.
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LITERATURE CITED
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H. H. Stein and G. C. Shurson
BOARD-INVITED REVIEW: The use and application of distillers dried grains with solubles in swine diets
J Anim Sci,
April 1, 2009;
87(4):
1292 - 1303.
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Abstract
INTRODUCTION
