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ANIMAL PRODUCTION |
* USDA, ARS, National Soil Erosion Research Laboratory, West Lafayette, IN 47906;
and
USDA, ARS, Poultry Production and Products Safety Research Unit, Fayetteville, AR 72701;
and
Departments of Animal Science and
and
Crop, Soil, and Environmental Sciences, University of Arkansas, Fayetteville 72701; and
and
¶ Cooperative Extension Service, University of Arkansas, Little Rock 72204
Abstract
Ammonia (NH3) losses from swine manure contribute to odor problems, decrease animal productivity, and increase the risk of acid rain deposition. This study was conducted to determine whether aluminum chloride (AlCl3) or dietary manipulation with phytase could decrease relative NH3 losses from swine manure. Twenty-four pens of nursery pigs were used in two trials, and the pigs were fed normal or phytase-supplemented (500 IU/kg) diets. Aluminum chloride was added to manure pits (1.9 x 1.2 x 0.5 m) under each pen at 0, 0.25, 0.50, or 0.75% (vol:vol) of final manure volume. Manure pH and NH3 losses (measured by relative NH3 flux) were determined twice weekly. The addition of AlCl3 at 0.75% decreased (P < 0.05) manure pH from 7.48 to 6.69. Phytase decreased (P < 0.05) manure pH to 7.07 compared with 7.12 in the normal diet manure. Aluminum chloride administered at 0.75% without phytase reduced (P < 0.05) relative NH3 losses 52% for the entire 6-wk period. Relative NH3 losses were decreased (P < 0.05) from 109 mg of NH3/(m2•h) in pens containing pigs fed the normal diet without AlCl3 to 81 mg of NH3/(m2•h) in pens housing pigs administered the phytase diet, a 26% reduction. When the phytase diet and 0.75% AlCl3 additions were used in combination, relative NH3 losses were reduced (P < 0.05) by 60% compared with pens of pigs fed the control diet without AlCl3. Decreases in manure pH were likely responsible for the observed reduction in NH3 losses. Multiple regression was performed with relative rates of NH3 losses as the dependent variable and rate of AlCl3 addition, diet, and manure pH as independent variables. The model was tested using a stepwise regression (P < 0.001), and results indicated that the most important factors determining NH3 losses were manure pH and diet. However, the contribution of AlCl3 cannot be discounted. When manure pH was regressed against AlCl3 and dietary phytase, AlCl3 levels accounted for 64% of the variation in manure pH (P < 0.001). Dietary manipulation with phytase and application of AlCl3 to manure are promising management practices for the reduction of NH3 from swine facilities.
Key Words: Aluminum Chloride • Ammonia • Phytase • Swine Manure
Introduction
Swine facilities are under increasing pressure to reduce potential pollution, including nutrient and gaseous (odor) losses. Ammonia losses from swine facilities contribute to odor problems, environmental degradation, and health problems in both animals and humans. ApSimon et al. (1987)
suggested that atmospheric NH3 pollution may play a role in acid rain production, and that the dominant source of NH3 in Europe was from animal wastes. Ammonia losses also impact animal health and production. High levels of atmospheric NH3 increase swine susceptibility to respiratory problems from microorganisms such as Pasteurella multocida (Neumann et al., 1987), conchal atrophy (Drummond et al., 1981), and atrophic rhinitis (Robertson et al., 1990), and also reduce feed consumption and ADG by pigs (Strombaugh et al., 1969).
Decreasing NH3 losses through dietary modification or manure amendments could hold many advantages to swine producers. Inclusion of adipic acid (van Kempen, 2001), increasing dietary carbohydrate levels (Cahn et al., 1998), and reducing CP in diets (James et al., 1999) have all been shown to decrease manure pH and NH3 volatilization. Manure pH directly affects NH3 volatilization (O’Hallaron, 1993; Burgess et al., 1998), such that dietary modifications that decrease manure pH will also reduce NH3 losses. Aluminum sulfate (alum) added to poultry litter reduced litter pH and NH3 losses by 99% (Moore et al., 1995), which related to improved weight gains and feed conversions, and reduced costs associated with ventilating NH3 contaminated air (Moore et al., 1999). Alum and AlCl3 were found to reduce swine manure pH significantly (Smith et al., 2001); however, NH3 losses were outside the scope of that study. The objective of this study was to evaluate the ability of dietary modification with phytase and AlCl3 manure amendments on relative NH3 losses from swine manure.
Materials and Methods
This study was conducted in a nursery at the University of Arkansas swine farm, with 24 pens measuring 1.8 x 1.2 m. In each of the two trials, pigs were blocked into three weight groups; each weight group was further divided into eight subgroups of six pigs per pen. The pigs used for this study were bred from Yorkshire x Landrace sows and Hampshire x Duroc boars. Six nursery pigs were randomly assigned to each pen at weaning (approximately 19 d of age and approximately 6.5 kg at weaning). Individual manure analysis from each pen was possible due to the construction of individual manure collection pits under each pen. The manure pits were constructed from stainless steel and were 1.9 x 1.2 x 0.5 m. A pull/plug manure management system with a 2-wk flush cycle was used to manage the manure. Lagoon water was pumped into each pit at the beginning of the flush cycle, at which time AlCl3 additions were made. Aluminum chloride treatment volumes were based on estimated manure production volumes from spreadsheets obtained from the University of Arkansas Cooperative Extension Service and verified using existing data from these pens (Table 1).
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. The high level of AlCl3 treatment was based on a 1:1 molar ratio of P:Al, because reducing P solubility and P runoff are documented benefits of AlCl3 use in swine manure (Smith et al., 2001). There were two phytase treatments: 1) normal diet without phytase based on NRC (1998) recommendations for all nutrients using available P (aP) values; and 2) phytase diet based on NRC aP minus 0.1%, with phytase mixed into feed after pelleting at 500 U of phytase/kg of feed.
A three-phase diet system was used in this study, and pigs were fed dietary treatments throughout phase 1 (d 0 to 14 after weaning), phase 2 (d 14 to 28 after weaning), and phase 3 (d 28 to 42 after weaning). Diet change and pit flush/recharge occurred at the same time. Both trials ended at the end of the sixth week. Diets for each phase were the same for both trials and are noted in Table 2.
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) was modified for this study due to strict space limitations. An electrochemical NH3 sensor (model E/C-P1-NH3, Manning Systems, Lenexa, KS) was attached to a chamber that measured 21.9 x 21.9 x 7.0 cm (Figure 1) and floated on the manure surface. Air circulated through the enclosed system at a rate of 2.5 L/min using a modified aquarium pump. Ammonia concentrations were measured at 0, 10, 30, 60, 90, 120, and 150 s following chamber placement on the manure surface, which was not sufficient time to change the manure or air temperature inside the chamber. However, air and manure temperature were monitored continuously throughout each set of measurements. Only one chamber was used to minimize differences that could exist between different chambers. Between measurements of different manure pits, 2 to 5 min lapsed in order to ensure adequate time for the air inside the flux chamber and air pump to reach background levels. From these NH3 measurements, relative flux calculations were made using the ideal gas law (Moore et al., 1997). The chamber method used was required due to the mixed atmosphere in the production facility and the space limitations of each manure pit. Manure pH and foam pH were measured at the same time as flux measurements (Piccolo 2, Hanna Instruments, Pardova, Italy). At the end of each diet phase in both trials, all manure in each pit was homogenized for 5 min and manure samples were collected and analyzed for total N using a Skalar FORMACS HT analyzer (Skalar Analytical, Breda, The Netherlands).
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Results and Discussion
Decreases in pH and Ammonia Losses
The treatment main effects of AlCl3 and dietary phytase addition on manure and foam pH are reported in Figure 2 (phytase x AlCl3 interaction; P > 0.10). The addition of AlCl3 reduced (P < 0.01) manure pH from 7.48 in the control pits to 6.69 in the manure pits containing 0.75% AlCl3 (Figure 2A). Phytase diets reduced (P < 0.05) manure pH from 7.12 in the normal diet to 7.07. When manure pH was regressed against the AlCl3 treatment level and dietary phytase, AlCl3 rates accounted for 64% of the variation in manure pH (P < 0.001; Table 3). Using stepwise procedures, dietary phytase was not found to be sufficient to enter into the model (P > 0.15).
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) when AlCl3 was added to swine manure, foam formed on the surface, probably resulting from CaCO3 dissolution. This hypothesis is supported by the fact that titratable alkalinity was inversely proportional to the level of AlCl3 treatment (data not shown). The foam was extremely dense and lasted for a period of 12 d. It has been suggested that this foam may act as a barrier to gaseous losses (Smith et al., 2001), but this was not measured in the current study. As with manure pH, foam pH decreased (P < 0.001) with increasing levels of AlCl3 addition to manure (Figure 2B). Smith et al. (2001) observed a foam pH around 5.0, whereas in this study, the pH ranged from about 7.2 to 7.6. Although the reason for the discrepancy in foam pH is not clearly understood, the diets, which alter manure and thus foam chemistry, were not documented in the previous study.
As was expected, addition of AlCl3 to manure reduced (P < 0.001) relative NH3 losses (Figure 3), such that increasing the amount of AlCl3 resulted in greater reductions in NH3 losses. Aluminum chloride at the 0.75% level, without dietary phytase, reduced (P < 0.001) relative NH3 losses from 109 mg of NH3/(m2•h) (control pens) to 52 mg of NH3/(m2•h), a 52% reduction for the entire 6-wk period. Phytase diets without AlCl3 added to manure also reduced (P < 0.01) relative NH3 losses compared with normal diets from 109 mg of NH3/(m2•h) in the control pens to 81 mg of NH3/(m2•h) (Figure 3). This is the first study to show that use of phytase and/or reduction of P supplementation can decrease NH3 losses from swine manure. When the phytase diet and AlCl3 manure additions were used in combination at the 0.75% rate of AlCl3, relative NH3 losses were decreased (phytase x AlCl3 interaction; P < 0.10) compared with the control diet without AlCl3. Numerical reductions (P > 0.10) in relative NH3 losses were noted when comparing phytase-supplemented diets with normal diets within 0.50 and 0.75% AlCl3 treatments to manure. Although this decrease was not significant statistically, the use of these best management practices (BMP) together could help producers reduce NH3 losses more than if either AlCl3 or dietary phytase treatment was used alone. In addition, the combination of these BMP also reduces total P and P solubility in swine manure, providing further benefit to the environment (our unpublished results).
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). The ammonia equilibrium equation shows the relationship to pH; as more H+ ions are released in solution (pH decrease) the ammonia equilibrium shifts from volatile NH3 to nonvolatile ammonium (
):
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Multiple regression analysis suggested manure pH and diet were the most important factors determining relative ammonia losses (Table 3). Addition of AlCl3 to manure was not important for this model. However, AlCl3 additions were most likely accounted for in the manure pH because AlCl3 accounted for 64% of the variation in manure pH (Table 3).
Effect of Time on pH and NH3 Losses
During each flush cycle, mean pH and relative NH3 fluxes showed similar trends with time (Figure 4). The effects of AlCl3 addition on manure pH and NH3 losses were the greatest immediately after treatment and diminished with time (AlCl3 x day interaction; P < 0.001; Figure 4). Over time, swine manure and urine were deposited in the pits, raising (P < 0.05) manure pH from 6.4 at the beginning of the flush cycle to slightly above 6.9 on d 11 in manure from 0.75% AlCl3-treated pens with the normal diet. The effects of dietary phytase on manure pH, although following the same trend as manure from pigs fed the normal diet, resulted in a lower (P < 0.05) pH throughout the flush cycle. This might be expected because the root cause of the relative NH3 reductions is a reduction in manure pH at the source (less dicalcium phosphate in the feed).
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). Aluminum chloride (0.75% treatment) without phytase decreased (P < 0.001) relative NH3 losses from 149 to 36.6 mg of NH3/(m2•h) on d 0, a 75% initial reduction. Changes in relative NH3 fluxes taken on d 7 to 11 for most treatments had leveled off. Hence, decreasing the length of the flush cycle to 1 wk would likely improve the overall effectiveness of reducing NH3 losses. Many swine operations that use pull/plug systems to manage manure use a 1-wk flush cycle, which could potentially show greater reductions than the 2-wk flush cycle used in this study. The 2-wk cycle used in this study was required because not enough manure was produced in the first 3 wk of either trial to properly dispose of, or sample, the manure. Greater NH3 reductions near the time of treatment is consistent with data from commercial broiler houses treated with aluminum compounds (Moore et al., 1999), where the majority of NH3 reduction occurred in the first 4 wk of the 6-wk growing period.
As with manure pH, reductions in relative NH3 losses due to phytase were more consistent with time, indicating that there was not a significant interaction between the phytase diet treatment and time (phytase x day interaction; P = 0.86). The initial reduction (P < 0.01) in NH3 losses using phytase diets compared with the normal diet and no AlCl3 was 23%, whereas the relative reduction (P < 0.01) between these two treatments at the final reading of each phase was 22%. The lack of a significant interaction between phytase and time indicates that the effects of NH3 reduction due to the diet treatments was not affected by time, which was not the case with the AlCl3 manure treatments (AlCl3 x day interaction; P < 0.001), where the effects did significantly diminish with time. This is an important point and should be verified by other researchers. Reducing NH3 losses from poultry litter improved the ambient NH3 levels within poultry facilities sufficiently to improve ADFI, ADG, mortality, and morbidity (Moore et al., 1999). Reducing atmospheric NH3 levels inside the rearing facility could increase swine productivity. Productivity measurements resulting from altered ambient levels of NH3 were outside the scope of the current study due to the mixed atmosphere in the nursery, where all 24 pens were in the same room. Increased weight gains and feed conversions might be expected to result from these treatments due to their ability to reduce NH3 losses, and in turn, atmospheric NH3 levels. Taking these technologies to commercial production facilities to test this hypothesis is the next logical step for these technologies.
Nitrogen Retention in Manure
The chambers used in this study were intended to show relative differences in NH3 loss, and not necessarily to calculate cumulative or annual N losses. However, total N retained in the manure at the end of the 6-wk growing period was significantly related to relative NH3 loss (P < 0.001), rate of AlCl3 treatment (P < 0.05), and manure pH (P < 0.05; Table 3). The parameters explained 25% of the variability in total N mass, with relative NH3 loss explaining 20% independently.
Implications
Use of dietary phytase and aluminum chloride manure amendments decreased manure pH and ammonia losses. These management practices could be effective at decreasing ambient ammonia levels, which in commercial facilities, should also translate to improved production as measured by feed intake, average daily gain, and reduced susceptibility to respiratory ailments. Combinations of these management practices could aid producers in waste application when manure application rate is based on the nitrogen content of the manure. The next logical progression for this research is to compare the effects of these treatments in different swine rearing facilities under the same management. This would provide data to determine whether the relative ammonia reductions noted here translate into actual reductions in ambient ammonia levels within the facility, as well as whether these potential reductions could increase productivity and reduce respiratory ailments in swine.
Footnotes
1 Mention of a trade name, proprietary product, or specific equipment does not constitute a guarantee or warranty by the USDA and does not imply its approval to the exclusion of other products that may be suitable. 
2 Correspondence: 275 S. Russell St., Purdue University, West Lafayette, IN 47907-1196 (phone: 765-494-0330; fax: 765-494-5948; e-mail: drsmith{at}purdue.edu).
Received for publication March 20, 2003. Accepted for publication September 26, 2003.
Literature Cited
ApSimon, H. M., M. Kruse, and J. N. B. Bell. 1987. Ammonia emissions and their role in acid deposition. Atmos. Environ. 21:1939–1946.
Burgess, R. P., J. B. Carey, and D. J. Shafer. 1998. The impact of pH on nitrogen retention in laboratory analysis of broiler litter. Poultry Sci. 77:1620–1622.
Cahn, T. T., A. L. Sutton, A. J. A. Aarnink, M. W. A. Verstegen, J. W. Schrama, and G. C. M. Bakker. 1998. Dietary carbohydrates alter the fecal composition and pH and the ammonia emission from slurry of growing pigs. J. Anim. Sci. 76:1887–1895.
Drummond, J. G., S. E. Curtis, R. C. Meyer, J. Simon, and H. W. Norton. 1981. Effects of atmospheric ammonia on young pigs experimentally infected with Bordetella bronchiseptica. Am. J. Vet. Res. 42:463–468.
James, T., D. Meyer, E. Estarza, E. J. Depeters, and H. Perez-Monte. 1999. Effects of dietary nitrogen manipulation on ammonia losses from manure from Holstein heifers. J. Dairy Sci. 82:2430–2439.[Abstract]
Moore, Jr., P. A., T. C. Daniel, and D. R. Edwards. 1999. Reducing phosphorus runoff and improving poultry production with alum. Poultry Sci. 78:692–698.
Moore, Jr., P. A., T. C. Daniel, D. R. Edwards, and D. M. Miller. 1995. Effects of chemical amendments on ammonia losses from poultry litter. J. Environ. Qual. 24:293–300.
Moore, Jr., P. A., W. E. Huff, T. C. Daniel, D. R. Edwards, and T. C. Sauer. 1997. Effect of aluminum sulfate on ammonia fluxes from poultry litter in commercial broiler houses. Pages 883–891 in Proc. Fifth Int. Symp. on Livest. Environ. Vol. 2. ASAE, St. Joseph, MI.
NRC. 1998. Nutrient Requirements of Swine. 10th ed. Natl. Acad. Press, Washington, DC.
Neumann, R., G. Mehlorn, I. Buchholz, U. Johannsen, and D. Schimmel. 1987. Experimental studies of the effects of chronic aerogenous toxic gas exposure of unweaned piglets with ammonia of various concentrations. II. Reaction of cellular and humoral defense mechanisms of ammonia exposed unweaned piglets under conditions of experimental Pasteurella multocida infection with and without thermomotor stress. J. Vet. Med. 34:241–253.
O’Halloran, I. P. 1993. Ammonia volatilization from liquid hog manure: Influence of aeration and trapping systems. Soil Sci. Soc. Am. J. 57:1300–1303.
Robertson, J. F., D. Wilson, and W. J. Smith. 1990. Atrophic rhinitis: The influences of the aerial environment. Br. Soc. Anim. Prod. 50:173–182.
Smith D. R., P. A. Moore, Jr., C. L. Griffis, T. C. Daniel, D. R. Edwards, and D. L. Boothe. 2001. Effects of alum and aluminum chloride on phosphorus runoff from swine manure. J. Environ. Qual. 30:992–998.
Strombaugh, D. P., H. S. Teague, and W. L. Roller. 1969. Effects of atmospheric ammonia on the pig. J. Anim. Sci. 28:844–847.
Van Kempen, T. A. T. G. 2001. Dietary adipic acid reduces ammonia emission from swine excreta. J. Anim. Sci. 79:2412–2417.
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