Date Full Report Received01/06/2009
Date Abstract Report Received01/06/2009
InvestigationInstitution: Purdue University
Primary Investigator: Brian Richert
Co-Investigators: Alan Sutton
Funded ByNational Pork Board
A simulated manure system was used to evaluate the potential for soybean peroxidase (SoyP) added to swine manure to control phenolic and other odorous compounds in head space air and manure. The SoyP was added to the manure columns (350 mL of manure in 500 mL flasks) at increasing amounts of 7.5, 15, and 30 mg and calcium peroxide (CaP) levels increased from 0, 12.5, to 25 mmoles in a factorial approach of treatments plus 2 controls, a 0-0 SoyP-CaP and 0-25 SoyP-CaP treatments. Manure was collected from a 6 ft deep pit where the pigs had been placed in the facility for approximately 12 weeks. The base manure had no appreciable levels of soybean peroxidase (SoyP) as indicated by the near zero detection in the two control treatments that did not have additional SoyP added to these manure columns. As the SoyP was added to the manure columns at increasing amounts of 7.5, 15, and 30 mg the average analyzed levels of SoyP increased linearly. Adding CaP to the manure resulted in a 14.5% linear decline in the average level of SoyP activity. The average SoyP levels were at their highest levels at the 2 hr sampling and then declined to 48 hrs and remained at this level to 120 hr, maintaining 81% of the initial level of SoyP activity at 120 hr. Manure pH, ammonium N, manure ash content as a % of manure DM were not affect by SoyP levels, however manure DM declined slightly as SoyP increased (7.98, 8.00, 7.87%, respectively). As CaP levels increased, manure pH (6.54, 7.00, and 7.25, respectively), manure DM (7.42, 8.03, 8.40%, respectively) linearly increased and manure ammonium N linearly decreased (3492, 3310, 3293 ppm, respectively). The increasing levels of SoyP reduced manure phenol and manure total phenolic compounds by 27-28% on its own compared to the 0-0 control. The addition of SoyP also had linear numerical reductions in head space air phenol (13.2, 9.0, 6.0 ppm) and total phenolics (16.3, 11.2, 8.0 ppm). As CaP increased, all manure phenolic compounds linearly declined. Total manure phenolic compounds decreased by 30 and 59% as CaP increased to 12.5 and 25 mmoles. Increasing levels of CaP also linearly decreased head space air phenol and total phenolics by 10 and 41% as CaP increased to 12.5 and 25 mmoles. Neither SoyP or CaP had any effect on manure total VFA’s however, individual manure volatile fatty acids (VFA) were impacted by the inclusion of SoyP and CaP. Manure acetic acid increased slightly while butyric and isovaleric decreased slightly with increasing SoyP enzyme levels. While increasing levels of CaP increased manure acetic acid and decreased butyric acid. Increasing levels of CaP also decreased head space air total VFA’s by 60%. Careful evaluation of the data clearly shows that it is the combination of SoyP enzyme and CaP that clearly reduces the phenolic compounds. This is best displayed when you compare the 25 mmole level of CaP with no SoyP enzyme having a manure total phenolics level of 15.6 ppm and when any level of the SoyP is added to the 25 mmole level of CaP the total phenolics in the manure are reduced on average by 50% to 7.9 ppm. Also the greatest reduction (63%) in phenols and total phenolics (from 13.1 to 4.8 ppm) in manure column head space air occurred at the highest inclusion rate of SoyP (30 mg) in combination with the highest CaP (25 mmoles). This research proves that the soybean peroxidase enzyme can survive in swine manure up to 5 days. The use of soybean peroxidase in combination with a catalyst (calcium peroxide) may be a viable option to reduce both manure content and air emissions of phenolic compounds, but by its self soybean peroxidase only can reduce phenolic compounds by 27-28% compared to up to 63% with a catalyst. The increased losses of ammonium N with the increased manure pH as calcium peroxide was added to the manure is a potential negative result of this research. This research indicates there may be potential to evaluate either a spray application system that may be applied weekly or potentially even less frequently to help control phenolic compounds from swine manure storage systems. Additionally, potential research evaluating the feeding of soybean hulls (the source of the soybean peroxidase) high in the enzyme through the pig may have similar results if the enzyme can remain intact during the digestion process or sequester phenolic compounds in the gut of the pig. There appear to be many potential future research and applications to this technology that may help the swine industry meet its goal of being a good, responsible neighbor in their rural community.