Summary

A new housing system for grower-finisher pigs that incorporates a belt conveyor (BC) system to separate feces from the urine at the pen level was developed. Comparative tests showed that the performance and well-being of the animals were not adversely affected by the use of the BC pen design. The system was effective in isolating most of the phosphorus in a low mass solid phase. The overall trends in gas emission rates showed that the BC pen design concept can help reduce the emission rate of carbon dioxide. No significant impact was observed for ammonia and odour emissions.

Introduction

Environmental concerns from handling large volumes of manure from livestock operations have led to exploration of new and innovative strategies to be able to manage manure in an economical and environment-friendly manner. In this research project, a new pen design concept for swine barns in which the slatted portion of the pen was replaced with a tilted belt conveyor (BC) to separate the feces and urine at the pen level was investigated. This project was implemented in two phases: Phase 1 conducted at the IRDA facilities in Québec involved the development of the BC pen design concept and assessment of efficiency of separation of the solid and liquid components. The main goal of Phase 2 trials conducted at PSCI was to compare the odour and gaseous emissions from a chamber with the BC system (Figure 1) with those from another chamber with a conventional (slats and underfloor gutter) manure handling system.

Results and Discussion

Results of four trials conducted at IRDA showed that the BC system has been very effective in isolating most of the phosphorus in a low mass solid phase; 76 to 81% of the phosphorus excreted by the pigs in the BC room was isolated within the solid phase of excreta. Results also showed that 39 to 48% of total nitrogen in the urine while feces contained almost the same nitrogen concentration (40 to 45% of total nitrogen). The total ammonia nitrogen (TAN) content of the urine ranged from 75 to 79%, which was the level expected because TAN originates mainly from urea degradation produced in urine. From a phosphorus management perspective, the new pen design concept thus showed the potential to isolate approximately 80% of the phosphorus in a solid phase representing 20% of the total manure mass.

Pigs housed in the pen equipped with the BC system were more frequently observed lying down in the resting area than pigs housed in the conventional (control) pen. They also tended to use the dunging zone less frequently for lying than pigs in the control pen, suggesting that the BC system may possibly promote pen cleanliness. The frequency of feeding and drinking episodes was unaffected by the BC system, which is in agreement with the feed intake and feed conversion data.

The overall trends in gas concentration levels (e.g., ammonia (NH3) and carbon dioxide (CO2)) observed in trials conducted at PSCI and IRDA indicated that the BC pen design contributed to the reduction in the levels of these gases. The odour concentration values for samples taken from the conventional and BC rooms were highly variable, thus statistical comparison of the odour values from the two chambers showed no significant difference (p>0.05). In terms of gas emissions, the BC pen design concept can help reduce the emission rate of specific gases (e.g., CO2) compared to the conventional room (Table 1). No significant impact of the system was observed for emissions of other gases (e.g., NH3) and odour.

Conclusions

1. The BC pen design concept proved effective in separating the urine and solid manure components on a continuous basis, thereby allowing more effective management and handling of the nutrients (particularly phosphorus and nitrogen) in the separated components.
2. The performance and well-being of the animals were not adversely affected by the use of the BC pen design.
3. The overall trends in gas (ammonia and carbon dioxide) concentration levels observed indicated that the BC pen design contributed to the reduction in the levels of these gases.
4. The odour concentration values for the samples taken from the conventional and BC rooms were highly variable, thus statistical comparison of the odour values from the two chambers showed no significant difference.
5. The overall trends in gas emission rates showed that the BC pen design concept can help reduce the emission rate of carbon dioxide compared to the conventional room design. However, the BC system had no significant impact on ammonia and odour emissions. Further work to better assess the technology can be made with enhanced control of inlet air contaminant levels and improved techniques for measuring odour.

The experiments with the BC pen design concept also revealed potential areas for further work to optimize the system and to realize significant benefits from the use of such a system in addition to those already identified. By separating the manure into two streams, the BC system can help mitigate the hazard from H2S exposure in swine barns. An optimized BC pen design can be potentially incorporated into a deep-pit barn construction with separate in-barn long-term storage for the separated components, without the typical hazards from high H2S levels associated with conventional deep-pit barns.

Acknowledgement

Strategic funding provided by Sask Pork, Alberta Pork, Manitoba Pork Council and Saskatchewan Agriculture and Food. Project funding provided by Cement Association of Canada and Institut de Recherche et de Développement en Agroenvironnement. Technical assistance provided by Garth MacDonald, Scott Cortus, Robert Fengler, and Erin Cortus is acknowledged.