The climate of Manitoba, as well as the cost of these systems, has prevented the widespread use of aeration as a means of controlling storage odours. Aeration and other alternate methods of treatment and utilization are discussed in greater detail in Appendix D . For a long time, producers have been offered a broad selection of chemical or biological products to reduce emission or mask unpleasant odours. Evaluations of the efficacy of manure and feed additives is currently underway in many research centers. When effective, manure additives tend to have a short term effect.
Cost is often prohibitive for many of the additives.
The addition of relatively low amounts of enzymes or bacteria mixtures in gutters or directly into outdoors manure storage structures is unlikely to influence the naturally occurring microbial flora developing under our relatively cold climate. However, the latter effect often disappears when anaerobic decomposition of manure begins in the gutter or in the storage. Nevertheless, the improvement of feed digestibility, along with potentially lower odour levels in the swine housing may impart an economic viability to some of these products. Prior to being commercially available, feed additives must be registered under The Federal Feeds Act and Regulations. To date, results from many research centers in United States and Canada report very disappointing results with manure additives.