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Three experiments were conducted by using a total of 336 crossbred barrows and gilts. In each experiment, 2 dietary treatments (0 and 0.05% direct-fed microbial (DFM)) were fed during the growing-finishing period throughout the experiment. Additionally a commercial trial was conducted in a commercial swine production facility. Average BW and feed disappearance were determined for each pen at start at the end of the starter, grower, and finisher phases in order to calculate ADG, ADFI, and G:F whereas death loss percentage were monitored at each site. The time required to clean each pen was determined by time required to scrape the manure buildup from the pen floor surface and to wash with a higher-pressure washer. A couple of solid manure samples (approximately 4 g each) were collected from solid manure buildup in each pen (16 pens/treatment), and the time required to completely disperse each manure sample was determined.
Higher G:F was observed in pigs fed the diets containing Bacillus than those fed the control diet during the finisher phase and in the overall growing-finishing period (P<0.05). Manure samples obtained from pens housing pigs fed Bacillus dispersed faster than those obtained from pens fed the control diet (P<0.01), representing a reduction of 33% in the time required to dissolve the manure from those animals fed the Bacillus supplementation. The quicker dispersal time of the manure mat from Bacillus-treated pens was supported by numerically less total time required to clean (scrape and wash) pens housing Bacillus-supplemented pigs. Furthermore, when evaluated in a commercial swine production facility, the Bacillus-based DFM improved ADG in a 7,6% and reduced mortality of pigs during the growing-finishing period in a 40%.
It is concluded that feed supplementation with a specifically selected Bacillus strains improves feed efficiency, decreases the death loss percentage and reduces the time required to disperse swine manure.
ME Davis, T Parrott, DC Brown, BZ de Rodas, ZB Johnson, CV Maxwell and T Rehberger. Journal of Animal Science, 2008, 86: 1459-1467.
