Swine diets impact manure characteristics and gas emissions: Part II protein source

Soybean meal is the dominate protein source for swine diets in the world driven largely by economics, nutritive value, and availability; but conditions can change requiring growers to consider more economical and available protein alternatives. A feeding trial was conducted to determine the impact dietary protein source material on manure slurry chemical properties and manure gas emissions. A total of 32 gilts averaging 130 kg BW were fed either a control diet formulated with soybean meal (SB) or an alternative protein source that included corn gluten meal (CG); canola meal (CM); or poultry meal (PM), with all diets containing 176 g protein kg^-1. Diets were fed for 45 d with an average daily feed intake of 2.68 kg/d. Feces and urine were collected twice daily after each feeding and added to animal-specific manure storage containers. At the end of the study, manure slurries were monitored for gas emissions and chemical properties. Dietary protein source had a significant effect (P < 0.05) on manure pH, total solids, total C, protein N, and total S. Pigs fed the diets containing CM had significantly higher levels of sulfide, butanoic acid, and branch chain fatty acids compared to pigs fed SB diets (P < 0.05). Pigs fed CM diets had significantly lower emissions of NH₃ compared to pigs fed SB diets (P < 0.05). There were no significant differences in C or S emissions or in odorant emission as affected by source of dietary protein. Hydrogen sulfide was the most dominate odorants for all dietary treatments.