Submitted to: Journal of Animal Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/11/2006
Publication Date: 6/1/2006
Citation: Kerr, B.J., Ziemer, C.J., Trabue, S.L., Crouse, J.D., Parkin, T.B. 2006. Manure composition of swine as affected by dietary protein and cellulose concentration. Journal of Animal Science. 84:1584-1592. Interpretive Summary: Animal manure is an excellent resource for amending soil through its ability to supply carbon and nitrogen, both components of soil organic matter. However, storing manure and land application can result in the release of carbon and nitrogen into the air environment resulting in less of these nutrients being applied to the soil. The objective of this study was to investigate the effects of feeding pigs diets containing different levels of crude protein and cellulose on subsequent nutrients (carbon, nitrogen, and sulfur) and malodorous chemicals (namely volatile fatty acids, indoles, and phenols) in manure. Experimentation utilized finishing pigs, 105 kg initial body weight, fed diets containing either 14.5% or 12.0% crude protein in combination with either 2.5% or 8.65% cellulose. Over the 56 day trial, urine and feces were collected and added to manure storage containers designed with similar surface area per animal as deep pit manure storage in finishing barns. Decreasing dietary crude protein reduced manure pH, NH4, isovaleric acid, phenol, and 4-ethyl phenol concentration. Increasing dietary cellulose decreased pH and NH4 concentration, but increased acetic acid, propionic acid, butyric acid, and cresol concentrations in the manure. Increasing dietary cellulose also increased manure carbon concentration and increased manure dry matter. The data can be utilized by manure action plan personnel and agronomists indicating that changes in levels of dietary crude protein and cellulose fed to finishing pigs can impact the concentration of malodorous compounds in stored swine manure which may have both positive and negative impact on odor emissions. In addition, this study demonstrates that these diets will significantly impact manure nutrient composition which will affect nutrients applied to the soil and ultimately available to crops for utilization.
Technical Abstract: An experiment was conducted to investigate the effects of reducing dietary CP and increasing dietary cellulose concentrations on manure DM, C, N, S, VFA, indole, and phenol concentrations. Twenty two pigs, 105 kg initial BW, were fed diets averaging 14.5% or 12.0% CP in combination with diets averaging 2.5% or 8.7% cellulose. Pigs were fed twice daily over the 56 d trial, with feed intake totaling 2.74 kg/d. Feces and urine were collected after each feeding and added to manure storage containers. Manure storage containers were designed to provide similar unit area per animal as found in industry (7393 cm2). Prior to sampling on d-56, manure was gently stirred to obtain a representative sample for subsequent analyses. Decreasing dietary CP reduced manure pH (P = 0.01), NH4 (P = 0.01), isovaleric acid (P = 0.06), phenol (P = 0.05), and 4-ethyl phenol (P = 0.02) concentration. Increasing dietary cellulose decreased pH (P = 0.01) and NH4 (P = 0.06) concentration, but increased manure C (P = 0.03), acetic acid (P = 0.03), propionic acid (P = 0.01), butyric acid (P = 0.03), and cresol (P = 0.09) concentrations in the manure. Increasing dietary cellulose also increased manure DM (P = 0.11), N (P = 0.11), and C (P = 0.02) content as a percent of nutrient intake. Neither cellulose or CP level of the diet impacted manure S composition or output as a percent of S intake. Headspace N2O concentration was increased by decreasing dietary CP (P = 0.03) or by increasing dietary cellulose (P = 0.05). Neither dietary CP nor cellulose affected headspace concentrations of CH4. This study demonstrates that diets differing in CP and cellulose content can significantly impact manure composition and concentrations of VFA, phenol, and indole concentrations, and headspace concentrations of N2O, which may in-turn, affect the environmental impact of livestock production on soil, air, and water.