Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/5/2007
Publication Date: 7/17/2007
Citation: Roberts, S.A., Xin, H., Kerr, B.J., Russell, J.R., Bregendahl, K. 2007. Effects of dietary fiber and low crude protein on ammonia emission from laying-hen manure. Poultry Science. 86:1625-1632. Interpretive Summary: Ammonia is a major aerial pollutant lost from livestock operations with domestic animals the largest global contributor of atmospheric ammonia emissions, and poultry (including laying hens) being the largest contributor amongst domestic animal species in the United States. Not only can ammonia adversely affect bird health and production by contributing to deciliation of the trachea, impairment of macrophage function, reduced lung function, reduced egg production, and lower body weight gains, it may also cause water eutrophication and nuisance odor generation. Maintaining air ammonia concentrations below maximum allowable amounts is difficult in high-rise laying-hen houses, especially during winter when ventilation is decreased and ammonia concentrations may rise above 100 ppm. In order to comply with government and industry group regulations, minimize health risks, and maximize egg-production potential, egg producers either need to decrease hen numbers at each production site or develop methods to lower ammonia emission with current hen populations. Adjusting diet composition may decrease the amount of ammonia that is lost from laying-hen facilities. Inclusion of feed ingredients with high concentrations of fiber have been shown to lower ammonia emission from pigs, and feeding low-crude protein diets have also been shown to decrease nitrogen excretion and ammonia emission from pigs, broilers, and laying hens. We hypothesized that lowering dietary crude protein content and including high-fiber feed ingredients would lower ammonia emission from laying hen manure, and that these effects would be additive. Data from this experiment indicated that supplementing the diet with 10% dietary corn dried distiller grains with solubles (DDGS), 7.3% wheat middlings (WM), or 4.8% soybean hulls (SH) lowered the 7-d cumulative manure ammonia emission from 3.9 g/kg DM manure for the control to 1.9, 2.1, and 2.3 g/kg DM manure in birds fed diets with DDGS, WM, or SH, respectively. In contrast to other reported research, this study did not show that reducing the dietary crude protein by one percentage unit had any measurable effect on ammonia emission. Research results described in this report provides scientists at universities, feed companies, allied industries, and laying hen-egg production facilities data showing that feeding diets containing moderate levels of dietary fiber can dramatically reduce ammonia emission rates.
Technical Abstract: Ammonia emission is a major concern for the poultry industry. The objectives of this research were to determine if inclusion of dietary fiber and a lowered dietary crude protein content would decrease ammonia emission from laying-hen manure. A total of 256 Hy-Line W-36 hens were fed diets with 2 contents of crude protein (normal and low) and 4 fiber treatments in a 2 x 4 factorial arrangement. The fiber treatments included a corn and soybean meal-based control diet and diets formulated with either 10.0% corn distiller’s dried grains with solubles (DDGS), 7.3% wheat middlings (WM), or 4.8% soybean hulls (SH) added to contribute equal amounts of neutral-detergent fiber. The crude protein contents of the low-crude protein diets were approximately 1 percentage unit lower than the normal-crude protein diets. All diets were formulated on a digestible amino acid basis and were isoenergetic. Fresh manure was collected after 22 wk and the pH, uric acid, and Kjeldahl N contents were measured. The ammonia emission from the manure was measured over 7 d by placing pooled 24-h manure samples in ammonia-emission vessels. Data were analyzed by analysis of variance; contrasts were used to compare results from the fiber treatments to the control, whereas the main effect of crude protein was used to compare the normal- and low-crude protein treatments. Dietary corn DDGS, WM, or SH lowered (P ' 0.01) the 7-d cumulative manure ammonia emission from 3.9 g/kg DM manure for the control to 1.9, 2.1, and 2.3 g/kg DM manure, respectively, and lowered (P < 0.05) daily ammonia emission rate. Results of this study show that dietary inclusion of 10.0% corn DDGS, 7.3% WM, or 4.8% SH lowers ammonia emission from laying-hen manure; however, the 1 percentage unit lower crude protein had no measurable effect on ammonia emission.