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ARS Home » Plains Area » Bushland, Texas » Conservation and Production Research Laboratory » Livestock Nutrient Management Research » Research » Publications at this Location » Publication #245932
Title: Influence of feedlot pen surface layers and distillers' grain diets on microbial community structure associated with beef cattle feedlots

Author
item Rice, William
item Cole, Noel
item Clark, Ray

Submitted to: Manure Management Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 8/30/2009
Publication Date: 9/28/2009
Citation: Rice, W.C., Cole, N.A., Clark, R.N. 2009. Influence of feedlot pen surface layers and distillers' grain diets on microbial community structure associated with beef cattle feedlots. Proceedings of the Texas Animal Manure Management Issues Conference, September 28-30, 2009, Round Rock, Texas. p.155-165.

Interpretive Summary: Cattle feedlots on the Southern High Plains annually produce approximately 7 million beef cattle accounting for 30% of the total U.S. fed beef cattle production. The high density of beef cattle results in concentration of nutrients (carbon-C, nitrogen-N, and phosphorus-P) in manure wastes and may create an environment favorable for the survival and persistence of fecal pathogens. Little is known about feedlot pen surface chemistry and biology, especially the underlying microbial community composition. The feedlot pen surface profile is comprised of four layers: an unconsolidated top layer, dry-pack, wet-pack, and underlying soil layer. The influences of these feedlot pen surface layers on microbial community composition were determined. In this study, we provide a description of a complex microbial ecosystem that is clearly influenced by the distinct physical and chemical characteristics of the various feedlot pen surface layers. This in turn has lead to the established microbial communities which both influence and reinforce some of the observed physical and chemical changes. The agroecosystem described here is markedly different from a cow manure-pasture ecosystem and has important implications for the cycling of N in the environment. Feedlot pen surface soil is 90% dissimilar from surrounding homologous soil. Feeding Distiller's Grain (DG) diets appeared to have a complex effect on fecal microbiota. Feeding corn and sorghum DG had a significant impact of the fecal microbial community structure. Thus, changes in beef cattle diets will affect the microbial community composition in the beef cattle feedlot pen surface environment.

Technical Abstract: Cattle feedlots on the Southern High Plains annually produce approximately 7 million beef cattle accounting for 30% of the total U.S. fed beef cattle production. The high density of beef cattle results in concentration of nutrients (C, N, and P) in manure wastes and may create an environment favorable for the survival and persistence of fecal pathogens. Little is known about feedlot pen surface chemistry and biology, especially the underlying microbial community composition. The feedlot pen surface profile is comprised of four layers: an unconsolidated top layer, dry-pack, wet-pack, and underlying soil layer. The influences of these feedlot pen surface layers on microbial community composition were determined. Feedlot layers significantly affected bacterial and fungal community composition. Lineages of ammonia- and nitrite- oxidizing bacteria were distributed differently within the feedlot layers. The fungal community was significantly reduced in the wet-pack layer, compared with other layers. Escherichia coli O157:H7 was primarily confined to the unconsolidated and dry-pack feedlot pen surface layers and was not observed within the wet-pack layer. Microbial community composition of the unconsolidated layer (here fresh feces and urine deposition occurs) may also be affected by diets. Feeding DG based diets resulted in significant shifts of the fecal microbial community structure compared to traditional steam flaked corn (SFC) diet. This effect was revealed in ordination plots of community structure based on principal components analysis of DDGE-PCR assays and supported by group separation scores using dietary treatments as group factors. Fecal microbial populations varied across all diets with an overall similarity range of 39% to 83%. The long-term consequence of beef cattle dietary shifts on the beef cattle concentrated animal feeding operation (CAFO) microbial community composition remains unknown.