Impact of Dietary Carbohydrate and Protein Source and Content on Swine Manure Foaming Properties

Abstract

Diet ingredients are thought to contribute to foaming problems associated with swine manure stored in deeppit systems. Two experiments explored the impact of protein and carbohydrate sources and levels in swine diets on the physicochemical properties, methane production potential, and foaming potential of swine manure. The first experiment was specific to protein and evaluated the impact of dietary protein level and source on manure properties, while the second experiment focused on evaluating the impact of different dietary carbohydrate sources on manure foaming properties. Manure from the animals was tested for total and volatile solids, methane production rate and biochemical methane potential, surface tension, foaming capacity and stability, and microbial community structure. No single diet yielded manure with all of the anticipated qualities associated with foaming manure. However, manure collected from pigs fed diets containing soy hulls and distillers dried grains with solubles (DDGS) exhibited higher methane production rates (0.95 ±0.20 and 0.96 ±0.20 L CH 4 kg -1 VS, respectively) and biochemical methane potential (322 ±25 and 269 ±22 mL CH 4 g -1 VS, respectively) when compared to manure obtained from pigs fed the other diets. Additionally, the results showed that both protein level and source exhibited greater influence over the microbial community than carbohydrate source, with manipulations in the protein diet leading to positive correlations with specific microbial community and higher methane production rates, foaming capacity, and foam stability. In this study, these parameters appeared to be tied to higher levels of corn, or corn protein, in the diet. Although some of the microbial community was explained by diet, this study also demonstrated that factors other than diet have significant influence on microbial community. RightsWorks produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted. Authors

Microbial assemblages and methanogenesis pathways impact methane production and foaming in manure deep-pit storages

“…Bray-Curtis dissimilarity revealed that the farm where the manure sample originated contributed to the largest variation in microbial community structures (R 2 = 0.48 for bacteria, R 2 = 0.83 for methanogens) (S3 Table ). This is consistent with the findings of previous studies where individual storage tank explained the manure microbiome the best, better than diet, suggesting that the unique microbiome of each manure storage tank is contributing to the manure condition [5,6]. Given the high variability among farms, we treated individual farms as experimental blocks and found that bacterial communities differed significantly, with the greatest variation (P = 0.001, R 2 = 0.12) among no-foam and foaming manures (Fig 3A).…”

“…However, the concentration of LCFA was significantly enriched in crust-forming manure, with 15 and 22 times more observed than no-foam and foaming manure, respectively. This is surprising as animals associated with the foaming manure were fed significantly more DDGS, which contains more lipids than other diet ingredients, such as SBM (Table 1) [6]. Dietary lipids are main sources of LCFA and it is natural to expect the amount of LCFA measured corresponds to the amount of lipids received.…”

“…In the Midwestern US, there has been an increase in the frequency of foaming events [3,4]. The inability to replicate this phenomenon in the laboratory makes ascertaining the cause of foaming a challenge [5,6]. Consequently, the only knowledge of its causes is mainly limited to its correlation with high (� 0.1 L methane / L manure • day) methane production rates (MPR), with little knowledge of its abiotic or biotic drivers.…”

Eubacterium coprostanoligenes and Methanoculleus identified as potential producers of metabolites that contribute to swine manure foaming

“…It has been hypothesized that three factors are necessary for manure foaming to occur (Davenport & Curtis, 2002;Van Weelden et al, 2015;Van Weelden, Andersen, Kerr, Trabue, Rosentrater, et al, 2016). These are (1) production of biogas; (2) the presence of surfactants that lower surface tension and allow for the capture and accumulation of gas inside bubbles; (3) hydrophobic solids that F I G U R E 5 (a) Mean relative abundance of functional groups assigned by FAPROTAX to OTUs in manure layers A, B, and C. Rare functions, defined as those making up fewer than 1% of reads, are listed as "Rare.…”

“…A study comparing the effects of different feed types on swine manure characteristics found that corn dried distiller grains with solubles (corn-DDGS), a by-product of corn ethanol production, resulted in greater manure foaming than more conventional diets consisting of cornsoybean meal or corn-soybean meal with soybean hulls (Van Weelden, Andersen, . It was hypothesized that use of corn-DDGS as swine feed resulted in the generation of more fine particles in manure that acted as stabilizers of the foam (Van Weelden, Andersen, Van Weelden, Andersen, Kerr, Trabue, Rosentrater, et al, 2016).…”