Browsing by Subject "Continuous culture"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Effects of bismuth subsalicylate and beta extract of hops (Humulus lupulus) on in vitro fermentation with ruminal microbes
    (2013-08) Fessenden, Samuel William
    Symbiosis between microbes and ruminants gives the animal a unique ability to digest fiber and transform it into meat, milk, power and other useful products. Manipulation of rumen ecology with selective antimicrobial compounds can have beneficial effects by altering microbial output, allowing the animal to achieve greater levels of production per unit of input. Two experiments were conducted to determine effects of antimicrobial compounds on in vitro fermentation with ruminal microbes in continuous culture. Inclusion of bismuth subsalicylate decreased (P < 0.05) organic matter digestion, volatile fatty acid production and had negative influences on nitrogen and fatty acid metabolism. Results indicate that bismuth subsalicylate at 0.5% of diet dry matter was detrimental to overall fermentation with rumen microbes, and lower dosage levels should be investigated. In experiment 2, beta extract from the hop plant (Humulus lupulus) was administered to continuous culture fermenters at 0, 600, 1200 or 1800 mg of beta acids / kg of dry matter. Inclusion of beta extract did not affect (P > 0.05) ingredient digestion, volatile fatty acid production or nitrogen metabolism. Beta extract tended (P = 0.09) to increase culture pH, however effects were modest and lower than biologically relevant values. Further research investigating the adaptation of microbial populations to hop beta extract was recommended.
  • Thumbnail Image
    Item
    Effects of dietary roughage and sulfur in diets containing corn dried distillers grains with solubles on hydrogen sulfide production and rumen fermentation by rumen microbes in continuous and batch culture
    (2014-04) Binversie, Elizabeth Y.
    Dried distillers grains with solubles (DDGS) is an inexpensive feed alternative to corn. Previously, over-inclusion of DDGS has produced toxic concentrations of ruminal hydrogen sulfide (H2S) gas, resulting in polioencephalomalacia (PEM), a degenerative brain disease. Production of ruminal H2S requires an acidic environment conducive to converting free sulfur to H2S in the rumen. Therefore, it was hypothesized that creating a less acidic rumen environment would help mitigate ruminal H2S production. Two experiments were conducted to determine the effects of dietary roughage and sulfur on in vitro fermentation with ruminal microbes in continuous culture and batch culture. Six dietary treatments were formulated that paired 3 concentrations of sulfur (0.3, 0.4 and 0.5% of diet DM) with 2 concentrations of roughage (3 and 9% of diet DM) and are as follows: low roughage low sulfur (LRLS), low roughage moderate sulfur (LRMS), low roughage high sulfur (LRHS), moderate roughage low sulfur (MRLS), moderate roughage moderate sulfur (MRMS) and moderate roughage high sulfur (MRHS). A diet comprised of 0% DDGS was used as the control (CON) diet. Roughage had no effect on H2S production but it did increase fermenter pH, creating a less acidic environment. In experiment 2, an increase in dietary sulfur caused an increase in total H2S production, but there was no direct effect of roughage on total H2S production. Higher dietary roughage created a less acidic pH but at the expense of in vitro fermentation, because of the lower total VFA concentration. Further investigation is needed to determine more effective methods of mitigating H2S production using dietary manipulation, such as higher inclusion of dietary roughage or use of different roughage sources.
  • Thumbnail Image
    Item
    Nutrient digestion and nitrogen metabolism of dried fermentation biomass and various fractions of rumen microbes.
    (2012-08) Carpenter, Abigail Joy
    An experiment was performed to investigate if fermentation biomass (FB), a dried bacterial co-product derived from lysine production (Ajinomoto Heartland, Inc.) can be used as a protein source in ruminant diets. Eight dual-flow continuous culture fermenters were inoculated with rumen fluid and used during one experimental period consisting of a 7-d adaptation period followed by 3 sampling days. Substrate for the microbes was provided by one of two isonitrogenous diets, CON or DFB. In CON, soybean meal (SBM) provided 57% of total CP, and in DFB, SBM and FB provided 12 and 45% of total CP, respectively. CON contained 3% molasses, 16% ground corn, 13% grass hay, 48% corn silage, and 20% SBM on a DM basis. DFB contained 3% molasses, 18.4% ground corn, 13% grass hay, 50% corn silage, 8.5% SBM, and 6.7% FB. Fermenters were supplied with 75 g/d of DM divided into 8 equal portions. Anaerobic conditions were maintained by infusion of N2; pH was maintained between 5.8 and 6.8; and temperature was set at 39C. On sampling days, liquid and solid effluent were collected, combined, and homogenized to be used for chemical analysis and in vitro estimation of intestinal digestibility (ID). Treatment did not affect (P > 0.1) average, maximum, or minimum fermenter pH. There was no effect (P > 0.1) on apparent or true OM, NDF, or ADF digestibility (%) or total VFA (mM), although branched-chain VFA (mM) was higher (P = 0.01) in CON because isobutyrate (mol/100 mol) tended (P = 0.06) to increase with CON treatment. Source of N had no effect (P > 0.1) on total, dietary, or bacterial-N flows. Addition of FB decreased (P < 0.05) NH3-N flow from 0.4 to 0.2 g/d and tended to decrease (P =0.06) effluent NH3-N concentration from 17.1 to 9.7 mg/100 mL. His and Met flows increased (P < 0.05) from 0.48 to 0.53 and 0.18 to 0.20 g/d, respectively, when FB partially replaced SBM in the diet, but there were no effects (P > 0.1) on other AA or total AA flows. There was a trend (P = 0.08) in percent non-essential AA input (CON = 73.6% vs. DFB = 82.2%) in effluent; however, there was no effect (P > 0.1) on percent of essential AA or total AA input in effluent. Effluent from the DFB treatment was higher (P < 0.05) in ID than CON (CON = 70.4% vs. DFB = 79.6%). These results indicate that FB elicited a similar response in N metabolism and AA flows to SBM but had a higher estimated digestibility in the intestine, and has potential use as a protein source in ruminant diets. In a second experiment, rumen fluid was collected from 4 steers fed the same diet, and 3 populations of rumen microorganisms (liquid-associated bacteria (LAB), solid-associated bacteria (SAB), and liquid-associated protozoa (LAP)) were isolated by differential centrifugation. Intestinal digestibility of N (ID) was determined using the in vitro (pepsin and pancreatin) steps of the 3-step procedure of Calsamiglia and Stern (1995). Total-N content of each fraction was different (P < 0.05) with LAB having the highest N content (8.1 vs. 6.1 vs. 5.6% of DM for LAB, SAB, and LAP, respectively). Purine concentration was greatest (P < 0.05) in LAB compared with SAB and LAP (3.1 vs. 1.0 vs. 0.9 mg/g bacterial DM, respectively). Similarly, LAB had a higher (P < 0.05) purine:N ratio compared with SAB and LAP (37.4 vs. 12.3 vs. 11.1 mg/g of bacterial N, respectively). Total amino acids (AA) (wt/wt) varied (P < 0.05) with each treatment (35.9 vs. 29.8 vs. 27.72% for LAB, SAB, and LAP, respectively). Most individual AA (g/100 g of total AA and wt/wt) exhibited differences (P < 0.05) between the 3 populations. Essential AA content (g/100 g of total AA) was highest (P < 0.05) in LAB and lowest in LAP (47.15 vs. 46.02, respectively). Non-essential AA content was greatest (P < 0.05) in LAP followed by SAB and LAB (53.3 vs. 52.3 vs. 51.8 g/100 g total AA, respectively). LAB was highest (P < 0.05) in ID followed by LAP and SAB (71.2% vs. 68.2% vs. 57.5% for LAB, LAP, and SAB, respectively). These results demonstrate that microbial fractions have differing digestibilities in the small intestine and suggest that ID of mixed rumen microbes can be influenced by the relative amount of each microbial population.