Biomedical subjects

D L Harmon

Publications and source records attributed to D L Harmon.

103 records · Page 6Linked to original sources

PubMed1987

Effect of wheat and high-moisture sorghum grain fed singly and in combination on ruminal fermentation, solid and liquid flow, site and extent of digestion and feeding performance of cattle.

Two experiments were conducted to determine how varying the proportion of wheat (W) and high-moisture sorghum grain (SG) in 80% grain dies would affect ruminal fermentation, liquid and solid flow, site and extent of digestion (Exp. 1) and feeding performance of cattle (Exp. 2). In Exp. 1, three ruminal, duodenal and ileal cannulated steers (average weight 295 kg), fed at 1.54% of body weight, were used in a six-period crossover design. Treatments were: W, 50W:50SG (W:SG) and SG. Increasing wheat level decreased ruminal pH, molar proportion of acetate, and acetate:propionate ratio (P less than .05) and increased (P less than .05) L-lactate concentration, molar proportions of propionate and valerate and total volatile fatty acid concentration. Ruminal liquid dilution and outflow rates were faster (P less than .05) and retention time was shorter (P less than .05) for the W diet. Duodenal and ileal liquid flow increased (P less than .05), and solid flow decreased (P less than .05), as dietary level of wheat increased. Apparent ruminal digestion (% of intake) of dry matter (DM) and organic matter (OM) was greater (P less than .01) with the wheat-containing diets. Intestinal DM and OM digestion (percent of intake) was higher (P less than .05) with the SG and W:SG diets. Ruminal, small intestine, large intestine and total tract starch digestion (percent of intake) was 93.5, 5.6, .7, 99.8, 71.5, 20.4, 5.7, 97.6; and 48.0, 32.5, 10.5, 91.0 with the W, W:SG and SG diets, respectively. In Exp. 2, group-fed (24 pens) steers (avg initial weight 341 kg) were fed ad libitum once daily for 121 d. Treatments were: W, 67W:33SG, 33W:67SG and SG. Rates of gain (kg/d) with the W (1.32), 67W:37SG (1.33) and 33W:67SG (1.30) diets were similar (P greater than .05), but faster (P less than .05) than those with the SG diet (1.16). Feed intake was lower (P less than .01) with the W and 67W:33SG diets, but the wheat-containing diets were utilized more efficiently (P less than .01). Increasing the proportion of wheat in sorghum grain feedlot diets improved cattle performance by optimizing ruminal and post-ruminal digestion.

Animal Feed↗

PubMed1987

Influence of decoquinate on ruminal fermentation, diet digestibility and cattle performance.

Three experiments utilizing three Holstein steers (235 and 299 kg avg body weight for Exp. 1 and 2, respectively) were conducted to evaluate the effects of decoquinate, a synthetic coccidiostat, on ruminal fermentation, diet digestibility and performance of steers fed a finishing diet containing monensin and tylosin. Experiment 1 utilized a 70% forage diet, whereas Exp. 2 utilized a 20% forage diet. Each experiment was a 3 X 3 Latin-square design with treatments being 0, .5 and 5 mg decoquinate/kg body weight. Ruminal fermentation characteristics, water kinetics and blood constituents were measured on d 11 of each period, and zero-time volatile fatty acid (VFA) production was measured at 3 and 6 h post-feeding on d 12 to 14. No changes were seen in plasma glucose or L-lactate, ruminal pH, NH3-N or ruminal L-lactate for either experiment. Dry matter digestibility was depressed (P less than .05) at the .5- and 5-mg levels of decoquinate in Exp. 1, but dry matter digestibility was not affected in Exp. 2. No changes were seen in ruminal volume, outflow or total VFA concentration for either experiment. Molar proportions of VFA were not affected in Exp. 1, but the proportions of isobutyrate and butyrate decreased (P less than .05) at the 5-mg level of decoquinate in Exp. 2. Volatile fatty acid production was not changed in Exp. 1, but butyrate production was decreased (P less than .05) at the 5-mg level in Exp. 2. Experiment 3 involved 135 crossbred steers (259 kg avg initial wt), which were stratified by weight into 12 pens.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1987

In vitro lactic acid inhibition and alterations in volatile fatty acid production by antimicrobial feed additives.

Batch culture fermentations were used to determine the effects of avoparcin, lasalocid, monensin, narasin, salinomycin, thiopeptin, tylosin, virginiamycin, monensin + tylosin combination, and two new ionophore compounds (RO22-6924/004 and RO21-6447/009) on lactic acid and volatile fatty acid (VFA) production. Ruminal fluid from cattle fed a high alfalfa hay diet was incubated with glucose for 12 h in a buffered medium to determine the effect of antimicrobial compounds on lactic acid concentration. Fermentations treated with antimicrobial compounds had higher final pH and lower L(+) lactic acid concentration. Narasin and salinomycin were more inhibitory than other ionophore compounds. Monensin and tylosin in combination was more effective than monensin alone. Among the nonionophore compounds, avoparcin was the least effective and thiopeptin, tylosin and virginiamycin were extremely effective in reducing lactic acid concentration. Ruminal fluid from cattle fed a diet of alfalfa hay and grain (50:50) was incubated with a mixture of sugars, casein and urea for 12 h in a buffered medium to determine the effect of antimicrobial compounds on VFA production. Generally, total VFA concentration was not affected by antimicrobial compounds except RO22-6924/004, tylosin and virginiamycin, which caused a reduction at high concentrations. Tylosin, monensin and tylosin mixture, thiopeptin and virginiamycin at high concentrations (greater than 6.0 micrograms/ml) increased the acetate proportion. All compounds increased the molar proportion of propionate. Tylosin and virginiamycin at high concentrations (greater than 6.0 micrograms/ml) decreased the proportion of propionate. Monensin and tylosin in combination had no effect on propionate proportion. Among the compounds tested, narasin and salinomycin were the most effective in enhancing propionate proportion. Ionophore compounds were more inhibitory to butyrate production than the nonionophore compounds. Batch culture fermentations may be used to quantitate the relative efficacy of antimicrobial compounds to alter ruminal fermentation characteristics.

Animals↗

PubMed1987

Induced non-enzymatic browning of soybean meal. II. Ruminal escape and net portal absorption of soybean protein treated with xylose.

Non-enzymatic browning was tested as a means of increasing ruminal escape of soybean meal N. Soybean meal was treated with xylose (3 mol/mol SBM-lysine), sodium hydroxide (pH 8.5) and enough water to achieve an 83% dry matter mixture and then heated at 150 C for 30 min (XTS-30). Trial 1 evaluated ruminal escape of N from XTS-30 compared with commercial soybean meal (CS) or urea (U) in a replicated 3 X 3 Latin square design using six duodenally cannulated Angus X Hereford steers (24.7 kg). Duodenal flow of dietary N was higher (P less than for steers fed XTS-30 (47.9 g/d) than for steers fed CS (39.5 g/d). The ruminal escape estimate for XTS-30 (33.7%) was higher (P less than .10) than CS (13.1%), whereas total tract apparent N digestibility was not different among treatments. In trial 2, net portal absorption of alpha-amino N was measured in Finnsheep X Suffolk ram lambs (24.7 kg) fed U, CS or XTS-30 in a 3 X 3 Latin square design. Portal blood flow was measured by primed, continuous infusion of para-aminohippuric acid. Portal blood flow was lower (P less than .05) for U.fed lambs than for lambs fed CS or XTS-30, and tended to be lower for lambs fed CS than those fed XTS-30. Net portal absorption of alpha-amino N tended to be lowest for lambs fed U (281 mmol/d) and highest for lambs fed XTS-30 (578 mmol/d). The results are interpreted to show that non-enzymatic browning increased flow of soybean meal N to the intestine.

Animal Feed↗

PubMed1987

Effects of dietary monensin and sodium propionate on net nutrient flux in steers fed a high-concentrate diet.

Four Holstein steers (mean body weight, 211 +/- 20 kg) were utilized in a Latin-square design with a 2 X 2 factorial arrangement of treatments to investigate the effects of monensin (0 or 220 mg/d) and sodium propionate (0 or 450 g/d) on net nutrient flux. Steers were surgically prepared with hepatic portal and mesenteric venous catheters and an elevated carotid artery, after which they were adjusted to their basal diet (85% concentrate) and initial treatment over 19 d. Samples of arterial and portal venous blood were taken hourly over 3 h for the final 3 d of each 2-wk period. Portal blood flow was determined by primed continuous infusion of para-aminohippurate. No changes were seen in dry matter intake, portal blood flow, or net portal flux of any of the volatile fatty acids with the exception of butyrate flux, which decreased with monensin addition. Addition of monensin decreased net portal flux of ammonia, decreased recycling of urea, and tended to increase the net portal flux of glucose. Addition of sodium propionate increased the net portal flux of glucose and decreased the net portal flux of alpha-amino-N. These results are interpreted to suggest that changes in the products of ruminal fermentation may not be exactly translated into the products appearing in the portal circulation, and more information is needed to describe these relationships.

Animal Nutritional Physiological Phenomena↗

PubMed1986

Influence of dietary energy intake and substrate addition on the in vitro metabolism of glucose and glutamine in rumen epithelial tissue.

Ten Holstein steers were fed either 14.2 or 26.2 Mcal ME for 28 days prior to investigating the effect of dietary energy on epithelial metabolism. Rumen papillae were incubated in vitro with glucose (5 mM) or glutamine (1 mM) as well as additional energy substrates. Increased dietary intake increased production of 14CO2 from glucose and glutamine, increased uptake and net lactate production from glucose, and decreased net glutamate and alanine production from glutamine. At these substrate concentrations, rates of glucose oxidation to 14CO2 were sevenfold higher than glutamine.

Animals↗

PubMed1986

Effect of sodium bicarbonate and sodium bentonite on digestion, solid and liquid flow, and ruminal fermentation characteristics of forage sorghum silage-based diets fed to steers.

Six ruminally cannulated steers, five Holsteins and one Hereford (250 to 295 kg), were fed 84% forage sorghum silage plus 16% supplement or 50% forage sorghum silage plus concentrate and supplement diets containing either no addition (controls), 1% sodium bicarbonate (NaHCO3) or 2% sodium bentonite in a 2 X 3 factorial arrangement of treatments in a 6 X 6 Latin-square experiment with 3-wk periods. Sodium bicarbonate increased dry matter (DM) intake when concentrate was included, but neither compound affected intake of the 84% silage diet. Bentonite lowered DM, neutral detergent fiber (NDF), and acid detergent fiber (ADF) digestibilities, but NDF disappearance from nylon bags was unchanged. Ruminal pH, osmolality and L(+) and D(-) lactate were not affected by treatment. Both NaHCO3 and bentonite tended to lower ruminal NH3-N concentrations. Bentonite lowered the molar proportion of isobutyrate in ruminal fluid relative to controls, but proportions of other volatile fatty acids (VFA) and total VFA concentrations were unchanged. Neither NaHCO3 nor bentonite affected ruminal liquid or solid volumes, dilution rate constants or ruminal outflow rates. Markers overestimated volumes, but correction with measured volumes did not change interpretation of treatment effects. It was concluded that control diets had sufficiently high baseline values of pH, dilution rate and acetate proportion to preclude changes induced by either compound, especially at 1 or 2% of DM intake. An effect on palatibility through neutralization of silage acids may have been responsible for the intake response to NaHCO3.

Animal Feed↗

PubMed1986

In vitro fermentation of sugars, grains, and by-product feeds in relation to initiation of ruminal lactate production.

In vitro fermentations of various sugars, grains, and by-products were conducted to investigate the relationships between soluble carbohydrates and initiation of ruminal lactate production. Fermentation of hexose sugars, both monosaccharides and disaccharides, resulted in greater accumulation of lactate than did fermentation of pentoses. Results of fermentation of grains and by-products, in order of greatest to least potential to produce lactic acid, were steam-flaked barley = barley = wheat greater than moisture corn = sorghum grain. Water-soluble fractions of the grains and by-products were more rapidly fermented to lactate than the insoluble fractions. Combining 10% soluble fractions from wheat, barley, and steam-flaked barley with 90% insoluble fractions from corn resulted in significant increases in lactate concentration. Analysis of sugar composition of these water soluble materials indicated that monosaccharides and disaccharides constitute 23 to 46% by weight. Data suggest that water-soluble materials play a role in initiation of lactate production from grains, and further production is dependent on starch fermentability.

Animal Feed↗

PubMed1985

Net portal absorption of lactate and volatile fatty acids in steers experiencing glucose-induced acidosis or fed a 70% concentrate diet ad libitum.

Five crossbred steers (347 kg) were surgically fitted with rumen fistulae, hepatic portal, abdominal aorta and mesenteric catheters to measure organic acid absorption from the gut during acute [intraruminal glucose, 12 g/kg body weight (G)] or subacute [ad libitum 70% concentrate diet (C)] acidosis. Samples were taken at time 0, then every 2 h for 48 h after a switch from an alfalfa diet to C, or dosing with G. Steers receiving C received G 1 wk later so that five steers provided four observations/treatment. Blood flow rates were determined by infusion of para-amino hippuric acid (PAH) and averaged 767.8 and 712.5 liters/h for C and G, respectively. Animals consuming C averaged 13.6 kg dry matter from 0 to 24 h and 1.5 kg from 24 to 48 h. Rumen pH declined to 4.2 for G compared with 6.0 for C. Blood pH and HCO3 showed only slight depressions for G from 16 to 26 h, the period of lowest rumen pH. Rumen L-lactate concentration averaged 53.4 mM (peak 77 mM) and 2.1 mM for G and C, respectively. Rumen D-lactate concentration averaged 30.2 mM (peak 47 mM) for G and 1.2 mM for C. Net portal absorption of L-lactate averaged 96.6 and 164.4 mmol/h, whereas that of D-lactate averaged 10.5 and 71.8 mmol/h for C and G, respectively. Mean net portal volatile fatty acid absorptions were 442.8, 192.1, 53.8, 5.3 and 10.4 mmol/h (C) and 100.0, 47.2, 9.4, .98 and .78 mmol/h (G) for acetate, propionate, butyrate, isobutyrate and isovalerate, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Acidosis↗

PubMed1985

Effect of ionophore antibiotics on experimentally induced lactic acidosis in cattle.

Salinomycin, a new ionophore antibiotic, was tested and compared with lasalocid and monensin for preventing experimentally induced lactic acidosis. Five rumen-fistulated adult cattle were used in a 5 X 5 Latin square design, and the treatments were as follows: no treatment (control), 0.11 mg of salinomycin/kg of body weight (S1), 0.22 mg of salinomycin/kg (S2), 0.66 of lasalocid/kg, and 0.66 mg of monensin/kg. Acidosis was induced by intraruminal administration of a ground corn-corn starch mixture (50:50, 12.5 g/kg) once a day for up to 4 days. Antibiotics were administered along with grain-starch mixture. Rumen and blood samples were obtained before and at 6, 12, and 24 hours after each carbohydrate-antibiotic dosing to monitor acid-base status. Control and S1-treated cattle became ruminally acidotic within 54 hours, whereas cattle treated with S2, lasalocid, and monensin resisted acidosis for up to 78 hours after dosing. Cattle treated with S2, lasalocid, or monensin had higher rumen pH and lower L(+)- and D(-)-lactate concentrations than did control or S1-treated cattle. Rumen pH decrease to below 5.0 in S2-, lasalocid-, and monensin-treated cattle was not due to lactic acid, but to increased production of volatile fatty acids. Rumen propionate proportion increased initially in antibiotic-treated cattle, but after 48 hours, butyrate proportion increased significantly. Despite low rumen pH and high lactate concentration, lacticacidemia was not evident, and the systemic acid-base disturbance was mild in control cattle.(ABSTRACT TRUNCATED AT 250 WORDS)

Acidosis↗

PubMed1984

In vitro rates of oxidation and gluconeogenesis from L(+)- and D(-)lactate in bovine tissues.

Slices of bovine kidney cortex, liver, heart and sternomandibularis muscle actively metabolized D- and L-lactate. Rates of D-lactate oxidation were greatest in kidney cortex followed by heart and liver with muscle exhibiting the lowest rates. L-lactate oxidation was greatest in kidney cortex followed by heart with liver and muscle exhibiting similar rates. Rates of oxidation of gluconeogenesis were similar for D- and L-lactate at 0.1 mm lactate but D utilization, as a percent of L, decreased as substrate concentrations increased to 50 mM. Bovine tissues appear to possess significant potential for D(-)lactate utilization. Estimates of this and possible interactions are discussed.

Animals↗

PubMed1983

Influence of diet on glucose turnover and rates of gluconeogenesis, oxidation and turnover of D-(-)-lactate in the bovine.

D-(-)-Lactate metabolism as influenced by the level of roughage in the diet was examined in eight Hereford heifers (306 kg) fed ad libitum as alfalfa hay diet (R) (2.02 Mcal ME/kg) (ME, metabolizable energy) or a 90% concentrate diet (C) (2.95 Mcal ME/kg) for 18 days. Animals were adjusted to negative pressure hoods (188 liter/minute airflow) and fitted with jugular and urinary catheters. Animals received 32.2 and 71.4 microCi of D-[U-14C]lactate and 435.7 and 233.3 microCi of 2-[3H]glucose for the primer dose and hourly infusion rates, respectively. Blood, expired CO2 and urine samples were taken at 30-minute intervals for 6 hours with CO2 and urine samples taken for an additional 24 and 42 hours, respectively. ME intakes were not different between diets (P greater than 0.05) for the day of infusion. Glucose turnover rates were 143.3 and 154.3 mmol/hour, whereas, D-(-)-lactate turnover was 0.67 and 0.57 mmol/hour for R anc C, respectively. Rates of oxidation and gluconeogenesis were 0.61 and 0.22 mmol/hour for R and 0.55 and 0.16 mmol/hour for C. Recovery of 14C in urine and expired air accounted for 3.73 and 44.3% of the infused dose for R and 2.13 and 43.5% of the infused dose for C. Oxidation was the major route of D-(-)-lactate elimination but the potential for D-(-)-lactate elimination from the bovine under high D-(-)-lactate loads is as yet undetermined.

Animal Nutritional Physiological Phenomena↗

PubMed1983

Balance and urinary excretion of calcium, magnesium and phosphorus in response to high concentrate feeding and lactate infusion in lambs.

Two experiments were conducted to investigate the influence of dietary concentrate level and iv lactate infusion on the urinary excretion and balance of Ca, Mg and P in lambs. In Exp. 1, six ruminal fistulated, crossbred wethers (25 kg) were fed diets of 0, 50 and 70% concentrate for 5-d periods (periods 1, 2 and 3, respectively) followed by 25 d on a 90% concentrate diet (periods 4, 5 and 6, respectively). Collections were made for all days except 6 to 10 and 16 to 20 on the 90% concentrate diet. Dry matter intakes increased with each increase in dietary concentrate until the initial period of 90% concentrate (period 4) when intakes were lowest. Intakes increased (P less than .05) during the latter two periods of 90% concentrate feeding compared with period 4. Rumen fluid pH decreased and rumen L (+) lactate increased with increasing concentrate intake. Blood pH and bicarbonate both decreased with increasing concentrate intake indicating a mild disturbance in acid-base balance. Plasma concentrations of Ca, Mg and P decreased with increased concentrate intake and were elevated (P less than .05) for periods 5 and 6 compared with period 4. Plasma alkaline phosphatase activity and urinary hydroxyproline excretion both increased (P less than .05) for periods 5 and 6. Four of the six animals were in negative Ca balance for the initial period of 90% concentrate feeding, but showed highest Ca retentions for periods 5 and 6. Magnesium and P balance appeared unaffected by increased concentrate intake. Disturbances in Ca metabolism appeared to be short-term and nondetrimental; the animals responded with increased growth and Ca retentions once adjusted to the high concentrate diet. In Exp. 2, four Hampshire ewes (32 kg) were used in a 4 X 4 Latin square design with treatments being saline (.9% NaCl, w/v), L (+) lactate, D (-) lactate and D, L-lactate infused iv in a saline solution to supply .6 mM/kg body weight of each isomer in 15 min. Plasma and urine samples were taken 0, .5, 1, 1.5, 3, 6 and 12 h from the start of infusion. Total urinary excretion of Ca (P less than .04) and Mg (P less than .02) were elevated for all lactate infusions as compared with saline. Total P excretion was greater (P = .06) for all lactate infusions compared with saline and was increased (P less than .05) for the D, L-lactate treatment as compared with the D- and L-lactate treatments.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗