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Biomedical subjects

R A Britton

Publications and source records attributed to R A Britton.

At least 55 records · Page 3Linked to original sources
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

Induced non-enzymatic browning of soybean meal. III. Digestibility and efficiency of protein utilization by ruminants of soybean meal treated with xylose or glucose.

Trials were conducted to evaluate effects of non-enzymatic browning of soybean meal (SBM) on efficiency of protein utilization and N digestibility. In trial 1, 48 Suffolk-Finnsheep lambs (22 kg) were fed 80 d to evaluate efficiency of protein utilization for growth when supplemental protein was fed as urea (U), commercial SBM (CS), or commercial SBM (pH 8.5, 83% dry matter) containing xylose (3 mol/mol SBM-lysine) and heated 30 min (XTS-30) or 55 min (XTS-55). Diets containing graded levels of N from CS, XTS-30 and XTS-55 were fed. Response criterion was efficiency of protein utilization, plotted as gains of lambs fed test proteins minus gain of lambs fed U vs supplemental test protein fed. Efficiencies of protein utilization were .62, 1.27 and .91 for CS, XTS-30 and XTS-55, respectively. Protein from XTS-30 was used more efficiently (P less than .05) than that from CS. In trial 2, apparent digestibility of N from CS (97%) was higher (P less than .01) than XTS-30 (77%) and XTS-55 (82%) by Suffolk-Finnsheep lambs (27 kg). In trial 3, 60 mixed-breed steers (218 kg) were fed individually for 105 d to evaluate glucose as a reducing sugar. Glucose-treated SBM (GTS) was prepared by mixing glucose (3 mol/mol SBM lysine) with SBM, adjusting pH and dry matter content to 8.5 and 80%, respectively, and heating at 150 C for 60 min. Supplemental N sources were U, CS, GTS and a 50:50 mixture (protein basis) of corn gluten meal and blood meal (CGM/BM).(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1987

Feeding combinations of dry corn and wheat to finishing lambs and cattle.

Two finishing trials, one with lambs and one with cattle, were conducted to determine the effect of combinations of dry corn (whole or rolled) with dry rolled wheat on animal performance. The cattle (mixed crossbred yearlings) trial also evaluated methods of getting cattle to full feed by stepping-up using either grain combinations or dry rolled corn and then feeding the appropriate grain combination. In the lamb trial, as the level of dry whole corn increased in the diet of 80 Rambouillet X Suffolk lambs (29 kg), feed intake (linear, P less than .01), gain (linear, P less than .01; quadratic, P less than .15) and feed efficiency (linear, P less than .01; quadratic, P less than .15) were improved. The major improvement occurred in the first 30 d of feeding when feed efficiency was improved (linear, P less than .01; quadratic, P less than .01) by the inclusion of dry whole corn. In the cattle trial (272 mixed crossbred yearling cattle, avg = 358 kg), as the level of dry rolled corn increased, feed intake (linear, P less than .01), gain (linear, P less than .01; quadratic, P less than .01) and feed efficiency (linear, P less than .05; quadratic, P less than .05) were improved. Cattle fed 67 or 33% dry rolled corn with 33 or 67% dry rolled wheat gained 4% faster and 4.4% more efficiently than the average performance of cattle fed 100% corn or wheat. Cattle stepped-up on dry rolled corn and then switched to 100% wheat, tended to gain faster (.1 kg/d) than cattle stepped-up on 100% wheat.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1986

Response to monensin in cattle during subacute acidosis.

A steer metabolism study was conducted to measure changes in ruminal and blood components in response to monensin level following an abrupt switch from forage to a concentrate diet. Six ruminal-cannulated crossbred steers (373 kg) were fed either 0, 150 or 300 mg monensin per head daily in a replicated 3 X 3 Latin-square design. In all treatments, ruminal pH declined to a low of 5.4 to 5.6 12 h post-feeding, suggesting steers experienced subacute acidosis. Also in the first 12 h post-feeding, all treatments exhibited nearly a twofold increase in total ruminal volatile fatty acid (VFA) concentrations, while peak ruminal lactate concentrations ranged from .86 to 1.50 mM. During the entire 48-h period, there were no significant treatment differences in blood pH, HCO3- or ruminal lactate, although there was a trend of higher ruminal and blood lactate associated with increased level of monensin supplementation. Feeding higher levels of monensin resulted in higher pH and propionate with lower acetate and butyrate concentrations. Increasing the level of monensin fed resulted in reduced (P less than .01) total ruminal VFA concentrations. Ruminal pH was more highly correlated to total ruminal VFA concentrations (r = -.69, P less than .01) than lactate concentrations (r = -.14, P less than .10). Results from this study indicate the significance of total ruminal organic acid concentration rather than ruminal lactate concentration during subacute acidosis. Monensin maintained a higher ruminal pH by reducing concentrations of VFA.

Acidosis↗
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

Monensin effects on digestibility, ruminal protein escape and microbial protein synthesis on high-fiber diets.

The influence of monensin level (0, 6.1, 12.2, 18.3 and 36.6 ppm) on diet fiber digestibility, microbial protein synthesis and ruminal escape of dietary protein was evaluated in two steer metabolism trials. A growth trial was conducted to study possible interactions of forage quality and monensin level. In metabolism trial 1, four ruminal-cannulated steers were assigned to four monensin levels in a 4 X 4 Latin square design to measure fiber digestibility, rate of passage and protein metabolism. In metabolism trial 2, five duodenal-cannulated steers were assigned to five monensin levels in a 5 X 5 Latin square design to measure fiber digestibility, bacterial N flow and plant N flow. In the two metabolism trials, the level of monensin influenced organic matter (OM) digestibility, neutral detergent fiber (NDF) digestibility and ruminal NDF digestibility quadratically, with the intermediate levels of monensin being superior either to the high level of monensin or no monensin. A quadratic increase in particulate disappearance rate (P = .09) and no effect (P = .95) on liquid disappearance were also observed in trial 1. In trial 1, monensin level quadratically decreased (P = .10) the bacterial protein concentration and increased (P = .02) the ratio of total N:diaminopimilic acid in whole rumen contents. In trial 2, no overall difference in duodenal N flow (P = .64) or flow of individual amino acids (P = .46) was observed. In the growth trial, no interaction of cornstalk quality and monensin was observed (P less than .38).(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1985

Protein supplementation of ammoniated roughages. III. Corncobs supplemented with a blood meal-corn gluten meal mixture--steer studies.

Two factorial experiments were conducted to investigate site and extent of organic matter (OM) digestion, nitrogenous fractions flowing at the abomasum and rates-of-passage in steers fed 0, 2 or 4 g NH3/100 g dry matter of treated corncobs supplemented with either a corn or a blood meal-corn gluten meal (BM-CGM) supplement. Rumen and total tract OM digestion coefficients were quadratically increased (P less than .05) and dietary N was quadratically increased (P less than .07) due to the main effect of ammonia. The main effect of protein supplement increased (P less than .05) postruminal OM digestibility, nonammonia N and dietary-N flow. Quadratic protein X ammonia interactions were noted for fluid flow, total-N flow, total amino acid flow and ammonia-N flow. Linear protein X ammonia interactions were noted for bacterial-N flow, which appeared to indicate that N utilization of the ammoniated corn-cob was improved by the inclusion of BM-CGM in the diet. Diet dry matter intake, fluid volume, rate of fluid passage, particulate mass and rate of particulate passage in rumen-fistulated steers were unaffected by either main effect. However, rumen fluid pH of steers fed BM-CGM was lower than that from steers fed the corn supplement.

Animal Feed↗
PubMed1985

Effect of additive on alfalfa silage fermentation characteristics and feedlot performance of steers.

In each of two trials four large plastic bags were filled with approximately 72 mt of first cutting, early bloom alfalfa (35% dry matter). Fresh alfalfa in two bags was treated with .5 kg/metric ton of a commercial silage additive (Silo-Best). Two bags were left untreated. When compared with steers fed untreated alfalfa silage, weight gains, intakes, and feed efficiencies were not significantly (P greater than .05) altered for steers fed treated silage. However, laboratory analysis showed silage treatment increased in vitro dry matter digestibility (57.0 versus 60.6%) and decreased silage pH (4.98 versus 4.83). Concentrations of propionic and butyric acid were decreased by the additive. Data suggest that anaerobic fermentation was enhanced with the additive. Slight but significant improvements of silage in vitro dry matter digestibility, obtained by treating alfalfa silage with the inoculant-type preservative, did not result in improved performance in feeding trials.

Animal Feed↗
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↗
PubMed1982

Oxidation rates of major fatty acids in fasting neonatal pigs.

Thirty-two pigs were used to compare the oxidation rates of uniformly labeled (U-14C) palmitic (16:0), stearic (18:0), oleic (18:1) and linoleic (18:2) acids in fasting neonatal pigs. The pigs were allowed to nurse the sow for 24 to 48 h following birth. Subsequently, they were removed, an indwelling catheter was surgically placed in the external iliac vein and the pigs were fasted for 12 h to attain a postabsorptive state. The 14C fatty acids were administered as a single infusion (10 microCi) via the catheter, and recovery of the label as expired 14CO2 was determined at 45-min intervals for a 6-h period. Blood samples were taken following the infusion (15, 60, 120, 240, 360 min) to monitor activity maintained within the free fatty acid (FFA) fraction of the plasma pool. The oxidation rate of each fatty acid was corrected for the difference in dose dilution using a uniform factor based on plasma concentration of 18:1. The cumulative 6-h 14CO2 recovery rates (percentage of dose) were 19.1, 6.6, 30.1 and 13.1% for 16:0, 18:0, 18:1 and 18:2, respectively. Oleic acid was oxidized at a more (P less than .05) rapid rate than the other fatty acids. Palmitic acid and 18:2 were oxidized more rapidly than 18:0, although the difference between 18:0 and 18:2 was not significant. Plasma FFA pools differed with respect to the proportion of infused activity remaining at various times after administration. At 60 and 120 min postinfusion, the greatest (P less than .05) proportion of activity was maintained in the 18:1 pool (11.9 and 6.6%, respectively, vs 7.7 and 4.3% for 16:0, 6.9 and 3.9% for 18:2 and 3.6 and 2.2% for 18:0). Palmitic acid and 18:2 had a greater (P less than .05) level of activity in the plasma FFA pool at 60 min than did 18:0. This same pattern was observed through 2 h, but by 240 min postinfusion, the proportion of activity remaining in each of the plasma pools was similar. Rate of oxidation appeared to corrrespond with plasma concentration and proportion of activity remaining in the plasma FFA pool.

Animals↗
PubMed1981

Influence of diet on amino acid absorption in beef cattle and sheep.

Six sheep and three steers were fed pelleted alfalfa hay prior to and during the first blood sampling period (BSP) and then switched to an 85% concentrate (HC) diet at least 28 days before a second BSP. Portal plasma flow rates were higher in steers than sheep (7.9 versus 5.0 liters/hr per kg0.75). With HC feeding, sheep and cattle had higher plasma femoral arterial concentrations of glycine and 3-methylhistidine and lower concentrations of valine and isoleucine than when fed hay. When fed HC diets, sheep, but not cattle, had lower glutamate and histidine and higher serine concentrations than when fed hay. Sheep had higher concentrations of aspartate, asparagine, threonine, glycine, tyrosine, phenylalanine, valine, leucine, citrulline, arginine, lysine, 3-methylhistidine and histidine than cattle. Diet did not affect the portal venous-arterial concentration difference or the net portal amino acid appearance (NPAAA) rate of any of the amino acids in sheep or cattle. With sheep, there was a tendency for the NPAAA rate to be higher for all amino acids, except aspartate, with HC compared to hay feeding. Expressed on the basis of metabolic body size, NPAAA rate was qualitatively and quantitatively similar between sheep and cattle.

Absorption↗
PubMed1981

Glucose and lactate absorption and metabolic interrelationships in steers changed from low to high concentrate diets.

Cannulas were surgically implanted in the portal and mesenteric veins and femoral artery of eight crossbred steers averaging 270 kg. They were given primed, continuous 3-hour infusions of U-[14C]-L-lactate and 2-[3H]- or 6-[3H]-glucose into the jugular vein and para-aminohippuric acid (portal blood flow indicator) into the mesenteric vein before and after being changed from a pelleted alfalfa hay to a pelleted 85% concentrate diet. Blood samples were collected at 20-minute intervals during infusions. Reliable blood flow data were obtained on four of the eight steers during the first infusion; the other four were not infused the second time. Dry matter intake, portal blood flow, net portal D-lactate absorption (P less than 0.10), net portal glucose absorption and L-lactate turnover rate (P less than 0.10) increased as a result of increased concentrate (energy) intake. Glucose turnover rate (P less than 0.10), L-lactate absorbed as a percentage of turnover rate, L-lactate converted to glucose and glucose derived from L-lactate concomitantly decreased. Net portal L-lactate absorption was not affected. The direction of the response for portal blood flow, net portal D-lactate absorption, net portal glucose absorption, L-lactate turnover and L-lactate absorbed as a percentage of turnover was the same as that previously observed in lambs under similar experimental protocol. Differences in responses between lambs and steers for glucose turnover and L-lactate converted to glucose may be attributable to differences in dry matter or energy intake or both.

Absorption↗
PubMed1981

Ammonia treatment of corn plant residues: digestibilities and growth rates.

Two lamb digestion trials and two steer growth trials were conducted to evaluate NH3 treatment of cornstalks and cobs. In digestion trial 1, cornstalks were treated to contain 0, 2, 3 or 4 g NH3/100 g dry matter (DM); DM intake of lambs increased (P greater than .05) with increasing levels of NH3 (from 398 to 997 g). DM digestibility (DMD) increased (p greater than .05) from 36.8 to 47.0% with 2% NH3 but did not increase further with 3 or 4% NH3. In digestion trial 2, 3% NH3-treated cornstalks produced higher (P greater than .01) DMD, DM intake and cell wall digestibility than untreated cornstalks. No positive associative effects on DMD were observed from the addition of 50% alfalfa to treated stalks, but DM intake showed positive associative effects (P greater than .01). Steers fed stalklage harvested shortly after the harvest of high moisture grain gained more weight per day (P greater than .05) but were not more efficient (P less than .10) than steers fed stalklage harvested 1 month after grain harvest. NH3 treatment of stalklage did not improve rate or efficiency of gain over that obtained with the corresponding untreated stalklage (P less than .10). Steers fed 3% NH3-treated corn cobs gained .72 kg/day, compared with .39 kg/day for steers fed untreated cobs. DM intake increased (P greater than .05) from 4.22 kg/day for steers fed untreated cobs to 7.17 kg/day for steers fed 3% NH3 cobs.

Ammonia↗
PubMed1980

Glucose and lactate absorption and metabolic interrelationships in lambs switched from low to high concentrate diets.

Two experiments were conducted to measure glucose and lactate absorption and metabolic interrelationships in lambs either switched gradually (experiment 1) or abruptly (experiment 2) from hay to a high concentrate diet. In experiment 1, seven lambs were given primed, continuous, 3-hour infusions of 2-0[3H]glucose, U-[14C]L-lactate and para-aminohippuric acid (portal blood flow indicator) before and after switching from a pelleted hay to a pelleted, 85% concentrate diet. Blood samples were collected at 20-minute intervals during infusions. In experiment 2, four lambs were abruptly switched from a pelleted hay to an all-concentrate diet. Portal and arterial blood samples were collected before and up to 1 week after the diet switch. As a result of increased concentrate intake (experiment 1) net portal absorption and turnover of L-lactate and glucose increased. Percentage of glucose derived from L-lactate decreased. Net portal D-lactate absorption, L-lactate absorption as a percentage of turnover and conversion of L-lactate to glucose were not affected by diet. Lambs in experiment 2 did not become acutely acidotic. The insult to acid-base status peaked 12-16 hours after the diet switch, concurrent with maximum arterio-venous differences in plasma L-lactate and glucose. Arterio venous differences in plasma D-lactate were not significantly affected.

Absorption↗