Biomedical subjects

D L Harmon

Publications and source records attributed to D L Harmon.

At least 19 recordsLinked to original sources

PubMed2007

The impact of dietary protein source on observed and predicted metabolizable energy of dry extruded dog foods.

Fifty-five observations were used to determine the ME content of 8 foods containing different protein sources. The major protein sources tested included low-oligosaccharide whole soybeans; 2 low-oligosaccharide, low-phytate whole soybeans; 2 conventional soybean meals; low-ash poultry meal; low-oligosaccharide, low-phytate soybean meal; and conventional whole soybeans. The ME content of all foods ranged from 3,463 to 4,233 kcal/kg of DM. The first objective was to utilize the observed ME data and test the accuracy of the modified Atwater equation. In this study, the modified Atwater equation generally underpredicted ME compared with the observed ME (residual mean = 247 kcal/kg). The second objective was to use individual data to develop an equation, based on the chemical composition of the food, to predict the ME content of the foods. A multivariate regression analysis was used to predict ME content based on chemical composition. Five models were fitted to the data. Model 1 included CP, ether extract (EE), and crude fiber (CF). Because the foods varied in protein sources, and the ratio of total AA (TAA) to non-AA (NAA) CP ranged from 3.5:1 to 14.4:1, it was hypothesized that accounting for the proportion of TAA and NAA in CP would improve the fit of the model. Therefore, model 2 included TAA, NAA, EE, and CF. Defining CP in terms of TAA and NAA improved the r2 of the model from 0.46 to 0.79. Subsequently, models 3, 4, and 5 replaced the CF term with ADF, NDF, and hemicellulose (HEM). Model 3 included TAA, NAA, EE, and NDF. Model 4 included TAA, NAA, EE, ADF, and HEM. Model 5 included TAA, NAA, EE, and HEM. Defining dietary fiber in terms of HEM improved the r2 of model 2 from 0.79 to 0.81. Residual analysis suggested that replacing the CF term with HEM (model 5) improved the prediction of ME content. In contrast, defining fiber in terms of NDF (model 3) did not result in an improvement over model 2, whereas the ADF term (model 4) did not (P > 0.34) contribute to the overall model. Fractionating CP into TAA and NAA components further defined the chemical composition of the food. These data suggest that defining protein composition improves the accuracy of predicting the ME content of dog foods.

Animal Feed↗

PubMed2006

Effects of a dietary Aspergillus oryzae extract containing alpha-amylase activity on performance and carcass characteristics of finishing beef cattle.

Three experiments were conducted to examine the effects of an Aspergillus oryzae extract containing alpha-amylase activity on performance and carcass characteristics of finishing beef cattle. In Exp. 1, 120 crossbred steers were used in a randomized complete block design to evaluate the effects of roughage source (alfalfa hay vs. cottonseed hulls) and supplemental alpha-amylase at 950 dextrinizing units (DU)/kg of DM. Significant roughage source x alpha-amylase interactions (P < 0.05) were observed for performance. In steers fed cottonseed hulls, supplemental alpha-amylase increased ADG through d 28 and 112 and tended (P < 0.15) to increase ADG in all other periods. The increases in ADG were related to increased DMI and efficiency of gain during the initial 28-d period but were primarily related to increased DMI as the feeding period progressed. Supplemental alpha-amylase increased (P = 0.02) the LM area across both roughage sources. In Exp. 2, 96 crossbred heifers were used in a randomized complete block design with a 2 x 3 factorial arrangement of treatments to evaluate the effects of corn processing (dry cracked vs. high moisture) and supplemental alpha-amylase concentration (0, 580, or 1,160 DU/kg of DM). Alpha-amylase supplementation increased DMI (P = 0.05) and ADG (P = 0.03) during the initial 28 d on feed and carcass-adjusted ADG (P = 0.04) across corn processing methods. Longissimus muscle area was greatest (quadratic effect, P = 0.04), and yield grade was least (quadratic effect, P = 0.02) in heifers fed 580 DU of alpha-amylase/kg of DM across corn processing methods. In Exp. 3, 56 crossbred steers were used in a randomized complete block design to evaluate the effects of supplemental alpha-amylase (930 DU/kg of DM) on performance when DMI was restricted to yield a programmed ADG. Alpha-amylase supplementation did not affect performance when DMI was restricted. We conclude that dietary alpha-amylase supplementation of finishing beef diets may result in increased ADG through increased DMI under certain dietary conditions and that further research is warranted to explain its mode of action and interactions with dietary ingredients.

Animal Feed↗

PubMed2006

Sites, rates, and limits of starch digestion and glucose metabolism in growing cattle.

Growing cattle in the United States consume up to 6 kg of starch daily, mainly from corn or sorghum grain. Total tract apparent digestibility of starch usually ranges from 90 to 100% of starch intake. Ruminal starch digestion ranges from 75 to 80% of starch intake and is not greatly affected by intake over a range of 1 to 5 kg of starch/d. Starch apparently digested in the small intestine decreases from 80 to 34% as starch entering the small intestine increases from 0.2 to 2 kg/d. Starch apparently digested in the large intestine ranges from 44 to 46% of starch entering the large intestine. Approximately 70% of starch digested in the small intestine appears as glucose in the bloodstream. Within the range of starch intakes that do not cause rumen upsets, increasing starch (and energy) intake increases the amount of starch digested in the rumen, increases the supply of starch to the small intestine, increases starch digested in small intestine (albeit at reduced efficiency), and increases starch digested in the large intestine, such that total tract digestibility remains relatively constant. With increased starch intake, most of the starch is still digested in the rumen, but increasing amounts of starch escape ruminal and intestinal digestion, and disappear distal to the ileocecal junction. Again, within the range of starch intakes that do not cause rumen upsets, as starch intake increases, hepatic gluconeogenesis increases, glucose entry increases, and glucose irreversible loss increases, with a significant portion lost as CO2. The ability to increase use of dietary starch to support greater weight gains or improved marbling could come from increasing starch digestion in a healthy rumen or in the small intestine, but we conclude that the main limit to use of dietary starch to support live weight gain is digestion and absorption from the small intestine. Increased oxidation of glucose at greater starch intakes may alter energetic efficiency by sparing other oxidizable substrates, like amino acids.

Animals↗

PubMed2005

Evaluation of low-oligosaccharide, low-phytate whole soybeans and soybean meal in canine foods.

Eight mature dogs (19.3 +/- 0.1 kg) were used in an experiment to compare the effects of feeding soybeans containing low concentrations of oligosaccharides and phytate on nutrient availability in complete foods fed to dogs. All foods were formulated to be isonitrogenous and contained low-oligosaccharide, low-phytate soybean meal (LLM); conventional soybean meal (SBM); low-oligosaccharide, low-phytate whole soybeans (LLB); or conventional whole soybeans (WSB) as the protein source. Daily DMI averaged 287 +/- 4 g/d. Fecal outputs were greatest for LLB and WSB, averaging 48.2 g DM/d. Small intestinal DM digestibility ranged from 80.9% (LLM) to 74.0% (LLB) but was unaffected by treatment. Large intestinal DM digestibility did not differ among treatments (P = 0.652). Total-tract DM digestibility was higher (P = 0.020) for LLM (87.0%) than for SBM (84.8%). No difference in total-tract DM digestibility was observed for the two WSB foods (average = 83.3%; P = 0.286). Nitrogen retention did not differ among foods containing LLM and SBM (1.2 g of N/d; P = 0.486) or LLB and WSB (0.9 g of N/d; P = 0.225). Small intestinal N digestibility did not differ among LLM- and SBM-containing foods (80.6%; P = 0.190) or LLB and WSB (69.3%; P = 0.640). Total-tract N digestibility did not differ among foods containing LLM and SBM (83.5%; P = 0.627) or LLB and WSB (76.8%; P = 0.968). Tryptophan digestibility was higher for SBM than for LLM (P = 0.039). Histidine and tryptophan digestibilities were higher in WSB compared with LLB (P = 0.049 and P < 0.001, respectively). No differences in nonessential AA digestibility were observed when comparing soy-based foods. The results of this study demonstrate that LLM, SBM, LLB, and WSB can be effective sources of protein for canine foods and have a high digestibility. Differences in small intestinal digestibility of tryptophan and histidine may require consideration when formulating diets using low-oligosaccharide, low-phytate soybeans or meal.

Amino Acids↗

PubMed2005

Effects of adding valerate, caproate, and heptanoate to ruminal buffers on splanchnic metabolism in steers under washed-rumen conditions.

Four steers fitted with a ruminal cannula and chronic indwelling catheters in the mesenteric artery, mesenteric vein, hepatic portal vein, hepatic vein, and the right ruminal vein were used to study VFA absorption from bicarbonate buffers incubated in the washed reticulorumen, and metabolism by splanchnic tissues. Portal and hepatic vein blood flows were determined by infusion of p-aminohippurate into the mesenteric vein. The steers were subjected to four experimental treatments in a Latin square design. The treatments were Control (ruminal bicarbonate buffer with [mmol/kg]: acetate = 72; propionate = 30; isobutyrate = 2.1; butyrate = 12; valerate = 1.2; caproate = 0; and heptanoate = 0); Val (same as control except for valerate = 8 mmol/kg); Cap (same as control except for caproate = 3.5 mmol/kg); and Hep (same as control except for heptanoate = 3 mmol/kg). All buffers were incubated for 90 min in the rumen, and ruminal VFA absorption rates were maintained by continuous intraruminal infusion of VFA. The arterial concentrations of valerate and heptanoate showed a small increase (< or = 1 micromol/L; P < 0.05) with inclusion of the respective acid in the ruminal buffer, but no change (P = 0.57) in arterial concentration of caproate was detected. Valerate increased (P < 0.05) the net portal flux of butyrate and valerate, as well as the net splanchnic flux of propionate, butyrate, and valerate. With Cap and Hep, the net portal flux of caproate and heptanoate accounted for 54 and 45% of ruminal disappearance rates, respectively, indicating that these acids were extensively metabolized by the ruminal epithelium. Caproate was ketogenic both in the ruminal epithelium and in the liver, and Cap increased (P < 0.05) the arterial concentration, ruminal vein minus arterial concentration difference, net hepatic flux, and net splanchnic flux of 3-hydroxybutyrate. The net hepatic flux of glucose decreased (P = 0.02) with Cap and Hep compared with Control and Val; however, no effect (P = 0.14) on the net splanchnic flux of glucose could be detected. We conclude that the strong biological activity of valerate, caproate, and heptanoate warrant increased emphasis on monitoring their ruminal presence and their potential systemic effects on ruminant metabolism.

Absorption↗

PubMed2004

Influence of abomasal carbohydrates on small intestinal sodium-dependent glucose cotransporter activity and abundance in steers.

Most animals adapt readily to increased supplies of carbohydrate in the intestinal lumen by increasing enzymes for degradation and increasing glucose transporter activity. However, the extent of upregulation of Na+-dependent glucose cotransporter 1 (SGLT1) activity and content in response to increased delivery of carbohydrate to the small intestinal lumen of ruminants is unclear. Therefore, an experiment was conducted to determine the effect of glucose and starch hydrolysate on the activity and abundance of SGLT1 in the small intestine of steers. In a randomized complete block design, 40 crossbred beef steers (243+/-2 kg BW) were fed 0.163 Mcal of ME/(kg BW0.75(d; W), 0.215 Mcal of ME/(kg BW0.75 x d; 2M), or 0.163 Mcal ME/(kg BW0.75 x d) and infused for 35 d into the rumen (R) or abomasum (A) with 12.6 g/(kg BW0.75 x d) of starch hydrolysate (S) or into the abomasum with 14.4 g/(kg BW0.75 x d) of glucose (G). Steers were slaughtered, and brush-border membrane vesicles were prepared from the small intestinal samples obtained from five equidistant sites along the intestine. Maltase activity in vesicles and homogenates differed with intestinal sampling site (quadratic, P < 0.001). Steers on the AG treatment yielded a greater intestinal maltase activity (38 nmol glucose x mg protein(-1) x min(-1)) compared with the AS, RS, W, or 2M treatments (34, 26, 23, and 23 nmol glucose x mg protein(-1) x min(-1) respectively [SEM = 3; P = 0.02]). Sodium-dependent glucose uptake averaged 18.4+/-3.94 pmol glucose/(mg protein x s) and was not affected by treatment, but uptake decreased distally along the intestine (P < 0.001). There was no effect of treatment on SGLT1 protein abundance, but SGLT1 protein abundance increased linearly from the duodenum to the ileum (P = 0.05). The inverse relationship between glucose uptake and SGLT1 abundance suggests that the regulation of brush border Na+-dependent glucose transport capacity is complex, involving factors other than the presence of luminal carbohydrate.

Abomasum↗

PubMed2004

Effect of increasing ruminal butyrate absorption on splanchnic metabolism of volatile fatty acids absorbed from the washed reticulorumen of steers.

Four steers fitted with a ruminal cannula and chronic indwelling catheters in the mesenteric artery, mesenteric vein, hepatic portal vein, hepatic vein, and the right ruminal vein were used to study the absorption and metabolism of VFA from bicarbonate buffers incubated in the temporarily emptied and washed reticulorumen. Portal and hepatic vein blood flows were determined by infusion of p-aminohippurate into the mesenteric vein, and portal VFA fluxes were calibrated by infusion of isovalerate into the ruminal vein. The steers were subjected to four experimental treatments in a Latin square design with four periods within 1 d. The treatments were Control (bicarbonate buffer) and VFA buffers containing 4, 12, or 36 mmol butyrate/kg of buffer, respectively. The acetate content of the buffers was decreased with increasing butyrate to balance the acidity. The butyrate absorption from the rumen was 39, 111, and 300 +/- 4 mmol/h for the three VFA buffers, respectively. The ruminal absorption rates of propionate (260 +/- 12 mmol/h), isobutyrate (11.4 +/- 0.7 mmol/h), and valerate (17.3 +/- 0.7 mmol/h) were not affected by VFA buffers. The portal recovery of butyrate and valerate absorbed from the rumen increased (P < 0.01) with increasing butyrate absorption and reached 52 to 54 +/- 4% with the greatest butyrate absorption. The liver responded to the increased butyrate absorption with a decreasing fractional extraction of propionate and butyrate, and with the greatest butyrate absorption, the splanchnic flux was 22 +/- 1% and 18 +/- 1% of the absorbed propionate and butyrate, respectively. The increased propionate and butyrate release to peripheral tissues was followed by increased (P < 0.05) arterial concentrations of propionate (0.08 +/- 0.01 mmol/kg) and butyrate (0.07 +/- 0.01 mmol/kg). Arterial insulin concentration increased (P = 0.01) with incubation of VFA buffers compared with Control and was numerically greatest with the greatest level of butyrate absorption. We conclude that the capacity to metabolize butyrate by the ruminal epithelium and liver is limited. If butyrate absorption exceeds the metabolic capacity, it affects rumen epithelial and hepatic nutrient metabolism and affects the nutrient supply of peripheral tissues.

Absorption↗

PubMed2004

Pancreatic exocrine secretion and plasma concentration of some gastrointestinal hormones in response to abomasal infusion of starch hydrolyzate and/or casein.

Eight Angus steers (290 +/- 8 kg), surgically prepared with pancreatic pouch-duodenal reentrant cannulas and abomasal infusion catheters were used in a replicated 4 x 4 Latin square experiment to investigate the effects of abomasal infusion of starch hydrolyzate (SH) and/or casein on pancreatic exocrine secretion and plasma concentration of hormones. Steers were fed a basal diet of alfalfa (1.2 x NEm) in 12 equal portions daily. Abomasal infusion treatments (6-L total volume infused per day) were water (control), SH [2.7 g/(kg BW x d)], casein [0.6 g/(kg BW x d)], and SH + casein. Periods were 3 d for adaptation and 8 d of full infusion. Pancreatic juice and jugular blood samples were collected over 30-min intervals for 6 h on d 11. Weight and pH of pancreatic samples were measured, and a 10% subsample was composited and frozen until analysis of total protein and pancreatic enzyme activities. The remaining sample was returned to the duodenum. Plasma was harvested and frozen until analyzed. Pancreatic juice (67 mL/h) and protein (1.8 g/h) secretion rates were not affected by nutrient infusion. There were SH x casein interactions for all pancreatic enzyme secretions (U/h; alpha-amylase, P < 0.03; trypsin, P < 0.08; and chymotrypsin, P < 0.03) and plasma insulin concentration (P < 0.10). Secretion of pancreatic enzymes was increased by SH (trypsin) and casein (alpha-amylase, trypsin, and chymotrypsin) but not when SH + casein were infused together. Glucose (P < 0.10) and cholecystokinin octapeptide concentrations (CCK-8; P < 0.05) were increased by SH, but glucagon was decreased (P < 0.10). Casein decreased (P < 0.10) plasma CCK-8 concentrations. These data indicate that positive effects of postruminal casein on enzyme secretion were inhibited by SH, emphasizing the complexity of the regulatory mechanisms involved in dietary adaptation of pancreatic exocrine secretion. Changes in hormone concentration may not relate directly to changes in enzyme secretion.

Abomasum↗

PubMed2004

Splanchnic metabolism of volatile fatty acids absorbed from the washed reticulorumen of steers.

Six steers fitted with a ruminal cannula and chronic indwelling catheters in the mesenteric artery, mesenteric vein, hepatic portal vein, hepatic vein, as well as in the right ruminal vein were used to study metabolism of VFA absorbed from buffers in the emptied and washed reticulorumen. [2-(13)C]Acetate was infused into a jugular vein to study portal-drained visceral (PDV) uptake of arterial acetate, hepatic unidirectional uptake of acetate, and whole-body irreversible loss rate (ILR). Isobutyrate was infused into the right ruminal vein to calibrate VFA fluxes measured in the portal vein. On sampling days, the rumen was emptied and incubated in sequence with a 0-buffer (bicarbonate buffer without VFA), a VFA-buffer plus continuous intraruminal infusion of VFA, and finally another 0-buffer. Ruminal VFA absorption was determined as VFA uptake from the VFA-buffer and metabolic effects determined as the difference between metabolite fluxes with VFA-buffer and 0-buffers. Steady absorption rates of VFA were maintained during VFA-buffer incubations (4 h; 592+/-16, 257+/-5, 127+/-2, 17+/-<1, 20+/-<1 mmol/h, respectively, of acetate, propionate, butyrate, isovalerate, and valerate). The portal flux of acetate corrected for PDV uptake of arterial acetate accounted for 105+/-3% of the acetate absorption from the rumen, and the net portal flux of propionate accounted for 91+/-2% of propionate absorption. Considerably less butyrate (27+/-3%) and valerate (30+/-3%) could be accounted for in the portal vein. The sum of portal VFA and 3-hydroxybutyrate as well as lactate represented 99+/-3% of total VFA acetyl units and 103+/-2% of VFA propionyl units. Estimates are maximum because no accounting was made for lactate derived from glycolysis in the PDV. The net splanchnic flux of VFA, lactate, 3-hydroxybutyrate, and glucose accounted for 64+/-2% of VFA acetyl units and 34+/-5% of VFA propionyl units. Results indicate that there is a low "first-pass" uptake of acetate and propionate in the ruminal epithelium of cattle, whereas butyrate and valerate are extensively metabolized, though seemingly not oxidized to carbon dioxide in the epithelium but repackaged into acetate, 3-hydroxybutyrate, and perhaps other metabolites. When PDV "second-pass" uptake of arterial nutrients is accounted for, PDV fluxes of VFA, lactate, and 3-hydroxybutyrate represent VFA production in the gastrointestinal tract and thereby VFA availability to the ruminant animal.

Absorption↗

PubMed2004

Evaluation of perennial ryegrass straw as a forage source for ruminants.

Two experiments were conducted to evaluate perennial ryegrass straw as a forage source for ruminants. Experiment 1 evaluated digestion and physiological variables in steers offered perennial ryegrass straw containing increasing levels of ergot alkaloid, lolitrem B. Sixteen ruminally cannulated Angus x Hereford steers (231+/-2 kg BW) were blocked by weight and assigned randomly to one of four treatments. Steers were provided perennial ryegrass straw at 120% of the previous 5-d average intake. Before straw feeding, soybean meal was provided (0.1% BW; CP basis) to meet the estimated requirement for degradable intake protein. Low (L) and high (H) lolitrem B straws (<100 and 1,550 ppb, respectively; DM basis) were used to formulate treatment diets: 100% L; 67% L:33% H; 33% L:67% H; 100% H (DM basis). Intake and digestibility of DM and OM, and ruminal pH, total VFA, and NH3-N were not affected by increasing lolitrem B concentration. Ruminal indigestible ADF (IADF) fill increased linearly (P = 0.01) and IADF passage rate decreased linearly (P = 0.04) as lolitrem B increased. Experiment 2 evaluated performance and production by 72 Angus x Hereford cows (539+/-5 kg BW) consuming perennial ryegrass straw containing increasing lolitrem B during the last third of gestation. Cows were blocked by body condition score and randomly assigned to one of three treatments. Cows were provided perennial ryegrass straw ad libitum and supplemented with soybean meal (0.1% BW; CP basis) to meet the estimated requirement for degradable intake protein. Mixtures of a L and H lolitrem B straw (467 and 2,017 ppb, respectively) were used to formulate treatment diets: 100% L, 50% L:50% H, 100% H (DM basis). Thirteen of 24 cows on the 100% H treatment exhibited signs of ryegrass staggers and were removed from the study; nevertheless, lolitrem B concentration did not influence pre- or postcalving weight or body condition score change. These data suggest that feeding perennial ryegrass straw containing up to 1,550 ppb lolitrem B (DM basis) did not adversely affect nutrient digestion or physiological response variables in steers. However, providing straw with a lolitrem B concentration of approximately 2,000 ppb (DM basis) resulted in 54% of cows exhibiting signs of ryegrass staggers. These data suggest that blending straws with a high (>2,000 ppb) and low (<500 ppb) concentration of lolitrem B can be a successful management practice.

Animal Feed↗

PubMed2003

Pancreatic exocrine secretion in steers infused postruminally with casein and cornstarch.

Our objective was to evaluate the effect of postruminal protein infusion on pancreatic exocrine secretions. One Holstein, two crossbred, and five Angus steers (305 +/- 5 kg) with pancreatic pouch-duodenal reentrant cannulas and abomasal infusion catheters were used in a replicated 4 x 4 Latin square. All steers were abomasally infused with 1,050 g/d of raw cornstarch with treatments of 0, 60, 120, or 180 g/d of sodium casein suspended in water to yield 6,000 g/d of infusate daily. Steers were limit-fed (1.5 x NEm; 12 equal portions daily) a 90% corn silage, 10% supplement diet formulated to contain 12.5% CP. Periods consisted of 3 d of adaptation to infusion, 7 d of full infusion, 1 d of collection, and 7 d of rest. Pancreatic juice was collected in 30-min fractions continuously for 6 h. Total juice secreted and the pH of individual fractions were recorded, a 10% subsample was retained to form a composite sample, and remaining fluid was returned to the duodenum. Juice composite samples were stored (-30 degrees C) until analyzed for total protein and activities of alpha-amylase, trypsin, and chymotrypsin. Casein infusion linearly increased alpha-amylase concentration (182 to 271 units/mL; P < 0.02; 17.5 to 24.6 units/mg of protein; P < 0.03) and secretion rate (26,847 to 41,894 units/h; P < 0.01). Total juice secretion (155 g/h), pH of pancreatic juice (8.13), secretion rate of protein (1,536 mg/h), and concentration of protein (10.2 mg/mL) in pancreatic secretions were not affected (P > 0.05) by casein infusion. Similarly, casein infusion did not change 0.05) trypsin and chymotrypsin concentrations (1,379 and 349 units/L or 0.134 and 0.033 units/mg of protein, respectively) or secretion rates (206 and 52 units/h, respectively). Abomasal infusion of protein with starch stimulated a greater pancreatic secretion of alpha-amylase activity into the intestine than infusion of starch alone.

Abomasum↗

PubMed2003

Influence of substrate and/or neurohormonal mimic on in vitro pancreatic enzyme release from calves postruminally infused with partially hydrolyzed starch and/or casein.

Our objectives were to determine the effects of neuroendocrine challenge and substrates on in vitro alpha-amylase and trypsin release in pancreatic tissue collected from Holstein calves (n = 24; 88 +/- 3 kg) abomasally infused for 10 d with tap water (control), partially hydrolyzed starch (SH; 4 g/[kg of BW x d]) and/ or casein (0.6 g/[kg of BW x d]). The caudal portion of the pancreas was removed, rinsed with ice-cold saline, cut into approximately 2 x 2-mm segments, and incubated in oxygenated Krebs Ringer bicarbonate buffer containing no substrate (control), glucose, amino acids, or VFA at 39 degrees C. After 60 min of incubation, neurohormonal mimics (none; control), carbachol (acetylcholine analog; 10 microM final), or caerulein (cholecystokinin mimic; 100 nM final) were added to the flasks and tissue was incubated for 60 min. Pancreatic tissue concentrations and in vitro release of alpha-amylase and trypsin decreased (P < 0.001) in calves abomasally infused with SH. Carbachol increased (P < 0.10) alpha-amylase and trypsin release in tissue collected from all calves. An effect of caerulein to increase alpha-amylase release (P < 0.10) was only observed with prior exposure to abomasal casein infusion in vivo or with simultaneous incubation with amino acids in vitro. Caerulein increased (P < 0.10) trypsin release in tissue collected from all calves except for those receiving SH + casein. Glucose decreased (P < 0.10) alpha-amylase release from pancreatic tissue collected from calves receiving abomasal control and casein treatments. Amino acids decreased (P < 0.10) alpha-amylase and trypsin release from pancreatic tissue collected from calves receiving the abomasal control treatment. Glucose, amino acids, and VFA decreased (P < 0.10) trypsin release from tissue collected from calves receiving abomasal SH. These data indicate that carbachol can stimulate pancreatic enzyme release in vitro. Caerulein, however, is only effective in stimulating in vitro pancreatic enzyme release in tissue from calves with an increased postruminal protein supply or in tissue incubated with amino acids. The results indicate that postruminal and local nutrients might be important in altering the responsiveness to a neuroendocrine challenge and could be an important regulatory event involved with dietary adaptation in ruminants.

Abomasum↗

PubMed2003

Evaluation of low-ash poultry meal as a protein source in canine foods.

Eight mature female dogs (18.0 +/- 0.2 kg) were used in a replicated 4 x 4 Latin square experiment to determine the feeding value of low-ash poultry meal (PM) in a complete food fed to dogs. All foods contained graded concentrations of PM (10.4 to 32.5% DM), resulting in foods that were 10, 15, 20, and 25% CP. Daily DMI averaged 284 +/- 14 g/d. An increase in PM resulted in an increase in fecal moisture from 44.7 to 55.1% (linear; P < 0.01), and fecal DM output increased from 24.8 to 31.6 g/d (linear; P < 0.05). Ileal DM flow increased from 27.1 to 40.7 g/d (linear; P < 0.01). Small intestinal DM digestibility decreased from 90.4 to 86.1% (linear; P < 0.01) and total-tract DM digestibility decreased from 91.2 to 89.4% (linear; P < 0.01) as PM increased. Large intestinal DM digestibility increased from 8.4 to 21.1% with increasing PM (linear; P < 0.05). Fecal excretion of CP increased from 5.6 to 10.0 g/d (linear; P < 0.01) and ileal flow of CP increased from 6.9 to 15.6 g/d (linear; P < 0.01) as PM increased. Small intestinal CP digestibility was unaffected with treatment (P > 0.05). Large intestinal CP digestibility increased from 21.6 to 37.1% (linear; P < 0.05) with increasing PM. Total-tract CP digestibility increased from 81.0 to 86.6% (linear; P < 0.01) as PM increased. Arginine had the highest overall digestibility ranging from 88.5 to 91.3%, whereas cysteine had the lowest digestibility, ranging from 67.1 to 71.4%. These data indicate that PM is a highly digestible protein source for canine foods with inclusions of 10.4 to 32.5% of DM.

Amino Acids↗

PubMed2002

Postruminal administration of partially hydrolyzed starch and casein influences pancreatic alpha-amylase expression in calves.

The objective was to examine the effects of postruminal partially hydrolyzed starch (SH) and/or casein on the expression of pancreatic alpha-amylase mRNA, protein and activity in calves. Holstein calves [(n = 24) 88 plus minus 3 kg body weight (BW)], fitted with abomasal infusion cannulas, were randomly assigned within block (week of infusion) to one of four abomasal infusion treatments. Calves were fed an alfalfa-based diet, and SH [4 g/(kg BW.d)] and/or casein [0.6 g/(kg BW.d)] was infused abomasally for 10 d before tissue collection. There was a SH x casein interaction (P < 0.10) for pancreatic weight (g and g/kg BW) because casein increased pancreatic weight in the absence of SH but did not influence pancreatic weight in the presence of SH. Pancreatic alpha-amylase mRNA tended to be lower (P = 0.06) and protein and activity (U/g pancreas and U/g protein) were lower (P = 0.02) in calves receiving abomasal SH. The concentration of pancreatic trypsin activity (U/g pancreas and U/g protein) was lower (P < 0.03) in calves receiving abomasal SH. There was a SH x casein interaction for total alpha-amylase and trypsin activity [U/pancreas and U/(pancreas.kg BW)] because casein increased total activity in the absence of SH but not in the presence of SH. These data suggest that increases in small intestinal protein flow enhance pancreatic weight and thus total pancreatic alpha-amylase and trypsin activity, yet small intestinal SH inhibits the increase in pancreatic weight resulting from increased small intestinal protein flow. Additionally, postruminal SH decreases alpha-amylase expression largely by translational events.

Abomasum↗

PubMed2002

Intestinal starch disappearance increased in steers abomasally infused with starch and protein.

Steers (379 +/- 10 kg) with ruminal, duodenal, and ileal cannulas were used in a 5 x 5 Latin square digestion trial to quantify and evaluate the relationship between intestinal protein supply and intestinal starch disappearance. Treatments were infusions of 0, 50, 100, 150, or 200 g/d of casein along with 1,042 g/d of raw cornstarch. Abomasal infusions were accomplished by passing tubing and a pliable retaining washer through the reticular-omasal orifice into the abomasum. Steers were fed a 93% corn silage, 7% supplement diet that contained 12% crude protein at 1.65% body weight in 12 equal portions/d. Periods lasted 17 d (12 d for adaptation, 2 d of collections, and 3 d of rest). The quantity and percentage of organic matter and protein disappearance from the small intestine increased linearly (P < 0.03) with infused casein. Greater quantities of starch disappeared with increased casein infusion (P < 0.01). The infusion of 200 g/d of casein increased small intestinal starch disappearance by 226 g/d over the control. Casein infusion did not affect the quantity or percent of organic matter, starch, or protein disappearance in the large intestine. Treatments did not change ruminal ammonia N, ruminal pH, or plasma glucose concentrations. Starch disappearance from the small intestine was increased with greater protein flow to the duodenum of steers.

Abomasum↗

PubMed2002

Influence of abomasal infusion of glucose or partially hydrolyzed starch on pancreatic exocrine secretion in beef steers.

Five crossbred steers (348 +/- 12 kg) fitted with a pancreatic pouch draining the main pancreatic duct and duodenal re-entrant and abomasal infusion cannulas were used in a 5 x 5 Latin square design to determine the influence of postruminal carbohydrate source and level on pancreatic exocrine secretion in beef steers. Abomasal infusion treatments (250 mL infused/h) were water (control), 20 g/h glucose, 40 g/h glucose, 20 g/h starch hydrolysate (SH), and 40 g/h SH. Infusion periods were 8 d with 3 to 4 d of rest between periods. Pancreatic juice was collected for 6 h on d 8 of each collection period. Every 30 min a 10% subsample was composited and frozen and the remainder was infused into the duodenum via the reentrant cannula. Abomasal infusion of glucose or SH increased (P < 0.10) total secretion of pancreatic juice and decreased (P < 0.10) secretion of alpha-amylase activity. Abomasal carbohydrate infusion did not influence total secretion of protein, trypsin activity, or chymotrypsin activity. This experiment indicates that increasing postruminal glucose or SH decreases pancreatic alpha-amylase secretion.

Abomasum↗

PubMed2002

NutriDense and waxy corn hybrids: effects on site and extent of disappearance of nutrients in sheep.

Six Suffolk wether lambs (40.9+/-1.05 kg) surgically fitted with ruminal and double-L-shaped duodenal and ileal cannulas were used in a 3 x 6 Latin rectangle design to investigate the effects of three corn hybrids on site and extent of disappearance of nutrients and rumen characteristics. Treatments were 1) a conventional yellow dent corn (CC) diet, 2) a NutriDense corn (NC) diet, and 3) a waxy corn (WC) diet. Diets consisted of 43.9% cracked corn grain, 39.1% cottonseed hulls, 15.3% soybean meal, 1.49% vitamin and mineral supplement, and 0.21% chromic oxide (DM basis). Lambs were fed twice daily at 1.8 x NEm requirement. Ruminal pH, fluid dilution rate, volume, NH3 N, and total VFA concentrations, as well as molar proportions of isobutyrate, butyrate, and valerate, were similar (P > 0.10) among dietary treatments. Apparent and true OM disappearances (g/d and percentage of OM intake) from the stomach were similar (P > 0.10) among dietary treatments. Apparent OM disappearance (percentage of duodenal OM flow) from the small intestine was higher (P < 0.05) for the WC than for the NC treatment. Apparent total tract OM disappearance (percentage of OM intake) was also similar (P > 0.10) among dietary treatments. Total apparent and true starch disappearances (g/d) from the stomach were higher (P < 0.05) for the WC diet than for the CC and NC diets. However, apparent and true starch disappearances from stomach as percentage of starch intake were higher (P < 0.05) for the WC diet than for the CC diet. Starch disappearance (g/d) from the small intestine was higher (P < 0.05) for the CC diet than for the WC diet; however, apparent starch disappearance (percentages of duodenal starch flow) from the small intestine was higher (P < 0.05) for the WC diet than for the CC diet. Duodenal flows of total N, bacterial N, NH3 N, and non-NH3 nonbacterial N (g/d) and efficiencies of bacterial protein production (g of bacterial N/kg of true or apparent OM disappearing in the stomach) were similar (P > 0.10) among dietary treatments. Apparent and true N disappearance from stomach (g/d) and apparent total tract N disappearance (percentage of N intake) were also similar (P > 0.10) among dietary treatments. Total N disappearance from the hindgut was -0.81, -1.06, and -1.46 g/d for CC, NC, and WC, respectively, and was different (P < 0.05) between CC and WC diets. Results indicated that higher ruminal starch disappearance in WC did not increase microbial N production or efficiency when compared to CC.

Animal Nutritional Physiological Phenomena↗

PubMed2001

Influence of alpha-linked glucose on jejunal sodium-glucose co-transport activity in ruminants.

Eight steers and 12 lambs were used in a completely randomized experimental design to determine the effect of partial alpha-amylase starch hydrolysate (SH) on small intestinal sodium-dependent glucose transport activity. Starch hydrolysate was delivered ruminally or abomasally to steers (960 g/day) and sheep (144 g/day) for 7 days. On day 7, the steers were rendered unconscious, exsanguinated and eviscerated. A 1-m section of jejunum was collected starting at the duodenojejunal flexure. Sheep were anaesthetized with pentobarbital and the second meter of small intestine (jejunum) was collected. Brush-border membrane vesicles were prepared and sodium-dependent glucose uptake activity was measured using the rapid uptake/filtration technique. Alkaline phosphatase and maltase activity was enriched by 8.2+/-0.5- and 8.4+/-1.2-fold in the vesicle preparation, respectively, and was not different between treatments. Abomasal SH increased (P=0.03) the Na/glucose co-transport approximately two-fold in both cattle (47.2-114.0+/-31.5 pmol/mgxsec) and sheep (77.4-152.0+/-25.7 pmol mg(-1) s(-1)). We conclude that Na/glucose co-transport activity by enterocytes responds to luminal alpha-linked glucose (from abomasal infusion) in ruminants, compared with controls. Intestinal maltase-specific activity does not respond to alpha-linked glucose in cattle, and decreases slightly in sheep.

Alkaline Phosphatase↗