HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Richards, C. J. Articles by Huntington, G. B. Search for Related Content PubMed PubMed Citation Articles by Richards, C. J. Articles by Huntington, G. B.

Pancreatic exocrine secretion in steers infused postruminally with casein and cornstarch^1,2

C. J. Richards^*,3, K. C. Swanson^*,4, S. J. Paton^*,5, D. L. Harmon^*,6 and G. B. Huntington

^* Department of Animal Sciences, University of Kentucky, Lexington 40546-0215 and and Department of Animal Sciences, North Carolina State University, Raleigh 27695-7621

⁶ Correspondence:
814 W.P. Garrigus Bldg. (phone: 859-257-7516; fax: 859-257-3412; E-mail:
dharmon{at}uky.edu).

	Abstract

Top Abstract Introduction Experimental Procedures Results Discussion Implications Literature Cited

 
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 NE_m; 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°C) until analyzed for total protein and activities of -amylase, trypsin, and chymotrypsin. Casein infusion linearly increased -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 (P > 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 -amylase activity into the intestine than infusion of starch alone.

Key Words: -Amylase • Beef Cattle • Pancreas • Protein Digestion • Ruminants • Starch Digestion

	Introduction

Top Abstract Introduction Experimental Procedures Results Discussion Implications Literature Cited

 
Today’s cattle finishing and milk production industries rely on starch in grains to supply the majority of dietary energy. Diet and intake affect ruminal fermentation and subsequent supply of starch to the small intestine. At high diet intakes, 400 to 2,300 g of starch can flow to the small intestine of beef steers (Stock et al., 1987), with an intestinal digestibility ranging from 47 to 88% (Owens et al., 1986). Starch digestion in the small intestine is theoretically more energetically efficient than ruminal fermentation (Harmon and McLeod, 2001). However, shifting digestion to the small intestine has not commonly resulted in increased efficiency of growth. This suggests that small intestinal starch assimilation is limited in the ruminant. It has been proposed (Owens et al., 1986) that inadequate access by enzymes to starch granules, insufficient time for hydrolysis, limited glucose absorption, insufficient intestinal mucosal enzymes, and insufficient pancreatic -amylase are possible causes. Results from recent work showed that infusing protein with starch into the small intestine enhanced small intestinal starch disappearance (Richards et al., 2002) and net portal appearance of glucose (Taniguchi et al., 1995) over infusing starch alone. It is unclear what mechanisms are responsible for the increases in small intestine starch disappearance and portal glucose appearance. Our hypothesis, based on the above data, was that increasing postruminal protein would increase pancreatic output of -amylase. In the present experiment, our objective was to evaluate the influence of abomasally infused casein on pancreatic exocrine secretions of steers abomasally infused with starch.

	Experimental Procedures

Top Abstract Introduction Experimental Procedures Results Discussion Implications Literature Cited

 
One Holstein, two crossbred, and five Angus steers (305 ± 5 kg) were used in a replicated 4 x 4 Latin square design. Steers were housed in individual (2.5 x 2.5 m) pens within a temperature- (23°C) and light- (16 h light:8 h dark) controlled room with ad libitum access to water. The University of Kentucky Institutional Animal Care and Use Committee approved all procedures.

Before surgeries, steers were withheld from feed (48 h) and water (24 h). Pancreatic pouch-duodenal reentrant cannulas and abomasal infusion catheters were placed during an aseptic surgery under general anesthesia. Anesthesia was introduced with 8 mg of thiopental sodium/kg of BW and maintained with halothane in O₂. All animals were allowed to recover a minimum of 14 d before being placed on treatment. Rectal temperature was monitored daily for 7 d after surgery as an indicator of animal health.

The reentrant cannula linked a pouch of duodenum containing the primary pancreatic duct with the duodenum. This procedure was similar to that described by (St-Jean et al., 1992). However, the single-unit cannula was replaced by open-T cannulas in both the duodenal pouch and duodenum. These cannulas were exteriorized and connected in a manner allowing all pancreatic juice to flow into the duodenum. The open-T cannulas were constructed by removing half of the continuous barrel from a 1.25-cm polyvinyl chloride T-shaped tubing adapter (Walker et al., 1994a). Silicone tubing (20-cm; 0.95-cm i.d., 1.43-cm o.d.) was placed over the intact barrel. The exposed portion of the "T" was primed with General Electric SS4179 primer (Waterford, NY) and coated with General Electric RTV118 self leveling silicone. A 5-cm section of 1.11-cm i.d., 1.75-cm o.d. silicone tubing was used to connect the cannulas externally.

Abomasal catheters were made by securing a 1.25-cm section of Tygon tubing (0.95 cm i.d., 1.43 o.d.) as a cuff 1.5 cm from one end of a 45-cm section of Tygon tubing (0.64-cm i.d., 0.95-cm o.d.) with cyclohexanone. After the cyclohexanone dried, a 2.5-cm vinyl flat washer with 0.95-cm hole was slid over the smaller tubing to the cuff. The cuff and washer were placed into the pyloric region of the abomasum with the remaining tubing exteriorized through the adjacent body wall. Patency was maintained by filling the catheter with mineral oil between infusions.

Steers were weighed at the beginning of each period and individual DMI adjusted to 1.5x the NE_m requirement (NRC, 1984). The diet contained 90% corn silage and 10% supplement on a DM basis (Table 1). Diets were balanced to meet the urea fermentation potential (Burroughs et al., 1974) and CP requirements of a 318-kg steer gaining 0.45 kg/d (NRC 1984). Each day, silage and supplement were weighed out separately, thoroughly mixed, divided into 12 equal portions, and fed at 2-h intervals using automated feeders (Ankom Co, Fairport, NY).

On the sampling day, continuity of the reentrant cannula was interrupted and the duodenal reentrant section was plugged. A 24-French Foley catheter was inserted into the pancreatic pouch portion of the cannula. Approximately 200 mL of tap water was injected through the Foley catheter to flush the pancreatic pouch. The Foley catheter was removed and a plastic "T" tubing connector was inserted. A 2.5-m section of Tygon tubing was attached to the "T" connector while the other end was placed through the center of a No. 8 rubber stopper. The stopper was inserted into the top of a 1,000-mL sidearm Erlenmeyer flask under vacuum. The third arm of the "T" was left open as a vent to prevent vacuum damage to the pouch. Fluid was continuously collected under vacuum into the Erlenmeyer flask in an ice-bath for 7 h. At 30-min intervals, the flasks were switched and the weight and pH (Accumet Basic pH Meter, Fisher Scientific) of the fraction were measured. Ten percent of each 30-min sample was retained to form a composite sample. After the subsample was taken, remaining pancreatic fluid was returned to the duodenum by temporarily removing the plug from the duodenal reentrant section of the cannula and using a catheter-tip syringe to transfer fluid to the duodenum. The first two incremental samples were returned to the duodenum without measurement to ensure the purity of fluids collected. Sample composites were stored at -20°C between fluid additions.

Samples were stored (-30°C) until analysis for total protein by the bicinchoninic acid procedure (Smith et al., 1985) and activities of -amylase (Walker and Harmon, 1996), trypsin (Geiger and Fritz, 1986), and chymotrypsin (Wirnt 1986) with modifications described by Walker and Harmon (1995). All analyses were completed within 2 wk of collection. Enzyme activities were expressed with 1 unit (U) equal to the production of 1 µmol of product/min.

Silage and supplement samples were analyzed for DM (55°C for 48 h) before each period to ensure the proper amount of diet (DM basis) was offered daily. Feed bunks were cleaned daily and remaining orts were weighed with 10% retained for composite samples. Composite silage and supplement samples were formed during each period. Feed samples were ground through a 1-mm screen (Cyclotech 1093 Sample Mill, Tecator, Hoganas, Sweden) and analyzed for N (Leco FP-2000, Leco Corp., St. Joseph, MI) and NDF (Robertson and Van Soest, 1981).

Statistics
Data were analyzed as a replicated 4 x 4 Latin square design using the GLM procedure of SAS (SAS Inst., Inc., Cary, NC). The statistical model included square, period(square), steer(square), and treatment. Linear and quadratic orthogonal contrasts were used to separate treatment means. Results were considered significant when P < 0.05.

	Results

Top Abstract Introduction Experimental Procedures Results Discussion Implications Literature Cited

 
The quantity of pancreatic juice secreted (Table 2) was not altered (overall mean, ±SEM; 155 ± 11 mL/h) by infusion of casein with starch. Treatments also had no effect on the pH (8.13 ± 0.04) or protein concentration (10.23 ± 0.64 mg/mL) of juice secreted from the pancreas. No differences were detected in the rate of protein secretion (1,536 ± 117 mg/h).

View this table: [in this window] [in a new window]   Table 2. Influence of postruminal protein infusion on secretion, pH, protein, -amylase, trypsin, and chymotrypsin

	Discussion

Top Abstract Introduction Experimental Procedures Results Discussion Implications Literature Cited

 
Pancreatic juice secretion rates in the current experiment, when expressed per unit of body weight (0.47 to 0.55 mL/[kg BW h]), were similar to those reported by Walker and Harmon (1995; 0.59 mL/[kg BW h]), but less than values reported previously (Swanson et al., 2002; 0.67 mL/[kg BW h]) when partially hydrolyzed starch (SH) was infused abomasally. Both of these experiments reported an increase in pancreatic juice secretion resulting from the abomasal infusion of carbohydrate. However, a study with sheep (Wang and Taniguchi, 1998) found no differences in the volume of bile-pancreatic juice secreted when infusion of starch and casein was compared to starch alone.

Walker and Harmon (1995) demonstrated that infusion of SH abomasally tended to decrease pancreatic juice pH when compared to ruminal SH or water infusion treatments (8.17, 8.32, and 8.20, respectively). In our experiment, the addition of casein to starch infusion did not alter the pH (8.13 ± 0.02) of juice secreted.

Protein concentrations (9.65 to 10.87 mg/mL) and secretion rates (1,414 to 1,645 mg/h) are within the range previously reported for cattle. Walker and Harmon (1995) reported mean pancreatic juice protein concentrations in steers of 10.2 to 15.6 mg/mL and secretion rates of 1,382 to 1,634 g/h. In cows, Pierzynowski (1990) reported pancreatic protein secretions decreasing from 2,700 to 1,050 mg/h with fasting (1 d). The protein concentration in pancreatic juice has been shown to decrease in steers when abomasal water infusion is replaced with SH infusion (Walker and Harmon, 1995). However, in a study with sheep, Wang and Taniguchi (1998) reported finding no differences, which is consistent with the present study. The importance of supplying quality dietary protein with dietary carbohydrates to maximize pancreatic protein secretions has been demonstrated in nonruminants (Johnson et al., 1977; Schick et al., 1984). However, differences between the digestive systems of ruminants and nonruminants likely affect pancreatic protein secretions. In nonruminants, a postprandial intermittent flow of dietary nutrients enters into the small intestine resulting in a flux of metabolites and exocrine pancreatic secretions closely related to the feeding pattern and diet (Croom et al., 1992; Harmon, 1992). In ruminants, pregastric fermentation of substrates produces a more continuous flow of nutrients from dietary and microbial origin that are less variable than the diet consumed. This appears to produce a more consistent flow of protein from the pancreas (Aust and Cook, 1968; Walker and Harmon, 1995).

Protein, or the balance of energy and protein, flowing to the duodenum may influence the enzymatic profile of pancreatic exocrine secretions. As increasing quantities of casein were infused with starch in this study, the concentration, specific activity, and secretion rate of -amylase increased. Previous studies designed to investigate the effects of protein flow to the small intestine on pancreatic -amylase in ruminants have produced conflicting results. Kato et al. (1986) infused a soybean extract, containing trypsin inhibitors, into the duodenum of sheep and increased pancreatic juice and -amylase secretion. Reynolds and Heath (1981) infused 100 and 200 µg/min of peptone (amino acids and small peptides) for periods up to 2.5 h into the duodenum of anesthetized sheep with the duodenum ligated to prevent gastric contents from entering the duodenum without altering the pancreatic secretion of -amylase. Walker and Harmon (1995) reported that steers receiving ruminal and abomasal infusion of SH tended to have a greater secretion of pancreatic -amylase than steers receiving abomasal infusion alone. When steers received ruminal SH infusions in addition to abomasal SH infusions, they received greater quantities of total energy, and should have had increased flows of microbial protein to the small intestine from the increased ruminal digestible energy. Assuming a microbial efficiency of 13% of TDN, a 97% TDN value for infused SH, and that microbial protein is 80% true protein and 80% digestible (NRC, 1996), ruminal SH infusion would have resulted in an additional 67 g/d metabolizable protein supply. Therefore, increases in -amylase in the ruminal plus abomasal SH infusion treatment may have resulted from greater small intestinal protein flows or an increase in total energy input as previously reported (Russell et al., 1981; Kreikemeier et al., 1990). Wang and Taniguchi (1998) infused 150 g/d of starch into the small intestine of fed sheep with or without 50 g/d of casein. Small intestinal starch infusion decreased secretion of -amylase activity from preinfusion rates. However, when casein was infused with starch, -amylase secretion was not different from the preinfusion. Whereas preinfusion pancreatic secretions were not measured in the present study, the response obtained may be similar. Our results represent an increase in -amylase secretion above a starch infusion control that may be depressing -amylase secretion as shown by infusion of water or SH abomasally (Walker and Harmon, 1995). These results suggest that the balance of energy and protein flow to the duodenum may be an important aspect in regulating pancreatic -amylase secretion.

Several studies have evaluated the effects of altering energy and protein supplies on nutrient digestion in the small intestine or blood parameters. The infusion of 200 g/d of casein with approximately 1,050 g/d of starch resulted in a 226 g/d greater disappearance of starch and 227 g/d greater disappearance of protein from the small intestine than infusion of starch alone (Richards et al., 2002). Taniguchi et al. (1995) measured net portal nutrient flux of steers infused with 800 g/d of raw cornstarch into the rumen or abomasum in a factorial design with 200 g/d of casein infused into the rumen or abomasum. Starch infusion into the abomasum increased net appearance of glucose in portal blood, whereas abomasal infusion of starch and casein further increased appearance of glucose and increased appearance of -amino N in the portal vein. When Lemosquet et al. (1997) intravenously infused amino acids, glucose, or a combination of the two in dairy cows, the plasma insulin increase with the glucose-amino acid mixture synergistically exceeded that obtained by separate but isocaloric infusions of amino acids or glucose.

Small intestinal protein infusion has been shown to increase -amylase secretion (Wang and Taniguchi, 1998). Because blood insulin concentration appears to be positively correlated to protein intake (Guerino et al., 1991; Harmon, 1992), it is possible that insulin may be operative in the regulation of -amylase secretion. This increase in insulin may have been involved when diets balanced to supply similar amounts of metabolizable protein at two energy and carbohydrate levels were fed to sheep (Swanson et al., 2000). In that experiment, feeding a high-energy, high-starch diet resulted in greater concentrations and total activity of -amylase in pancreatic tissues than a low-starch diet fed at the same energy level or either diet fed at a lower energy level. However, when undegradable intake protein (UIP) was supplied in a diet to meet the estimated metabolizable protein requirement and glucose or SH was infused continuously into the abomasum, secretion of -amylase activity was reduced (Swanson et al., 2002). If plasma glucose and insulin are both involved in regulating pancreatic -amylase secretion, studies providing additional carbohydrate alone may be limited by plasma insulin. Increases in plasma -amino N from additional small intestinal protein may enhance plasma insulin resulting in greater pancreatic -amylase secretion.

Increases in -amylase in nonruminants correspond generally with postprandial changes in blood glucose and insulin (Lahai, 1984). Tissue contents of -amylase can increase from 50 to 500%, and secretion rates can increase from 200 to 800% when carbohydrates replace fat or protein in the diet of nonruminants (Brannon, 1990). Tsai et al. (1994) demonstrated that plasma insulin and carbohydrate intake are independently involved with the adaptive response of pancreatic -amylase. Brannon (1990) discussed that while the primary signal for regulating -amylase in nonruminants is increasing carbohydrates, others (Snook, 1971; Johnson et al., 1977; Schick et al., 1984) have demonstrated that maximal -amylase production is dependent on adequate protein availability and essential amino acids. The notable difference between ruminants and nonruminants is that when starch is supplied alone, -amylase activity decreases in ruminants (Walker and Harmon, 1995; Wang and Taniguchi, 1998). Results from the present study and Wang and Taniguchi (1998) indicate secretion of -amylase activity does not decrease when proteins are supplied with starch.

Whereas treatments did not affect protease (trypsin and chymotrypsin) secretions, both the concentration (U/L) and total secretion (U/h) of proteases in this experiment were less than values reported in previous experiments with steers (Walker et al., 1994b; Walker and Harmon, 1995). Trypsin secretion (U/h) was greater and chymotrypsin secretion (U/h) was less than previously reported in cows (Pierzynowski et al., 1988; Pierzynowski 1990). Walker and Harmon (1995) reported decreased protease concentrations (U/L) for steers fed a 98% fescue hay diet (12 and 12.5% CP) with SH infused abomasally. In contrast, when steers were fed fescue hay at 1.5x NE_m with sufficient metabolizable protein to gain 0.83 kg/d, infusion of glucose or SH postruminally did not affect protease secretions (Swanson et al., 2002). Duodenal casein infusion did increase trypsin activity by 36% and chymotrypsin activity by 114% in sheep digesta (Ben-Ghedualia et al., 1982). However, bile-pancreatic juice protease activities were not altered from preinfusion levels when starch or starch and casein were infused abomasally in sheep (Wang and Taniguchi, 1998). Our data in cattle appear to support the results presented by Wang and Taniguchi (1998) showing that in the presence of starch, pancreatic secretion of protease is not dependent on protein flow to the small intestine.

It has been suggested that the positive response to increased dietary protein in monogastrics is regulated by a cholecystokinin (CCK)-releasing peptide (Fushiki and Iwai, 1989). If a CCK-releasing peptide was involved in ruminant pancreatic protease regulation, the infusion of casein postruminally in this study and in Wang and Taniguchi (1998) should have increased protease secretion unless the interaction of starch with protein depresses the response. Increases in protease secretions may occur with protein infusion alone.

To determine the adequacy of metabolizable protein of our treatments, we estimated the additional UIP that would be necessary to meet the growth potential of our steers due to infusions of starch. We used the NRC (1996) model, the animal and nutrient parameters from the present study, and a digestibility of 70% for infused carbohydrate (Kreikemeier et al., 1991) to make the estimate. Infusion of starch increased energy intake from 1.5x NE_m for the basal diet to 1.84x NE_m. With this increase in energy intake, estimated daily gain was increased by 290 g/d. The estimated metabolizable protein supply that is necessary to support this gain is 85 g/d. Our basal diet was estimated to supply an adequate quantity of metabolizable protein to meet the energy predicted rate of gain from the basal diet, but not to supply the additional metabolizable protein needs due to starch infusion. With postruminal introduction of carbohydrates, no additional bacterial protein production can be assumed. Therefore, additional protein would need to be supplied as UIP or infused postruminally. If infused casein is assumed to be 100% digestible and the rate of gain estimated from dietary and infused energy was truly obtained, the 180 g/d casein treatment would exceed the metabolizable protein requirement by 47 g/d. Actual gains during this experiment were not estimated as steers were only weighed immediately prior to each infusion period and accurate short-term gains are difficult to obtain.

	Implications

Top Abstract Introduction Experimental Procedures Results Discussion Implications Literature Cited

 
Results indicate that small intestinal protein supply was important in maintaining or stimulating pancreatic -amylase production. The estimated quantity of metabolizable protein supplied in this experiment ranged from deficient to exceeding current recommendations for the estimated growth of our steers. Our results cannot be extrapolated to determine whether protein alone or greater quantities of protein would increase pancreatic -amylase secretion. If starch digestion and assimilation in the small intestine are limited by the activity of -amylase, additional protein might increase energy available from the diet for the animal.

	Footnotes

 
¹ This research was supported by grant No. U.S.-2431-94 from BARD, the U.S.-Israel Binational Agricultural Research & Development Fund.

² Published as publication No. 02-07-015 of the Kentucky Agric. Exp. Stn.

³ Current address: Animal Sci. Dept., University of Tennessee, 2505 River Dr., Knoxville, TN 37996.

⁴ Current address: ARS, USDA, U.S. Meat Animal Research Center, P.O. Box 166, Clay Center, NE 68933.

⁵ Current address: Wright State University, 237 Health Sciences, 3640 Colonel Glenn Hwy, Dayton, OH 45435.

Received for publication January 31, 2002. Accepted for publication December 12, 2003.

	Literature Cited

Top Abstract Introduction Experimental Procedures Results Discussion Implications Literature Cited

 


Aust, S. D., and R. M. Cook. 1968. Pancreatic activity of ruminants. J. Anim. Sci. 27(Suppl. 1):1160.

Ben-Ghedalia, D., J. Miron, and A. Hasdai. 1982. Effect of protein infused into sheep duodenum on activities of pancreatic proteases in intestinal digesta and on the absorption site of amino acids. J. Nutr. 112:818–824.

Brannon, P. M. 1990. Adaptation of the exocrine pancreas to diet. Annu. Rev. Nutr. 10:85–105.[Medline]

Burroughs, W., A. H. Trenkle, and R. L. Vetter. 1974. A system of protein evaluation for cattle and sheep involving metabolizable protein (amino acids) and urea fermentation potential of feedstuffs. Vet. Med. /Small Anim. Clin. 69:713–719.[Medline]

Croom, W. J., Jr., L. S. Bull, and I. L. Taylor. 1992. Regulation of pancreatic exocrine secretion in ruminants: A review. J. Nutr. 122:191–202.

Fushiki, T., and K. Iwai. 1989. Two hypotheses on the feedback regulation of pancreatic enzyme secretion. FASEB J. 3:121–126.[Abstract]

Geiger, R., and H. Fritz. 1986. Trypsin. Pages 119–128 in Methods of Enzymatic Analysis. Vol. 5. H. Bergmeyer, ed. Academic Press, New York.

Guerino, F., G. B. Huntington, R. A. Erdman, T. H. Erdman, T. H. Elsasser, and C. K. Reynolds. 1991. The effects of abomasal casein infusions in growing beef steers on portal and hepatic flux of pancreatic hormones and arterial concentrations of somatomedin-C. J. Anim. Sci. 69:379–386.[Abstract]

Harmon, D. L. 1992. Impact of nutrition on pancreatic exocrine and endocrine secretion in ruminants: A review. J. Anim. Sci. 70:1290–1301.[Abstract]

Harmon, D. L., and K. R. McLeod. 2001. Glucose uptake and regulation by intestinal tissues: Implications and whole-body energetics. J. Anim. Sci. 79:E59–E72.[Abstract/Free Full Text]

Johnson, A., R. Hurwitz, and N. Kretchmer. 1977. Adaptation of rat pancreatic amylase and chymotrypsinogen to changes in diet. J. Nutr. 107:87–96.

Kato, S., T. Ando, N. Adachi, and H. Mineo. 1986. The effects of atropine on pancreatic responses to intravenous CCK-8 and intraduodenal soybean extract in sheep. Jpn. J. Zootech. Sci. 57:1002.

Kreikemeier, K. K., D. L. Harmon, R. T. Brandt, Jr., T. B. Avery, and D. E. Johnson. 1991. Small intestinal starch digestion in steers: Effect of various levels of abomasal glucose, corn starch and corn dextrin infusion on small intestinal disappearance and net glucose absorption. J. Anim. Sci. 69:328–338.[Abstract]

Kreikemeier, K. K., D. L. Harmon, J. P. Peters, K. L. Gross, C. K. Armendariz, and C. R. Krehbiel. 1990. Influence of dietary forage and feed intake on carbohydrase activities and small intestinal morphology of calves. J. Anim. Sci. 68:2916–2929.[Abstract]

Lahai, R. G. 1984. Dietary regulation of protein synthesis in the exocrine pancreas. J. Pediatr. Gastroenterol. Nutr. 3(Suppl. 1):S43–S50.

Lemosquet, S., N. Rideau, and H. Rulquin. 1997. Insulin response to amino acid and glucose intravenous infusions in dairy cows: Synergistic effect. Horm. Metab. Res. 29:556–560.[Medline]

NRC. 1984. Nutrient Requirements of Beef Cattle. 6th ed. Natl. Acad. Press, Washington, DC.

NRC. 1996. Nutrient Requirements of Beef Cattle. 7th ed. Natl. Acad. Press, Washington, DC.

Owens, F. N., R. A. Zinn, and Y. K. Kim. 1986. Limits to starch digestion in the ruminant small intestine. J. Anim. Sci. 63:1634–1648.

Pierzynowski, S. G. 1990. The effect of fasting and subsequent long-term intraduodenal glucose infusion on the exocrine pancreas secretion in cattle. J. Anim. Physiol. Anim. Nutr. 63:198–203.

Pierzynowski, S. G., W. Barej, M. Mikolajczyk, and R. Zabielski. 1988. The influence of light fermented carbohydrates on the exocrine pancreatic secretion in cows. J. Anim. Physiol. Anim. Nutr. 60:234–238.

Reynolds, J., and T. Heath. 1981. Non-parallel secretion of pancreatic enzymes in sheep following hormonal or vagal stimulation. Comp. Biochem. Physiol. 68A:495–500.

Richards, C. J., A. F. Branco, D. W. Bohnert, G. B. Huntington, M. Macari, and D. L. Harmon. 2002. Intestinal starch disappearance in steers abomasally infused with starch and protein. J. Anim. Sci. 80:3361–3368.[Abstract/Free Full Text]

Robertson, J. B., and P. J. Van Soest. 1981. The detergent system of analysis and its application to human foods. Pages 123–158 in The Analysis of Dietary Fiber. W. P .T. James and O. Theander, ed. Marcell Dekker, New York.

Russell, R. W., A. W. Young, and N. A. Jorgensen. 1981. Effect of dietary corn starch intake on pancreatic amylase and intestinal maltase and pH in cattle. J. Anim. Sci. 52:1177–1182.

Schick, J., R. Verspohl, H. Kern, and G. Scheele. 1984. Two distinct adaptive responses in the synthesis of exocrine pancreatic enzymes to inverse changes in protein and carbohydrate in the diet. Am. J. Physiol. 247(Gastrointest. Liver Physiol. 10):G611–G616.

Smith, P. K., R. I. Krohn, G. T. Mallia, F. H. Gartner, M. D. Provenzano, E. K. Fujimoto, N. M. Goeke, B. J. Olson, and D. C. Klenk. 1985. Measurement of protein using bicinchoninic acid. Anal. Biochem. 150:76–85.[Medline]

Snook, T. J. 1971. Dietary regulation of pancreatic enzymes in the rat with emphasis on carbohydrate. Am. J. Physiol. 221:1383–1387.[Free Full Text]

St. Jean, G., D. L. Harmon, J. P. Peters, and N. K. Ames. 1992. Collection of pancreatic exocrine secretions by formation of a duodenal pouch in cattle. Am. J. Vet. Res. 53:2377–2380.[Medline]

Stock, R. A., D. R. Brink, R. A. Britton, F. K. Goedeken, M. H. Sindt, K. K. Kreikemeier, M. L. Bauer, and K. K. Smith. 1987. Feeding combinations of high moisture corn and dry-rolled grain sorghum to finishing steers. J. Anim. Sci. 65:290–302.[Abstract/Free Full Text]

Swanson, K. C., C. J. Richards, and D. L. Harmon. 2002. Influence of abomasal infusion of glucose or partially hydrolyzed starch on pancreatic exocrine secretion in beef steers. J. Anim. Sci. 80:1112–1116.[Abstract/Free Full Text]

Swanson, K. C., J. C. Matthews, A. D. Matthews, J. A. Howell, C. J. Richards, and D. L. Harmon. 2000. Dietary carbohydrate source and energy intake influence the expression of pancreatic alpha-amylase in lambs. J. Nutr. 130:2157–2165.[Abstract/Free Full Text]

Taniguchi, K., G. B. Huntington, and B. P. Glenn. 1995. Net nutrient flux by visceral tissues of beef steers given abomasal and ruminal infusions of casein and starch. J. Anim. Sci. 73:236–249.[Abstract]

Tsai, A., M. R. Cowan, D. G. Johnson, and P. M. Brannon. 1994. Regulation of pancreatic amylase and lipase gene expression by diet and insulin in diabetic rats. Am. J. Physiol. 267:G575–G583.

Walker, J. A., D. L. Harmon, K. L. Gross, and G. F. Collings. 1994a. Evaluation of nutrient utilization in the canine using the ileal cannulation technique. J. Nutr. 124:2672S–2676S.

Walker, J. A., C. R. Krehbiel, D. L. Harmon, G. St. Jean, W. J. Croom, Jr., and W. M. Hagler, Jr. 1994b. Effects of slaframine and 4-diphenylzcetoxy-N-methylpiperidine methiodide (4DAMP) on pancreatic exocrine secretion in the bovine. Can. J. Physiol. Pharmacol. 72:39–44.[Medline]

Walker, J. A., and D. L. Harmon. 1995. Influence of ruminal or abomasal starch hydrolysate infusion on pancreatic exocrine secretion and blood glucose and insulin concentrations in steers. J. Anim. Sci. 73:3766–3774.[Abstract]

Walker, J. A., and D. L. Harmon. 1996. Technical Note: A simple, rapid assay for -amylase in bovine pancreatic juice. J. Anim. Sci. 74:658–662.[Abstract]

Wang, X. B., and K. Taniguchi. 1998. Activity of pancreatic digestive enzyme in sheep given abomasal infusion of starch and casein. Anim. Sci. Technol. 69:870–874.

Wirnt, R. 1986. Chymotrypsin. Page 1013 in Methods of Enzymatic Analysis. Vol. 2. H. Bergmeyer, ed. Academic Press, New York.

This article has been cited by other articles:

				K. C. Swanson, N. Kelly, H. Salim, Y. J. Wang, S. Holligan, M. Z. Fan, and B. W. McBride Pancreatic mass, cellularity, and {alpha}-amylase and trypsin activity in feedlot steers fed diets differing in crude protein concentration J Anim Sci, April 1, 2008; 86(4): 909 - 915. [Abstract] [Full Text] [PDF]

				K. C. Swanson, J. A. Benson, J. C. Matthews, and D. L. Harmon Pancreatic exocrine secretion and plasma concentration of some gastrointestinal hormones in response to abomasal infusion of starch hydrolyzate and/or casein J Anim Sci, June 1, 2004; 82(6): 1781 - 1787. [Abstract] [Full Text] [PDF]

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Richards, C. J. Articles by Huntington, G. B. Search for Related Content PubMed PubMed Citation Articles by Richards, C. J. Articles by Huntington, G. B.