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Intestinal starch disappearance increased in steers abomasally infused with starch and protein^1,2

C. J. Richards^*,3, A. F. Branco^*, D. W. Bohnert^*,4, G. B. Huntington, M. Macari and D. L. Harmon^*,5

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

⁵ Correspondence:
814 W.P. Garrigus Bldg. (phone: 859-257-7516; fax: 859-257-3412; E-mail:
dharmon{at}uky.edu).

	Abstract

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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.

Key Words: Beef Cattle • Intestines • Protein Digestion • Ruminants • Starch Digestion • Steers

	Introduction

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Approximately 18 to 42% of starch consumed by beef cattle may escape ruminal digestion and be available for small intestinal digestion (Owens et al., 1986). Of the starch reaching the duodenum, 17 to 96% (Streeter et al., 1989; Zinn, 1991) may be digested in the small intestine. The quantity of starch consumed and the extent of grain processing affect the rate of passage from the rumen and the extent of ruminal fermentation. Owens et al. (1986) calculated that intestinal starch digestion is more energetically efficient than ruminal fermentation. However, shifting digestion from the rumen to the small intestine has not consistently increased feed efficiency (Axe et al., 1987; Stock et al., 1987), which suggests that ruminants have a limited ability to utilize starch in the small intestine. Recently, it has been shown that supplying a combination of protein and starch to the small intestine increases -amylase secretion (Richards et al., 1998; Wang and Taniguchi, 1998) and portal-drained visceral appearance of glucose (Taniguchi et al., 1995) over starch infusion alone. Based on these data, we hypothesized that increasing protein flow to the small intestine would increase intestinal starch digestion. Therefore, this study was conducted to quantify and evaluate the relationship between protein supply and starch disappearance in the small intestine.

	Materials and Methods

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Animals and Diets
Five Angus steers (379 ± 10 kg) were used in a 5 x 5 Latin square experimental design. Steers were surgically fitted with a ruminal cannula and double-L shaped intestinal cannulas (Streeter et al., 1991) in the duodenum (10 cm distal to the pylorus) and ileum (15 cm proximal to the ileocecal junction) as described by Bohnert et al. (1998). The University of Kentucky Animal Care and Use Committee approved surgical procedures, postsurgical animal care, and the experimental protocol. Steers were individually housed (2.5-m² pens) in a temperature-controlled room (23°C) with 16 h of light and 8 h of dark. A corn silage-based diet (Table 1) was balanced with a soybean-urea protein supplement to contain 12% CP. Chromic oxide was included in the supplement as a total digesta flow marker. Steers were offered the diet in 12 equal portions at 2-h intervals using automated feeders (Ankom Co., Fairport, NY) and were given ad libitum access to fresh water. Steers were weighed at the beginning of each period and DMI was adjusted to 1.65% of BW.

Experimental Periods and Sampling.
Experimental periods consisted of 17 d with 14 d of infusion and sampling followed by 3 d of rest (no infusion). Silage and supplement samples were collected from d 10 to 14 of each period and composited. During the 14 d of infusion, the first 12 d were used for adaptation and the last 2 d for sampling of ruminal fluid, ruminal contents, duodenal and ileal digesta, feces, and blood. On d 13, samples were taken from 0800 to 1800, and on d 14 samples were taken from 0900 to 1900. Duodenal digesta (250 g) and ruminal fluid (100 mL) were sampled every 2 h. Ileal digesta (250 g) and feces (100 g) were sampled every 4 h. Ruminal fluid was sampled only on d 13. The schedule allowed collection of 12 duodenal digesta samples and six ruminal fluid, ileal digesta, and fecal samples. After the last sampling on d 14, jugular blood samples (20 mL) were collected by venipuncture using heparinized syringes and placed into vacutainer tubes containing NaF (Fisher Scientific, #02-688-69). Plasma was harvested (centrifuged at 15,000 x g, 4°C) and frozen (-20°C) for subsequent analysis of glucose (Sigma Diagnostics Procedure 16-UV) and urea (Marsh et al., 1965).

Duodenal and ileal digesta samples were frozen until the formation of composite samples by steer within period. Duodenal and ileal composite samples were formed by combining 100 g from each duodenal and ileal sample and homogenizing for 1 min (Waring blender; Waring Products, New Hartford, CT). Composite duodenal and ileal samples were lyophilized. Fecal subsamples (equal wet weights) were composited by steer within period and frozen. Feed and fecal samples were dried in a forced-air oven at 55°C for 48 and 96 h, respectively. Samples were ground through a 1-mm screen (Cyclotec 1093 Sample Mill; Tecator, Hoganas, Sweden) and analyzed for DM, OM (AOAC, 1990), N (Leco FP-2000, Leco Corp., St. Joseph, MI), and starch (Herrera-Saldana and Huber, 1989). Samples were prepared for Cr analysis (Williams et al., 1962) and analyzed by atomic absorption using a nitrous oxide/acetylene flame (Unicam 929 AA Spectrometer; ATI Unicam, Cambridge, UK). Sample Cr and nutrient concentrations were used to determine nutrient flows (Merchen, 1988).

Ruminal fluid (100 mL) was collected and pH measured immediately (Accumet Basic pH Meter, Fisher Scientific). Ruminal fluid samples (5 mL) were acidified with 1 mL of 25% (wt/vol) metaphosphoric acid and stored frozen (-20°C). Frozen ruminal fluid samples were thawed, centrifuged (39,000 x g for 20 min, 4°C), and the supernatant collected for analysis of VFA (Bock et al., 1991) and ammonia N (Broderick and Kang, 1980).

Statistics.
Data were analyzed as a 5 x 5 Latin square design using the GLM procedure of SAS (SAS Inst. Inc., Cary, NC). The model contained period, steer, and casein infusion treatment. Linear and quadratic orthogonal contrasts were performed for the effects of casein infusion treatment. Treatment effects were considered significantly different at P < 0.05. Ruminal VFA, ammonia N, and pH data collected at set times over the sampling period were analyzed as repeated measures. No treatment x time interactions were detected; therefore, measurements were averaged across time, and treatment means were compared as previously described. All nutrient disappearance values were calculated as a percentage of the nutrient flowing into that segment. Infused nutrients were subtracted from duodenal nutrient flows before calculating stomach disappearances. When intake or infusion problems compromised collections from a steer, the collection was repeated after completion of the initial treatment randomization. Repeat collections were performed for one steer for each of the 0°C, 100°C, and 200°C treatments. Due to the failure of ileal cannulas in two steers, we were unable to obtain intestinal disappearance results for two animals on the 100°C treatment. The two observations without ileal measures were not included in the statistical analysis and least squares means were calculated.

	Results and Discussion

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Organic Matter Disappearance.
Duodenal OM flow tended (P < 0.09) to increase linearly with increased casein infusion (Table 2). However, when corrected for differences in infused casein, duodenal OM flow was unchanged (linear: P > 0.21; quadratic: P > 0.56). Organic matter flow at the ileum and feces was not affected by casein infusion. Apparent OM disappearance (quantity and percentage of intake) in the stomach (linear: P < 0.18) tended to decrease with increased casein infusion. The quantity (g/d; P < 0.02 ) and percentage of apparent OM disappearance (percent duodenal flow; P < 0.03) in the small intestine increased linearly with increased casein infusion. However, differences in infused casein are included in duodenal flows and small intestinal disappearances. When we assumed that infused casein would be completely digested and performed corrections to duodenal flows and small intestinal disappearances, there was still a linear increase (P < 0.05) in the quantity, but only a tendency (P < 0.10) for an increase in the percentage of OM disappearance in the small intestine. Differences in small intestinal OM disappearance, corrected for casein infusion, are consistent with the tendency for increased OM flow to the duodenum and the trend for reduced OM disappearance in the stomach as casein infusion increases. The quantity and percent of apparent OM disappearance in the large intestine and total tract were not affected by the infusion of casein.

Starch Disappearance.
The quantity of apparent starch disappearance in the stomach tended to decrease (Table 4; P < 0.07) and the percentage of apparent starch disappearance decreased (P < 0.01) in the stomach with abomasal casein infusion. Starch disappearance in the stomach paralleled the tendencies observed for OM disappearance in the stomach. The reduction in stomach starch disappearance resulted in a linear increase (P < 0.01) in duodenal starch flow with increased casein infusion. This is in contrast to the lack of change detected in duodenal OM or CP flows corrected for infused casein. The percentage of starch that disappeared in the small intestine did not change. This resulted in greater quantities (P < 0.01) of starch disappearing in the small intestine. Differences in duodenal starch flow were altered by digestion in the small intestine, which resulted in the quantities of starch flowing past the ileum and appearing in the feces not being affected by treatment.

The apparent small intestinal starch disappearance percentages for all treatments in this study are lower than the 67% disappearance obtained when cornstarch was infused into the abomasum at 40 g/h in unadapted steers (Kreikemeier et al., 1991). Although starch was infused at a rate of 43 g/h in the current study, duodenal flows ranged from 53 to 67 g/h, with an average of 60 g/h. The average percentage and quantity of starch disappearing in the small intestine for all five of the current treatments is 54% and 34 g/h, which is comparable to the 55% and 33 g/h reported by Kreikemeier et al. (1991) with 60 g/h infusions.

Normally, increasing the amount of starch escaping ruminal fermentation (Russell et al., 1981; Owens et al., 1986) or supplied postruminally (Little et al., 1968; Kreikemeier et al., 1991) results in a greater quantity but decreased percentage (percentage of flow to the duodenum) of starch disappearing from the small intestine. With greater quantities of starch calculated to be flowing to the duodenum with increased casein infusion in the current study, there is no change in the disappearance percentage. This is similar to results from small intestinal starch digestion data of Milton et al. (1992). In their study, steers fed 75% concentrate diets at two energy and protein levels had increased quantities of starch disappearing from the small intestine as the energy level increased, but starch disappearance (percentage of duodenal flow) did not change. Postruminal protein infusion has also been shown to increase the percentage of starch disappearing from the small intestine. Taniguchi et al. (1993) infused casein into the abomasum of sheep maintained on intragastric infusion. Small intestinal disappearance of starch increased from 55 to 93%.

The apparent quantity of large intestinal starch disappearance (Table 4) was unaffected by treatment, whereas the percentage of large intestinal digestion tended to increase (P = 0.15). Trends for the increase in quantity (P = 0.20) and percentage (P = 0.22) of total-tract apparent starch disappearance agree with results from steers abomasally infused with starch and ruminally or abomasally infused with casein (Taniguchi et al., 1995). For Taniguchi et al. (1995), abomasal casein infusion tended to increase the percentage of apparent total-tract starch disappearance and doubled the portal-drained visceral flux of glucose. Increasing the quantity of dietary CP supplied has also increased total-tract starch disappearance. Veira et al. (1980) fed weaned Holstein calves high-concentrate diets with 0 to 15% soybean meal replacing cracked corn and showed that total-tract apparent starch disappearance increased linearly with increased dietary protein.

Streeter and Mathis (1995) fed beef steers high-concentrate diets with fish meal supplemented to supply 0, 25, 50, and 75 g/d of additional N to represent 1.0- to 1.5-fold of the steers’ CP requirement. They regressed starch disappearance in the small intestine with N flow to the duodenum and found a poor relationship. However, when they regressed percent starch disappearance to percent N disappearance, starch disappearance increased 0.9% units for each percentage unit increase in N disappearance. In the current study, regressing percent starch disappearance on percentage CP disappearance results in a poor relationship (r² = 0.31). This is because of a lack of change in the percent starch disappearance in this experiment. However, the expression of intestinal disappearance as a percentage of nutrients flowing to the segment does not account for quantities flowing to the segment or potential differences in the extent of nutrient digestion. This suggests that the relationship between the quantities of N and starch disappearing may be of greater significance. We regressed the average quantity of starch disappearance as a function of the average quantity of CP disappearing for each treatment in the current study:

y = 1.223x - 29.114 (r² = 0.87)

where x is the quantity of small intestinal protein disappearance and y is equal to the quantity of starch disappearance. If the regression intercept is set to 0, y = 1.1812x (r² = 0.87). These regressions indicate that increases in the quantity of CP disappearing are positively associated with increases in the quantity of starch disappearing.

Several reports have suggested from indirect evidence that increased pancreatic -amylase secretion, in response to increased duodenal CP supply is responsible for improvements in small intestinal starch disappearance. In sheep (Castlebury and Preston, 1993; Taniguchi et al., 1993) and beef steers (Taniguchi et al., 1995), small intestinal starch disappearance or net absorption of glucose has increased with infusion of casein into the abomasum. This may then be related to the increased synthesis and secretion of pancreatic -amylase that has occurred with greater CP flows to the duodenum in sheep (Magee, 1961; Wang and Taniguchi, 1998) and the greater concentrations and total secretion of -amylase in pancreatic juice from steers infused with starch and increasing quantities of protein into the abomasum (Richards et al., 1998).

Plasma and Ruminal Measures.
Treatments did not affect plasma glucose or urea concentrations (Table 5). The effect of intestinal CP supply on plasma glucose concentrations is not clear. Feeding a 90% concentrate diet and infusion of 150 or 300 g/d of casein into the abomasum did not alter arterial glucose concentrations in steers (Guerino et al., 1991). In lactating cows fed a 56% concentrate diet and infused with 0, 240, or 460 g/d of casein into the abomasum, Konig et al. (1984) found no differences in plasma glucose concentrations. In contrast, increased plasma glucose concentrations have been reported with increased dietary CP in prepartum sheep (McNeill et al., 1998) or cows (Putnam and Varga, 1998) fed approximately 50% concentrate diets.

Ruminal pH and concentrations of ammonia were not affected by abomasal infusion of casein. Ruminal pH was not expected to change with abomasal infusion and was monitored to ensure the effectiveness of our abomasal infusions. If starch infused through the reticular-omasal orifice was being digested in the rumen, ruminal pH could have decreased. Ruminal ammonia concentrations ranged from 4.63 to 5.58 mM, which are above the reported levels needed to maximize rumen microbial growth (Satter and Slyter, 1974; Slyter et al., 1979). Therefore, ruminal ammonia N was sufficient such that additional dietary N from abomasally infused casein should not affect ruminal digestion.

Total ruminal VFA concentrations increased linearly (P < 0.02) with abomasal casein infusion. However, molar percentages of individual ruminal VFA were not affected by casein infusion in the current study. Because all animals were fed equally, differences in total VFA concentrations, without changes in molar percentages, may be due to a decrease in rumen volume associated with numerically greater flows of duodenal OM as casein infusion increased. Increases in efficiency of microbial growth are also associated with increased ruminal passage rates (Isaacson et al., 1975; Owens and Bergen, 1983), but increased efficiencies in VFA production would be counteracted by the tendency for a reduction in the quantity of OM disappearing in the rumen as casein infusion increased.

If increases in ruminal VFA concentrations were related to increased VFA production, VFA may be involved in increased small intestinal starch disappearance. Although ruminal VFA concentrations or production do not necessarily correspond to plasma concentrations (Huntington, 1990) or flow to the pancreas, VFA have been shown to stimulate pancreatic -amylase secretion (Katoh and Yajma, 1989). In their study, Katoh and Yajma (1989) found that increasing in vitro concentrations of VFA resulted in increased release of pancreatic -amylase. The most potent stimulators of -amylases secretion were butyrate and isovalerate.

	Implications

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Optimizing the digestive efficiency of ruminants involves digestion in both the rumen and intestines. In ruminants fed diets with large quantities of starch reaching the duodenum, simultaneously supplying protein to the small intestine may increase the quantity of starch disappearing from that site. Whether these relationships are a viable means to improving intestinal digestibility in the fed animal remains to be determined.

	Footnotes

 
¹ This research was supported by grant no. US-2431-94 from BARD, the United States-Israel Binational Agricltural Research & Development Fund.

² Published as publication no. 01-07-178 of the Kentucky Agri. Exp. Stn.

³ Present Address: Anim. Sci. Dept., Univ. of Tennessee, 2505 River Dr., Knoxville 37996.

⁴ Present Address: Eastern Oregon Agric. Res. Center, Oregon State Univ., Burns 97720.

Received for publication January 16, 2002. Accepted for publication August 19, 2002.

	Literature Cited

Top Abstract Introduction Materials and Methods Results and Discussion Implications Literature Cited

 


AOAC. 1990. Official Methods of Analysis. 15th ed. Assoc. Offic. Anal. Chem., Arlington, VA.

Axe, D. E., K. K. Bolson, D. L. Harmon, W. N. P. Lee, G. A. Milliken, and T. B. Avery. 1987. Effect of wheat and high moisture sorghum grain fed singly and in combination on ruminal fermentation, solid and liquid flow, site and extent of digestion and feeding performance of cattle. J. Anim. Sci. 64:897–906.[Abstract/Free Full Text]

Bock, B. J., D. L. Harmon, R. T. Brandt, Jr., and J. E. Schnieder. 1991. Fat source and calcium level effects on finishing steer performance, digestion, and metabolism. J. Anim. Sci. 69:2211–2224.[Abstract]

Bohnert, D. W., B. T. Larson, M. L. Bauer, A. F. Branco, K. R. McLeod, D. L. Harmon, and G. E. Mitchell, Jr. 1998. Nutritional evaluation of poultry by-product meal as a protein source for ruminants: Effects on performance and nutrient flow and disappearance in steers. J. Anim. Sci. 76:2474–2484.[Abstract/Free Full Text]

Broderick, G. A., and J. H. Kang. 1980. Automated simultaneous determination of ammonia and total amino acids in ruminal fluid and in vitro media. J. Dairy Sci. 63:64–75.[Abstract/Free Full Text]

Castlebury, R. E., and R. L. Preston. 1993. Effect of dietary protein level on nutrient digestion in lambs duodenally infused with cornstarch. J. Anim. Sci. 71(Suppl. 1):264 (Abstr.).

Guerino, F., G. B. Huntington, and R. A. Erdman. 1991. The net portal and hepatic flux of metabolites and oxygen consumption in growing beef steers given postruminal casein. J. Anim. Sci. 69:387–395.[Abstract]

Herrera-Saldana, R., and J. T. Huber. 1989. Influence of varying protein and starch degradabilities on performance of lactating cows. J. Dairy Sci. 72:1477–1483.[Abstract/Free Full Text]

Huntington, G. B. 1990. Energy metabolism in the digestive tract and liver of cattle: influence of physiological state and nutrition. Reprod. Nutr. Dev. 30:35–47.[Medline]

Isaacson, H. R., F. C. Hinds, M. P. Bryant, and F. N. Owens. 1975. Efficiency of energy utilization by mixed rumen bacteria in continuous culture. J. Dairy Sci. 58:1645–1659.[Abstract/Free Full Text]

Katoh, K., and T. Yajma. 1989. Effects of butyric acid and analogues on amylase release from pancreatic segments of sheep and goats. Eur. J. Physiol. 413:256–260.[Medline]

Konig, B. A., J. D. Oldham, and D. S. Parker. 1984. The effect of abomasal infusion of casein on acetate, palmitate and glucose kinetics in cows during early lactation. Br. J. Nutr. 52:319–328.[Medline]

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]

Little, C. O., G. E. Mitchell, Jr. and C. M. Reitnour. 1968. Postruminal digestion of corn starch in steers. J. Anim. Sci. 27:790–792.[Abstract/Free Full Text]

Magee, D. F. 1961. An investigation into the external secretion of the pancreas in sheep. J. Physiol. 158:132–143.[Free Full Text]

Malbert, C. H., and R. Baumont. 1989. The effects of intake of lucerne (Medicago sativa L.) and orchard grass (Dactylis glomerata L.) hay on the motility of the forestomach and digesta flow at the abomaso-duodenal junction of the sheep. Br. J. Nutr. 61:699–714.[Medline]

Marsh, W. H., B. Fingerhut, and H. Miller. 1965. Automated and manual direct methods for determination of blood urea. Clin Chem. 11:624–627.[Abstract]

Mathison, G. W., E. K. Okine, A. S. Vaage, and L. P. Milligan. 1995. Current understanding of the contribution of the propulsive activities in the forestomach to the flow of digesta. Page 23 in Proc. 8th Int. Symp. Ruminant Physiol. W .V. Engelhardt, S. Leonhard-Marek, G. Breves, and D. Giesecke, ed. Ferdinand Enke Verlang, Germany.

McNeill, D. M., R. Slepetis, R. A. Ehrhardt, D. M. Smith, and A. W. Bell. 1998. Protein requirements of sheep in late pregnancy: partitioning of nitrogen between gravid uterus and maternal tissues. J. Dairy Sci. 81:1608–1618.[Abstract]

Merchen, N. R. 1988. Digestion, absorption and excretion in ruminants. Page 172 in The Ruminant Animal. D. C. Church, ed. Simon & Schuster, New York.

Milton, C. T., D. L. Harmon, C. K. Reynolds, R. C. Cochran, and J. A. Walker. 1992. Influence of ME and CP intake on digestibility and N metabolism in steers. J. Anim. Sci. 70(Suppl. 1):316(Abstr.).

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

Owens, F. N., and W. G. Bergen. 1983. Nitrogen metabolism of ruminant animals: Historical perspective, current understanding and future implications. J. Anim. Sci. 57(Suppl. 2):498–518.[Abstract/Free Full Text]

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.[Abstract/Free Full Text]

Putnam, D. E., and G. A. Varga. 1998. Protein density and its influence on metabolite concentration and nitrogen retention by Holstein cows in late gestation. J. Dairy Sci. 81:1608–1617.[Abstract]

Richards, C. J., K. C. Swanson, D. W. Bohnert, S. J. Lewis, D. L. Harmon, and G. B. Huntington. 1998. Effect of postruminal protein infusion on pancreatic exocrine secretion in beef steers. J. Anim. Sci. 76(Suppl. 1):312(Abstr).

Russell, J. R., A. W. Young, and N. A. Jorgensen. 1981. Effect of dietary cornstarch intake on ruminal, small intestinal and large intestinal starch digestion in cattle. J. Anim. Sci. 52:1170–1176.[Abstract/Free Full Text]

Satter, L. D., and L. L. Slyter. 1974. Effects of ammonia concentration on rumen microbial protein production in vitro. Br. J. Nutr. 32:199–208.[Medline]

Slyter, L. L., L. D. Satter, and D. A. Dinius. 1979. Effect of ruminal ammonia concentration on nitrogen utilization by steers. J. Anim. Sci. 48:906–912.[Abstract/Free Full Text]

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]

Streeter, M. N., S. J. Barron, D. G. Wagner, C. A. Hibberd, F. N. Owens, and F. T. McCollum. 1991. Technical note: A double L intestinal cannula for cattle. J. Anim. Sci. 69:2601–2607.[Abstract]

Streeter, M. N., and M. J. Mathis. 1995. Effect of supplemental fish meal protein on site and extent of digestion in beef steers. J. Anim. Sci. 73:1196–1201.[Abstract]

Streeter, M. N., D. G. Wagner, C. A. Hibberd, and F. N. Owens. 1989. Combinations of high-moisture harvested sorghum grain and dry-rolled corn: Effects on site and extent of digestion in beef heifers. J. Anim. Sci. 67:1623–1633.[Abstract/Free Full Text]

Swingle, R. S., T. P. Eck, C. B. Theurer, M. De la Llata, M. H. Poore, and J. A. Moore. 1999. Flake density of steam-processed sorghum grain alters performance and sites of digestibility by growing-finishing steers. J. Anim. Sci. 77:1055–1065.[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]

Taniguchi, K., Y. Sunada, and T. Obitsu. 1993. Starch digestion in the small intestine of sheep sustained by intragastric infusion without protein supply. Anim. Sci. Technol. 64:892–902.

Theurer, C. B., O. Lozano, A. Alio, A. Delgado-Elorduy, M. Sadik, J. T. Huber, and R. A. Zinn. 1999. Steam-processed corn and sorghum grain flaked at different densities alter ruminal, small intestinal, and total tract digestibility of starch by steers. J. Anim. Sci. 77:2824–2831.[Abstract/Free Full Text]

Thompson, F. 1973. The effect of frequency of feeding on the flow and composition of duodenal digesta in sheep given straw-based diets. Br. J. Nutr. 30:87–94.[Medline]

Veira, D. M., G. K. MacLoed, J. H. Burton, and J. B. Stone. 1980. Nutrition of the weaned Holstein calf. II. Effect of dietary protein level on nitrogen balance, digestibility and feed intake. J. Anim. Sci. 50:945–951.[Abstract/Free Full Text]

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.

Williams, C. H., D. J. David, and O. Iismaa. 1962. The determination of chromic oxide in feces samples by atomic absorption spectrophotometry. J. Agric. Sci. 59:381–385.

Zinn, R. A. 1991. Comparative feeding value of steam-flaked corn and sorghum in finishing diets supplemented with or without sodium bicarbonate. J. Anim. Sci. 69:905–916.[Abstract]

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