Effects of postruminal flows of amino acids on small intestinal starch digestion in cattle

EFFECTS OF POSTRUMINAL FLOWS OF AMINO ACIDS ON SMALL INTESTINAL STARCH DIGESTION IN CATTLE

Sponsoring Institution

National Institute of Food and Agriculture

Project Status

COMPLETE

Funding Source

AFRI COMPETITIVE GRANT

Reporting Frequency

Annual

Accession No.

1007874

Grant No.

2016-67016-24862

Cumulative Award Amt.

$500,000.00

Proposal No.

2015-06373

Multistate No.

(N/A)

Project Start Date

Jan 15, 2016

Project End Date

Jan 14, 2021

Grant Year

2016

Program Code

[A1231]- Animal Health and Production and Animal Products: Improved Nutritional Performance, Growth, and Lactation of Animals

Recipient Organization
SOUTH DAKOTA STATE UNIVERSITY
PO BOX 2275A
BROOKINGS,SD 57007

Performing Department
Animal Science

Non Technical Summary
Starch is an energy dense polymer of glucose that makes-up most of the dietary energy found in cereal grains (e.g., corn, sorghum, wheat). Small intestinal digestion of starch is very poor in cattle in comparison to many nonruminants (e.g., pigs, humans, mice), and almost one-third of the energy absorbed from small intestinal starch digestion contributes to omental (i.e., belly) fat accretion, which provides little benefit in production of beef or milk. Greater flow of high-quality protein (i.e., casein) or a specific amino acid (i.e., glutamic acid) can increase small intestinal starch digestion in cattle; however, little is known about how greater flows of casein or glutamic acid increase small intestinal starch digestion or potential impacts on beef or milk production. We hypothesize that greater flows of casein or glutamic acid increase small intestinal starch digestion by different mechanisms in cattle and that apparent influences on beef production will differ. This project will allow greater understanding of how increased absorption of casein or glutamic acid increase small intestinal starch digestion by directly measuring pancreatic and small intestinal enzymes that can limit small intestinal starch digestion in cattle. Additionally, this project will provide insight to the potential value of increasing small intestinal starch digestion in cattle by greater postruminal flow of casein or glutamic acid by measuring increases in dietary energy (i.e., retained energy) and quantify fates in the body from starch digested in the small intestine. It is likely that the mechanisms that increase small intestinal starch digestion in response to greater postruminal flow of casein or glutamic acid differ and differences may have large impacts on dietary energy retained by cattle. Additionally, amounts of digested starch used for omental fat accretion may be less when small intestinal starch digestion is increased in response to greater small intestinal flows of casein or glutamic acid. Greater knowledge of how postruminal flow of casein or glutamic acid increase small intestinal starch digestion in cattle and subsequent impacts on beef production may allow for broader application of diets that can increase efficiency of beef production in the United States.

Animal Health Component

50%

Research Effort Categories

Basic

50%

Applied

50%

Developmental

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
302	3310	1010	100%

Knowledge Area
302 - Nutrient Utilization in Animals;

Subject Of Investigation
3310 - Beef cattle, live animal;

Field Of Science
1010 - Nutrition and metabolism;

Keywords

Goals / Objectives
A major goal of this project is to improve knowledge of post-absorptive and metabolic effects among cattle with increased small intestinal starch digestion in response to to greater postruminal flows of glutamic acid or casein. Specific objectives of this project will include measures of : 1) increases in retained energy, 2) response among alpha-glycohydrolases important to small intestinal starch digestion in cattle, 3) fatty acid synthesis ratesamong different adipose depots from luminally assimilated glucose carbon, 4) response in hepatic gluconeogenesis, and 5) splanchnic extraction rates of luminally assimilated glucose carbon. Direct measures of small intestinal starch digestion will allow greater extrapolation of data by regression of responses relative to increased amounts of starch digested.

Project Methods
Post-absorptive and metabolic effects of increased small intestinal starch digestion in response to postruminal flow of casein or glutamic acid will be facilitated by use of typical beef cattle (i.e., British x Continetal) fitted with intestinal cannulae. Cattle will be limit-fed a diet nearly devoid of starch to minimize variation in energy intake, ruminal volatile fatty acid production and postruminal starch flow from diet that may effect response among small intestinal starch digestion to postruminal flow of casein or glutamic acid. All cattle will be provided continuous infusion of cornstarch similar to amounts of cornstarch that would flow to the small intestine of cattle consuming cereal grain-based diets. Treatments will include infusion of a high-quality protein (i.e., casein), glutamic acid or water (control). Direct measures of retained energy will include indirect calorimetry and collection of feces and urine. Hepatic gluconeogenesis, splanchnic extraction of luminally assimilated starch, and palmitate fractional synthesis rates will be determined by use of stable isotopomers. Activitiy of pancreatic and small intestinal alpha-glycohydrolases will be quantified from tissue homogenates. Data will be analyzed using commonly accepted statistical methods and interpreted in a manner that will minimize potential for error. Efforts to cause a change in knowledge and actions of the target audience will include: 1) publication of abstracts and presentation of results at scientific conferences, 2) training of graduate students, and 3) publication of producer focused articles. Outputs will be evaluated by number of peer-reviewed articles, abstracts, and producer articles published and number of students trained.

Progress 01/15/16 to 01/14/21

Outputs
Target Audience:The target audience in the final year of this project included scientists, academics, graduate students, and professionals interested in the field of ruminant nutrition. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?During this project we trained 2 Ph.D. students (Subash Acharya and Emily Petzel) and 2 M.S. students (Leonardo Sitorski and Ronald Trotta). These students were involved in data collection using live animals, and learned about experimental design, statistical analysis of data, and transitioning data into presentations and publications The M.S. students successfully defended their theses and graduated. The two Ph.D. students continue to make good progress toward completion of their dissertations. SA anticipated date of graduation is May 2021, and EP anticipated date of graduation is December 2021. How have the results been disseminated to communities of interest?A peer-reviewed paper related to impacts of postruminal flows of casein or glutamic acid on small intestinal enzyme concentration and tissue morphology was published in the Journal of Nutrition. We also presented preliminary data and a synopsis of this experiment at the International Symposium on Ruminant Physiology. An abstract and proceedings of this presentation were published in Advances in Animal Biosciences. Additionally, these data were also published in a M.S. thesis published from North Dakota State University. Data related to the impact of postruminal glutamic acid and casein flows on small intestinal starch digestion, total-tract nutrient balance, and energy balance were presented at the American Dairy Science Association Annual Meeting. A manuscript including data related to effects of casein or glutamic acid flow on small intestinal starch digestion and energy balance has been prepared for peer-review in a journal with readership that includes our targeted audience (e.g., Journal of Dairy Science, Journal of Nutrition, Journal of Animal Science). A manuscript including data on effects of postruminal glutamic acid or casein flows on hepatic gluconeogenesis and fractional palmitate synthesis rates in different lipid depots is in preparation for publication. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Goal 1: Improve knowledge of post-absorptive and metabolic effects among cattle with increased small intestinal starch digestion in response to greater postruminal flows of glutamic acid or casein. (85% accomplished) Animal work occurred in 4 blocks of 6 British-influence steers (initial BW = 180.4 ± 19.8 kg) fitted with duodenal and ileal cannulas. Steers were fitted with duodenal and ileal cannulas and limit-fed a soybean hull based diet and duodenally infused with raw cornstarch (1.45 ± 0.00176 kg/d) and either 412 ± 0.62 g casein/d, 121 ± 0.16 g glutamic acid/d, or water (control) for 58 days. We have completed animal work regarding the impacts of postruminal flows of glutamic acid or casein on small intestinal and pancreatic enzyme activity. Additionally, tissue samples were collected from 2 additional steers prior to initiating work within each block of animals. These tissues will be used to determine background enrichments of each isotopomer infused at the end of the study. Additionally, body composition was estimated from 3 of the 4 blocks and this data will be used to compare measures of energetics from infusions with measures obtained by indirect calorimetry. Laboratory analyses of digesta have been completed. Analyses completed to this point indicate that casein increased final body weight by 18% compared to infusions of glutamic acid or control (P=0.003), and average daily gain was nearly 3-times greater among steers provided infusions of casein compared to steers infused with glutamic acid or control (P<0.001). Pancreatic mass, protein concentration, and trypsin activity were unaffected by treatments. Casein increased alpha-amylase activity by 183% (P<0.05) and the alpha-amylase:trypsin ratio by 216% (P<0.001). Small intestinal mass, length, and mass:length were not affected by treatment. Casein tended to increase isomaltase activity (P=0.10) in the jejunum by 60%, but isomaltase activity did not differ between treatments in the duodenum or ileum. Glutamic acid increased (interaction P=0.01) maltase activity in the ileum by 59.8% and casein increased (interaction P=0.01) maltase activity in the jejunum by 80.1%. These results suggest that small intestinal starch digestion may be improved with increased small intestinal flow of casein or glutamic acid through increases in post-ruminal alpha-glycohydrolase activities. Evaluation of nutrient flows to the ileum among cattle in the project revealed that small intestinal starch digestion tended (P = 0.11) to be 26.6% greater among calves provided casein, compared to Glu or control. Additionally, measures of ileal ethanol-soluble starch (small-chain α-glycosides) flows were nearly 2-times greater (P < 0.01) among calves provided casein compared to Glu and control. Similar to measures of ileal starch flow, fecal starch flow tended (P = 0.10) to be least among calves provided casein, and was not different between Glu or control. Fecal flow of ethanol-soluble starch was similar (P = 0.89) across treatments. Overall, large intestinal starch digestion was similar (P = 0.39) across treatments, but postruminal starch digestion tended to be greater (P = 0.15) among calves provided casein compared to calves that received postruminal infusions of cornstarch or cornstarch and Glu. Measures of energy and nitrogen balance indicated that N retention was nearly 2-times greater (P < 0.01) in response to casein compared to control and Glu, which did not differ. Duodenal infusion of casein tended (P = 0.15) to decrease fecal energy output compared to duodenal infusion of Glu or cornstarch alone, which resulted in measures of digestible energy (P = 0.04) that were greatest among calves infused with casein, and did not differ between calves provided Glu or control. There were no differences in urinary (P = 0.69) or methane energy (P = 0.90) losses. Thus, duodenal infusion of casein also increased (P = 0.02) metabolizable energy and measures of metabolizable energy were not different between Glu and control. However, measures of heat production tended (P = 0.06) to be 19% greater among calves infused with casein and 6% greater in calves provided Glu compared to calves infused with cornstarch alone. Overall, retained energy tended (P = 0.12) to be 34% greater among calves provided casein and 10% greater among calves provided duodenal infusion of Glu compared to control. To date we have published 3 peer-reviewed manuscripts. Additionally, we have presented 4 presentations at professional national and international conferences and the contents of these presentations have been published as proceedings in several leading agricultural journals. Furthermore, we plan to submit at least 2 more publications for review and present further findings at another national meeting of animal science professionals. The discovery that postruminal infusion of casein, but not glutamic acid, has long-term impacts provides data that indicate that differences in postruminal protein flow is important to increasing the efficiency with which cattle convert corn-based diets to meat and milk. Laboratory analyses of stable isotopic enrichment of carbon and hydrogen isomers in different lipid tissues were completed in 2020 and these data have been evaluated. A manuscript including data related to small intestinal starch digestion, nutrient and energy balance has been prepared for publication in a peer-reviewed journal. A second manuscript including data on effects of postruminal glutamic acid or casein flows on hepatic gluconeogenesis and fractional palmitate synthesis rates in different lipid depots is in preparation for publication.

Publications

Type: Journal Articles Status: Published Year Published: 2020 Citation: Trotta, R.J., L.G. Sitorski, S. Acharya, D.W. Brake, and K.C. Swanson. 2019. Duodenal infusions of starch with casein or glutamic acid influence pancreatic and small intestinal carbohydrase activities in cattle. J. Nutr. DOI: 10.1093/jn/nxz319.
Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Acharya, S., E. A. Petzel, E. A. Bailey and D. W. Brake. Effects of duodenal casein and glutamic acid infusion on small intestinal starch digestion and energy and nitrogen balance in cattle. J. Dairy Sci. 103(Suppl. 1):70.
Type: Journal Articles Status: Awaiting Publication Year Published: 2021 Citation: Acharya, S., E. A. Petzel, E. A. Bailey, K.M. Cammack, and D. W. Brake. Effects of long-term duodenal casein and glutamic acid infusion on small intestinal starch digestion and energy and nitrogen balance in cattle. J. Dairy Sci. (in press).
Type: Journal Articles Status: Awaiting Publication Year Published: 2021 Citation: Acharya, S., E. A. Petzel, E. A. Bailey, K.M. Cammack, and D. W. Brake. 2021. Effects of long-term duodenal casein and glutamic acid infusion on hepatic gluconeogenesis, splanchnic extraction rate of glucose and palmitate fractional synthesis rates in cattle. J. Nutr. (in press)

Progress 01/15/19 to 01/14/20

Outputs
Target Audience:The target audience in the fourth year of this project included scientists, academics, graduate students, and professionals interested in the field of ruminant nutrition. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?During the fourth year of this project we trained 2 Ph.D. students (Subash Acharya and Emily Petzel) and 2 M.S. students (Leonardo Sitorski and Ronald Trotta). These students were involved in data collection using live animals, and learned about experimental design, statistical analysis of data, and transitioning data into presentations and publications The M.S. students successfully defended their theses and graduated. The two Ph.D. students continue to make good progress toward completion of their dissertations. How have the results been disseminated to communities of interest?A peer-reviewed paper related to impacts of postruminal flows of casein or glutamic acid on small intestinal enzyme concentration and tissue morphology was published in the Journal of Nutrition. We also presented preliminary data and a synopsis of this experiment at the International Symposium on Ruminant Physiology. An abstract and proceedings of this presentation were published in Advances in Animal Biosciences. Additionally, these data were also published in a M.S. thesis published from North Dakota State University. Next year we plan to present results related to the impact of postruminal glutamic acid and casein flows on small intestinal starch digestion, total-tract nutrient balance, and energy balance at the American Dairy Science Association Annual Meeting. Additionally, we plan to submit data related to effects of casein or glutamic acid flow on small intestinal starch digestion and energy balance for publication in a peer-reviewed journal with readership that includes our targeted audience (e.g., Journal of Dairy Science, Journal of Nutrition, Journal of Animal Science). What do you plan to do during the next reporting period to accomplish the goals?Goal 1: Improve knowledge of post-absorptive and metabolic effects among cattle with increased small intestinal starch digestion in response to greater postruminal flows of glutamic acid or casein. We plan to complete laboratory analyses of stable isotopic enrichment of carbon and hydrogen isomers in different lipid tissues in 2020. Further, we plan to submit data related to small intestinal starch digestion, nutrient and energy balance for publication in a peer-reviewed journal.

Impacts
What was accomplished under these goals? Goal 1: Improve knowledge of post-absorptive and metabolic effects among cattle with increased small intestinal starch digestion in response to greater postruminal flows of glutamic acid or casein. (85% accomplished) Animal work occurred in 4 blocks of 6 British-influence steers (initial BW = 180.4 ± 19.8 kg) fitted with duodenal and ileal cannulas. Steers were fitted with duodenal and ileal cannulas and limit-fed a soybean hull based diet and duodenally infused with raw cornstarch (1.45 ± 0.00176 kg/d) and either 412 ± 0.62 g casein/d, 121 ± 0.16 g glutamic acid/d or water (control) for 58 days. We have completed animal work regarding the impacts of postruminal flows of glutamic acid or casein on small intestinal and pancreatic enzyme activity. Additionally, tissue samples were collected from 2 additional steers prior to initiating work within each block of animals. These tissues will be used to determine background enrichments of each isotopomer infused at the end of the study. Additionally, body composition was estimated from 3 of the 4 blocks and this data will be used to compare measures of energetics from infusions with measures obtained by indirect calorimetry. Laboratory analyses of digesta have been completed. We anticipate completion of laboratory analyses in 2020. Analyses completed to this point indicate that casein increased final body weight by 18% compared to infusions of glutamic acid or control (P=0.003) and average daily gain was nearly 3-times greater among steers provided infusions of casein compared to steers infused with glutamic acid or control (P<0.001). Pancreatic mass, protein concentration, and trypsin activity were unaffected by treatment. Casein increased a-amylase activity by 183% (P<0.05) and the a-amylase:trypsin ratio by 216% (P<0.001). Small intestinal mass, length, and mass:length were not affected by treatment. Casein tended to increase isomaltase activity (P=0.10) in the jejunum by 60%, but isomaltase activity did not differ between treatments in the duodenum or ileum. Glutamic acid increased (interaction P=0.01) maltase activity in the ileum by 59.8% and casein increased (interaction P=0.01) maltase activity in the jejunum by 80.1%. These results suggest that small intestinal starch digestion may be improved with increased small intestinal flow of casein or glutamic acid through increases in post-ruminal a-glycohydrolase activities. To date we have published 2 peer-reviewed manuscripts. Additionally, we have presented 3 presentations at professional national and international conferences and the contents of these presentations have been published as proceedings in several leading agricultural journals. Furthermore, we plan to submit at least 2 more publications for review in 2020 and present further findings at another national meeting of animal science professionals. The discovery that postruminal infusion of casein, but not glutamic acid, has long-term impacts provides data that indicate that differences in postruminal protein flow is important to increasing the efficiency with which cattle convert corn-based diets to meat and milk.

Publications

Type: Journal Articles Status: Published Year Published: 2018 Citation: Brake, D.W., and K.C. Swanson. 2018. RUMINANT NUTRITION SYMPOSIUM: Effects of postruminal flows of protein and amino acids on small intestinal starch digestion in beef cattle. J. Anim. Sci. 96:739-750. DOI:10.1093/jas/skx058
Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Brake, D.W. 2018. Nutrition of glutamate, glutamine, glycine, proline, and arginine in ruminants. Am. Soc. Anim. Sci. Annual Mtg. July 9-12. Vancouver, Canada.
Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Trotta, R., L. Sitorski, S. Acharya, D. Brake, and K. Swanson. 2019. Duodenal infusions of starch with casein or glutamic acid increase postruminal ?-glycohydrolase activities in cattle. Adv. Anim. Biosci. 10:510.
Type: Journal Articles Status: Published Year Published: 2019 Citation: Trotta, R.J., L.G. Sitorski, S. Acharya, D.W. Brake, and K.C. Swanson. 2019. Duodenal infusions of starch with casein or glutamic acid influence pancreatic and small intestinal carbohydrase activities in cattle. J. Nutr. ACCEPTED Nov. 30, 2019. DOI PENDING.

Progress 01/15/18 to 01/14/19

Outputs
Target Audience:The target audience in the third year of this project included scientists, academics, graduate students, and professionals interested in the field of ruminant nutrition. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?During the fourth year of this project we trained 2 Ph.D. students (Subash Acharya and Emily Petzel) and 1 M.S. student (Leonardo Sitorski). These students were involved in data collection using live animals, and learned about experimental design, statistical analysis of data, and transitioning data into presentations and publications The M.S. student successfully defended his thesis and matriculated. The two Ph.D. students continue to make good progress toward completion of their thesis. How have the results been disseminated to communities of interest?A peer-reviewed paper was published in the Journal of Animal Science. We also presented preliminary data and a synopsis of this experiment at the Annual ASAS-CSAS meeting in Vancouver, Canada. An abstract of this presentation was published in the Journal of Animal Science. Next year we plan to present results related to impacts of postruminal flows of casein or glutamic acid on small intestinal enzyme concentration and tissue morphology at the International Symposium on Ruminant Physiology (September, 2019). Additionally, we plan to submit data related to effects of casein or glutamic acid flow on small intestinal starch digestion and energy balance to be presented at the 6th EAAP International Symposium on Energy and Protein Metabolism and Nutrition (September, 2019). What do you plan to do during the next reporting period to accomplish the goals?Goal 1: Improve knowledge of post-absorptive and metabolic effects among cattle with increased small intestinal starch digestion in response to greater postruminal flows of glutamic acid or casein. We plan to complete analyses of the digesta and present finding related to small intestinal digestibility, nutrient and energy balance. We plan to complete laboratory analyses of stable isotopic enrichment of carbon and hydrogen isomers in different lipid tissues in 2019. Further, we plan to present finding at the International Symposium on Ruminant Physiology in Leipzig, Germany in September 2019. Additionally, we plan to submit data related to small intestinal starch digestion, nutrient and energy balance for publication in a peer-reviewed journal.

Impacts
What was accomplished under these goals? Goal 1: Improve knowledge of post-absorptive and metabolic effects among cattle with increased small intestinal starch digestion in response to greater postruminal flows of glutamic acid or casein. (80% accomplished) Animal work in this project is designed to occur in 4 blocks of 6 steers. Currently, we have completed animal work. Additionally, tissue samples were collected from 2 additional steers prior to initiating work within each block of animals. These tissues will be used to determine background enrichments of each isotopomer infused at the end of the study. Additionally, body composition was estimated from 3 of the 4 blocks and this data will be used to compare measures of energetics from infusions with measures obtained by indirect calorimetry. Laboratory analyses of digesta have been completed. We anticipate completion of laboratory analyses by 2019. Analyses completed to this point indicate that casein increased final body weight (P=0.003) and average daily gain (P<0.001). Pancreatic mass, protein concentration, and trypsin activity were unaffected by treatment. Casein increased a-amylase activity (P<0.05) and the a-amylase:trypsin ratio (P<0.001). Mass of the small intestine was greatest (P<0.001) in the ileum. Small intestinal mass, length, and mass:length were not affected by treatment. Casein increased small intestinal protein concentration (P=0.05). Isomaltase activity tended to increase (interaction P=0.07) with glutamic acid in the ileum and with casein in the jejunum and ileum. Glutamic acid increased (interaction P=0.01) maltase activity in the ileum and casein increased (interaction P=0.01) maltase activity in the jejunum and ileum. Glucoamylase activity was greatest (P<0.001) in the ileum. These results suggest that small intestinal starch digestion may be improved with increased small intestinal flow of casein or glutamic acid through increases in post-ruminal a-glycohydrolase activities.

Publications

Type: Journal Articles Status: Published Year Published: 2018 Citation: Brake, D. W., and K. C. Swanson. 2018. RUMINANT NUTRITION SYMPOSIUM: Effects of postruminal flows of protein and amino acids on small intestinal starch digestion in beef cattle. J. Anim. Sci. 96:739-750. DOI:10.1093/jas/skx058
Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Brake, D. W. 2018. Nutrition of glutamate, glutamine, glycine proline and arginine in ruminants. Am. Soc. Anim. Sci. Annual Mtg. July, July 9 - 12. Vancouver, Canada.

Progress 01/15/17 to 01/14/18

Outputs
Target Audience:The target audience of this project included scientists, academics, graduate students and professionals interested in the field of ruminant nutrition. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Three graduate students (Subash Acharya, Ph.D; Emily Petzel, Ph.D.; and Leonardo Sitorski, M.S.) have made good progress toward completion of their thesis. Two doctoral students have been trained in infusion methods, indirect calorimetry procedures and tissue collection methods. Further, each student has had opportunity to develop general laboratory techniques, technical writing skills, and make presentations to professional audiences. How have the results been disseminated to communities of interest?During the second year of this project, we presented our experimental approach, hypotheses and a thorough review of literature relevant to impacts of postruminal protein or amino acids on small intestinal starch digestion in cattle at the national ASAS conference in Baltimore. Additionally, a peer-reviewed paper that corresponded to our presentation at the ASAS meeting was published in the Journal of Animal Science. What do you plan to do during the next reporting period to accomplish the goals? Goal 1: Improve knowledge of post-absorptive and metabolic effects among cattle with increased small intestinal starch digestion in response to greater postruminal flows of glutamic acid or casein. We plan to complete the fourth and final block of cannulated by August or September of 2018. Currently, we have begun laboratory analyses related to samples collected from the first 3 blocks of cattle. We plan to continue laboratory analyses and complete this work in 2019.

Impacts
What was accomplished under these goals? ? Goal 1: Improve knowledge of post-absorptive and metabolic effects among cattle with increased small intestinal starch digestion in response to greater postruminal flows of glutamic acid or casein. (40% accomplished) During the second year of this project, we trained 2 Ph.D. and 1 M.S. student. Animal work in this project is designed to occur in 4 blocks of 6 steers. Currently, we have completed animal work with 3 of 4 blocks of cannulated cattle. Tissue samples have been collected from 2 additional steers prior to initiating work with each block of animals. These tissues will be used to determine background enrichments of each istopomer infused at the end of the study. Additionally, body composition was estimated from 2 of the 3 blocks and this data will be used to compare measures of energetics from infusions with measures obtained by indirect calorimetry. The final block of cattle has been acquired and we anticipate to have completed the animal work for this study by August or September of 2018. Laboratory analyses of digesta and tissue samples have begun. We anticipate completion of laboratory analyses by 2019.

Publications

Type: Journal Articles Status: Accepted Year Published: 2018 Citation: Brake, D. W., and K. C. Swanson. 2018. RUMINANT NUTRITION SYMPOSIUM: Effects of postruminal flows of protein and amino acids on small intestinal starch digestion in beef cattle. J. Anim. Sci. 96:739-750. DOI:10.1093/jas/skx058

Progress 01/15/16 to 01/14/17

Outputs
Target Audience:The target audience reached in the first year of this project were scientists, academics and graduate students. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Three graduate students (i.e., Subash Acharya, Brooke Brunsvig and Leonardo Sitorski) have begun their doctoral and master's research on this project. Two doctoral students have been trained to infusion methods, indirect calorimetry procedures and tissue collection methods. How have the results been disseminated to communities of interest?During the first year of this project we presented our experimental approach and hypotheses to scientists and academics at South Dakota State University and at an annual PI meeting. What do you plan to do during the next reporting period to accomplish the goals?Goal 1: Improve knowledge of post-absorptive and metabolic effects among cattle with increased small intestinal starch digestion in response to to greater postruminal flows of glutamic acid or casein. Measures of increases in retained energy, response among alpha-glycohydrolases important to small intestinal starch digestion in cattle, fatty acid synthesis ratesamong different adipose depots from luminally assimilated glucose carbon, response in hepatic gluconeogenesis, and splanchnic extraction rates of luminally assimilated glucose carbon will be quantified from 12 of the 24 steers to be used in this experiment. Additionally, our experimental approach and hypotheses will be presented at the National American Society of Animal Science Meeting in Baltimore in July.

Impacts
What was accomplished under these goals? Goal 1: Improve knowledge of post-absorptive and metabolic effects among cattle with increased small intestinal starch digestion in response to to greater postruminal flows of glutamic acid or casein. (20% accomplished) During the first year of this project, we recruited 2 Ph.D. and 1 M.S. students to particpate in this experiment. Animal work in this project will take place across 4 replicates of 6 steers. Currently, the first replicate of 6 steers has been fitted with intestinal cannulas and are receiving infusions of starch and casein, glutamic acid or water. Tissue samples were collected from 2 additional steers acquired within the same cohort as the 6 steers in the first replicate of the experiment. These tissue samples will be used to determine basal levels of stable isotopomers in cattle and to estimate body composition at the beginning of the experiment. The first replicate in this experiment will be completed March 4, 2017 and the second replicate will be initiated this summer.

Publications