Nutrition Research Programs

 My overall program of research and graduate training has been 1) to carry out a beef cattle research program emphasizing applied problems in cattle feeding, growth and development of bulls, and cow/calf management; and 2) to engage in cooperative research with other faculty in the area of fundamental ruminant nutrition.  With increased economic pressure to become more efficient, beef cattle producers are continually in need of new information and methods which improve their efficiency of production.  My research program has focused on selenium, copper, and zinc supplementation levels best suited to the cow/calf industry in Virginia.  Monocyte and immune function has been studied and recommendations have been given to cattle producers experiencing these mineral deficiencies.

Major Activities Underway:

 Two studies are currently being conducted with the beef teaching herd.  One study is assessing the effects of late gestation vitamin E supplementation on maternal and calf serum vitamin E concentrations, and determining the effects of maternal supplementation on calf growth.  The other study involves body condition scoring (BCS) cows at three strategic times:  calving, breeding, and weaning.  Changes in body condition are then determined by using ultrasonography.  The primary goal of this study will be to correlate actual fat thickness with BCS.

Progress (past 5 years):

 Seven abstracts have been presented at national meetings, and four refereed journal articles have been published.  All studies have been reported in the Virginia Tech Livestock Research Report, and several were summarized in the popular press.

Cooperative Work:

 Laboratory analyses are done in the College of Veterinary Medicine.  Several faculty with similar interests from the veterinary school have collaborated in these applied beef cattle studies.

Future Plans:

 There is interest among beef producers in the value of by-product feeds in beef cattle diets. A pilot study with wet brewers’ grain was conducted earlier in the development of heifer calves.  Short-term studies will continue in this area of by-product feeding.
 

 The major goal of my research program is the efficient production of animal products, which will be nutritious and safe, while enhancing the environment.  The program encompasses both basic and applied research.  The main areas of emphasis are utilization of forages and underutilized by-products.  The research is coordinated with the graduate-training program.

Major Activities Underway:

 The research in progress includes forage utilization, nutrient management, and sustainable forage livestock systems.  The work on forage utilization includes evaluation of different forages and adaptability of different forages in forage-cattle systems.  The work on nutrient management includes studies to lower excretion of nitrogen and phosphorus and relative effect of application of plant nutrients by feeding or soil application of animal waste.

Progress (past 5 years):

 Mixtures of poultry litter and apple pomace ensiled satisfactory.  Dry matter digestibility of the mixtures was about 50%.  Feeding beef cattle up to 90% of apple pomace-litter silage produce similar gains as feeding alfalfa hay.  A number of chemicals were effective in preserving crab-processing waste.  Feeding crab meal as a supplement produced similar gains in beef cattle as soybean meal.  Protein separated from crab processing waste produced satisfactory gains in chicks when substituted for 25% of soybean protein.  Performance was similar for beef steers fed broiler litter on fescue pasture or grazing fescue fertilized with broiler litter.  Mineral composition of forages and blood serum were in normal ranges.  Inclusion of warm season perennials such as bluestem and bermudagrass fill the gap in year-round grazing.  Best performance was obtained with cattle grazing fescue/clover with bluegrass or bermudagrass in year-round forage-cattle systems. Phosphorus and protein supplementation may be reduced, thereby decreasing phosphorus and nitrogen contamination in water supplies.  In a sustainable forage livestock system, use of rotation and more legumes reduced markedly soil application of nitrogen and pesticide and herbicide application, and had no effect on performance of cattle and profitability.

Cooperative Work:

 Most of the research is cooperative with scientists from other disciplines such as soil science, forages, entomology, veterinary medicine, agricultural engineering and agricultural economics on campus.  Also, some research was conducted in cooperation with other universities.

Future Plans:

 Research will be continued on year-round forage systems; evaluations of different forages; nutrient management to reduce nitrogen and phosphorus excretion, and optimizing utilization of poultry litter and other by-products; sustainable crop-livestock systems; use of alfalfa to alleviate effects of endophyte-infected fescue.  A regional effort was initiated concerning "Pasture Based Beef Systems for Appalachia," in cooperation with West Virginia University and USDA-ARS.  In all of the research, emphasis will be placed on enhancement of the environment.
 

 The goal of swine research at the Virginia Tech Tidewater AREC swine unit is to conduct relevant practical swine research that is beneficial the Virginia and regional swine industry.  Specifically, the research focus is directed toward resolving important issues in the swine industry such as reducing nutrient excretion in swine to protect the environment, cost effective production practices to enhance swine production efficiency and to enhance swine welfare and pork quality.

 Major Activities Underway:

 Research activities currently underway include: 1) an experiment to evaluate the efficacy of various sources of folic acid (oxidized and reduced forms) as folacin supplements in breeding sow diets, 2) an experiment to determine the efficacy of microbial phytase to reduce phosphorus supplementation in gestating-lactating sow diets, and 3) a study to evaluate the efficacy of phytase in commercial diet formulations to reduce phosphorus excretion in growing-finishing pig diets.

Progress (past 5 years):

Provided a significant body of data in a regional cooperative project determined that vitamin A injection of sows (250,000 or 500,000 I.U.) improved litter size at weaning.

Conducted a series of experiments on supplementation of growing pig and breeding sow diets with chromium picolinate.  These experiments were a critical component of the data base that led to FDA approval of chromium picolinate for feed supplementation in U.S. swine diets.

Conducted a major trial with growing-finishing pigs that produced data that allows for accurate prediction of the effects of the “Halothane” gene on growth performance and pork quality in heterozygous carrier pigs.  The graduate student that was involved in this project was subsequently employed by a major swine seedstock company to work on pork quality issues.

Completed in cooperation with main campus faculty a major study evaluating the efficacy of a commercially available phytase supplement as a means to reduce phosphorus excretion in growing-finishing swine.  Results from this study were used to justify implementation of phytase application equipment in the major swine feed mill in Virginia.

Cooperative Work:

 Cooperative research with APSc departmental and other faculty is extensive.  These cooperators have included the late E. T. Kornegay, C. M. Wood, and J. W. Knight from the Animal and Poultry Sciences Department, J. Claus from the Food Science and Technology Department, and faculty at other experiment stations as part of the S-288 Southern Regional Committee for Improvement in Sow Nutrition.

Future Plans:

 Near future research plans at the Virginia Tech Tidewater AREC swine unit include continued experiments in the use of alternative sources of phytase to reduce nutrient excretion in swine with particular emphasis on growing-finishing pigs and breeding sows.  In addition the unit will be involved in assessing the nutritional value of hull-less barley for swine and investigating the supplementation of mannan-oligosaccharide extract in weanling pigs as a means to reduce dependence on antimicrobial feed additives.  Dr. Mark Estienne, a swine research physiologist, was recently hired and is scheduled locate at the Tidewater unit in June of 1999.  This new faculty member will significantly enhance swine research capability and productivity.
 

 My program goals are to: 1) generate new information through original research that results in new knowledge about the utilization of nutrients by ruminants and other species,
2) help educate persons concerning established principles of nutrition through both undergraduate and graduate instruction, and 3) interact in meaningful ways with undergraduate and graduate students in their independent quests for knowledge.  Proteins occupy my major interests as a nutrient category and I have special interests in the digestion, absorption, and transport of these.

Major Activities Underway:

 Our research activities now are largely focused on the study of the distribution of peptide transport proteins in the animal and the characterization of these proteins.  At present, we have cloned the peptide transporters located in the sheep, chicken, and pig gastrointestinal tract.  We are in the process of sequencing these clones and using them for expression studies in which we are examining the transport characteristics of the expressed proteins.

Progress (Past 5 Years):

 Our long-time efforts in the study of amino acid and peptide absorption have yielded much new information.  Of particular significance, is our discovery that significant quantities of amino acids in the form of peptides are absorbed from the stomach region in addition to the intestinal region of ruminants.  This is contrary to the belief that the stomach region is not involved in absorption of protein digestion products other than ammonia.  As a result of this discovery, we were, with the assistance of Virginia Tech Intellectual Properties, Inc., granted a patent to cover applications of this new technology.

Much of our effort in the past few years has been focused on determining the presence of and characterizing the function of gastrointestinal transport proteins responsible for the transmembrane absorption of amino acids and peptides.  We have completed three major studies that have confirmed the presence of peptide transport capability in the epithelium of the rumen and omasum.  Additionally, we have begun to characterize the protein involved and find that transport of peptides is limited to di-, tri- and some tetrapeptides.  We also have learned that the genetic message for a peptide transporter is expressed in the small intestine of pigs and chickens.  We have not been able to detect this transporter in muscle, kidney, or liver of cattle, sheep, pigs, or chickens.  Likewise, we were not able to detect the presence of the mRNA for the transporter in mammary gland of lactating cows.  Recently, we observed expression of mRNA for the transporter in the ceca and colon of chickens, but we have not observed the mRNA in the large intestine of other animals examined.

 The interest of the scientific community in our work and our thoughts about peptide absorption is illustrated by the fact that I continue to be asked to write reviews and to make major presentations on the subject.  It is difficult to comprehend the total significance of our discovery about peptide absorption.  Certainly from a feeding perspective, if our ideas are correct, the industry will approach supplying the dietary protein component of high producing animals in a different manner.  Strategies may include new processing methods for currently fed proteins and/or feeding new peptide supplements.  Regardless of what new feeding strategies may arise, it will be necessary to investigate the role played by these absorbed peptides in meeting the needs of specific tissues (e.g. muscle, liver, and mammary gland).  Presently, it is assumed that circulating free amino acids supply tissue needs for amino acids.  The high proportion of absorbed and circulating peptides we have observed indicates that peptide amino acids may likewise be involved in supplying tissue needs for amino acids.  Understanding the significance of peptide involvement in meeting tissue needs may result in substantial revisions of our knowledge of amino acid utilization by tissues and also to our experimental approaches to studying this.

Cooperative Work:

  Eric Wong (Department of Animal and Poultry Sciences), Jeff Bloomquist (Department of Entomology) and I have collaborated for the past several years in the studies concerning the detection of and characterization of amino acid and peptide transporters.  This has been a very productive and mutually beneficial collaboration that brings together faculty members from two departments with expertise in molecular biology, nutrition, and electrophysiology.  As a group, we have successfully competed for grant funds and this collaboration has produced one Ph.D. dissertation two M.S., theses, four refereed publications, and five abstracts.  Two Ph.D dissertations are currently in progress.

Future Plans:

 The major focus of my research effort will continue to be the investigation of amino acid/peptide absorption and utilization.  We have concentrated on the absorption aspect and we will continue these efforts.  We are in the process of cloning and sequencing mRNA for peptide transport proteins and this will continue.  We are using the Xenopus laevis oocyte system to express both mRNA and cRNA for peptide transporters so that we can characterize their transport capabilities.  These efforts will continue.  We will soon initiate the use of several mammalian cell lines to express cRNA for the peptide transporters.  From our clones we will determine the primary structure of the protein.  With this information we intend to make an antibody(ies) to the transport protein.  With the antibody then, levels of the transport protein present in intestinal epithelia will be measured by Western blot.  The next step, which is well into the future, is to investigate expression of the peptide transporter mRNA by in situ hybridization and the transport protein by immunohistochemistry along the longitudinal axis of the intestine.  We will also continue studies on the tissue utilization of peptides.