From Issue  Summer 2016

Q&A With David Peebles

Focus: Reproductive physiology

By: Vanessa Beeson

Dr. David Peebles and research technician Sharon Womack work with recently hatched chicks. Photo by David Ammon.

Poultry is Mississippiís number one commodity with a production value totaling $3.2 billion in 2015. Scientists in the Mississippi Agricultural and Forestry Experience Station conduct innovative research that drives the industry forward. One such researcher is Dr. David Peebles, MAFES scientist and professor in the Department of Poultry Science in the College of Agriculture and Life Sciences. Much of his research has been applied directly to the poultry industry while all of his students gain employment in their field of study.

MAFES Discovers sat down with Peebles to discuss how his research role helps inform the poultry industry while his academic appointment helps grow the poultry leaders of tomorrow. Here is what he had to say:

What inspired you to pursue a career in teaching and researching poultry science?

I began studying poultry while pursuing a Ph.D. at North Carolina State University. During my masterís program, I had studied the thyroid organ as it relates to the reproductive function in mice. I was interested in continuing that work. I was offered an assistantship at North Carolina State University working with an advisor who was researching the thyroid as it related to reproductive function in poultry. After graduation, I completed a postdoctoral fellowship with the avian genetics unit of the U.S. Department of Agriculture in Athens, Georgia. Once the fellowship was over, I joined the faculty at MSU.

Describe your current research:

I primarily focus on avian physiology. For the past 18 years, I have worked closely with the USDA Poultry Research Unit in Starkville.

Currently, we are working on a bacterial pathogen called Mycoplasma gallisepticum, which costs the global poultry industry approximately $780 million dollars a year. Field-strain infections of the disease are especially virulent and can lead to morbidity.

he industry standard for vaccinating layer flocks against the pathogen is administering a live-attenuated F-strain of Mycoplasma gallisepticum, called FMG. The vaccine is given to birds at approximately 12 weeks of age via a spray vaccinator. The way the vaccine is currently administered is costly and labor intensive. Additionally, FMG, while effective, can cause side effects like decreased and less efficient egg production.

First, we are evaluating physiological aspects of the vaccine such as its effects on various blood parameters, what the vaccine does in the blood, how it affects various tissues, and how it affects the eggs themselves. Since FMG can cause some delays in the production of commercial laying hens, we are also researching milder live-attenuated vaccine strains such as 6/85 and ts-11. We look at these alternate vaccines alone and in conjunction with FMG. We explore various vaccine regimens to see if we might get the same effect of FMG without some of the side effects.

Secondly, we are evaluating an alternative inoculation method. Up until now, these vaccines have always been given as a spray to the egg-laying flocks. This method is expensive and takes a lot of work. We are working with industry partners like the Zoetis Corporation to develop a way to inject the vaccine into the layer-hatching egg at 18 days of incubation, about three days before the chicks hatch. So far results are promising. This method causes an immune response in the embryo and the chick. Right now, we are evaluating the effectiveness of this new process, trying to determine if we need to follow up with a booster at some point. This research could potentially save the table egg industry millions. Cal-Maine Foods, an international egg production company headquartered in Mississippi, is also an industry partner on the project.

Another research area involves egg incubation. We have a telemetric device called a transponder, which we insert into the air cell of the egg at 12 days of incubation. It monitors very closely and accurately an embryoís temperature. The ability to measure an embryoís temperature accurately is vital in poultry research and the production environment. The embryoís temperature tells us how healthy it is, how much heat it produces, and how it responds to vaccines. Right now, the industry uses an infrared device to measure eggshell temperature but the device canít detect temperature fluctuations like the transponder can. It is also influenced by the airflow in the incubator and the shell, which serves as a protective cover that prevents some heat transfer. Getting a device in the egg close to the embryo is important. We are able to detect things that the eggshell temperature reader canít. The process is relatively noninvasive. We insert the transponder around 12 days of incubation and seal the hole and the embryo does fine.

In addition to and for use with the transponder, weíve also partnered with Dr. Filip To, professor in the Department of Agricultural and Biological Engineering, to develop incubation technology. The force-draft incubators currently in use heat and moisturize all of the air in the incubator. Producers spend energy and money trying to heat that whole environment while the new technology tries to do something that is much more cost-effective.

We also work with industry partners on various cooperative agreements on a range of projects. We partner with the U.S. Department of Agriculture, updating a comprehensive research plan every five years. We also work closely with the Mississippi Poultry Association and the U.S. Poultry and Egg Association.

Tell us about the academic side of your work.

When I started at MSU, I was asked to teach an introductory genetics course. Since then, each year I teach genetic basics to about 500 students. Currently, I have one doctoral student and one masterís student. Two more graduate students, a doctoral candidate and masterís student, graduated in December 2015.

We also have undergraduate researchers occasionally. Many of my students have received awards, honor society memberships, and paper presentation awards. Five students, in particular, over the last three years have received over a dozen accolades combined.

As an educator, what excites you most?

I enjoy helping students understand basic science and the physiological and biochemical mechanisms that give us the effects we see. I like teaching genetics because it deals with the underlying mechanisms that make things happen.

Discuss your role with the Poultry Science Association.

Last year, I was appointed to serve three years on the associationís board of directors. I am organizing an embryology symposium for the PSA national meeting in New Orleans this summer. In past years, Iíve served on various committees and was an associate editor for the Poultry Science journal. Additionally, Iíve served as section editor for PSAís other journal, the Journal of Applied Poultry Research.