Recent grants awarded to examine the metabolic pathways in broiler chicks and reproduction in turkey hens
Image Credit: Edwin Remsberg
Tom Porter, professor in Animal and Avian Sciences at the University of Maryland (UMD), has done something “unheard of” by receiving funding for four separate grants totaling $2 million from the United States Department of Agriculture National Institute for Food and Agriculture (USDA-NIFA) in the past three years, all in the field of poultry physiology, growth, and reproduction. In his two latest grants, Porter is examining a unique metabolic pathway in broiler chicks, and filling a national need for reproduction research in turkey hens, marking a return to his dissertation work in turkey hens as a young researcher. All this work aims to improve poultry production and welfare, while advancing agricultural sustainability and feeding a growing global population.
“Having four active USDA grants is unheard of and shows the importance of poultry in advancing overall food production,” says Porter. “I’m a physiologist, and the one common thread through all of this is physiology - of growth, metabolism, heat stress, reproduction.”
The first two grants in the series were awarded about three years ago. But over the last year, Porter has received two additional grants from the USDA that represent strong interagency collaborations. Porter was approached by Hsiao-Ching Liu, professor in Animal Science at North Carolina State University because of his expertise in poultry physiology to be a co-investigator on a project examining a critical stage for broiler chicks called the metabolic switch.
“Before hatch, all of the energy for a chick comes from the egg yolk, which involves metabolizing a high fat diet and making their own new sugars,” explains Porter. “Immediately after hatch, the chick’s needs change, and they are fed a corn and soybean-based diet. They have to switch from ingesting mostly fat to ingesting mostly carbohydrates and make their own lipids. This switch happens like that [snaps fingers] in one day. This is what is called the metabolic switch, and the mechanisms that control it aren’t well understood.”
This switch has implications for the welfare of the chick and how well the chick will grow in its adult life. The first week after hatch is a major indicator of how well the bird will do, and with researchers and nutritionists working to optimize nutrition for birds at every stage of development, understanding this switch would play a key role in that optimization and have an impact on a large number of birds.
“About 1-2% of chicks are given everything they need post-hatch, but they just never grow,” says Porter. “While that sounds like a small amount, when you think of the scale of the industry, this translates to millions of birds a year that could be performing much better, but instead aren’t really growing even with the same amount of feed, time, and resources.” In fact, according to the USDA, 9 billion birds were produced in 2018; this translates to between 90 million and 180 million birds each year that are affected.
For this collaboration, Liu’s lab has quantified all the genes expressed in the liver and examined their regulatory pathways, mapping this out in model systems. Porter will be taking those models and the molecular tools that Liu’s lab develops and testing the mechanisms in the liver cells of broiler chickens. The liver is responsible for the metabolism or conversion of nutrients into energy, so understanding these mechanisms will be a key factor in understanding this metabolic switch and why certain chicks fail to thrive. Nishanth Sunny, assistant professor in Animal and Avian Sciences at UMD, has also been brought into the project to examine the production of fatty acids involved in this metabolic switch.
Earlier this year, Porter received funding for his fourth USDA grant in a field that happens to be something he hasn’t worked with directly since his dissertation as a graduate student decades ago. “Reproduction in turkey hens has been largely a dying field of research,” says Porter. “No one is really working in this field currently except Julie Long with the Beltsville Agricultural Research Center. Since this was my original field of study, I saw a major need here and decided to discuss working with Julie.”
With some funding from a Maryland Agricultural Experiment Station (MAES) Seed Grant and money of his own, Porter began working with a doctoral student to quantify the genes expressed in reproductive tissues of high and low egg-producing turkey hens to determine differences that could be targeted for further research. It was this large amount of preliminary data, his partnership with Julie Long providing the turkey hens, and the national need for work in this area that Porter attributes to winning this fourth major grant award in three years.
“Fertile turkey eggs are about a dollar a piece during normal conditions, so they are quite expensive and valuable given that turkeys only really produce eggs for about three months at a time,” says Porter. “In our preliminary work, we noticed that the bottom 15% of egg producers are producing about half as many eggs as the top 15% of egg producers, and we want to be able to target why that is so that breeders and meat producers can improve production and even select for higher producing birds.”
Right now, Porter suggests that thyroid activity data looks promising as an indicator of egg production, and that the research has been producing exciting results. His lab will also be examining estrogenic hormone activity in relation to egg production, as well as looking at gene regulation for steroid hormone production. This work has been done largely in mammals, but has never before been examined in birds of any kind.
“All my work is physiology,” reiterates Porter. “It all involves molecular and cellular tools to study the physiology of poultry and hormone regulation, with the goal of improving poultry production and welfare.”