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Developments in molecular biology, immunology and genetic engineering have given new dimensions to research on farm animal production. The LSU AgCenter’s Reproductive Biology Center is recognized worldwide as a leader in assisted reproductive technologies for use in livestock improvement, biomedical applications, and propagation of exotic and endangered animal species.
The LSU AgCenter has been in the business of helping farm animals reproduce more efficiently since the early 1980s, and has had many “firsts” – the first calf in the world produced from an in vitro fertilized embryo where the egg was harvested from a live pregnant cow, for example, and the first cloned goats to produce a heart medication in their milk.
The research programs are now headquartered at the Reproductive Biology Center, a state-of-the-art facility near St. Gabriel. The research focus currently includes gamete technology and manipulation with emphasis on embryo biotechnology. Gametes are the sperm and eggs (ova) that carry single sets of unpaired chromosomes. When they come together, they form zygotes – or embryos – that have a full complement of chromosomes contributed by both parents.
Ken Bondioli, associate professor in the Department of Animal Sciences, said one of the major research areas at the Reproductive Biology Center deals with epigenetics – the study of heritable changes in gene function that occur without a change in the sequence of the DNA – and subsequent “reprogramming” of differentiated cells.
Epigenetics deals with a series of changes that occur in cells as they develop and become differentiated – developing the characteristics that determine what they’ll be, for instance skin, blood or bone cells. These changes don’t change the genetic code, just the active genes within the cell.
Researchers are interested in taking a differentiated cell – from skin, for example – and causing it to revert to a single cell resembling an embryo, then reprogramming that cell to stimulate different combinations of genes to become a different type of cell.
“Those are the mechanisms we’re studying,” Bondioli said. “We’re slowly trying to piece each part together.”
The researchers hope the final result will improve the efficiency of transferring a nucleus so they can apply the techniques to animal reproduction.
Making clones
When the researchers reprogram a cell, one of the things they can do is take the nucleus from the undifferentiated single cell and induce it to divide and behave like a fertilized egg cell. The result will be what’s called a clone.
“It will be a clone, but clones aren’t precisely identical to the animal they come from,” Bondioli said. “Several factors, such as environment, dictate how the closely it will match the first animal.”
The Reproductive Biology Center works with four species – cattle, goats, swine and horses. The focus on cattle and goats is for breeding applications to improve meat and milk production while all four species are used in biomedical research. In addition to cloning, researchers have been focusing on transgenic animal models – those with specific genes introduced from other sources – that can produce important pharmaceuticals and transfer that ability to their offspring.
Medical therapeutics
Researchers have been working on how they can cause cells to reproduce and express themselves as different body cell types. It may be possible, for example, to develop cells that could regenerate spinal cords or treat Parkinson’s disease or Alzheimer’s disease. Researchers might also be able to develop cells that could replace cardiac muscles or make cartilage to repair joints or replace bones as well as regenerate a diseased pancreas or liver.
“There’s potential for cell-based therapy for regeneration, repair or replacement for any organ,” Bondioli said. “The potential is limited by imagination; reality is limited by biology, which is where we’re trying to identify answers. Most of these questions will be answered by developing animal models.”
Biotechnology companies now produce new recombinant DNA proteins to treat various viral diseases in farm animals. An example is a class of natural antiviral proteins called interferons used to treat calf scours and various respiratory diseases, such as shipping fever in cattle.
Recent successes
AgCenter researchers were first in the world to produce in vitro fertilization-derived pregnancies and live offspring in beef cattle with cattle epididymal sperm. To save germplasm from deceased bulls, scientists saved epididymal sperm by storing it in the testes at 39 degrees F for 24 hours. Then they used a “test tube” fertilization (in vitro fertilization) procedure that produced viable embryos and living offspring from 46 percent of the beef females that received the embryos.
“With this capability, cattle producers will now have to opportunity to harvest germplasm – testicular sperm – from a recently deceased genetically valuable bull or from an injured breeding bull no longer able to mate,” said Robert Godke, Boyd Professor in the Department of Animal Sciences and internationally known for his research in assisted reproductive technologies in animals. “Cattle producers have requested this technology from scientists for decades.”
AgCenter researchers have successfully developed methods to harvest oocytes (eggs) from cattle, horses, goats and sows using transvaginal ultrasound-guided procedures. Read Oocyte Aspiration for In Vitro Embryo Production in Farm Animals.
Harvesting oocytes from live farm animals on multiple occasions in a noninvasive manner is an important breakthrough for test tube fertilization. Read Cattlemen Pleased with Cloned Calf, Thanks to LSU AgCenter Research and Graduate Student Produces First Cloned Cow From Frozen Egg.
Read Animal Biotechnology and the Future.
“Producing one or two extra calves per year from breeding herd females will increase the producer’s annual calf crop,” Godke said. “With the potential to increase the efficiency of animal production, this technology is now being implemented by progressive cattle producers.”
AgCenter researchers have successfully developed technologies to produce transgenic nuclear transfer dairy goats. This approach is being tested as an economically efficient method for the production of valuable human proteins in these animals’ milk. This approach using goats and cattle could be the method of choice in the future for the production of unique pharmaceutical proteins for human medicine. Not only is this an efficient method to produce valuable human proteins in these animals’ milk, it will result in an overall reduction in the production cost of human pharmaceuticals. The first transgenic goat-derived human protein for use in human medicine was approved for the commercial market in 2006.
Beef cow productivity
Glen Gentry, resident coordinator and assistant professor, has proposed a project to research leptin, a hormone derived from adipose tissue, and how it relates to reproductive efficiency in farm animals.
Gentry said puberty occurs when an animal becomes reproductively competent based on weight and age – generally 65 percent of mature body size. He said researchers believe leptin serves as a trigger mechanism that starts the process. So he’s looking at heifers and 2-year-old beef cows to see if leptin can be used in predicting success rates in pregnancy.
“A two-year-old is hardest to get pregnant because she is using her energy for growing and for making milk for a calf,” Gentry said. “A healthy cow needs to maintain body mass.”
Gentry said his research would measure leptin levels of heifers to determine if there’s a relationship between leptin levels and pregnancy success after the first calf.
“This would provide another measure producers can use to select future cows for their herds,” he said. “It would be another selection tool. The more parameters we can measure, the better control we can have of the reproductive efficiency of the herd. It costs the same to keep either animal.”
In another study, Gentry is working with Jason Rowntree, an AgCenter beef specialist, to increase capacity of the station through pasture management. The station currently supports about 300 beef cows, 45 horses and 80 goats. The study will look at rotational grazing as a method for increasing the number of animals the station can support.
Funding
In addition to funding from the AgCenter, the Reproductive Biology Center has received grants from the U.S. Department of Agriculture, National Institutes of Health, the Louisiana State Board of Regents and private companies.
“The infrastructure and capability to do a multitude of types of research with high potential to bring in the outside funding necessary for this work to be done,” Gentry said.
The LSU AgCenter is one of 11 institutions of higher education in the Louisiana State University System. Headquartered in Baton Rouge, it provides educational services in every parish and conducts research that contributes to the economic development of the state. The LSU AgCenter does not grant degrees nor benefit from tuition increases. The LSU AgCenter plays an integral role in supporting agricultural industries, enhancing the environment, and improving the quality of life through its 4-H youth, family and community programs.
(This AgCenter Lead was updated on Oct. 10, 2007, by Rick Bogren.)