Pullman, Wash. — Basic research in Washington State University’s animal sciences department has found that dozens of genes change in dairy cows when they start milking. The finding eventually may help dairy producers identify dairy cows that use feed most efficiently to make milk and stay healthy.
The research also may benefit humans by identifying gene patterns in adipose tissue, or fat, that best support breast-feeding and compounds made by cows that enter the milk and improve human health.
“The role of adipose tissue in reproduction has been a matter of study for decades,” said John McNamara, WSU animal scientist. “The pinnacle of adipose tissue function is reached in pregnancy and lactation, in which animals first store fat, and then use it during later pregnancy and lactation, followed by restoration for the next reproductive cycle.”
Excessive adipose growth is known as obesity. Understanding adipose tissue is critical in species survival, human breast-feeding, obesity and efficient food production.
“In addition to being a major energy storage organ, adipose tissue is a source of several regulatory and health proteins including those controlling feed intake, inflammation and immunity,” McNamara explained.
McNamara’s research team analyzed gene expression in adipose tissue of dairy cattle in late pregnancy and early lactation. They found that in dairy cattle, the ultimate milk machines, dozens of genes in adipose tissue change when the animals start making milk. Five major genes were shown to increase during lactation so that the cow can use her stored body fat to make milk.
These five genes included three which respond to nervous signals to allow body fat loss. The other two are the enzyme hormone-sensitive lipase, and its cofactor perilipin that allow the lipase to break down fat for the body to use.
“These proteins have been studied intensively in the control of obesity, but little was known about their role in species survival during pregnancy and lactation,” McNamara said.
Using newly available gene analysis technology, the scientists found that several other genes in adipose tissue dramatically change expression during early lactation.
“We expected many of the changes we saw,” McNamara said. “However, several other genes that affect immunity and inflammation were shown to increase and decrease.”
The assay was conducted in WSU’s Center for Reproductive Biology and the Bioinformatics Laboratory.
McNamara’s team found that feeding supplemental chromium, a required dietary supplement, changed expression of several critically important genes.
The scientists have filed a provisional patent application on use of the gene chip process to help identify the animals which respond most efficiently to diet.
The research was conducted by McNamara, who has been on the faculty for 23 years; Jennifer M. Sumner, who received a doctorate in December; and Jan Vierck, research technician in McNamara’s lab.
The work was funded by Kemin Agri-Foods North America, Inc., and Kemin Industries, Inc. The researchers recently received a National Research Initiative grant from the USDA’s Cooperative State Research, Education, and Extension Service to continue the work.
“We will identify our top genetic cows and our lower genetic cows and challenge them with two different diets to see how they respond,” McNamara said. “Based on a lot of different work, I’m convinced there will be differences. Sorting out what they mean is going to be the hard part.”
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