Guests: Dr. Pete Hansen, University of Florida

To conclude this mini series, Dr. Pete Hansen of the University of Florida presents on the topic of using methyl donors to regulate an early embryo and create an epigenetic effect. This talk was given at the 2022 Tri-State Dairy Nutrition Conference, and is the fourth part of this series.

Beginning his presentation, Dr. Hansen highlights how nutrition can cause epigenetic reprogramming of the fetus. Methyl groups can be added to increase the pattern of DNA methylation in cells and change the phenotype. 3:55

To elaborate on DNA methylation, Dr. Hansen gives the example of placenta vs. embryo cells. A micrograph of both cell types shows that placenta cells have much larger amounts of methylation than embryo cells, indicating that placenta cells are specifically programmed while methylation of embryo cells can still be influenced by the environment. 4:57

Continuing on the topic of methylation, Dr. Hansen discusses how DNA methylation silences specific genes, such as in skin cells or mammary glands. The methylation in the dam can be recapitulated in offspring, representing an epigenetic pattern. 14:42

Opportunities to increase DNA methylation exist. Dr. Hansen points out that altering the environment of an embryo by growing it in vitro for just seven days changes the phenotype. 23:10

How can this knowledge be used to the advantage of the dairy industry?

Seeking to answer this question, Dr. Hansen and his graduate students added large amounts of choline (excellent source of methyl groups) to cultured embryos. They found the addition of choline to increase triglyceride accumulation and DNA methylation. 31:45

After allowing the choline-treated embryos to mature in the recipient cattle, Dr. Hansen and his colleagues found the dams to have longer gestation lengths. This likely led to the higher birth weight of the calves which persisted into weaning. While a high birth weight is not particularly beneficial, a higher weaning weight certainly can be. 36:30

Finishing up his presentation, Dr. Hansen refers to the common animal science equation: phenotype = genetics + environment. He praises the dairy industry’s proficiency in using genetic selection to create better offspring, but he states that improvements could be made in the environment, suggesting that more focus be placed on the prenatal environment. 41:37

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