|Baldwin, Ransom - Randy|
|Li, Congjun - Cj|
|GROSSI, PAOLO - Collaborator|
|CHOUDHARY, RATAN - University Of Kentucky|
|BERTONI, GIUSEPPE - Collaborator|
|TREVISI, ERMINIO - Collaborator|
|MCLEOD, KYLE - University Of Kentucky|
Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: 4/15/2016
Publication Date: 7/15/2016
Citation: Baldwin, R.L., Li, C., Bickhart, D.M., Clover, C.M., Grossi, P., Choudhary, R.K., Elsasser, T.H., Bertoni, G., Trevisi, E., Aiken, G.E., Mcleod, K.R., Capuco, A.V. 2016. Consumption of endophyte-infected fescue seed during the dry period and lactation affects mammary gland gene expression in dairy cows. Journal of Dairy Science. Vol. 99 (E-Supplement 1):401.
Technical Abstract: Ergot alkaloids in endophyte-infected grasses inhibit prolactin (PRL) secretion and reduce milk production when fed to lactating cows. However, we have shown this affect is temporal in that pre-partum consumption of inflected seed throughout the dry period does not inhibit subsequent milk production and if fact, prior exposure to bromocriptine (ergot peptide) actually increases production. To identify changes in the transcriptome and pathways mediating the mammary gland’s response to ergot alkaloids in the diet, RNA sequencing (RNA-Seq) was performed on mammary tissue biopsies from 24 multiparous Holstein cows exposed to one of three treatments. Starting at 90 ± 4 d pre-partum, cows were fed endophyte-free fescue seed (control, C), endophyte-free fescue seed plus 3x/wk subcutaneous injections of bromocriptine (0.1 mg/kg BW, B), or endophyte-infected fescue seed (I), as 10% of the diet on an as fed basis. Mammary biopsies from 4 or 5 cows/treatment at each of 3 distinct phases were obtained: 7-d prior to dry off during the initial lactation (L1), mid-dry period (D), and 10-d post partum (L2). Biopsy samples from each treatment group at three phases of lactation (late lactation, dry period, and early lactation) were used to generate individual RNA-Seq libraries. Normalized reads of the RNA-seq data was organized into technical and biological replicates before processing with the RSEM software package. Each lactation phase was processed separately with the "rsem-run-ebseq" pipeline, and genes that differed between any of three treatments were identified from program output. A large proportion of genes considered to be differentially expressed in at least one treatment with a posterior probability of differential expression greater than 90% (n = 866) were found to be similarly expressed in B and I treatments but differentially expressed from a control group (n = 575, total for all three phases). When phases were compared, 104 genes that were differentially expressed compared to the control were found to be common to the L1 and L2 phases. The strong similarity in pattern of expression in B and I treatments during both late and early lactation, suggests, at least in part, the involvement of similar cell signaling pathways or mechanisms of action for both B and I, and the importance of prolactin messaging pathways.