Abstract
Ergot alkaloids in endophyte-infected grasses inhibit prolactin secretion and reduce milk production in lactating cows. However, we previously showed that prepartum consumption of infected seed throughout the dry period did not inhibit subsequent milk production and prior exposure to bromocriptine (ergot peptide) actually increased production in the next lactation. To identify changes in the transcriptome and molecular pathways mediating the mammary gland's response to ergot alkaloids in the diet, RNA sequencing (RNA-seq) was performed on mammary tissues obtained from 22 multiparous Holstein cows exposed to 1 of 3 treatments. Starting at 90 ± 4 d prepartum, cows were fed endophyte-free fescue seed (control; CON), endophyte-free fescue seed plus 3×/wk subcutaneous injections of bromocriptine (BROMO; 0.1 mg/kg of BW), or endophyte-infected fescue seed (INF) as 10% of the diet. Cows were dried off 60 ± 2 d prepartum. Mammary biopsies from 4 (BROMO, INF) or 5 (CON) cows/treatment at each of the 3 phases were obtained: 7 d before dry off during the initial lactation (L1), mid-dry period (D), and 10 d postpartum (L2). Although tissue from the same cow was preferentially used at 3 phases (L1, D, L2), tissue from additional cows were used to as necessary to provide RNA of sufficient quality. Individual samples were used to generate individual RNA-seq libraries. Normalized reads of the RNA-seq data were organized into technical and biological replicates before processing with the RSEM software package. Each lactation phase was processed separately and genes that differed between any of 3 treatments were identified. A large proportion of genes differentially expressed in at least 1 treatment (n = 866) were found to be similarly expressed in BROMO and INF treatments, but differentially expressed from CON (n = 575, total for 3 phases). Of genes differentially expressed compared with CON, 104 genes were common to the L1 and L2 phases. Consistent with the production findings, networks most affected by treatments in L1 and L2 included lipid metabolism, small molecule biochemistry, and molecular transport, whereas networks related more to developmental and cellular functions and maintenance were evident during D phase. Similar patterns of expression in BROMO and INF during late and early lactation suggest involvement of similar cell signaling pathways or mechanisms of action for BROMO and INF and the importance of prolactin messaging pathways.
Original language | English |
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Pages (from-to) | 10478-10494 |
Number of pages | 17 |
Journal | Journal of Dairy Science |
Volume | 101 |
Issue number | 11 |
DOIs | |
State | Published - Nov 2018 |
Bibliographical note
Funding Information:The authors thank Donald Carbaugh and Dennis Hucht (Animal Genomics and Improvement Laboratory, USDA-ARS, Beltsville, MD) for their excellent assistance with tissue sampling, feed preparation and animal handling, and Mary Niland (Animal Genomics and Improvement Laboratory, USDA-ARS, Beltsville, MD) for technical assistance. We also thank personnel of the Beltsville Agricultural Research Center (Beltsville, MD), particularly Jonathan Leith and Mike Kemp, for help initiating the project and for managing cows throughout the study. This work was funded by Current Research Information Service project no. 1265-3200-083-00D from USDA Agricultural Research Service (Beltsville Agricultural Research Center), by National Research Initiative Competitive Grant no. 2008-35206-18825 from the USDA National Institute of Food and Agriculture (Beltsville Agricultural Research Center), and by University of Kentucky Agriculture Experiment Station (Manuscript No. 18-07-059).
Funding Information:
The authors thank Donald Carbaugh and Dennis Hucht (Animal Genomics and Improvement Laboratory, USDA-ARS, Beltsville, MD) for their excellent assistance with tissue sampling, feed preparation and animal handling, and Mary Niland (Animal Genomics and Improvement Laboratory, USDA-ARS, Beltsville, MD) for technical assistance. We also thank personnel of the Beltsville Agricultural Research Center (Beltsville, MD), particularly Jonathan Leith and Mike Kemp, for help initiating the project and for managing cows throughout the study. This work was funded by Current Research Information Service project no. 1265-3200-083-00D from USDA Agricultural Research Service (Beltsville Agricultural Research Center), by National Research Initiative Competitive Grant no. 2008-35206-18825 from the USDA National Institute of Food and Agriculture (Beltsville Agricultural Research Center), and by University of Kentucky Agriculture Experiment Station (Manuscript No. 18-07-059).
Publisher Copyright:
© 2018 American Dairy Science Association
Keywords
- RNA sequencing
- ergot alkaloids
- milk yield
- prolactin
ASJC Scopus subject areas
- Food Science
- Animal Science and Zoology
- Genetics