0845 Effect of 17β-estradiol on milk production, hormone secretion, and mammary gland gene expression of dairy cows
Bibliographic record
Abstract
Estradiol inhibits milk production in dairy cows. The present study evaluated the impact of estradiol injections on prolactin (PRL) secretion and mammary gland responsiveness to PRL. Eight mid-lactation cows received either 17β-estradiol (2.5 mg; E2; n = 4) or soy oil (2.5 mL; CTL; n = 4) injections during 7 d (period 1). After a resting period of 3 wk, a second treatment period was performed where the cows were switched from treatments. For each period, blood and milk samples were collected from d −4 to 14 (relative to the first injection). In addition, blood samples were collected during the a.m. milking on d −4, 2, and 7 to determine the milking-induced PRL release. Mammary gland biopsies were harvested on the last injection day of both periods. Milk fat samples were collected on d 1, 4, 7, and 14. The mRNA levels of genes encoding proteins related to mammary activity (α-lactalbumin, β-casein, and acetyl-CoA carboxylase), apoptosis (Bax, Bcl2, and caspase-3), PRL receptors (PRLR, long and short forms), LIF, and suppressors of cytokine (SOCS1, 2, and 3) were measured by real-time RT-PCR using RNA extracted from milk fat and mammary gland. Injections of E2 decreased moderately milk production during the treatment period (36.70 ± 0.45 kg/d and 39.74 ± 0.45 kg/d, respectively; P = 0.01). The E2 treatment tended to increase fat (P = 0.08), increased lactose (P = 0.04), and increased protein (P = 0.03) content of milk. Serum PRL concentration was increased by E2 injections during the treatment (P = 0.04) and the post-treatment (P = 0.01) periods. Accordingly, milk PRL concentration tended to be increased by E2 (P = 0.09). Milking-induced PRL release was also increased by E2 injections (P = 0.03). Injections of E2 increased plasma concentrations of IGF-1 (P < 0.01) and estradiol (P < 0.01) during the treatment period. Milk BSA was not affected by treatments, suggesting that mammary tight junctions were not impaired by E2. In mammary tissue, the LIF mRNA level tended to be lower during the E2 treatment (P = 0.09). In milk fat, PRLRL mRNA level tended to be decreased (P = 0.07), and PRLRS mRNA level was decreased (P = 0.04) by E2 injections. No difference in expression was observed for the other genes in mammary tissue and milk fat. These results suggest that a decrease of mammary gland responsiveness to PRL may be involved in the estradiol-induced inhibition of milk production.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".