Effect of prolactin-release inhibition on milk production and mammary gland involution at drying-off in cows
Bibliographic record
Abstract
The end of each lactation is a challenging period for high-yielding cows as they are often dried off while still producing significant quantities of milk and, consequently, are highly susceptible to new intramammary infections. Once involution is complete, the mammary gland becomes much more resistant to infection. Therefore, it is critically important to develop strategies aimed at reducing milk production before drying-off and to accelerate mammary gland involution. This study assessed the effect of inhibition of the lactogenic signal driven by prolactin (PRL) on milk production and concentrations of involution markers in mammary secretions. Sixteen Holstein cows in late lactation were assigned to treatments based on milk yield, somatic cell count, and parity. Of those cows, 8 received twice-daily intramuscular injections (2 mg per injection) of quinagolide, a specific inhibitor of PRL release, from 4 d before drying-off to 3 d after (Quin). The other 8 cows received injections of the solvent (water, control). Blood and milk (mammary secretion) samples were collected on the last 5 d before and on d 1, 3, 5, 7, 10, and 14 after the last milking. Additionally, on the day preceding the first injection and on the following day, several blood samples were collected around milking time. Quinagolide reduced basal serum PRL concentrations on all injection days as well as PRL released in blood during milking. The PRL inhibitor decreased milk production before drying-off, which averaged, over the last 3 d of lactation, 19.3 and 15.5 kg/d for the control and Quin cows, respectively. Quinagolide had no significant effect on milk citrate:lactoferrin and Na:K ratios, which decreased and increased, respectively, during the first 2 wk of the dry period. Nevertheless, the increases in the number of somatic cells and bovine serum albumin concentration during early involution were greater and matrix metalloproteinase-2 activity tended to be greater in mammary secretions of the Quin cows compared with the control cows. This experiment shows that inhibition of PRL release decreases milk production of cows in late lactation. Changes in the composition of mammary secretions suggest that this approach also hastens mammary gland involution.
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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 | 0.001 |
| 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".