9 USE OF SEXED SEMEN FOR ARTIFICIAL INSEMINATION IN HOLSTEIN HEIFERS IN MEXICO: PRELIMINARY RESULTS
Bibliographic record
Abstract
Nowadays, X- and Y- sperm can be sorted reliably by flow cytometry/cell sorting. However, this new technology is rarely being adopted by dairy farmers in Mexico and in developing countries, mainly due to the higher price of sexed semen straws and to a lack of information and knowledge of the results that can be obtained with its use under field conditions. In 2004, a field experiment started in a dairy farm in Tizayuca, State of Hidalgo, Mexico, aimed to examine fertility and sex ratios after artificial insemination (AI) in heifers under field conditions. Semen from two Holstein bulls was used for the experiment. The semen was sexed and frozen by XY Mexico (subsidiary of XY, Inc., Fort Collins, CO, USA). Only the X fraction of spermatozoa was sorted and frozen in 0.25 cc plastic straws with 2.0 × 106 spermatozoa/straw. Sixty Holstein heifers averaging 14 months of age were artificially inseminated 12 hours after naturally occurring standing heat, using one straw of sexed semen, from June to October 2004. Fertility data of all inseminations were collected by rectal palpation from Days 45 to 60 after AI. A total of 30 heifers were pregnant, indicating a fertility of 50% froma single service. Sex of the calves was confirmed after calving between March and July 2005. From a total of 30 calves born after normal pregnancy, 27 were females (90%) and 3 were males (10%). In contrast, the pregnancy rate obtained in 60 heifers inseminated with non-sexed semen from the same two bulls was 68% (41 pregnant). From this group of heifers, 20 female (49%) and 21 male (51%) calves were born. Chi-square analysis indicated that pregnancy rates and sex ratios between the two groups were significantly different ( P < 0.05). This preliminary information indicates that there is an advantage in the sex ratio obtained when using sexed semen for AI in Holstein heifers. This is especially important at a time when importation of replacement heifers to Mexico from Canada and the USA is not an option. However, more experiments are needed to confirm the results obtained in this preliminary study. Sexed semen and Holstein heifers were provided by Rancho El Nacimiento, Establo 196, Tizayuca, State of Hidalgo, México.
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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 | 0.001 | 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 | 0.001 | 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".