9 USE OF SEXED SEMEN FOR ARTIFICIAL INSEMINATION IN HOLSTEIN HEIFERS IN MEXICO: PRELIMINARY RESULTS
Notice bibliographique
Résumé
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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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».