| Autor: |
Mellado, Miguel, Treviño, Lucía M., Chavez, María I., Véliz, Francisco G., Macías‐Cruz, Ulises, Avendaño‐Reyes, Leonel, García, José E. |
| Předmět: |
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| Zdroj: |
Reproduction in Domestic Animals; Jan2023, Vol. 58 Issue 1, p39-47, 9p |
| Abstrakt: |
The objective of this retrospective study was to assess the effect of receiving a single (n = 50,285) or double (n = 4392) artificial insemination (AI), 12 h apart, within a timed artificial insemination protocol on pregnancy per AI (P/AI) in nulliparous heifers (inseminated with either sex‐sorted or conventional semen) and pluriparous Holstein cows in a commercial dairy herd. Also, this study aimed to investigate the relationship between temperature‐humidity index (THI) and time of the first AI and fertility. Fertility of cows receiving two AI with normothermia (THI <68) was higher (p <.05) than cows receiving a single AI (42.9% vs. 36.4%). P/AI of cows receiving two AI with severe heat stress (THI >85) was higher (p <.05) than cows receiving a single AI (21.0% vs. 12.6%). Regardless of heat stress conditions, applying the first AI in the morning increased (p <.05) P/AI in cows with double AI than in cows whose first AI occurred in the afternoon (38.4 vs. 33.3%). With moderate heat stress, and sexed‐sorted semen, P/AI to timed AI was higher (65.0 vs. 51.9%; p <.05) in heifers receiving double AI than those serviced once. It was concluded that double AI, 12 h apart, enhanced fertility at timed AI than herd mates with a single AI, particularly with heat stress at breeding. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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