Effect of GnRH injection at day 6 and 12 after insemination on fertility of Holstein dairy cows during the warm season
Journal Title: International journal of Advanced Biological and Biomedical Research - Year 2014, Vol 2, Issue 1
Abstract
The objective of this study was to determine the effects of two different time of GnRH injection after artificial insemination (A.I) (d 6 and d 12) on reproductive performances of Holstein cows during the warm season. Cows randomly assigned to treatments 1) No GnRH injection (control, n = 300),2) GnRH injection at day 6 after A.I (G6, n=300) and 3) GnRH injection at day 12 after A.I (G12, n=300). Ultrasonography was used to detect pregnancy and late embryonic/fetal mortality between Days 32 and 60 after AI. Data were analyzed using Proc GLM of SAS. Results showed treatment affected the percentage of cows diagnosed pregnant at 32±1 d and 60±3 d after resynchronized AI. A greater percentage of G6 (25.0%) cows were pregnant at 32 d after resynchronized AI than control cows (19.3 %) and G12 cows (20.0 %). The risk of pregnancy loss between d 32 and 60 of gestation was affected by treatments and decreased in cows received GnRH injection after AI Compared to control cows. Percentage of cows that showed estrus at 19-24 d after AI was highest in G6 cows and lowest in control cows compared to other treatments. In summary, administration of a GnRH on Day 6 after AI improved reproductive performance in dairy cows.
Authors and Affiliations
E. Dirandeh| Sari Agricultural Sciences and Natural Resources University, Department of Animal Science, Sari, Iran, PO BOX, 578, E-mail: Dirandeh@gmail.com, A. Rezaei Roodbari| University of Tehran, College of Agricultural and Natural Resources, Department of Animal Science, Karaj, Iran, PO BOX, 4111, B. Shohreh| Sari Agricultural Sciences and Natural Resources University, Department of Animal Science, Sari, Iran, PO BOX, 578
Keywords
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