Effect of an injection of PGF2[alpha] administered 11 days prior to Double-Ovsynch on first service conception risk in lactating dairy cows
May, Hillary Alicia
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The objective of this study was to determine if the administration of a single injection of PGF 11 d prior to the start of Double-Ovsynch would improve first service conception risk and reduce the time from calving to conception. Lactating Holstein cows (n= 1,043) were randomly assigned to one of two groups; the treatment group (n=531) received an injection of PGF at 35 ±3 DIM, which corresponded to 11 d prior to starting the Double-Ovsynch protocol. The control group (n=512) received the standard Double-Ovsynch protocol beginning at 46 ±3 DIM without any additional treatments. Results indicate that PGF did not increase first service conception risk to Double-Ovsynch; further, first service conception risk was not different for primiparous or multiparous cows. Future studies are needed to assess the potential impact of presynchronization with PGF prior to Double-Ovsynch and to develop additional ways of improving first service conception risk and pregnancy rate.