Physiological and management advances enhancing adoption of applied reproductive management procedures in dairy cattle

Abstract Text:

Since the first meeting of the Dairy Cattle Reproduction Council in 2006, several advances occurred to upgrade reproductive management programs in dairy herds. Many advancements are refinements of the currently applied standard 7-d Ovsynch program (GnRH [d 0; G1]; PGF_2α [1 dose on d 7]; GnRH [G2; d 9.5]; and AI 16 h after G2). Key advances: (1) including GnRH in presynchronization programs to facilitate ovulation before first or repeat AI to change the proportion of cows with a corpus luteum (CL) and more moderate progesterone concentrations to start Ovsynch, thus increasing G1-induced LH release and subsequent ovulation to G1 and greater pregnancy per AI (P/AI). (2) Clarifying the specific role of progesterone in targeted sub-fertile populations before first or repeat AI of cows without a CL to facilitate greater P/AI compared with non-progesterone treated controls without a CL, but similar P/AI to cows starting Ovsynch in diestrus. (3) Applying increased dosages or additional injections of PGF_2α to enhance luteolysis before timed AI to increase P/AI in cows treated with either the 5- or 7-d Ovsynch program. (4) Increasing dosages of GnRH at G1 or G2 to increase ovulation incidence did not always increase P/AI. (5) Diagnosing pregnancy via blood or milk pregnancy-associated glycoprotein (PAG) tests beginning 28 d post-AI to spare veterinarians' time to address other health issues. (6) Field testing the role of a 5- or 7-d Ovsynch program with progesterone inserts to facilitate timed AI in dairy heifers to increase early pregnancy in replacement heifer programs and reduce days on feed before first calving. (7) Incorporating gender-selected semen in AI programs to increase herd size from within, allow for more selective culling, and less outsourced heifer purchases. (8) Applying software tools to project revenues and costs associated with various timed AI and estrus-detection AI programs. (9) Detecting ovarian structures to more accurately diagnose large anovulatory follicles or ovarian cysts, early pregnancy, and subsequent embryo survival via diagnostic transrectal ultrasonography. (10) Applying technologies such as activity monitors to assess increased physical activity associated with estrus, monitor rumination and ear temperature, and RFID for accurate cow identification. (11) Clarifying the role of postpartum health (clinical and subclinical disease) on subsequent P/AI. (12) Applying genomics and fertility-selection traits to enhance fertility. These physiological advances have impacted reproductive management, increased P/AI, and promoted sustainability of dairy herds to provide dairy products to feed a hungry world.

Keywords: dairy, fertility, management