Brief Summary of Minutes of Annual Meeting

Please see the attached document with the complete Annual Meeting Minutes.

Overall across the experiment stations participating in NC-1201, 13 experiments/projects were conducted to meet Objective 1 and 23 experiments/projects were conducted to meet Objective 2. Many of these projects were collaborative efforts among stations and many have impacted not only future research in the field but are directly applicable to producers and other Extension efforts in the U.S. Individual experiment station accomplishments for each objective are listed below. Objective 1. To determine mechanisms that regulate reproductive processes impacting production efficiency in cattle. Mississippi State University: Gestational environment may impact growth and some hemodynamic parameters in young calves. Further research can lead to understanding the correlations and implications they may have on the dairy industry. Additional analyses of data are being conducted to potentially elucidate the mechanisms of these initial results. South Dakota State University: Follicle size had a positive relationship with peak concentrations of estradiol, but only among cows that exhibited standing estrus. Cows with greater circulating concentrations of estradiol during the preovulatory period had increased ability to produce estradiol and increased numbers of visible antral follicles. Thus, selection for both follicle numbers and estradiol concentrations during the preovulatory period may be a better indicator of fertility than either trait alone. Initiation of standing estrus prior to TAI resulted in improved embryo stage and quality and tended to improve accessory sperm numbers and percentage of live cells. University of Minnesota: Immediate alterations in early embryonic development are observed in heifers that fail to receive adequate nutritional inputs following insemination and these alterations are likely due to insufficient oviduct and uterine support of the developing embryo. Therefore, nutritional management following AI may influence subsequent pregnancy success. Administration of FSH increased the number of follicles aspirated, oocytes collected, proportion of grade 1 to 3 oocytes, and number of grade 1 to 3 oocytes per cow. Administration of FSH, however, did not affect the ability of the oocyte to cleave or develop into a blastocyst or affect the characteristics of subsequently developed blastocysts. Reducing progesterone concentrations during follicular development increased the number of follicles present at aspiration but did not impact quality of oocytes recovered or the ability of the oocytes recovered to cleave and develop into a blastocyst. Of interest, blastocysts generated from oocytes collected in cows with low progesterone concentrations were advanced in development had greater number of blastomeres following in vitro embryo production. In beef heifers, reducing progesterone concentrations within an ultrasound-guided ovum pick-up protocol that included FSH administration resulted in more oocytes collected and increased the number of grade 1 to 3 oocytes recovered per female. Amount of rumen undegradable protein present in the diet of beef females affects ovarian follicular development. Additional research is required to determine if these alterations to follicle dynamics due to RUP amount influence fertility. USDA-MARC: We demonstrated that the previous published work on the GRIA1 polymorphism as a functional mutation that influences antral follicle count is erroneous and that this genetic test should be used with care. We demonstrated that a previously published GnRHr polymorphism reported to impact reproductive performance in cattle may in fact do that, although there is very little evidence that this polymorphism is functional. We demonstrated that the myostatin F94L polymorphism, which has positive influences on carcass traits, may cause delayed puberty in beef heifers. University of Nebraska: Supplementation during winter grazing does not appear to impact cow rebreeding or progeny, however, supplementation does benefit heifer calves and primiparous heifer during the breeding season in a May calving herd. Low input heifer development systems result in acceptable AI and final pregnancy rates. Objective 2. Increase the efficiency and predictability of sustainable reproductive management programs for cattle. South Dakota State University: A decrease in bPAGs but not progesterone, in heifers that experienced late embryonic/fetal mortality, suggests that failure to maintain pregnancy may be initiated by the conceptus rather than due to inadequate luteal secretion of progesterone. There was no difference in the overall accuracy of the test (percent of time correctly identified; 92, 86, 89, and 92%, for estrous detection, Genex, UM, and Biotracking, respectively). Therefore, several options are available to determine pregnancy status in cattle. Prior grazing experience can impact grazing behavior and heifer performance when heifers are moved to spring forage. Kansas State University: In 3 experiments in lactating dairy cows whose ovulation was synchronized with a 5-d Ovsynch protocol, we concluded that the single 50-mg dose of PG administered on d 6 was equivalent to the control in which 25 mg of PG was administered on d 5 and d 6 based on actual luteal tissue regression and decreased concentrations of progesterone to verify luteolysis. We concluded that fewer Presynch10 (two 25-mg injections of PGF2± (PG-1 and PG-2) 14 d apart (Presynch) than PG3G (one 25-mg injection of PG 3 d before 100 ¼g GnRH (G-1), with the PG injection administered at the same time as PG-2 cows) subsequently enrolled in a TAI protocol 10 d after PG-2 (Ovsynch; injection of GnRH 7 d before [G-2] and 56 or 72 h after [G-3] PG-3 with AI at 72 h after PG-3) ovulated and had LH surges at G-1. This observation is consistent with our earlier report (J. Dairy Sci. 95:1831-1844) in which PG3G cows had increased ovulation rates at G-1 and greater (P = 0.069) progesterone at G-2 (4.1 vs. 2.7 ± 0.5 ng/mL) than Pre10 cows. We concluded that effective use of the CIDR insert to increase P/AI is progesterone-dependent for cows initiating RES on d 34. Although d 31 PG3G increased luteolysis and greater ovulation rates before RES, no increase in P/AI compared with RES started on d 41 with or without a CIDR insert. A close relationship exists between onset of standing-to-be-mounted and increased physical activity as measured by neck-mounted accelerometers. Strong correlations were detected between estrual and ovulation traits as defined by standing-to-be-mounted and the activity monitors. Near perfect correlations between HW- and SD-defined onset and end of estrus were detected. Preliminary results indicated little if any effect of semen placement on pregnancy outcomes in heifers when inseminated with gender-biased semen. Mid-range progesterone concentrations (1 to 4 ng/mL) measured 10 d before the onset of the CO-Synch + CIDR protocol in suckled beef cattle tended to predict subseqeuent pregnancy per timed AI. Concentrations of progesterone at CIDR insert were not predictive of subsequent pregnancy outcome. A 3-way interaction of parity, days postpartum, and BCS indicated that older, more conditioned, and further postpartum cows were more likely to conceive in a CO-Synch + CIDR timed AI protocol than thinner contemporaries and those that inseminated earlier postpartum. Cows at greatest risk for not conceiving to AI were primiparous, thin, and earlier postpartum cows. University of Minnesota: Within the 5-day CO-Synch + CIDR protocol in beef heifers, the necessity to administer GnRH at CIDR insertion is questionable. Pregnancy rates were not affected when GnRH administration was withheld. Additional research, in larger numbers of heifers, is required to confirm this finding. University of Kentucky: Preliminary data indicts that cows with the AFI system had an additional 15 days to first service compared to cows on the OVSYNCH treatment. Milk-based PAG ELISA results were accurate in predicting pregnancy in 7 of 7 pregnant cows. University of Wisconsin-Madison: Presynchronization with a modified Ovsynch protocol increased P/AI by increasing synchrony to the Ovsynch56 protocol particularly during heat stress compared to presynchronization with a single injection of GnRH. A single dose of long-acting rbFSH (either 100 µg of A-rbFSH or 50 µg of B-rbFSH but not 50 µg of A-rbFSH) induced superovulation and produced the same quantity of good-quality embryos compared to pituitary-derived FSH. Supplementing RPC during the transition period did not affect milk components but increased milk yield for older cows during and beyond the postfresh supplementation period. USDA-MARC: In collaboration with two other Experiment Stations (SDSU and UNL), we published further supportive evidence that calving early as a heifer has positive influences on reproductive longevity and calf weaning weights through six parturitions. North Dakota State University: Experiment 1 provided insight into the effects of cyclic status of cattle bred via AI systems compared with those bred with natural service. The theory that products used for estrous synchronization can positively impact reproductive success of non-cyclic females was not supported by our data. Further research is warranted to validate the findings from the first year of this multi-year project. Calves generated from respective breeding systems in Experiment 1 will serve as experimental units for studies that focus on post-weaning performance. University of Nebraska: Calving distribution impacts steer and heifer progeny. Synchronization systems improve early calving frequency. University of Missouri: Results from Experiment 1 indicate that greater FTAI pregnancy rates to sex-sorted semen may be achieved by delaying insemination of non-estrous cows. Use of an estrus detection aid may be useful for producers in classifying females as having expressed estrus or as having failed to express estrus prior to FTAI. Females classified as having expressed estrus could be inseminated at the standard time, and females classified as not having expressed estrus could receive GnRH followed by insemination 20 h later. This strategy offers producers the opportunity to achieve acceptable AI pregnancy rates to sex-sorted semen without the need to visually detect estrus and inseminate over multiple days as in an estrus detection system. Results summarized from the Missouri Show-Me-Select Replacement Heifer Program indicate that evaluation of reproductive status of heifers prior to the first breeding season is useful in determining success of the development period and in determining which protocol to use to synchronize estrus prior to FTAI. Results from these field data suggest that the 14-d CIDR-PG protocol provides an advantage in synchronizing estrus and ovulation prior to FTAI, primarily among non-cycling heifers. University of Florida: We determined that administration of PGF2± at CIDR insertion during the CO-Synch + CIDR estrus synchronization protocol failed to enhance pregnancy rates in cows and heifers. Based on actual experimental data a smart phone application was developed to assist beef cattle producers and industry professionals as a decision aid when deciding whether to utilize artificial insemination or purchase herd sires. The application allows user to utilize their own costs and anticipated outcomes.

Please see the attached document.