NC_old1201: Methods to Increase Reproductive Efficiency in Cattle (NC1038)

(Multistate Research Project)

Status: Active

NC_old1201: Methods to Increase Reproductive Efficiency in Cattle (NC1038)

Duration: 10/01/2012 to 09/30/2017

Administrative Advisor(s):


NIFA Reps:


Statement of Issues and Justification

STATEMENT OF THE ISSUES


Need as Indicated by Stakeholders


The United Nations 2009 Food and Agricultural Organization (FAO) indicated that the worlds agriculture will face one of the greatest challenges of all times: to produce enough food to feed the 9 billion people the earth will harbor by 2050. Without question, this will demand the concerted efforts of producers, researchers, and policy makers, to provide the experience and technology to achieve such an endeavor. Obviously, increasing reproductive efficiency of both beef and dairy cattle will contribute to the milk and meat supplies for our future world food needs and for the U.S. to maintain a competitive advantage in production of milk and meat products.


A recent report, Power & Promise: Agbioscience in the North Central United States was prepared for the 12 North Central Land-Grant Universities by Battelle, a Columbus Ohio-based independent research and development group (full report is available at http://nccea.org/documents/powerandpromiseweb.pdf). The report, released August 2011, finds that agriculture and agricultural bioscience -- collectively termed Agbioscience -- are providing wide-ranging opportunities for economic growth and job creation in the U.S.
The report also notes that bioscience professionals at U.S. land-grant universities are leveraging advancements in modern science and technology to address crucial national and global needs, including improving agricultural productivity, food security, human health, renewable resource development (such as bioenergy and biobased materials) and environmental sustainability.


In our science and technology-based economic development practice at Battelle, we have observed the consistent rise of agbioscience as a core driver of economic growth and business expansion opportunities for the U.S., said Simon Tripp, lead author of the study. This is an extremely dynamic sector, leveraging sustainable bio-based resources to produce goods that meet large-scale market needs. Tripp said the North Central region is well positioned to fulfill the promise of new product development and job growth in modern agbioscience.


The North Central region contains 37% of all U.S. farmland. Further, the North Central region is Americas agricultural export engine with 60% of all U.S. live animals and meat exports notwithstanding the region accounts for exports of 83% of soybeans, 85% of all feed grains, and 51% of wheat. Although the North Central region contains but 21% of U.S. land area, it accounts for 45% of all U.S. agricultural exports.


The NC-1038 committee is a long-standing group (previously known as the NC-113 and NC-1006 with more than 35 years of multi-state cooperation since its inception in the early 1970s) that has contributed greatly to the increase in reproductive efficiency of cattle. Its long-term goal is to identify and develop strategies to improve reproductive efficiency for sustainable cattle production and is consistent with the consensus goals set forth by FAIR 2002 and the FAO 2009 and directions described by Tripps Power and Promise.


Importance of the Work, and What the Consequences Are If It Is Not Done


Beef Cattle. Successful management of estrus and ovulation to facilitate artificial insemination (AI) are reproductive management tools available to beef and dairy producers since the 1990s. Manipulation of the estrous cycle shortens the calving season, increases calf uniformity, and facilitates the use of AI. Artificial insemination allows infusion of superior genetics at costs far below the cost of purchasing a herd sire of less than similar standards. These tools remain the most important and widely applicable assisted-reproductive technologies available to beef cattle operators. Current and past research by NC-1038 committee tested protocols for synchronizing estrus, ovulation, or both, which addressed two strategies that are key factors for their implementation by producers. The protocols: 1) minimize the frequency of times cattle must be moved through a cattle-handling facility; and 2) eliminate or minimize detection of estrus before AI or before a timed AI. Application of these methods has already increased the use of AI in beef cattle.


Unless owners of commercial herds aggressively implement genetic improvement through reproductive management, the U.S. will lose its competitive advantage in high quality beef production to countries such as Brazil and Argentina, which are the leading export countries for U.S. beef genetics. According to the U.S. National Association of Animal Breeders and the Association for Brazilian Artificial Insemination, sales of beef semen for AI increased from 3.3 to 10.5 million units between 1993 and 2010 in Brazil, whereas that in the U.S. it only increased from 2.9 to 3.7 million units during the same period. International players, now becoming more technically astute and competitively advantaged, have positioned themselves to dominate the production and sale of beef worldwide.


Dairy Cattle. Total milk production in dairy cattle is determined by the proportion of cows producing milk at any given time and the level of milk production of the individual cows within the herd. Both of these factors are dramatically affected by the rate at which cows become pregnant in the herd. Two factors that determine this rate are the AI submission rate (i.e., managements ability to inseminate nonpregnant cows thereby giving them a chance to conceive) and the conception rate (i.e., the proportion of inseminated cows that actually conceive). The body of scientific literature supports that conception rates in lactating dairy cows have decreased by 25 percentage points to less than 40% during the past 50 years (Lucy, 2001). Until the underlying causes of poor conception rates in lactating dairy cows can be understood and mitigated, pregnancy rates must be increased by focusing on improving the AI submission rate.


Three strategies can be implemented to improve AI submission rates: 1) submit all cows for first postpartum AI at the end of the voluntary waiting period rather than waiting for cows to express estrus; 2) identify nonpregnant cows early after AI; and 3) resynchronize estrus or ovulation in cows failing to conceive to previous AI services. Dairy managers traditionally relied on visual detection of estrus to submit cows for AI. Detection of estrus is often inefficient because of limited observations for estrus and expression of estrus. Development of Ovsynch, a hormonal protocol that synchronizes follicular development, luteal regression, and ovulation thereby allowing for timed AI has radically changed reproductive management by providing dairy managers a practical and effective tool for improving AI submission rate. Pregnancy rates after the Ovsynch protocol are increased by 10 to 12 percentage points compared with Ovsynch alone when estrous cycles are presynchronized (i.e., Presynch), before applying the Ovsynch protocol. Regardless of presynchronization scheme, improved pregnancy rates in timed AI programs is associated with: 1) greater ovulation response to the first GnRH injection of Ovsynch; 2) more cows with a functional corpus luteum at the first GnRH injection; 3) greater ovulatory response to the first and second GnRH injection; and 4) greater ovulation response after timed AI.


Anovulation is an increasing problem in lactating dairy cows. In previous research by the NC-1006 committee, we found that more than 26% of lactating dairy cows were anovulatory near the end of the voluntary waiting period. Recent studies by NC-1038 confirmed a similarly large percentage of anovulatory cows based on multiple blood samples and ultrasound evaluations of the ovaries. Thus, it is clear that anovulation is a significant problem in lactating dairy cows. Modifying timed AI programs to synchronize the time of ovulation in lactating cows may further reduce labor inputs for reproductive management; however, it may be possible to improve fertility with the Ovsynch protocol (one of the purposes of the current proposal).


Although use of reproductive programs to improve first service pregnancy rate reduces the impact of poor detection and expression of estrus, systematic strategies to improve fertility of those services and methods to resynchronize estrus or ovulation in nonpregnant cows (i.e., Resynch) are only beginning to be developed and evaluated. Because conception rates of high-producing lactating dairy cows average 40% or less, 60% or more of cows that receive a timed AI fail to conceive and, therefore, resynchronization strategies are necessary to aggressively initiate subsequent AI services. However, management strategies to reinseminate nonpregnant cows has improved reproductive efficiency, thereby increased AI submission rate. Development of management strategies to identify and resynchronize cows failing to conceive to a timed AI is still a critical step to improved reproduction in lactating dairy cows.


Technical Feasibility of the Research


During the last 25 years, the NC-1038 project (including its predecessor projects NC-113 and NC-1006) has contributed greatly to the development of several breeding programs to maximize pregnancy rates. These successes directly address the objections or reasons given by cow-calf producers for not adopting reproductive technologies. Information accrued by our group led to the development of the Ovsynch protocol in dairy cattle and its variations (i.e., the CO-Synch protocol, progestins + the Ovsynch protocol) used in beef cattle. These protocols generally increased pregnancy rates beyond controls, because in both dairy and beef cattle, they induce fertile ovulation in postpartum cows that have not resumed estrous cycles by the end of the voluntary waiting period (dairy cows) or at the onset of the breeding season (beef cows). During the last 15 years, we tested the efficacy of adding progesterone to the Ovsynch protocol in lactating dairy cows. This experiment was replicated at seven (IL, IN, KS, OH, MI, MO, and WI) of the experiment stations involved in NC-1038 (Stevenson et al., 2006). In beef cattle, the experiment was replicated at four (IL, KS, MN, and MO) of the stations (Lamb et al., 2001). During the past 5 years, a number of other large, multi-state collaborative studies have been completed in dairy (Stevenson et al., 2008; Chebel et al., 2010; Bilby et al., 2011) and beef (Larson et al., 2009; Dahlen et al., 2010; Bridges et al., 2011; Marquezini et al., 2011) reproduction.


Advantages for Doing the Work as a Multi-State Effort


The past four NC-1038 projects have received considerable national attention and acceptance by producers, and it is the aim of the current project to improve fertility and ease of adoption of our developments. Our NC-1038 group has long-standing university and industry relationships and has demonstrated the ability to coordinate multi-location experiments designed to improve fertility in dairy and beef cattle. This is a distinct advantage to successful multi-state efforts. Common interests and strong relationships stem from three of the current collaborators in NC-1038 having been former students of other collaborators. The multi-state collaborations planned in this project will continue to provide new information applicable to beef and dairy producers and additional stakeholders. An important strength of our past multi-state collaborations is that they have increased the statistical power to detect differences in treatment alternatives and allow application of our results to other regions of the U.S. In addition, individual members of the NC-1038 have diverse skills and available laboratory expertise that strengthen our collaborations (e.g., genomics, reproductive biology, nutrition, and behavior expertise).


What the Likely Impacts Will Be from Successfully Completing the Work


Several factors, especially during early development of estrus-synchronization programs, may contribute to poor adoption rates. In addition, these earlier protocols failed to manage follicular waves, resulting in more days during the synchronized period in which detection of estrus was necessary. This ultimately precluded acceptable pregnancy rates after a timed AI. More recent developments focused on control of corpus luteum lifespan and follicular maturation in protocols to synchronize ovulation. These developments facilitate use of timed AI, and should result in increased adoption of these important management practices.


Modifying reproductive management programs to synchronize time of ovulation in lactating dairy cows may substantially reduce labor inputs for reproductive management; however, it may be possible to improve fertility. Development of resynchronization strategies to submit cows failing to conceive to previous inseminations will further improve overall pregnancy rates in lactating dairy cows. In addition, preliminary work from our group and elsewhere has shown promise to improve AI pregnancy rate at first services. This work requires multiple herd collaborations to acquire sufficient numbers of observations in varying environments, dictating multiple investigators working together.

Related, Current and Previous Work

Related Regional Projects


The NE-1027 (formerly NE-1007 and NE-161) committee is addressing parallel work, but their focus is a broad overview addressing factors related to embryonic or fetal survival in cattle. They are addressing multiple events and mechanisms associated with follicular growth and maturation, corpus luteum formation and development that may prevent embryonic or fetal loss. Additional objectives of NE-1027 are to focus on potential environmental and metabolic factors that are related to embryonic survival. The W-1112 (formerly W-112) committee also addresses parallel work, but their focus addresses a range of physiological and endocrine systems related to reproduction in multiple species, mostly utilizing sheep as a model. Their focus is more basic in nature in an effort to discover underlying mechanisms associated with reproduction. They are addressing basic physiological, immunological, metabolic, and genetic systems that may be utilized for further development of reproductive management. The objectives of the NC-1038 project are specifically related to development of reproductive management programs and to understand the underlying mechanisms that responsible for their success.


Dairy Cattle


Pregnancy rates in high-producing lactating dairy cows are less than desirable. Pregnancy rates per AI have decreased from 66% in 1951, to about 50% in 1975, to less than 40% today (Lucy, 2001). Decrease in conception rates in lactating dairy cows is most likely related to the dramatic increase in milk production per cow during the same period.


One possible mechanism for decreased fertility is changes in circulating reproductive hormone concentrations particularly progesterone. Studies indicate that reduced progesterone concentrations before AI result in poor fertility. Characterization studies (Fonseca et al., 1983) have indicated a strong correlation between plasma concentrations of progesterone during the luteal phase before AI and subsequent conception rates. For example, Fonseca et al. (1983) showed an average of a 12.4% decrease in conception rates for every 1 ng/mL decrease in progesterone concentration during the last half of the estrous cycle preceding first service. These studies clearly identified physiologic differences in cows of varying fertility, but did not define the mechanism underlying the difference.


When GnRH was administered at random stages of the estrous cycle, the dominant follicle in 83% of lactating dairy cows and 45% of heifers ovulated with subsequent initiation of a new follicular wave (Pursley et al., 1995). When PGF2a was given 7 days after GnRH, luteolysis occurred and the dominant follicle arising from a new wave of follicles that emerged after GnRH was capable of ovulation in response to a second GnRH injection given 48 h after PGF2a (Pursley et al., 1995). This treatment (GnRH + PGF2a + GnRH + timed AI), known as Ovsynch, has been adopted by many dairy producers as a method for programmed AI-breeding. Pregnancy rates resulting from such a treatment were similar to those achieved in lactating dairy cows inseminated after a detected estrus (Pursley et al., 1997a, b). Using this treatment, pregnancy rates in other studies were less than those in cows inseminated at estrus, but overall pregnancy rates (proportion of cows assigned to treatment that conceived) were similar. The improvement in AI submission rate and reducing the dependence on detection of estrus (reduced labor and errors) have made this protocol attractive to dairy producers despite the lack of improvement in pregnancy rate.


Our most recent NC-1006 joint project was designed to determine whether noncycling dairy cows could: 1) be identified accurately by use of a heatmount detection patch (Kamar); 2) be identified accurately by ultrasonographic exams; 3) have improved pregnancy rates by insertion of a CIDR in conjunction with an Presynch + Ovsynch ovulation-synchronization breeding protocol; 4) have improved pregnancy rates by altering timing of AI to occur concurrent with GnRH or 24 h after GnRH injection; and 5) have reduced pregnancy loss by previous exposure to the CIDR or altered timing of TA (Stevenson et al., 2008). Kamars slightly underestimated previous estrual activity in cows later classified as cycling. Fertility (pregnancy rate or pregnancy loss) was not improved significantly by addition of the CIDR insert to cows identified to be anestrous. Cows previously identified as anestrus, however, had reduced pregnancy rates at days 33 and 61 (regardless of whether they received a CIDR insert) compared with control cows classified as cycling.


Beef Cattle


Estrus and ovulation synchronization programs in beef cattle were reviewed recently by several members of NC-1038 (Lamb et al, 2010). In short, various treatment procedures developed to either induce or synchronize ovulation in anestrous and estrus-cycling suckled cows by administering GnRH and PGF2a, with and without a progestin source, have resulted in pregnancy rates that exceeded controls. Use of Ovsynch in suckled beef cows with fixed-time AI at the time of the second GnRH injection (48 h after PGF2a) or 24 h after the second GnRH injection has produced promising results. Similar treatments (GnRH + norgestomet + PGF2a or GnRH + PGF2a) in suckled beef cows resulted in rates of detected estrus and pregnancy that exceeded controls given two injections of PGF2a (Stevenson et al., 2000). These Ovsynch or Ovsynch-like treatments induce estrus and subsequent pregnancy rates equal to those of estrus-cycling cows inseminated after a detected estrus regardless of whether AI occurred after detected estrus or after one timed AI.


In our NC-113 joint project (Lamb et al., 2001), we compared CO-Synch to a treatment in which progesterone (CIDR) was added between the first injection of GnRH and the injection of PGF2a. We concluded that treatment of suckled cows with CO-Synch yielded acceptable pregnancy rates, but addition of a CIDR improved pregnancy rates in noncycling cows. Body condition and days postpartum at initiation of the breeding season affected overall efficacy of the CO-Synch and CO-Synch + CIDR protocols. Several researchers from our NC-1006 project implemented and coordinated a multi-state, multi-location experiment to determine whether the CO-Synch + CIDR protocol could yield pregnancy rates similar to protocols requiring detection of estrus (Larson et al., 2006). The CO-Synch + CIDR protocol yielded fertility similar to the estrus-detection protocol (Select Synch + CIDR, plus a clean-up timed AI at 84 h after CIDR insert removal) with the greatest pregnancy rates (54 vs. 58%, respectively). In addition, these pregnancy rates were achieved despite 35% of cows being in anestrus at the onset of the treatment.


Researchers from the NC-1038 project also determined whether resynchronization of an ovulatory estrus could be accomplished in nonpregnant cows without compromising pregnancy in cows pregnant from a previous synchronized estrus or to those inseminated to the resynchronized estrus (Larson et al., 2009). Resynchronization with a CIDR after a timed AI did not alter timed AI or overall pregnancy rates, or affect embryo survival. Cows resynchronized with a CIDR between 5 and 21 days after timed AI, however, had greater synchrony of estrus than controls, but conception rates of cows receiving a CIDR until 21 days after timed AI was poorer than controls. In addition, several members of NC-1038 participated in a large multi-state research project aimed at determining the appropriate delivery of PGF2± in the 5 day CO-Synch + CIDR protocol in lactating beef cows. We determined that 50 mg of PGF2± was required in the 5 d CO-Synch + CIDR protocol; however, fixed-time AI pregnancy rates did not differ when 50 mg of PGF was administered simultaneously with CIDR removal or two separate injections of 25 mg each at 0 and 8 h following CIDR removal.


Because the collection of binomial data (pregnancy rates) requires large sample sizes to adequately test hypotheses, the NC-1038 (formerly the NC-113 and NC-1006) group has collaborated well to provide results to be used in a typical production setting. Our future NC projects will continue to include a high degree of collaboration among stations to ensure that our objectives are met and provide meaningful results for use by the dairy and beef cattle industries.

Objectives

  1. Determine mechanisms that regulate reproductive processes impacting production efficiency in cattle.
  2. Increase the efficiency and predictability of sustainable reproductive management programs for cattle.

Methods

Objective 1. Determine mechanisms that regulate reproductive processes impacting production efficiency in cattle Role of molecular pathways in regulating reproductive function (MN, SD, USDA-MARC) A successful pregnancy requires synchrony between embryo development and the uterus. Therefore, understanding the factors that influence follicular development, oocyte competence, embryo development, and fetal survival will lead to the development of procedures that facilitate a large rate of pregnancy success, expedite genetic progress, and increase the profitability and sustainability of the beef and dairy industries. Planned research will investigate the changes in 1) ovarian gene expression associated with the age related decline in fertility, 2) age and nutritional influences on oocyte gene expression, and 3) and steroid influences on uterine gene expression and embryo/fetal survival. Impact of maternal environment on progeny (FL, MN, MS, ND, NE, ND, MN, USDA-MARC, FL) With the advancement of the theory of developmental programming it is becoming evident that nutrient intake by the pregnant female can influence progeny performance via epigenetic modifications of gametes and the early embryo in addition to alterations in nutrient partitioning that may augment placental function. Hence, a paradigm shift has occurred with the realization that modifying diets of reproducing females to enhance reproductive or growth performance may indirectly impact performance of their progeny. Our goal is determine how specific nutrients (corn, corn co-products, fats, etc.) impact reproductive processes and their subsequent effects on progeny via developmental programming, to better integrate these discoveries into management strategies in cattle that will enhance whole-system productivity and efficiency. Preliminary results from our group demonstrated that protein supplementation positively affects both steer performance and heifer reproductive success. Developmental programming effects have been demonstrated after supplementation during two key periods; 1) early in pregnancy during cell differentiation, and 2) during the third trimester of pregnancy. Additional models will be developed by the group to continue to elucidate key periods during pregnancy when nutrient supplementation may have positive impacts on progeny performance. Specific effects of excess or deficient nutrient status during early or late pregnancy need to be identified. Basic research in this area is a critical step needed to bring developmental programming to the applied producer level. To examine the use of new technologies to assist with enhancing reproductive performance (KY, WI) Synergies between existing reproductive management strategies and new technologies hold the potential to improve reproductive efficiency on dairy farms; however, the efficacy and accuracy of any new reproductive technology must be evaluated before they can be widely implemented in the industry. The cardinal sign of estrus in dairy cattle is standing to be mounted by a herdmate, and the timing of the LH surge and ovulation are temporally associated with the onset of that behavior (Walker et al., 1996), allowing for the correct timing of AI for optimal fertility. Increased physical activity associated with behavioral estrus is considered a secondary sign of estrus, and inseminating heifers based on secondary signs of estrus resulted in reduced fertility compared with insemination at a standing estrus (Donovan et al., 2003). A new generation of devices for monitoring a variety of traits in dairy cattle have been developed and marketed to the dairy industry . These include temperature sensing boluses for determining body temperature (SmartBolus, TenXsys Inc., Eagle, ID, USA) and activity monitors (accelerometers) for detecting behavioral estrus (Heatime, SCR Engineers Ltd., Netanya, Israel). Experiments under this sub-objective are designed to assess these technologies as a means for timing of insemination for maximal fertility in lactating dairy cows. Furthermore, we will characterize temporal relationships between physiological, endocrine and behavioral parameters during the periestrual period in dairy cows as well as define the duration and intensity of estrus and anovulation in dairy cows. Utility of accelerometer-based insemination versus timed AI programs also will be examined under field conditions in collaboration with commercial dairy farms. Objective 2. Increase the efficiency and predictability of sustainable reproductive management programs for cattle Pre- and post-insemination strategies to optimize reproductive efficiency (FL, KS, KY, MN, MO, MS, ND, NE, SD, USDA-MARC, WI) Management pre- and post-insemination may influence fertility through many mechanisms such as changes to the uterine environment, embryo survival, impacts to production efficiency of offspring, and future fertility of females. Inclusion of particular feedstuffs, such as bi- or co-products and forages, may impact fertility. Management strategies such as grazing, heifer development, protein and energy availability, and changes in diets may affect reproductive efficiency. Measurements may include both hormonal and metabolite evaluation pre- and post-insemination, conception rates, and subsequent dam and progeny fertility will be evaluated. We will determine effective management strategies to optimize reproductive efficiency and also evaluate the cost-effectiveness of management strategies to increase profitability and sustainability of cattle operations. Reproductive management programs to facilitate artificial insemination in cattle (FL, KS, KY, MN, MO, MS, ND, NE, SD, USDA-MARC, WI) Collaborative studies have been planned to test various treatments designed to improve conception rates and pregnancy survival in lactating dairy cows, suckled beef cows, and beef and dairy heifers. Treatments will include single and combinations of gonadorelins, gonadotropins, and progesterone (intravaginal CIDR insert) applied at strategic points before or after insemination to induce ancillary luteal structures, increase progesterone, or both, in addition to improved fertility. Concurrently, methods of early pregnancy detection will be evaluated. Tools that will be used for early pregnancy status will include progesterone, interferon-tau, interferon-induced products, and pregnancy-associated glycoproteins (PAGs). Studies will be done in successive years based on results of previous years. Highly effective synchronization programs (before first insemination) are already established. Cows synchronized with these primary synchronization protocols will be used for the resynchronization and pregnancy determination studies. Resynchronization protocols used in conjunction with the primary synchronization will be evaluated by assessing pregnancy rates to second and cumulative (first and second) insemination (or embryo transfer). Success of early pregnancy detection determinations will be assessed retrospectively by examining for pregnancy via ultrasound examination. Once a complete program is established the complete protocol will be evaluated at multiple locations.

Measurement of Progress and Results

Outputs

  • All research proposed herein will be completed during the 5-year proposal period. Results of research will be published in experiment station reports, refereed publications, and in popular press. In addition, decision aid tools will be developed to assist cattle producers to enhance their ability to incorporate new reproductive management practices into their operations.

Outcomes or Projected Impacts

  • Data generated from the research conducted in experiments proposed herein are related to agricultural processes with the potential to enhance the productivity and quality of livestock in a sustainable manner that will boost U.S. agricultural production and improve global capacity to meet growing food demand, one of five national priority areas identified by the USDA in 2010. In beef cattle, loss of early embryos results in cows failing to conceive during the breeding season or to conceive late in the breeding season. This early embryonic loss costs the U.S. beef industry more than $1 billion annually. In addition, 1.1 kg of weaning weight is lost for each day between the start of calving season and when a calf is born, which translates to a loss of $2.42 per day per calf or almost $17 per week per calf as the calving season progresses, and the profitability of a steer born during the first vs. third 21 days of the calving season is estimated to be $80 greater at weaning and $77 greater at harvest! Our recent data have demonstrated that beef cows exposed to ovulation synchronization and fixed-time AI subsequently have 6% greater weaning rates and increase weaning weights by 17 kg per cow exposed. By improving reproductive management programs to increase the number of cows that utilize ovulation control and AI from approximately 2 million cows to approximately 30 million cows, would result in 476 million kg of increased weaning weights! Reproductive efficiency is poor in lactating dairy cows making it one of the most costly and production-limiting problems facing U.S. dairy farms. Recent studies conducted by members of NC-1038 and proposed studies have pushed conception rates of lactating dairy cows into the 40 to 50% range. These studies address cows inseminated for the first time as well as those reinseminated once diagnosed not pregnant. Increasing pregnancy rates by injecting GnRH at 48 to 56 h after PGF2a in an Ovsynch protocol doubled the proportion of pregnancies compared with injecting GnRH at the time of AI. Increasing pregnancy rates in resynchronized cows diagnosed not pregnant after a previous insemination results in fewer cull cows, more calves, and greater milk production. Cost of a cull is the cost of her replacement minus the market value of the cull sold at the sale barn times the remaining proportion of her expected herd life. For example, if the average cost of a replacement cow is $1,290, and the value of the cull cow sold at the sale barn is approximately $500, then for every cow culled from the herd, the loss averages $790. But the loss does not end there because the cull cow is replaced with a less milk-producing 2-year-old cow and one continues to lose milk from what would have been accrued from the higher producing cull cow, had she stayed in the herd as a pregnant cow. Therefore, the loss from each cow culled can easily reach $1,000. Therefore, the impact of experiments from researchers in this committee have the potential to continue to enhance overall reproductive efficiency of beef and dairy cattle as they have done so in past projects. The NC-1038 committee (formerly NC-113 and NC-1006) has an established successful track record of collaboration and impact on reproductive efficiencies of beef and dairy cattle in the North Central region.

Milestones

(2012): Initiate discovery of nutritional, physiological, and molecular factors associated with fertility in beef and dairy cattle, plus initiate development or refinement of reproductive management programs.

(2013): Preliminary reports indicating potential factors associated with fertility in cattle and continue generating data for development of reproductive management programs.

(2014): Initial summaries on new developments of ovulation synchronization, presynchronization, and resynchronization protocols.

(2015): Disseminate findings to scientific community, industry professionals, producers and veterinarians.

(2016): Publication in scientific journals.

Projected Participation

View Appendix E: Participation

Outreach Plan

The Beef Reproductive Task Force (http://beefrepro.unl.edu/) is composed of mostly scientists that are members of NC-1038 who major extension appointments (FL, KS, MO, NE, SD, KS). Their objectives and mission are to provide leadership and consistency in programming to the beef industry with the following goals: 1) promote wider adoption of reproductive technologies among cow-calf producers; 2) educate cow-calf producers in management considerations that will increase the likelihood of successful AI breeding; and 3) educate producers in marketing options to capture benefits that result from use of improved reproductive technologies. Four specialists in this task force are principal investigators and station representatives of NC-1038. Their efforts have been coordinated and correlated with our project during the last 11 years. This task force has been instrumental in providing the latest developments in reproductive management systems of beef cattle through workshops, publications, and maintaining an active relationship with veterinarians, pharmaceutical, and AI industries. An update of the Task Forces activity is published (Johnson et al., 2011).


The Dairy Cattle Reproduction Council (DCRC; www.dcrcouncil.org) is a newly established organization with similar goals to the Beef Reproduction Task Force to provide leadership in terms of educating the dairy industry on critical reproductive management systems. The DCRC leadership includes two specialists (KS, WI) that are active members of NC-1038 and both past program chairs. The inaugural DCRC convention convened in Denver, CO in November 2006 with over 300 attendees present. Representatives were present from industry groups, bovine practitioners, academia, and dairy producers from across the U.S. and Canada. Data acquired by scientists in NC 1006 will be presented at workshops and in publications to ensure that dairymen have access to the most current reproductive management programs.


Further, members from FL, MN, MO, ND, NE, and WI experiment stations have extension appointments in addition to their research appointments. Therefore, results derived from research conducted by the NC-1038 committee will be disseminated using traditional Extension education avenues.

Organization/Governance

The technical committee will consist of at least 1 officially designated representative from each participating agricultural experiment station in the region. The technical committee will meet annually. The USDA-NIFA will designate one nonvoting representative. Officers will be elected for a rotating period of 3 years, consisting of Chair, Secretary, and a Member-at-Large. Officers rotate from Member-at-large to Secretary to Chair. Elections will be held at the annual meeting. Officers will compose the executive committee. The executive committee, together with administrative advisors, is authorized to function on behalf of the technical committee in all matters pertaining to the regional project requiring interim action.


The Chair, in consultation with the administrative adviser, will arrange the time and place of the meeting, notify technical committee members of the meeting site, and prepare the agenda. The Chair is responsible for preparation of the annual report of the regional project. The Secretary will record and distribute minutes of the annual meeting. Subcommittees may be appointed by the Chair as needed for specific assignments. The executive committee will be in charge of coordinating cooperative research trials.

Literature Cited

Bello, N. M., J. P. Steibel, and J. R. Pursley. 2006. Optimizing ovulation to first GnRH improved outcomes to each hormonal injection of Ovsynch in lactating dairy cows. J. Dairy Sci. 89:34133424.


Bilby, T.R., R.G.S. Bruno, K.H. Lager, R.C. Chebel, J.G.N. Moraes, P.M. Fricke, G. Lopes, J.O. Giordano, J.E.P. Santos, F.S. Lima, J.S. Stevenson, and S.L. Pulley. 2011. Effects of supplemental progesterone and timing of initiation of resychronization on fertility in lactating dairy cows. J. Dairy Sci. 94(E-Suppl. 1):88 (Abstr.).


Bridges, G.A., L.H. Cruppe, J.F. Currin, M.L. Day, P.J. Gunn, J.R. Jaeger, G.C. Lamb,. A.E Radunz, P. Repenning, J.S. Stevenson, J.C. Whittier, and W.D. Whittier, 2011. Determination of appropriate delivery of PGF2a in the 5-day CO-Synch + CIDR protocol in lactating beef cows. J. Anim. Sci. 89(E-Suppl. 1): 251 (Abstr.).


Chebel, R.C., M. J. Al-Hassan, P. M. Fricke, J.E.P. Santos, J. R. Lima, C. A. Martel, J. S. Stevenson, R. Garcia, R. L. Ax, and F. Moreira. 2010. Supplementation of progesterone via CIDR inserts during ovulation synchronization protocols in lactating dairy cows. J. Dairy Sci. 93:922-931.


Chebel, R. C., J.E.P. Santos, R L.A. Cerri, H. M. Rutigliano, and R. G. S. Bruno. 2006. Reproduction in dairy cows following progesterone insert presynchronization and resynchronization protocols. J. Dairy Sci. 89:42054219.


Dahlen, C.S., S. L. Bird, C. A. Martel, KC Olson, J. S. Stevenson, and G. C. Lamb. 2010. Administration of human chorionic gonadotropin 7 days after fixed-time AI of suckled beef cows. J. Anim. Sci. 88:2337-2345.


Donovan, G. A., F. L. Bennett FL, and F. S. Springer. 2003. Factors associated with first service conception in artificially inseminated nulliparous Holstein heifers. Theriogenology 60:67-75.


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