NC1201: Methods to Increase Reproductive Efficiency in Cattle

(Multistate Research Project)

Status: Active

NC1201: Methods to Increase Reproductive Efficiency in Cattle

Duration: 10/01/2017 to 09/30/2022

Administrative Advisor(s):


NIFA Reps:


Statement of Issues and Justification

Needs as Indicated by Stakeholders


We define our stakeholders to be dairy and beef cattle producers, the scientific community, and consumers. The proposed research addresses national priorities to sustain the dairy and beef cattle industries by increasing reproductive efficiency through applying technologies to improve production of milk and meat. To maintain a stable milk and meat supply for consumers, dairy farms and cattle ranches must be sustainable and foster environmental stewardship. Reproductive efficiency drives all revenues in cattle operations. The United Nations 2009 Food and Agricultural Organization (FAO) indicated that the world’s 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 livestock 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 future world food needs and for the U.S. to maintain a competitive advantage in production of milk and meat products.


Another noteworthy report, “Power & Promise: Agbioscience in the North Central United States” was prepared in 2011 for the 12 North Central Land-Grant Universities by Battelle, a Columbus Ohio-based independent research and development group. The full report is available (http://nccea.org/documents/powerandpromiseweb.pdf). The report found that agriculture and agricultural bioscience ¾ collectively termed “Agbioscience” ¾ is providing wide-ranging opportunities for economic growth and job creation in the U.S. The report also noted 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 bio-based materials) and environmental sustainability.


According to Farm Animal Integrated Research-2012 (Key Topic 1-4: Reproduction, FAIR-2012) “reproductive performance has a substantial effect on the overall efficiency of use of feeds in livestock production by all species, especially in cattle (italics added). Recent improvements in reproductive performance are impressive and important contributors to increases in whole herd feed efficiency. There is a need to further extend these improvements in challenging environments, including those often found in developing countries. Special opportunities now exist for improvements in reproductive areas such as semen preservation and timing of insemination.”


Importance of the Proposed Work


The North Central region of the U.S. contains 37% of all U.S. farmland. Further, the North Central region is America’s 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. It is a critical bread basket of agricultural production to feed the masses.


The NC-1201 committee is a long-standing group (previously known as the NC-113, NC-1006, and NC-1038 with more than 40 years of multistate cooperation since its inception in the early 1970s). It 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 FAO 2009 and FAIR 2012, and consistent with the directions described by Tripps “Power and Promise” report cited previously. 


Technical Feasibility of the Research


During the past 25 years, the NC-1201 project (including its predecessor projects NC-113, NC-1006, and NC-1038) 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 ([1] don’t work; [2] cost; and [3] complicated procedures; NAHMS, 2007; www.aphis.usda.gov/animal_health/nahms/beefcowcalf/downloads/beef97/Beef97_is_ReprodTech.pdf). 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 have 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 8 years, a number of other large, multi-state collaborative studies and invited reviews have been completed by our group in dairy (Stevenson et al., 2008; Chebel et al., 2010; Lamb et al., 2010; Bilby et al., 2011; Mercadante at al., 2015; Stevenson and Lamb, 2016; Lamb et al., 2016; Perry and Cushman, 2016) and beef (Larson et al., 2006, 2009; Dahlen et al., 2010; Bridges et al., 2011; Marquezini et al., 2011; Hill et al., 2016a,b; Stevenson and Lamb, 2016) 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-1201 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. Most important to the point is that our committee composition includes members with long-term relationships and prior contributions to previous North Central projects (15+ years). Our track record of collaborative research and publication is most noteworthy among NC committees.


This is a distinct advantage to successful multi-state efforts. Common interests and strong relationships stem from three of the current collaborators in NC-1201 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 all regions of the U.S. In addition, individual members of the NC-1201 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- and ovulation 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 will require multiple herd collaborations to acquire sufficient numbers of observations in varying environments, dictating multiple investigators working together.


 A further need exists for understanding and validating the epigenetic mechanisms controlling developmental programming (e.g., ability of various nutritional treatments applied to dams that alter progeny while in utero). A number of studies have demonstrated impacts of fetal programming on progeny performance. Research will focus on identifying consistent changes in epigenetic mechanisms across locations (e.g., environments).

Related, Current and Previous Work

Related Regional Projects


The NE-1227 (formerly NE-161, NE-1007, and NE-1027) committee is addressing parallel work, but their focus is on ‘ovarian influences on reproductive success in ruminants’. They are addressing multiple events and mechanisms associated regulation of signaling pathways and gene expression in somatic and germ cells by paracrine factors and steroid hormones ensures ovarian cyclicity, the production of developmentally competent oocytes, and the regulation of early embryogenesis. An additional objective of NE-1227 is to identify inter-cellular interactions between somatic cells of the ovary, somatic cells and germ cells, or somatic cells and the embryo that promote follicular growth, oocyte maturation, early embryonic development, and establishment and maintenance of pregnancy . The W-2112 (formerly W-112 and W-1112) committee also addresses parallel work, but their focus is to discover and translate molecular, metabolic, genomic, endocrine, and immunologic mechanisms that influence testicular and ovarian function, reproductive behavior, conception rate, embryo and fetal development, attainment of puberty, and effects of climate/season on reproductive patterns of domestic ruminants. 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-1201 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% in 2010. However, as a result of much of the research and outreach completed by members of this committee (NC-113, NC-1006, NC1038, and NC-1201) several advances have occurred to upgrade reproductive management programs in dairy herds that have resulted in an increase in pregnancy rates per AI in recent years. Recently at a symposium focusing on enhancing the adoption of reproductive management tools for beef and dairy cattle at the Joint Annual Meeting in Salt Lake City, UT a summary (Stevenson and Mendonça, 2016) demonstrated key advancements in reproductive management of dairy cattle. Many of these advances were as a result of work completed by members of this committee. These advance are:



  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 progesterone at 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 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.


Specific previous contributions by this committee have demonstrated that 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 previous NC-1006 and NC-1038 joint projects were designed to determine whether noncycling dairy cows could: 1) be identified accurately by use of a heat mount 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.


Our most recent NC-1201 projects (Fricke et al., 2014a, ; Stevenson et al., 2014) indicated that utilizing activity monitors to predict estrus and ovulation is as effective as using rump-mounted radiotelemetric sensors that identify standing estrus at similar input costs. Further, labor inputs are significantly less in maintaining the rump-mounted sensors compared with neck-mounted accelerometers. Onset of estrus or onset of increased activity is accurately defined by both systems and ovulation is highly predictable based on time from onset or end of estrus or peak activity. Both systems may reduce inter-insemination intervals and increase pregnancy rates (shorted intervals from calving to pregnancy) compared with timed AI programs without detection of estrus.


Beef Cattle


Estrus and ovulation synchronization programs in beef cattle were reviewed recently by several members of NC-1201 (Lamb et al., 2010; Patterson et al., 2016). Various treatment procedures developed to either induce or synchronize ovulation in anestrous and estrus-cycling suckled cows by administering GnRH and PGF, with and without a progestin source, have resulted in pregnancy rates that exceeded controls. Breeding management technologies are currently available or emerging that offer the potential to more effectively manage reproduction, expedite genetic progress, enhance efficiencies of production, and add value to beef cattle produced and marketed in the U.S. Until recently, the inability to predict time of estrus. These strategies provide opportunities for producers to utilize sires of elite genetic merit, reduce length of the breeding and calving seasons, produce more uniform calf crops, and improve reproductive rates of replacement beef heifers and the mature cow herd. Collectively, advancements in applied reproductive technologies afford beef producers the flexibility to match specific breeding management protocols to a defined management system.


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 PGF in the 5 day CO-Synch + CIDR protocol in lactating beef cows.  We determined that 50 mg of PGF 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. 


Collaborations from our NC1201 projects have demonstrated that using estrus-detection patches as part of a fixed-time AI program allows managers to inseminate beef cows in two groups (Bishop et al., 2016; Hill et al., 2016). The first group includes cows detected in estrus, which are inseminated at 60 to 66 h after the end of the program, whereas in the second group of cows not in estrus at 60 h, AI is delayed approximately 15 to 20 h. In doing so, the percentage of cows with AI calves in the first group should average 65% and that in the second group should average more than 50%. As a result, for the same or lesser amount of input costs for materials, the proportion of AI calves should increase by 50%. In addition, analysis (Stevenson and Lamb, 2015) of previous studies involving more than 8,500 suckled beef cows demonstrated that management changes that increase body condition scores of cows that result in earlier calving during the next calving season may increase their AI pregnancy outcomes in the next breeding season by 25 to 30%. In addition, pregnancy outcomes in 2-year-old cows can be improved by increasing their progesterone status before the breeding period. Treatments that induce earlier estrous cycles are possible remedies in addition to earlier breeding of heifers compared with the cow herd so heifers calve earlier in their first breeding season as cows. Pregnancy rates per AI in 2-year-old cows that initiated estrous cycles before applying a fixed time AI program were increased by 30% compared with their anestrous contemporaries.


Because the collection of binomial data (pregnancy rates) requires large sample sizes to adequately test hypotheses, the NC-1201 (formerly the NC-113, NC-1006, and NC1038) 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. Increase the efficiency and predictability of sustainable reproductive technologies and management programs for cattle.
  2. Evaluate mechanisms that regulate reproductive processes impacting production efficiency in cattle.
  3. Disseminate reproductive management information to stakeholders to improve sustainability of cattle enterprises.

Methods

Objective 1

Increase the efficiency and predictability of sustainable reproductive technologies and management programs for beef cattle (TX, VA, OR, KS, SD, MO, ND, MS, IL).

 Increased efficiency in beef cattle management programs has occurred in part as a result of improvements in reproductive technologies. Development of protocols that facilitate synchronization of estrus and ovulation enabled beef producers to increase the use of fixed-time artificial insemination (FTAI), and as a result during the past 11 years, sales of beef semen in the U.S. have nearly doubled (Patterson et al., 2016). Although acceptable pregnancy rates can be achieved using FTAI, we know that heifers and cows that fail to express or exhibit estrus before insemination achieve poorer pregnancy rates to FTAI (Perry and Smith, 2016). In an effort to improve pregnancy rates to timed AI, Thomas et al. (2014) developed a modified approach in which timing of insemination is delayed for non-estrus-expressing females until 20 to 24 h after the FTAI scheduled time. This approach, termed “split-time AI (STAI),” improved pregnancy rates when using sex-sorted semen in mature beef cows after the 7-day CO-Synch + CIDR protocol (Thomas et al., 2014). More recently using conventional semen, STAI was found to improve pregnancy rates among beef heifers after treatment with the 14-day CIDR-PG protocol (Thomas et al., 2014; Bishop et al., 2016b; Bishop et al., 2017) as well as among mature cows after the 7-day CO-Synch + CIDR protocol (Bishop et al., 2016c). These improvements were observed as a result of an increase in total estrous response that occurred when GnRH was administered only to non-estrus-expressing heifers and cows concurrent with delayed insemination (Bishop et al., 2016b; Bishop et al., 2017).

 Increased adoption of advanced reproductive technologies in the beef industry relies upon the continued development of new or modification of existing timed protocols that do not require the labor and time commitment of detecting estrus (Trimberger, 1948). To be economically viable for widespread use in the beef industry, sex-sorted semen must achieve pregnancy rates comparable with conventional semen and must be suitable for use in FTAI protocols. Previous studies, however, have shown that pregnancy rates were reduced when sex-sorted semen was used in conjunction with FTAI (Hall et al., 2010; Thomas et al., 2014a; Sá Filho et al., 2012). Therefore, it has generally been recommended that sex-sorted semen not be used in conjunction with FTAI or that use of sex-sorted semen be restricted to only females that express estrus before FTAI (Seidel, 2003).

Research will focus on utilization of FTAI and STAI to facilitate expanded use of sex-sorted semen in beef heifers and cows. Improvements in pregnancy rates using STAI over FTAI are based largely on our improved understanding of the appropriate timing of GnRH administration and the associated increase in estrus expression that occurs before insemination when STAI is practiced. Research planned in support of this objective will be multifaceted. With heifers, results using STAI after administration of the 14-day CIDR-PG protocol were published (Thomas et al., 2014; Bishop et al., 2016b; Bishop et al., 2017), and the appropriate scheduling of GnRH administration and insemination was determined. This is not the case for three other FTAI protocols recommended for heifers, which include the 7- and 5-day CO-Synch + CIDR protocols, and MGA-PG. In addition, results after administration of the 7-day CO-Synch + CIDR protocol in cows used in conjunction with STAI are available (Thomas et al., 2014; Bishop et al. 2016a, b; Hill et al., 2016a,b). The research in cows will focus initially on determining the appropriate sequence of events involving CIDR removal, GnRH administration, and times at which STAI should be performed. In contrast, as in the case with heifers, the appropriate scheduling and timing of events need to be determined with the 5-day CO-Synch + CIDR protocol in cows. In addition, a long-term CIDR-based protocol recently developed for use in postpartum beef cows (9-day CIDR-PG; Thomas et al., 2016) will be evaluated and compared with the 7-day CO-Synch + CIDR protocol to determine which protocol offers the greatest potential to accommodate use of sex-sorted semen in postpartum beef cows using STAI. Furthermore, efforts will be made to improve or modify existing protocols hat are recommended for FTAI in addition to develop new protocols.

Outputs. We will evaluate pregnancy rates in beef heifers and beef cows using sex-sorted semen compared with conventional semen using FTAI and STAI and after administration of all protocols currently recommended for FTAI in beef heifers (7- and 5-day CO-Synch + CIDR protocols, and MGA-PG) and cows. Research efforts will continue to include a focus on strategies to improve or modify existing protocols that are recommended for FTAI along with efforts to develop new protocols.

Outcomes or Projected Impacts. This research will expand opportunities to increase pregnancy rates using FTAI and/or STAI after administration of the current list of recommended protocols to synchronize estrus before FTAI in beef heifers and cows. In addition, outcomes resulting from the research will lead to meaningful comparisons and evaluations of short- and long-term CIDR-based protocols for cows and determination of which protocols afford the greatest opportunity to improve pregnancy rates after FTAI or STAI. These results will then be considered to identify protocol(s) that offer the greatest potential, based on total estrous response and resulting pregnancy outcome, to then be evaluated using sex-sorted semen. Pregnancy rates will be compared using conventional and sex-sorted semen with the ultimate goal of delivering a viable breeding management strategy to the beef industry that expands use of sex-sorted semen with acceptable pregnancy rates.

Timeline. Several members of the committee are actively engaged in experiments involving STAI in beef heifers and cows along with evaluation of new or modified approaches to FTAI. These experiments will serve as useful spring-boards to expand research with other protocols and then follow with specific protocol comparisons in years 1 and 2 of the project. Collaborative efforts among the various institutions will easily facilitate successful completion of this phase of the overall project and before experiments involving use of sex-sorted semen. Once protocol(s) are identified that afford the greatest potential to increase total estrous response and resulting pregnancy rates, multi-state projects will be designed to then compare strategies using conventional versus sex-sorted semen in years 3 and 4 of the project. Upon completion of the multi-state field trials, the anticipated outcome of these collaborative efforts should result in the development of practical breeding management strategies that facilitate expanded use of sex-sorted semen in the beef industry without the need to perform visual detection of estrus.

Objective 2

Evaluate mechanisms that regulate reproductive processes impacting production efficiency in cattle (NE, OR, KS, MI, SD, US MARC, VA, WI)

Beef Cattle (NE, OR, SD, US-MARC, VA)

Early embryonic loss has been estimated to be as large as 60% (from fertilization through day 45 of pregnancy). Not all stresses during early pregnancy, however, result in early embryonic mortality; some result in changes in the developmental program of the progeny. Survival of the embryo requires communication between the embryo and the uterus. Therefore, a need exists to understand mechanisms that regulate the uterine environment to establish a viable pregnancy and influence embryonic and fetal development. Research will focus on identifying mechanisms that change or regulate the uterine environment and their impact on early embryonic development. Factors investigated will include preovulatory steroid production, estrus expression, nutritional impacts, and the influence of the ovarian reserve.

Use of lipids in cattle feeding with the objective of enhancing animal performance by increasing energy content of diets, has been extensively investigated. Although energy status is known to dictate reproductive performance in cows (Staples et al., 1990; Schillo, 1992; Staples et al., 1998; Hess et al., 2005), research indicates that reproductive performance is positively impacted by fat supplementation regardless of an increase in energy intake (Mattos et al., 2000; Santos et al., 2008; Thatcher et al., 2011), indicating that specific fatty acids may play a role in the control of the reproductive biology in cattle. Furthermore, lipid supplementation may impact cattle reproductive performance via several previously reported mechanisms, such as enhancing follicular development during the postpartum period, increasing progesterone production during the luteal phase, and altering oocyte and embryo quality (Mattos et al., 2000; Santos et al., 2008a). In addition, inclusion of fatty acids from the ω3 family on cattle diets can decrease endometrial production of PGF(Mattos et al., 2002; Mattos et al., 2004) during maternal recognition of pregnancy and potentially improve reproductive performance of bovine females by optimizing the interaction between uterus and conceptus (Mattos et al., 2000; Santos et al., 2008b; Thatcher et al., 2011).

Indeed, reports on beef cows supplemented with calcium salts of soybean oil, rich in linoleic acid, for 21 days post-AI showed an increase in pregnancy rates by 30% (Lopes et al., 2009; Lopes et al., 2011). All this research, however, was conducted in Bos indicus cattle reared in tropical environments. Hence, research is warranted to validate these outcomes in B. taurus cattle in typical U.S. operations particularly because pregnancy establishment and overall reproductive physiology differs among B. indicus and B. taurus breeds (Mercadante et al., 2013). Our objective will be to determine effects of supplementation with calcium salts of soybean oil during early gestation on pregnancy establishment and maintenance in B. taurus beef cows enrolled on fixed-time AI programs and reared in typical U.S. commercial cow-calf systems. In a multi-state project, a total of 1,000 beef cows at 8 commercial locations will be enrolled on a fixed-time AI programs and receive supplementation of calcium salts of soybean oil or a control supplement (prilled fat based on saturated fatty acids) for 21 days post-AI, and pregnancy rate will be determined by ultrasonography on or after day 30. Expression of interferon stimulated genes on days 18 and 21 will be determined in a subset of cows as well as plasma concentrations of pregnancy-associated glycoproteins (PAGs) and concentrations of progesterone, which have been positively associated with pregnancy maintenance in beef cattle (Pohler et al., 2013).

Previous results demonstrated that early embryonic development in vitro is improved in oocytes harvested from heifers and cows with increased numbers of follicles (Tessaro et al., 2011; Cushman and Perry unpublished data). These results indicate that epigenetic mechanisms controlling early embryonic development are improved in these oocytes. We will challenge oocytes from cows having high and low numbers of antral follicle counts with elevated non-esterified fatty acid concentrations (known to negatively impact the epigenome of developing embryos) in vitro to determine differential epigenetic responses that contribute to improved embryonic development in cows with increased numbers of follicles. Influence of non-esterified fatty acids (NEFA) on early embryonic development in vitro in ovaries differing in follicle number will be investigated. The hypothesis is that oocytes from ovaries with increased numbers of follicles are more resistant to the negative effects of NEFA on early embryonic development (Desmet et al., 2016). Our approach will be to collect slaughter house ovaries and classify as low antral follicle counts (AFC; < 10 follicles) or high AFC (>20 follicles). Aspirated cumulus-oocyte complexes will be exposed in culture to basal NEFA concentrations (Desmet et al., 2016). Replicates of experiment over a 2-year window will assess percentage of embryos that cleave and percentage that develop to blastocyst stage. Transcript analysis of the embryos at the end of the culture will examine early development genes that might be differentially expressed in the model system.

Developmental programming. A need exists for understanding and validating the epigenetic mechanisms controlling developmental programming. A number of studies have demonstrated impacts of fetal programming on progeny performance. Research will focus on identifying consistent changes in epigenetic mechanisms across locations (e.g., environments and production systems). Factors contributing to modification of the epigenome to be investigated include cortisol-mediated effects of stress resulting from stocking density (Schubach et al., 2016) or nutrient status (Marques et al., 2016). Based on the results from these analyses, we will initiate a multi-state experiment that attempts to developmentally program progeny consistently across locations.

Dairy Cattle (KS, WI, MI)

Progesterone is essential for maintenance of pregnancy in dairy cows as well as inhibiting estrus expression. Peripheral concentrations of progesterone are affected by both level of milk yield and the rate of metabolism in the liver (Lemley and Wilson, 2010). Selection for increased milk yield during several decades has resulted in greater milk yield and the necessity to feed cows less roughage and more high energy diets to support milk secretion. Furthermore, high energy diets chronically increase hepatic blood flow resulting in increased clearance of progesterone (Sangsritavong et al., 2002). Clearance rate of progesterone is a function of hepatic blood flow and liver enzyme activity (Sangsritavong et al., 2002; Lemley and Wilson, 2010). Cytochrome P450 2C and cytochrome P450 3A are enzymes that inactivate progesterone in hepatic tissue. Therefore, decreasing liver enzymatic activity may increase peripheral concentrations of progesterone (Lemley et al., 2010).

Previous research has shown that feeding a high starch diet, with glucose being a major product of starch digestion, causes an increase in insulin production resulting in decreased activity of cytochromes P450 2C and P450 3A (Lemley et al., 2010). Insulin, a metabolic mediator between nutrition and reproduction (Vieira et al., 2010), is secreted in response to increased concentrations of circulating glucose. Previous research also indicated that insulin can effectively decrease progesterone clearance in vivo (Moriel et al., 2008; Lemley et al., 2010). Glucose is a key nutrient required during lactation for milk synthesis and maintenance of other body tissues including those involved in reproduction (Bell, 1995; Lucy et al., 2013). In a ruminant, dietary glucose is rapidly converted to volatile fatty acids (VFAs), and then oxidized as an energy source in body tissues (Lucy et al., 2013). Because most glucose is converted into VFAs in the rumen, a cow must synthesize glucose de novo via gluconeogenesis in the liver (Drackley et al., 2001; Lucy et al., 2013). An early lactation cow can only achieve 85% of her glucose requirement via gluconeogenesis, which leaves her lacking approximately 500 g of glucose daily to meet demands for maintenance and milk synthesis (Drackley et al., 2001; Lucy et al., 2013). The extensive demand for glucose by the mammary gland for milk synthesis may decrease the amount of glucose readily available to other body tissues including those tissues involved in reproductive processes (Wathes et al., 2001; Green et al., 2012; Garverick et al., 2013). rumen-protected glucose should facilitate more glucose being delivered to the small intestine for absorption without relying solely on its de novo synthesis in the liver. Because circulating glucose induces secretion of insulin, the resulting increase in insulin may decrease the activity of hepatic enzymes involved in clearance of progesterone (Lemley et al., 2010), and thus, increase peripheral concentrations of progesterone. Increased concentrations of progesterone during the estrous cycle before insemination at estrus (Fonseca et al., 1983) or during the 7 to 10 days preceding a timed insemination (Stevenson, 2016) are predictive of subsequent pregnancy risk in lactating dairy cows. Therefore, research is warranted to determine if feeding rumen-protected glucose can increase peripheral concentrations of progesterone and indirectly improve pregnancy risk.

We hypothesize that cows fed rumen-protected glucose will have increased peripheral concentrations of insulin, glucose, and progesterone, and decreased enzymatic activity of cytochrome P450 2A and 3C. Cows will be stratified by parity and assigned randomly to four dietary supplements on day 0 (15 cows per treatment) consisting of (1) 0 kg (control); (2) 1 kg; (3) 2 kg; or (4) 4 kg of rumen-protected glucose. All cows will be provided the appropriate daily dose in 4 kg of top-dressed feed, blended in the upper 1/3 of the TMR. Daily supplement containing less than the 4-kg dose of rumen-protected glucose will be mixed into a concentrate mix of rolled corn and soybean meal formulated to make all diets (including supplements) isoenergetic and isonitrogenous. The total diet will be formulated to meet nutritional requirements of lactating dairy cows producing 45 kg per day of 3.5% fat-corrected milk (NRC, 2001).

Outputs (Beef). This research will identify nutritional strategies and uterine proteins that contribute to early embryonic development. The multi-state project on supplementation of calcium salts of soybean oil will validate a nutritional strategy to improve conceptus development and reduce early embryonic death in B. taurus beef cows. The uterine protein research will determine how these protein profiles are influenced by reproductive status, hormonal milieu, or nutritional status, how that influences embryonic and fetal development, and how that impacts progeny performance. We will provide information on changes in transcript abundance of development genes in response to nutritional stress and the mechanisms that control these changes. Studies will also determine if these mechanisms are altered in oocytes originating from ovaries with high numbers of follicles.

In addition, this research will identify uterine proteins that contribute to early embryonic development. The research will determine how these protein profiles are influenced by reproductive status, hormonal milieu, or nutritional status, how that influences embryonic and fetal development, and how that impacts progeny performance. We will provide information on changes in transcript abundance of development genes in response to nutritional stress and the mechanisms that control these changes. Studies will also determine if these mechanisms are altered in oocytes originating from ovaries with high numbers of follicles.

Outputs (Dairy). We will assess peripheral concentrations of glucose, insulin, and progesterone, hepatic enzymatic activity, and hepatic blood flow in response to feeding rumen-protected glucose in dairy cows and measure: (1) peripheral concentrations of progesterone from days 4 to 18 of an estrous cycle; (2) enzymatic hepatic activity of cytochromes P450 2A and P450 3C; (3) hepatic blood flow; (4) concentrations of insulin and glucose, (5) feed intake; and (6) fat-corrected milk yield and milk components.

Outcomes or Projected Impacts. Although a number of studies have been published that demonstrate developmental programming, validation and consistency of results are in question. This is complex research to perform, requiring large numbers of animals (a strength of this multi-state project). One valid reason for inconsistency of results is the differences in environment that can influence the epigenetic response in different production settings (again, this multi-state projected is suited for this challenge, having a long history of working across locations to compile data using a common experimental design). Another challenge is that additional environmental impacts that were not planned can change the programming status of an animal. If developmental programming strategies are going to be applied in management systems, the ability to understand and control these mechanisms in different environments will be extremely important. Although members of the committee are working with different model systems in different environments, we believe that by comparing data sets, identifying common pathways, and even performing similar developmental programming projects at multiple locations, we can provide the information producers and veterinarians need to determine if developmental programming can be used to consistently improve production efficiency. A manuscript that demonstrated similar progeny performance across multiple locations would have a high level of impact to start implementing these management strategies in production settings.

If peripheral progesterone concentrations are increased in lactating dairy cows by feeding rumen-protected glucose, we anticipate that pregnancy risk and embryonic survival may be enhanced. If rumen-protected glucose increases peripheral progesterone concentrations, further research will be warranted to assess improvement in fertility and reduction in early embryonic loss with the appropriate dose of rumen-protected glucose determined by the results of the current proposal.

Timeline. Several members of the committee already have ongoing experiments at their individual stations examining varying aspects of developmental programming. For collaborative efforts, analysis of tissues and uterine proteins will begin in year 1 of the project. A multi-state project that applies fetal programming and examines the impact on progeny growth and performance will be designed at the annual meeting in year 1 (attempting to use similar methods across locations). It will then require several years to generate the progeny performance data from this study. By year 3, we hope to have data sets from the individual studies that can be submitted to pathway analysis and identify common up-stream regulators across locations. If this is successful, by year 4 we could design a multi-state project that attempts to target a specific up-stream regulator to consistently program progeny performance (fertility, growth, or carcass traits, whichever seems most likely based on the data we compile). The completion of that project would most likely carry into the next project cycle.

Experiment on supplementation of calcium salts of soybean oil will occur on year 1, and depending on results several trials will be conducted to determine on uterus and conceptus. Experiments in feeding rumen-protected glucose to lactating dairy cows will occur in year 1 and 2. Depending on success of those experiments in increasing blood concentrations of progesterone, further field trials will be conducted to assess pregnancy rates in response to this feed additive.

Objective 3

Disseminate reproductive management information to stakeholders to improve sustainability of cattle enterprises (KS, MI, MO, ND, SD, TX, WI)

Beef Cattle

Accomplishments of the Beef Reproduction Task Force (BRTF) were reviewed during the 2016 Joint Annual Meeting of Animal and Dairy Science in Salt Lake City, UT (Johnson et al., 2016; Patterson et al., 2016). These presentations highlighted advances in research during the past two decades that expanded our understanding of the bovine estrous cycle and led to improvements in methods to more effectively control estrus and ovulation in beef heifers and cows. The Task Force was formed during a period of evolving science that resulted in systems to allow producer-acceptable results with a single FTAI. The BRTF organized and developed goals to enhance productivity and profitability of U.S. beef herds by integrating research and extension efforts with the intent of more effectively transferring the use of reproductive technologies to the field. A key early step was to coordinate efforts in identifying effective breeding management protocols for beef cattle and to clarify their associated acronyms. A short-list of recommended protocols and their acronyms for synchronization of estrus and ovulation in beef cattle was developed based on results from peer-reviewed, published research, and a comprehensive review of data collected from the field. The list of recommended protocols was developed by the BRTF in cooperation with veterinarians and representatives from associated industries. The synergies of this larger industry-centered working group have resulted in ideas for research and broader educational reach. These strategies provide opportunities for producers to utilize sires of elite genetic merit, reduce duration of the breeding and calving seasons, produce more uniform calf crops, and improve reproductive rates of replacement beef heifers and the mature cow herd. Collective advancements in applied reproductive technologies now afford beef producers the flexibility to match specific breeding management protocols to a defined management system, thereby creating the opportunity to significantly expand use of AI in beef herds across the U.S. and enhance profitability of the beef enterprise.

Dairy Cattle

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-1201 and both past program chairs or president of DCRC. 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 1210 have and will be presented at workshops.

Outputs. The BRTF planned and hosted 17 in-depth meetings at locations in key cow-calf areas across the country since 2002 (Johnson et al., 2016). These “Applied Reproductive Strategies in Beef Cattle” workshops targeted beef producers, AI industry personnel, veterinarians, allied industry representatives and academicians. A national media sponsor has provided online coverage of the meetings (www.appliedreprostrategies.com) since 2008. The effectiveness of the team was recognized with the NIFA Partnership Award for Multistate Efforts in 2013. A 2013 national survey of AI users indicated 97% of respondents (n = 425) were familiar with the BRTF recommended protocol lists. Recommendations from these guidelines were generally used by 65% and sometimes or occasionally used by 20% of respondents. Resources developed by the group include the Estrus Synchronization Planner in a mobile and spreadsheet version, tools to evaluate cost differences of AI and natural service breeding and numerous publications and support materials on a beefrepro.info website. The group has set in place a plan to bring in new members to help address changing industry needs. The multi-state research and extension effort combined with the industry group’s insight and support have provided valuable information in a growing beef AI industry.

The DCRC holds annual meetings directed to the AI industry, dairy producers, dairy practitioners, academia, and companies supporting the dairy industry. The DCRC was started with a vision that the organization will: (1) be a noncommercial, science-based organization whose main goal is to promote the development and adoption of reproductive technologies; (2) be open to all sectors in the dairy industry with an interest in dairy cattle reproduction. It will be an inclusive organization with the responsibility to reach out to several sectors of the dairy industry; (3) aim to become the primary source of information and technology regarding reproductive management and will become a conduit of information relative to integrated management considerations; (4) adopt a common terminology, identify key parameters and minimum goals for evaluation of reproductive performance, and provide educational material for reference; and (5) identify critical areas for technology development and disseminate information at the annual DCRC meeting.

Outcomes or Projected Impacts. Members of the NC-1201 group that are directly involved with the Beef Reproduction Task Force work closely with other members of the larger NC-1201 committee to encourage participation and support in hosting the Applied Reproductive Strategies in Beef Cattle workshops. Two members are involved in the DTRC. This, in large measure, has been and will continue to be one of the significant outcomes related to the NC-1201 committee. The infrastructure created from participating faculty with Extension and Research appointments affords the opportunity for a seamless transfer of technology to the field from a statewide, regional, and national perspective.

Timeline. The Beef Reproduction Task Force met in August in Des Moines, IA and agreed to meeting sites for the Applied Reproductive Strategies in Beef Cattle workshops for the next two years. The 2017 workshop will be hosted by Kansas State University and held in Manhattan, KS and the 2018 workshop will be hosted by New Mexico State University with the site to be determined. In addition, Extension guide sheets are being developed for new breeding strategies involving STAI, and as results from the proposed research efforts develop, educational materials in support of the proposed research will be developed for extension faculty, allied industry and lay audiences. The DCRC meets annually during the second week of November. In 2017, the annual meeting will be held in Reno. NV (November 8-9).

Measurement of Progress and Results

Outputs

Outcomes or Projected Impacts

Milestones

(0):Objective 1 Timelines Several members of the committee are actively engaged in experiments involving STAI in beef heifers and cows along with evaluation of new or modified approaches to FTAI. These experiments will serve as useful spring-boards to expand research with other protocols and then follow with specific protocol comparisons in years 1 and 2 of the project. Collaborative efforts among the various institutions will easily facilitate successful completion of this phase of the overall project and before experiments involving use of sex-sorted semen. Once protocol(s) are identified that afford the greatest potential to increase total estrous response and resulting pregnancy rates, multi-state projects will be designed to then compare strategies using conventional versus sex-sorted semen in years 3 and 4 of the project. Upon completion of the multi-state field trials, the anticipated outcome of these collaborative efforts should result in the development of practical breeding management strategies that facilitate expanded use of sex-sorted semen in the beef industry without the need to perform visual detection of estrus. Objective 2 Timelines Several members of the committee already have ongoing experiments at their individual stations examining varying aspects of developmental programming. For collaborative efforts, analysis of tissues and uterine proteins will begin in year 1 of the project. A multi-state project that applies fetal programming and examines the impact on progeny growth and performance will be designed at the annual meeting in year 1 (attempting to use similar methods across locations). It will then require several years to generate the progeny performance data from this study. By year 3, we hope to have data sets from the individual studies that can be submitted to pathway analysis and identify common up-stream regulators across locations. If this is successful, by year 4 we could design a multi-state project that attempts to target a specific up-stream regulator to consistently program progeny performance (fertility, growth, or carcass traits, whichever seems most likely based on the data we compile). The completion of that project would most likely carry into the next project cycle. Objective 3 Timelines The Beef Reproduction Task Force met in August in Des Moines, IA and agreed to meeting sites for the Applied Reproductive Strategies in Beef Cattle workshops for the next two years. The 2017 workshop will be hosted by Kansas State University and held in Manhattan, KS and the 2018 workshop will be hosted by New Mexico State University with the site to be determined. In addition, Extension guide sheets are being developed for new breeding strategies involving STAI, and as results from the proposed research efforts develop, educational materials in support of the proposed research will be developed for extension faculty, allied industry and lay audiences.

Projected Participation

View Appendix E: Participation

Outreach Plan

Outreach Plan


The Beef Reproductive Task Force (http://beefrepro.unl.edu/) is composed of mostly scientists that are members of NC-1201 who have major extension appointments (MO, NE, ND, and SD). 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-1201 and both past program chairs or president of DCRD. 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 1210 have and will be presented at workshops. A history of the first 10 years of the DCRC was published (Stevenson and Thatcher, 2016).


Organization and Governance


The technical committee will consist of at least 1 officially designated representative from each participating agricultural experiment station. The technical committee will meet annually. The USDA-NIFA will designate one nonvoting representative. Officers will be elected for a rotating period of 2 years, consisting of Chair and Secretary. Officers rotate from Secretary to Chair. Elections will be held at the annual meeting. Officers will compose the executive committee. The officers, 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 Secretary is responsible for preparing and distributing minutes of the annual meeting. The Chair is responsible for preparing the annual report of the annual meeting. Subcommittees may be appointed by the Chair as needed for specific assignments. One of the collaborators as designated in the project proposal under each objective will be in charge of coordinating cooperative research trials.

Organization/Governance

The technical committee will consist of at least 1 officially designated representative from each participating agricultural experiment station. The technical committee will meet annually. The USDA-NIFA will designate one nonvoting representative. Officers will be elected for a rotating period of 2 years, consisting of Chair and Secretary. Officers rotate from Secretary to Chair. Elections will be held at the annual meeting. Officers will compose the executive committee. The officers, 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 Secretary is responsible for preparing and distributing minutes of the annual meeting. The Chair is responsible for preparing the annual report of the annual meeting. Subcommittees may be appointed by the Chair as needed for specific assignments. One of the collaborators as designated in the project proposal under each objective will be in charge of coordinating cooperative research trials.

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