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ARS Home » Plains Area » Miles City, Montana » Livestock and Range Research Laboratory » Research » Research Project #423791

Research Project: Alleviating Rate Limiting Factors that Compromise Beef Production Efficiency

Location: Livestock and Range Research Laboratory

2017 Annual Report


Objectives
1: Determine the impact of the level of harvested feed input on the sustainability of beef production systems, including annual reproductive success, lifetime productivity, and progeny performance. 2: Evaluate use of dormant, animal-harvested forages as a substitute for mechanically harvested feeds in developing replacement heifers. 3: Develop new and better genetic and physiological indicators of fertility in yearling bulls and beef cows to enhance annual and life-cycle reproductive success. 4: Assess locus-specific genetic effects attributable to heterozygosity on reproductive success and productivity in production systems making differential use of native range forages. 5. Improve breeding and management decisions by characterizing current genetic and phenotypic variation within and between predominant beef breeds and crosses using novel genomic and genetic evaluation technologies and identify novel genomic variants to optimize forage based production efficiencies for beef cattle within and across diverse physical environments in the US Great Plains.


Approach
Feed consumption and replacement of cows, culled for reproductive failure, are two primary determinants of beef production efficiency. Our overarching goal is to develop strategies and technologies to alleviate these limitations. Sufficient nutrient intake resulting in adequate body energy stores are believed essential for reproduction. Thus, producers are challenged to match nutritional environment, which is subject to seasonal and annual variation, and various genotypes to obtain sustainable reproduction and retention rates. Our approach is, of necessity, long-term and multi-disciplinary, involving both basic and applied aspects of genetics, nutrition, and physiology in a semi-arid grazing production system. This proposal brings to fruition ongoing research and establishes investigations of genetic by environmental interactions and physiological mechanisms limiting reproductive success. Four distinct cattle populations (an intercross of Charolais (25%), Red Angus (50%) and Tarentaise (25%), Line 1 Hereford, purebred Angus, and Hereford-Angus herd) will be used to facilitate assessment of genetic factors affecting fitness (hybrid vigor). Distinct nutritional environments that utilize different contributions of harvested and grazed forage will be imposed to challenge the nutrition-reproduction interface to elucidate genetic, physiological, and management factors influencing feed utilization and lifetime productivity. Identification of genetic, nutritional, and physiological mechanisms that limit or contribute to beef production efficiency will facilitate early in life selection and management of replacement animals most fit for particular production environments. This research will result in the establishment of heifer development protocols that provide producers options for dealing with annual variations in availability and quality of forage.


Progress Report
Feed consumption and replacement of cows, culled for reproductive failure, are two primary determinants of beef production efficiency. Our overarching goal was to develop strategies and technologies to alleviate these limitations. We utilized a three-prong approach to achieve our goal by developing new management tools, increasing our understanding of physiological events that inhibit reproduction and identifying micro nutrients in range vegetation that due to low quantities hamper reproductive processes. Research evaluated two levels of nutritional management during winter supplementation on lifetime cow productivity, and the productivity of their daughters when managed on one of the two levels of nutritional input for heifer development and(or) cow winter supplementation. Heifers receiving the lower level of nutrition showed improved efficiency, as indicated by greater gain:feed during the 140 restriction and greater ADG and lighter weight after restriction, when grazing on summer pasture. There was a $30 reduced feed cost per pregnant heifer in the lower feed group. Cows managed with the lower input nutritional strategy (Marg) remained lighter than Controls reducing maintenance energy requirements. However, daughters out of lower input dams are heavier than daughters from normal input dams (Adeq) due, in part, to differences in body condition with the Marg daughters having higher body condition scores in the fall. Thus, nutritional input influences the subsequent generation. In addition to reducing cost of development, rearing young animals under caloric restriction was shown to prolong lifespan. Results demonstrated that increasing herd productive life can result in decreased cow replacements saving up to 25% of the cost of replacement heifer development (more calves to sell) and retaining a greater proportion of cows at peak productivity (at 4 to 11 yrs. old). Finally, the way we feed heifers has long-term implications on their offspring. Five genetic markers were reported that are related to cow lifetime productivity. Heifer energy expenditure and grazing behavior were altered in response to level of nutritional inputs. Heifers with lower nutritional inputs were shown to have lower resting energy expenditure and traveled further to explore and better-utilize pasture area compared to those that received the higher external nutritional contributions having an unexpected consequence of an overall increase in energy expenditure revealed by less efficient grazing. Managers with the objective to develop range cows to be more energy and grazing efficient can apply these nutritional practices. During winter, weaned heifers grazing dormant rangeland vegetation were shown to linearly improve nitrogen retention with supplementation 5, 10 and 15g per day of DL methionine. However, over three year’s heifers grazing winter range were shown to ingest sufficient quantities’ of the amino acid methionine from vegetation to support timely reproduction. Reproduction was not influenced by the presence of DL methionine in the supplement consumed. In the same study results demonstrated heifers fed supplements without metabolic glucose fortification from calcium propionate experienced lower pregnancy rates indicating the need to supply glucose precursors. These results can be applied to commercial heifer supplement formulations to promote onset of puberty and pregnancy. Results of another approach to improve cow reproduction efficiency has identified 31 genetic markers that account for 74% of the variation in fertility in beef heifers classified as highly fertile or subfertile. Twenty-two of these genetic markers accounted for 66% of the variation in fertility in dairy heifers identified as being highly fertile or subfertile. We also found 3 markers in the blood of cows on day 17 of pregnancy that are indicators of impending embryonic mortality which will enable detailed study into why cows lose pregnancies. Study results established multiple genes that are differentially expressed in the ovary, egg, and uterus of cows that possess higher or lower fertility, which will enable the study of mechanisms involved in pregnancy loss at the ovarian and uterine levels. In regards to male fertility, bull fertility is currently evaluated as Pass / Fail by veterinarians. If bulls possess greater than 30% sperm motility and 70% normal morphology then that bull is considered to have sufficient fertility to impregnate cows successfully. We have revealed novel molecular markers in bull sperm associated with fertility to suggest development of a graded scale predicting bull fertility with much greater accuracy and precision than the current test. One novel molecular marker in bull sperm is related to embryonic mortality.


Accomplishments
1. Cow longevity is of paramount economic importance to the beef cattle industry. To generate a profit a cow must remain in production for several years. Increase in longevity of beef cows increases the overall production by decreasing costs associated with replacement heifers and increasing the number of productive cows. Genetic improvement of longevity has been limited due to the complexity of the trait. However, with the advent of genomic information, this important resource could help improve the prediction and genetic selection of this trait. An analysis was carried out by scientists at ARS in Miles City, Montana to evaluate the use of genomic information in predicting this trait and also to identify genetic markers that explain variation associated with cow longevity. Results showed an increase of accuracy in predicting cow longevity when including genomic information. Moreover, four significantly associated single nucleotide polymorphisms (SNP) were identified by genome wide association study. These identified SNPs consisted of UA-IFASA-7571 on chromosome 19 (58.03 Mb), ARS-BFGL-BAC-15059 on chromosome 1 (28.8 Mb), Hapmap52423-rs29022902 on chromosome 2 (51.9 Mb) and Hapmap51103-BTA-98088 on chromosome 11 (56.8 Mb). Genomic information proved to be beneficial in increasing prediction accuracy of longevity. This is important since accuracy of prediction is directly related to genetic gain. Genome wide association study yielded significant markers that were associated with the trait which can be used in a marker assisted selection to better genetically select animals and improve genetic gain.

2. Female fertility is critically important to the beef and dairy cattle industries. It is generally measured as one trait (pregnant or not pregnant) at the end of a defined breeding season but includes a multitude of processes that must be successful including attainment of puberty or resumption of heat cycles after calving, production of a fertile egg, successful fertilization, preparation of a uterus to accept and maintain a pregnancy, and a multitude of synchronized hormone signals. However, the biggest obstacle to pregnancy success is maintaining a pregnancy. While fertilization occurs 90 to 95% of the time that cows are bred, 30 to 50% of embryos die in beef and dairy cows, respectively, resulting in an estimated $87 million-dollar loss to the U.S. cattle industry. One of the greatest hurdles to solving this problem is not being able to easily detect the pregnancy loss until most has already occurred. This is generally too late to do anything about it and understand why it occurred. In collaborative efforts, scientists at ARS in Miles City, Montana have identified 3 signals that can be measured in the blood of cows on day 17 of pregnancy to further identify why this loss is occurring. These signals are microRNA (mir25, mir16b, and mir3596) that likely come from the reproductive tract and identify the cows that will experience pregnancy loss. Use of these signals will allow us to identify what management and environmental inputs cause embryonic loss and how to prevent this loss.

3. Genetic markers of heifer fertility would be a huge benefit to replacement heifer selection. Selection and development of young females for replacements in a beef cattle operation are extremely costly. Producers lose out on the opportunity of selling those females as calves or yearlings and still must wait until they are about 2 years old to produce their own calf and more than 2.7 years old before they wean a calf that can be sold. Producers generally do not recover these opportunity costs and development costs from cows until they are at least 5 years old. This makes selection of the most fertile heifer calves for replacements extremely important. Scientists at ARS in Miles City, Montana have identified 22 genetic markers among heifers that can be evaluated at any age but more specifically 3 primary markers that are strongly related to fertility of a heifer. These markers are located within genes on the X-chromosome (KIF4A), chromosome 8 (TDRD7), and chromosome 15 (LOC507882). Each of these genes plays major roles in uterine receptiveness to early embryo attachment that is obligatory for pregnancy success in cattle. Several companies exist that currently assess genomic information to allow producers to “screen” their cattle for specific markers that affect economical traits. Fertility markers are not currently evaluated by these companies and will lead to better prediction of genetic value among heifers.

4. Selection of bulls with greater fertility would improve overall economic viability for ranchers. Bull fertility is currently assessed by veterinarians as Pass/Fail and includes a minimum of 70% normal shape and 30% motility. This pass/fail system is not a very critical evaluation of fertility and does not allow comparisons between bulls. If producers could identify the more fertile bulls in their herd, they might expose more cows to higher fertility bulls early during a breeding season with a goal of improving overall herd fertility. The problem is that most bulls are evaluated for fertility when they are young and not yet mature. New measures of fertility are badly needed to improve overall herd fertility in the livestock industries. Scientists at ARS in Miles City, Montana assessed several novel measures of bull fertility in bulls around one year of age. Bulls with semen containing a higher percentage of polarized mitochondria (indicative of energy potential), intact acrosome, and greater reactive oxygen species potential in sperm are more fertile. These traits improve in young bulls as they approach puberty and maturity. Addition of these variables to standard bull fertility exams may allow quantitative ranking of bull fertility that will lead to increased selection pressure on fertility, which is the most important trait for economic progress across all livestock species. Scientists at ARS in Miles City, Montana have used one of these novel markers of sperm fertility to show that more than 10% of embryonic mortality in cows may be due to fertilization of an egg by a sperm that is compromised in its ability to produce a healthy embryo. Universal adoption of assessing bull sperm for this trait or removing bull sperm from frozen straws of semen used with artificial insemination for this trait would return an estimated $21.2 Million annually to the beef and dairy industries due to decreased embryonic mortality.

5. Identifying the limitations to pregnancy success in cattle is obligatory to improved productivity. Understanding the mechanisms that affect fertility is important initially to the scientific community before an advantage is realized by the livestock producer. Scientists at ARS in Miles City, Montana studied gene expression from eggs (oocytes) in cattle that were more mature and prepared (competent) for pregnancy initiation and compared them to oocytes that were slightly less mature to determine what deficiencies existed among these less mature oocytes that is related to lesser pregnancy maintenance. Mature eggs had greater expression of specific genes that are known to be associated with RNA binding, transcription regulation, cell cycle progression, cell membrane synthesis and the ubiquitin proteasome pathway. Knowledge of these transcripts provides a mechanism for assessing oocyte maturity for oocytes routinely used with in-vitro embryo production that are less likely to create pregnancies. In addition, understanding the pathways that limit pregnancy success due to ovulation of less mature oocytes allows for the development of management strategies to enhance oocyte fertility.


Review Publications
Cronin, M.A., Leesburg, V.L. 2016. Genetic variation and differentiation in parent-descendant cattle and bison populations. Journal of Animal Science. 94:4491-4497. doi:10.2527/jas2016-0476.
Goodman, L.E., Cibils, A.F., Wesley, R.L., Mulliniks, J.T., Petersen, M.K., Scholljegerdes, E.J., Cox, S.H. 2016. Temperament affects rangeland use patterns and reproductive performance of beef cows. Rangelands. 38(5):292-296. doi:10.1016/j.rala.2016.07.002.
Lopez, R., Pulsipher, G.D., Guerra-Liera, J.E., Soto-Navarro, S.A., Balstad, L.A., Petersen, M.K., Dhuyvetter, D.V., Brown, M.S., Krehbiel, C.R. 2016. Effects of fat and/or methionine hydroxy analog added to a molasses-urea-based supplement on ruminal and postruminal digestion and duodenal flow of nutrients in beef steers consuming low-quality lovegrass hay. Journal of Animal Science. 94:2485-2496. doi:10.2527/jas2015-0228.
Sawalhah, M.N., Cibils, A.F., Maladi, A., Cao, H., Vanleeuwen, D.M., Holechek, J.L., Black Rubio, C.M., Wesley, R.L., Endecott, R.L., Mulliniks, T.J., Petersen, M.K. 2016. Forage and weather influence day versus nighttime cow behavior and calf weaning weights on rangeland. Rangeland Ecology and Management. 69(2):134-143. doi:10.1016/j.rama.2015.10.007.
Mulliniks, J.T., Sawyer, J.E., Waterman, R.C., Petersen, M.K. 2016. Delaying postpartum supplementation in cows consuming low-quality forage does not alter cow and calf productivity. Animal Feed Science And Technology. 7:642-649.
Dickinson, S.E., Geary, T.W., Monnig, J.M., Pohler, K.G., Green, J.A., Smith, M.F. 2016. Effect of preovulatory follicle maturity on pregnancy establishment in cattle: the role of oocyte competence and the maternal environment. Animal Reproduction(Colégio Brasileiro de Reprodução Animal?). 13(3):209-216. doi:10.21451/1984-3143-AR879.
Hay, E.A., Roberts, A.J. 2017. Genomic prediction and genome-wide association analysis of female longevity in a composite beef cattle breed. Journal of Animal Science. 95: 1467-1471. doi:10.2527/jas2016.1355.
Reese, S.T., Pereira, M.C., Vasconcelos, J.M., Smith, M.F., Green, J.A., Geary, T.W., Peres, R.G., Perry, G.A., Pohler, K.G. 2016. Markers of pregnancy: how early can we detect pregnancies in cattle using pregnancy-associated glycoproteins (PAGs) and microRNAs?. Animal Reproduction(Colégio Brasileiro de Reprodução Animal?). 13(3): 200-208.
Nix, E.E., Ragen, D.L., Bowman, J.G., Kott, R.W., Petersen, M.K., Lenssen, A.W., Hatfield, P.G., Glunk, E.C. 2016. Forage intake and wastage by ewes in pea/hay barley swath grazing and bale feeding systems. American Journal of Experimental Agriculture. 12(3):1-6. doi:10.9734/AJEA/2016/25197.
Waterman, R.C., Kelly, W.L., Larson, C.K., Petersen, M.K. 2017. Comparison of supplemental cobalt form on fibre digestion and cobalamin concentrations in cattle. Journal of Agricultural Science. 155(5):832-838. doi:10.1017/S0021859617000107.
Odhiambo, J.F., Dejarnette, J.M., Geary, T.W., Kennedy, C.E., Suarez, S.S., Sutovsky, M., Sutovsky, P. 2014. Increased conception rates in beef cattle inseminated with nanopurified bull semen. Biology of Reproduction. 91(4):1-10.
Pohler, K.G., Green, J.A., Moley, L.A., Gunewardena, S., Hung, W.T., Hong, X., Christenson, L.K., Geary, T.W., Smith, M.F. 2017. Circulating microRNA as candidates for early embryonic viability in cattle. Molecular Reproduction and Development. 84(8):731-743. doi:10.1002/mrd.22856.
Jones, C.P., Silvia, W.J., Hamilton, C.H., Geary, T.W., Zezeski, A.L., Wooding, F. 2017. Glycosylation and immunocytochemistry of binucleate cells in pronghorn (Antilocapra Americana, Antilocapridae) shows features of both Giraffidae and Bovidae. Placenta. 57:216-222. doi:10.1016/j.placenta.2017.07.011.