Progress 03/01/10 to 02/28/14
Outputs
Target Audience: The target audience included animal and veterinary scientsts, dairy farmers, extension agents, and personnel in allied industries. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? A large number of graduate students, postdocs and undergraduates received training on the project. How have the results been disseminated to communities of interest? The main method of dissemination was the two road shows held in 2012 and 2014. In addition, articles were published in popular press (Hoard's Dairyman and Progressive Dairyman). What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
1) Evaluate physiological, nutritional, and genetic approaches to improving fertility in summer. All research objectives under this goal have been accomplished. Among the accomplishments was the improvement of technologies for usingthe in vitro produced embryo as a tool for enhancing pregnancy rate in summer, demonsration that cooling cows during the dry period can have long term effects on the milk yield of the cow in the subsequent lactation as well as on the productive potential of the cow's calf,and identification of SNPs on the Bovine 50,000 SNP Bead Chip that predict genetic merit for fertility. Other hypotheses tested, namely that effects of heat stress on fertility could be altered by antioxidant feeding or administration of niacin, were not supported by the experimental evidence. 2) Develop software that a) evaluates the profitability of proposed investment decisions to alleviate the effects of heat stress at the farm level, b) optimizes breeding decisions for individual cows and c) is available online using DAIReXNET. This objective is still ongoing. 3) Engage in technology transfer regarding novel approaches for improving fertility to dairy farmers and dairy farm personnel in English and Spanish. The major accomplishments here were two extension road shows in 2012 and 2014 that brought up-to-date recommendations on coping with heat stress to dairy farmers and allied industry. The 2012 Road Show was held in Florida, Puerto Rico, New Mexico, and California. A written proceedings were prepared that was distributed to attendees and posted on the E-Extension website maintained by USDA. In addition, each of the speakers prepared webinars that are also posted on the E-Extension website. The 2014 Road Show was held in Puerto Rico, Florida, Arizona and New Mexico. A written proceedings was prepared and distributed to attendees. 4) Assess changes in producer behavior and seasonality of animal performance over time in response to the research and extension program. There were two aspects to this objective. First, we assessed producer learning in the road shows. Both road shows were very successful in terms of producer assessment of learning and planned changes to be made on the dairy operation based on information in the road show. In the 2014 Road Show for example, 76% of attendees stated that they planned totake action or make a change based on the information presented. Theother accomplishment for this objective was development of an assessment tool called the summer:winter ratio that allows producers to guage the effects of heat stress on reproduction on their farm vs other farms in the region. We are currently communicating with commercial partners to make this tool freely available to interested dairy farmers.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Sakatani, M., Bonilla, L., Dobbs, K.B., Block, J., Ozawa, M., Shanker, S., Yao, J.-Q., and Hansen, P.J. (2013) Changes in the transcriptome of morula-state bovine embryos caused by heat shock: relationship to developmental acquisition of thermotolerance. Reprod. Biol. Endocrinol. 11, 3.
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Dikmen, S., Cole, J.B., Null, D.J., and Hansen, P.J. (2013) Genome wide association mapping for identification of quantiative trait loci for rectal temperature during heat stress in Holstein cattle. PLoS ONE 8, e69202.
- Type:
Journal Articles
Status:
Published
Year Published:
2014
Citation:
Bonilla, L., Block, J., Denicol, A.C., and Hansen, P.J. (2014) Consequences of transfer of an in vitro produced embryo for the dam and resultant calf. J. Dairy Sci. 97, 229-239.
- Type:
Book Chapters
Status:
Published
Year Published:
2012
Citation:
Hansen, P.J. (2012) Prospects for improving fertility during heat stress by increasing embryonic resistance to elevated temperature. In: R.J. Collier and J.L. Collier, ed., Environmental Physiology of Livestock, John Wiley and Sons, Chicester, United Kingdom, pp 199-208.
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Hansen, P.J. (2013) Antecedents of mammalian fertility: Lessons from the heat-stressed cow regarding the importance of oocyte competence for fertilization and embryonic development. Anim. Frontiers 3, 34-39.
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Hansen, P.J. (2013) Cellular and molecular basis of therapies to ameliorate effects of heat stress on embryonic development in cattle. Anim. Reprod. 10, 322-333.
- Type:
Journal Articles
Status:
Published
Year Published:
2014
Citation:
Tao S, Monteiro AP, Hayen MJ, Dahl GE. Short communication: Maternal heat stress during the dry period alters postnatal whole-body insulin response of calves. J Dairy Sci. 2014 Feb;97(2):897-901.
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Tao S, Dahl GE. Invited review: heat stress effects during late gestation on dry cows and their calves. J Dairy Sci. 2013 Jul;96(7):4079-93.
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Thompson IM, Tao S, Branen J, Ealy AD, Dahl GE. Environmental regulation of pregnancy-specific protein B concentrations during late pregnancy in dairy cattle. J Anim Sci. 2013 Jan;91(1):168-73.
- Type:
Journal Articles
Status:
Published
Year Published:
2012
Citation:
Tao S, Monteiro AP, Thompson IM, Hayen MJ, Dahl GE. Effect of late-gestation maternal heat stress on growth and immune function of dairy calves. J Dairy Sci. 2012 Dec;95(12):7128-36.
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Anderson SD, Bradford BJ, Harner JP, Tucker CB, Choi CY, Allen JD, Hall LW,
Rungruang S, Collier RJ, Smith JF. Effects of adjustable and stationary fans with misters on core body temperature and lying behavior of lactating dairy cows in a semiarid climate. J Dairy Sci. 2013 Jul;96(7):4738-50.
- Type:
Journal Articles
Status:
Published
Year Published:
2010
Citation:
Zimbelman RB, Baumgard LH, Collier RJ. Effects of encapsulated niacin on
evaporative heat loss and body temperature in moderately heat-stressed lactating Holstein cows. J Dairy Sci. 2010 Jun;93(6):2387-94.
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Progress 03/01/11 to 02/28/12
Outputs
OUTPUTS: One objective was to estimate the genetic parameters of rectal temperature (RT) in dairy cows in freestall barns under heat stress conditions and to determine the genetic and phenotypic correlations of rectal temperature with other traits. Afternoon RT were measured in a total of 1,695 lactating Holstein cows sired by 509 bulls during the summer in North Florida. The heritability of RT was estimated to be 0.17 +/ 0.13. Approximate genetic correlations between RT and 305-d milk, fat, and protein yields, productive life, and net merit were significant and positive, whereas approximate genetic correlations between RT and somatic cell count score and daughter pregnancy rate were significant and negative. Another objective was to understand the role of heat shock at the zygote stage in causing infertility. Culture at 40 C reduced the percentage of inseminated oocytes that became a morula or blastocyst by d 6 or that were a blastocyst at d 8. An additional experiment was done to test whether effects of heat shock occur early in development or at the time of morula formation. Exposure to 40 C for 24 h decreased development to the blastocyst stage if exposure was at the zygote stage but not if exposure occurred at the morula stage. Heat shock increased amounts of steady-state mRNA for HSPA1A but not for HSP90AA, SOD1, or CAT at both the 1-cell stage and d 5. One goal of the project is to improve production of embryos in vitro because transfer of these embryos can be a method for improving fertility during heat stress. An experiment was conducted to determine whether inhibition of proteasomes with MG132 during oocyte maturation would alter competence of the bovine oocyte for fertilization and subsequent development. Treatment with MG132 late in maturation improved the percentage of oocytes and cleaved embryos that became blastocysts without affecting nuclear maturation or fertilization rate. The pregnancy rate of cows receiving embryos produced from oocytes treated with MG132 from 16-22 h of maturation was similar to that for control embryos, suggesting that use of MG132 for production of embryos in vitro does not cause a substantial decrease in embryo quality. Another experiment evaluated whether increasing free cholesterol content could improve embryonic resistance to heat shock. Culture of bovine embryos at 41 C at 30 h after insemination (1-to 2-cell stage) reduced development to the blastocyst stage. Reduction in embryonic cholesterol content by culture with methyl-beta-cyclodextrin (MBCD) reduced development. Even though culture with cholesterol-loaded MBCD increased free cholesterol content, it did not increase resistance of embryos to heat shock. Treatment of embryos with cholesterol-loaded high density lipoprotein (HDL) increased embryonic resistance to heat shock even though it slightly reduced embryo cholesterol content. It is likely that other actions of HDL (e.g., protection from free radicals) were responsible for the thermoprotective properties of this molecule. PARTICIPANTS: Miki Sakatani, National Ministry Serdal Dikmen, Department of Animal Science, Faculty of Veterinary Medicine, Uludag University, Bursa, Turkey Jinyoung You and Eensung Lee, College of Veterinary Medicine, Kangwon National University, Chunchon, Korea Haroya Kadokawa, Department of Veterinary Science, Yamaguchi University, Yamaguchi, Japan Miki Sakatani and M Takahashi, Kyushu Okinawa Agricultural Research Center, National Agriculture and Food Research Organization, Kumamoto, Japan TARGET AUDIENCES: The first target audience is the international community of scientists interested in heat stress and dairy production. The second is the dairy community and allied industries including pharmaceutical companies, feed industries, and the veterinary profession. Significant efforts to target this second group will be reported in the next reporting period. PROJECT MODIFICATIONS: A no-cost extension was requested.
Impacts
The first output was the finding that rectal temperature during heat stress has moderate heritability, but genetic correlations with economically important traits mean that selection for RT could lead to lower productivity unless methods are used to identify genes affecting RT that do not adversely affect other traits of economic importance. Secondly, our results on the zygote indicate that reduction in fertility caused by heat stress is due in part to disruption of developmental competence of bovine zygotes. Results reinforce the notion that it is the early embryo that is most susceptible to heat stress and that embryo transfer to bypass exposure of the early embryo to heat stress can improve fertility. Making embryo transfer a realistic approach for improving fertility during heat stress requires that the cost of producing an embryo be kept low. The study with MG132 indicates that this inhibitor can reduce costs of producing embryos in vitro by increasing the proportion of oocytes that become a transferrable embryo. Another approach to improving fertility is to make the embryo resistant to deleterious actions of heat shock. Raising cholesterol content is not effective at increasing thermotolerance but the fact that HDL improved resistance of embryos to heat shock strengthens the idea that regulation of antioxidant status may be a way to improve fertility in summer.
Publications
- Kadokawa, H., Sakatani, M., and Hansen, P.J. (2012) Perspectives on improvement of reproduction in cattle during heat stress for sustainable cattle production in a future Japan. Anim. Sci. J. 83, 439-445
- Sakatani, M., Alvarez, N.V., Takahashi, M., and Hansen, P.J. (2012) Consequences of physiological heat shock beginning at the zygote stage on embryonic development and expression of stress response genes in cattle. J. Dairy Sci. 95, 3080-3091
- Dikmen, S., Cole, J.B., Null, D.J., and Hansen, P.J. (2012) Heritability of rectal temperature and genetic correlations with production and reproduction traits in dairy cattle. J. Dairy Sci. 95, 3401-3405
- Moss, J.I., Garrett, T.J., and Hansen, P.J. (2012) Involvement of free cholesterol and high-density lipoprotein in development and resistance of the preimplantation bovine embryo to heat shock. J. Anim. Sci. 90, 3762-3769
- You, J., Lee, E., Bonilla, L., Francis, J., Koh, J., Block, J., Chen, X., and Hansen, P.J. (2012) Treatment with the proteasome inhibitor MG132 during the end of oocyte maturation improves oocyte competence for development after fertilization in cattle. PLoS One 7, e48613
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Progress 03/01/10 to 02/28/11
Outputs
OUTPUTS: Research outputs included the following experiment (representative of several conducted): The objective was to determine whether transfer of fresh or vitrified embryos produced in vitro with sexsorted semen improves pregnancy and calving rates during summer in lactating dairy cows compared with artificial insemination (AI). Lactating dairy cows (n = 722) were enrolled during summer months at 2 commercial dairies in Central Texas and randomly assigned to 1 of 3 treatments: AI with conventional semen (n = 227), embryo transfer-vitrified (ET-V; n = 279) or embryo transfer-fresh (ET-F; n = 216). Embryos were produced in vitro using sex-sorted semen and with Block-Bonilla-Hansen-7 culture medium. For vitrification, grade 1 expanded blastocysts were harvested on d 7 after fertilization and vitrified using the open-pulled straw method. Fresh embryos were grade 1 blastocysts and expanded blastocysts harvested on d 7 after fertilization. Cows were submitted to the Ovsynch56 protocol and AI following detected estrus (day of AI = d 0). On d 7, all cows were examined for presence of a corpus luteum (CL). A vitrified or fresh embryo was transferred to cows with CL in ET-V and ET-F groups. Cows were considered synchronized if progesterone was <1 ng/mL on d 0 and a CL was present on d 7. At d 40 of gestation, the percentage of cows pregnant was greater for the ET-F compared with the ET-V and AI groups among all cows (42.1 vs. 29.3 and 18.3%, respectively) and synchronized cows (45.5 vs. 31.6 and 24.8%, respectively). Also, the percentage of cows pregnant was greater for the ET-V than the AI group among all cows and tended to be greater among synchronized cows. At d 97 of gestation, the percentage of cows pregnant among all cows was greater for ET-F and ET-V groups than for the AI group (36.4 and 25.7 vs. 17.0%, respectively) and the percentage for the ET-F group was greater than for the ET-V group. Among synchronized cows, the percentage of cows pregnant was significantly increased for the ET-F group than for ET-V and AI groups (39.4 vs. 27.8 and 23.1%, respectively) and no difference was found between ET-V and AI groups. No effect of treatment on embryo loss was observed. The percentage of cows with live births was significantly increased for the ET-F than for ET-V and AI groups among all cows (27.5 vs. 17.1 and 14.6%, respectively) and synchronized cows (29.9 vs. 18.5 and 20.0%, respectively). The percentage of cows giving birth to a live heifer was significantly increased for the ET-F and ET-V groups compared with the AI group among all cows (79.1 and 72.5 vs. 50.0%, respectively) and synchronized cows (79.1 and 72.5 vs. 50.0%, respectively). No difference existed between ET-F and ET-V groups for percent live heifer births but both were greater than for the AI group. The transfer of fresh embryos produced in vitro using sex-sorted semen to lactating dairy cows during summer can effectively increase the percentage of cows that establish pregnancy and also the percentage of cows that give birth to a live heifer compared with percentages from AI with conventional semen. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: The extension part of the grant targets extension agents, consultants and dairy farmers. The research part of the grant targets scientists. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The outcome of the research was that methods were established to transfer fresh embryos produced in vitro using sex-sorted semen to lactating dairy cows during summer to increase the percentage of cows that establish pregnancy and also the percentage of cows that give birth to a live heifer compared with percentages from AI with conventional semen. The impact of the research is that embryo transfer can be used by producers to improve summer fertility.
Publications
- Stewart, B.M., Block, J., Morelli, P., Navarette, A.E., Amstalden, M., Bonilla, L., Hansen, P.J., and Bilby, T.R. (2011) Efficacy of embryo transfer in lactating dairy cows during summer using fresh or vitrified embryos produced in vitro with sex-sorted semen. J Dairy Sci. 94, 3437-3445
- Hansen, P.J. (2011) Managing reproduction during heat stress in dairy cows. In: Risco, C.A., and Melendez Retamel, P., Dairy Production Medicine, Wiley-Blackwell, Chicester, United Kingdom, pp. 153-163.
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