Source: UNIV OF WISCONSIN submitted to
METHODS TO INCREASE REPRODUCTIVE EFFICIENCY IN CATTLE (NC1006)
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
HATCH
Reporting Frequency
Annual
Accession No.
0225544
Grant No.
(N/A)
Cumulative Award Amt.
(N/A)
Proposal No.
(N/A)
Multistate No.
NC-1038
Project Start Date
Oct 1, 2011
Project End Date
Oct 1, 2012
Grant Year
(N/A)
Program Code
[(N/A)]- (N/A)
Recipient Organization
UNIV OF WISCONSIN
21 N PARK ST STE 6401
MADISON,WI 53715-1218
Performing Department
Dairy Science
Non Technical Summary
Within a dairy herd, total milk production is determined by the proportion of cows producing milk at any given time and the level of milk production of the individual cows within the herd. Both of these factors are dramatically affected by reproductive efficiency or the rate at which cows become pregnant within the herd. Two factors that determine the rate at which cows become pregnant are the artificial insemination (AI) service rate (i.e., management's ability to inseminate nonpregnant cows thereby giving them a chance to conceive) and the conception rate (i.e., the proportion of inseminated cows that actually conceive). The development of Ovsynch, a hormonal protocol that synchronizes follicular development, luteal regression, and ovulation thereby allowing for timed artificial insemination (TAI) without the need to detect estrus radically changed reproductive management by providing dairy managers a practical and effective tool for improving AI service rate. The Specific Aim of this proposal is to develop and assess management strategies to improve reproductive efficiency in lactating dairy cows. This Specific Aim will be addressed through four experiments under two objectives. Objective 1 (Experiments 1, 2 and 3) is to develop management strategies to resynchronize cows failing to conceive to a previous AI. Objective 2 (Experiment 4) is to assess an electronic activity monitor for detecting estrous behavior in lactating dairy cows.
Animal Health Component
(N/A)
Research Effort Categories
Basic
(N/A)
Applied
(N/A)
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
3013410102040%
3053410102020%
3073410102040%
Knowledge Area
305 - Animal Physiological Processes; 307 - Animal Management Systems; 301 - Reproductive Performance of Animals;

Subject Of Investigation
3410 - Dairy cattle, live animal;

Field Of Science
1020 - Physiology;
Goals / Objectives
The first objective is to elucidate mechanisms regulating reproductive efficiency in cattle.The last objective is to develop reliable, efficient, and economical breeding protocols for cattle.
Project Methods
Experiment 1: Characterization of ovarian and endocrine events after a synchronized ovulation in lactating dairy cows. Lactating Holstein cows will be allocated weekly to breeding groups to be scheduled for Double Ovsynch for first postpartum TAI. On the day of scheduled TAI, cows will be randomly assigned to each of two treatments to receive either no insemination (control) or TAI 16 h after the final GnRH injection of the protocol. To evaluate follicular and luteal dynamics after treatment, cows will undergo thrice weekly (MWF) transrectal ultrasonography for 32 days after treatment. Blood samples will be collected thrice weekly at each ultrasound examination. Cows will also be evaluated for behavioral estrus using rump-mounted, pressure-activated heatmount detectors during this time. Serum samples will be stored frozen until assayed for progesterone using a using a solid-phase, no-extraction RIA and for estradiol 17-β concentrations by using previously validated RIA's. Continuous variables will be statistically analyzed using the MIXED procedure of SAS. Experiment 2: Optimization of presynchronization methods for resynchronization of ovulation in lactating dairy cows. Lactating Holstein cows will receive a hormonal protocol for first TAI (as specified by the farm) and will be randomly assigned to one of three Resynch treatments: 1) initiation of the first GnRH injection of Resynch 7-d after an initial GnRH injection; 2) initiation of the first GnRH injection of Resynch 6-d after an initial GnRH injection; and 3) a non-presynchronized Resynch protocol (control). Blood samples will be collected from all cows at the first GnRH injection of the Resynch protocols to determine the progesterone concentration at initiation of Resynch, a factor we have shown to be highly related to fertility (Fricke et al., 2003; Silva et al., 2007a). Ultrasound and blood samples will be collected from a subset of cows in each treatment at the pre-GnRH injection, at the first GnRH injection, the first PGF2α injection, the second GnRH injection, and 7 d after that TAI to determine the ovarian responses to the protocols. Pregnancy status will be evaluated for all cows 32 and 60 d after Resynch TAI using transrectal ultrasonography to assess conception rate and pregnancy loss. Procedure LOGISTIC of SAS will be used to analyze the effect of treatment, parity, and the two-way interaction on conception rate using a backward selection procedure with treatment retained as a fixed factor in each of the models.

Progress 10/01/11 to 10/01/12

Outputs
OUTPUTS: 1. Resynchronized lactating cows that had high P4 at G1 and that ovulated after G1 had an increased synchronization rate resulting in increased fertility to TAI. 2. Circulating P4 reduces GnRH-induced LH secretion, and a higher dose of GnRH can increase LH secretion both in a high and low P4 environment. 3. Development and use of a stochastic model by commercial dairy herds may facilitate selection of economically-optimal reproductive programs based on farm-specific parameters. 4. Presynchronization with GnRH 7 d before initiation of Resynch increased fertility of resynchronized dairy cows whereas timing of initiation of Resynch did not. 5. Some, but not all, lactating dairy cows developed an Ab response after repeated exposure to hCG and that maximum response is observed within 14 d of hCG injection. PARTICIPANTS: Individuals who participated in this project included P. M. Fricke (project leader) and Milo Wiltbank, Department of Dairy Science, University of Wisconsin-Madison. Partner organizations included commercial dairy farms in Wisconsin. During the lifetime of this project, Dr. Julio Giordano conducted the research as a requirement for his Ph.D. degree in the Department of Dairy Science at the University of Wisconsin-Madison. In addition, several M.S. students including G. Lopes Jr. and A. Valenza particpated in the projects. TARGET AUDIENCES: Results from the experiments in this project were disseminated to a diverse audience including dairy scientists, reproductive physiologists, dairy farmers, county Extension agents, and veterinarians. Data were communicated to the research community through scientific abstracts presented at regional and national meetings and through scientific papers published in peer-reviewed research journals. Applied results were formulated into management recommendations and communicated to end users through the PI's Extension program in dairy cattle reproduction which includes state, regional, national, and international meetings, and articles published in national and regional trade magazines, newspapers, and newsletters. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Results from current and ongoing research have been used to make recommendations to stakeholders and their consultants regarding implementation of systematic synchronization and resynchronization systems for lactating dairy cows as well as timing and methods for pregnancy diagnosis. Data generated in these projects has been published in scientific journals and included in numerous extension proceedings.

Publications

  • Giordano, J. O., M. C. Wiltbank, J. N. Guenther, M. S. Ares, G, Lopes Jr., M. M. Herlihy, and P. M. Fricke. 2012. Effect of presynchronization with human chorionic gonadotropin (hCG) or GnRH seven days before resynchronization of ovulation on fertility in lactating dairy cows. J. Dairy Sci. 95:5612-5625.
  • Giordano, J. O., P. M. Fricke, J. N. Guenther, G. Lopes Jr., M. M. Herlihy, A. B. Nascimento, and M. C. Wiltbank. 2012. Effect of progesterone on magnitude of the luteinizing hormone surge induced by two different doses of GnRH in lactating dairy cows. J. Dairy Sci. 95:3781-3793.
  • Giordano, J. O., M. C. Wiltbank, and P. M. Fricke. 2012. Humoral immune response in lactating dairy cows after repeated exposure to human chorionic gonadotropin. Theriogenology 78:218-224.
  • Giordano, J. O., M. C. Wiltbank, J. N. Guenther, R. Pawlisch, S. Bas, A. P. Cunha, and P. M. Fricke. 2012. Increased fertility in lactating dairy cows resynchronized with Double-Ovsynch when compared to Ovsynch initiated 32 d after Timed AI. J. Dairy Sci. 95:639-653.
  • Giordano, J. O., J. N. Guenther, G. Lopes Jr., and P. M. Fricke. 2012. Changes in serum pregnancy-associated glycoprotein (PAG) pregnancy specific protein B (PSPB), and progesterone concentrations before and after induction of pregnancy loss in lactating dairy cows. J. Dairy Sci. 95:683-697.


Progress 01/01/11 to 12/31/11

Outputs
OUTPUTS: This project has just been initiated so there is no information to report at this time. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
This project has just been initiated so there is no information to report at this time.

Publications

  • No publications reported this period