Progress 05/15/12 to 09/30/13

Outputs
Target Audience: Target audiences include: dairy cattle producers and veterinarians who would apply these techniques to their herds, educators who would learn of these results and disseminate the information to their students, and students in animal and veterinary sciences to whom this information would be delivered. Efforts Efforts include adding the research results to formal classroom and laboratory instruction and workshops for extension presentations. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Training activities: The graduate student involved in the projectparticipated in the project design and analysis and interpretation of the results. The graduate student was trained in: drawing and assaying blood samples, uterine swabbing, counting neutrophils, culturing and counting bacteria and recording and managing data. Undergraduate students who worked on the project were trained in blood collections and assisted the graduate student in her bench work. Professional development: The graduate student presented the results of the research at a departmental seminar. How have the results been disseminated to communities of interest? Results of the research were published in the OSU Beef Research Report which is accessible to cattle producers inhard copy format orthrough the Oregon State University-Beef Cattle Sciences website. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? IMPACT: Uterine infections during the period after calving are a costly problem for dairy producers. Fertility is poorer in cows with uterine infections and in Oregon this reduced fertility can contribute to an income loss estimated to reach as high as $10 million annually. White blood cells, especially neutrophils, are the first line of defense against uterine infections. Preliminary experiments conducted in our laboratory investigated the effect of a single injection of the pharmaceutical product, Lutalyse, a drug commonly used in dairies for reproductive purposes, on plasma neutrophil numbers in dairy cows. Lutalyse caused the number of circulating neutrophils to increase within one hour after administration and remain elevated for four hours thereafter. These data suggest that Lutalyse recruits neutrophils into the cow’s plasma. This property of Lutalyse could be used to create a preemptive strategy that counters the development of uterine infections in dairy cattle. Therefore, this research evaluated the effects of a single injection of Lutalyseadministered14 days postpartum on uterine neutrophil and bacterial populations and numbers of days open and services per conception indairy cows. Cows in this study were from a dairy containing 3000 Holstein cows with 1500 in the milking string. Cows were supplied with water using a free-choice system. The ration fed included corn silage, grass silage, alfalfa, corn, cotton seed and soy bean meal. Postpartum cows were given a 55-day voluntary waiting period before synchronization and artificial insemination. Pregnancy was detected by a veterinarian through rectal palpation and ultrasound at 40 days of gestation. Ovarian structures were also palpated in the event that pregnancy did not occur in order to identify whether inability to conceive was the result of failure of resumption of the estrous cycle. A total of forty cows at 14 days postpartum were given an intramuscular injection of either PGF2α (Lutalyse) or saline. The first cow was chosen at random for injection of either Lutalyse or saline and subsequent cows were injected with alternating treatments to ensure randomization. Uterine bacteria samples were obtained at 0 and 24 h after injection through rectal palpation and swabbing the inside of the uterine body. For the 0-h sample recovery, the swab was conducted just before the injection was administered. To recover bacteria, the uterus was first palpated rectally, and once the cervix was grasped securely, the vulva was cleaned using paper towels and spread open and the first guarded tube of the swab was inserted into the vagina. This tube was inserted into the external cervical os and the second guarded tube was pushed thru the first tube into and through the cervix. Once the second guarded tube was in the uterine body approximately 2 cm, the swab was then pushed through the second guard tube and spun gently on the uterine body. The swab was then retracted back into the second guarded tube and both guarded tubes were removed from the vagina. The swab with the uterine sample was broken off and placed in a tube containing ten ml of Dulbecco’s phosphate buffered saline (DPBS). Samples were brought to the lab and a 1/10 dilution was made from the sample collected in the field using DPBS as the diluting fluid. One hundred microliters of each dilution (0 and 1/10) was spread onto each side of a Blood/MacConkey Agar bacteriological culture biplate. The biplates were covered and left facing up for one h at room temperature and placed face down in an incubator at 37°C for 24 h. The numbers of colonies that grew on either side of the biplates were counted and recorded. Services per conception and days open were recovered from breeding records maintained for the cows in the experiment. Differences in numbers of bacteria between the 0 and 24-h swabbing, services per conception and days open were analyzed using one-way ANOVA with treatment (Lutalyse or saline) as the main effect. Changes in uterine bacterial populations did not significantly differ between cows injected with Lutalyse or saline. However Lutalyse treatment reduced total bacteria by 30 cells compared to 3 cells in cows injected with saline.The dairy at which this study was performed chose to rebreed cows with exceptional milk production as many times as was financially feasible. It is for this reason some data for cows included beyond 2 or 3 services per conception. However this gave a clearer picture of reproductive performance for each cow. There was no significant difference in services per conception between cows injected with Lutalyse or saline however cows injected with Lutalyse had 0.2 fewer services per conception. Number of days open for these cows was also not significantly differentbetween cows injected with Lutalyse or saline. However, cows injected with Lutalyse had 15 fewer days open compared to cows injected with saline. Dairy producers implementing this protocol would experience reduced costs associated with breeding and using Lutalyse would reduce the overall need for antibiotics. Change in knowledge - Results of this basic research will be published in a scientific journal Change in action – Adoption and use of new methods Change in conditions - Better and less expensive animal health; higher productivity in food provision

Publications

• Type: Other Status: Published Year Published: 2014 Citation: Younger, K.G., Lulay, A.M., and Menino, Jr., A.R. 2014. Effects of prostaglandin F2a on reproductive performance in dairy cows. Oregon State University-Beef Research Report