Performing Department
Animal and Rangeland Sciences
Non Technical Summary
A costly challenge for dairy producers is reducing uterine infections during the early postpartum period. Uterine resistance to infection seems greater when the uterine hormone prostaglandin F2a (PGF) is high. Our laboratory demonstrated that a single injection of Lutalyse (the pharmaceutical product of PGF) induced a rapid and sustained increase in circulating neutrophils. When Lutalyse was injected on Days 0-1 and 14 or 14 and 28 postpartum, uterine neutrophils increased and uterine bacteria, days open and services per conception decreased. Cows injected on Days 0-1 and 14 exhibited the greatest effect. Based on these results, a project was started last year evaluating a single Lutalyse injection administered on Day 14. The rationale was endogenous PGF would be high around parturition but low by Day 14, therefore administering Lutalyse on Day 14 would maintain high plasma PGF during the susceptible infection period. Data collection from the 2012 projectis still ongoing but a high incidence of uterine infections was observed between parturition and Day 14, before Lutalyse was injected. Hence, endogenous PGF near parturition may not be adequate, therefore we proposed to shift the injection to Day 3 in an effort to prevent infection outbreak. A single Lutalyse injection on Day 3 may emerge as a simple and effective preemptive strategy to counter uterine infections. Therefore, our objective is to evaluate the effects of a single Lutalyse injection administered to dairy cows on Day 3 postpartum on uterine bacterial and neutrophil populations and numbers of days open and services per conception. Lutalyse treatment should increase uterine neutrophils and decrease uterine bacterial load thereby improving uterine health and decreasing days open and services per conception. Significant savings can be realized by dairy producers implementing such a protocol because of the reduced expense associated with fewer days open and reduced labor and semen costs associated with fewer services per conception. A functional pre-emptive strategy would also decrease antibiotic use, further reducing drug costs. Lutalyse is commonly used in dairy operations to synchronize estrous cycles for artificial insemination and a single dose is under $3.00. Therefore, this protocol can be easily implemented with relatively little cost. It is anticipated the results of this research will be distributedto dairy producers for information and, if successful, application.
Animal Health Component
20%
Research Effort Categories
Basic
60%
Applied
20%
Developmental
20%
Goals / Objectives
The major goalof this research is to evaluate the effects of a single Lutalyse injection administered to dairy cows on Day 3 postpartum on uterine bacterial and neutrophil populations and numbers of days open and services per conception.
Project Methods
For this research project,two hundred cows at a cooperating dairy will be randomly assigned to two treatments (100 cows/treatment) and injected with either saline (5 ml; im) or Lutalyse (25 mg/5 ml; im) on Day 3 postpartum (where Day 0 = day of calving). A subset of cows from each treatment (10 cows/treatment) will be randomly selected for assessing uterine bacterial load and neutrophil populations. Sampling for uterine bacterial load: On the day of the injection, the cow's uterus will first be sampled for uterine bacterial load using a double guarded swab (Time 0). The swab will be placed into a tube containing 10 ml of Dulbecco's phosphate buffered saline (DPBS) and transported to the laboratory within 1 hour of collection for bacterial culture. Twenty-four hours after the first swab, a second uterine swab will be collected (Time 24), placed into a tube containing 10 ml of DPBS and transported to the laboratory within 1 hour of collection for culture. Sampling to assess neutrophil populations: To provide an assessment of the uterine neutrophil population, a guarded CytoBrush will be passed into the uterus immediately following the uterine bacterial swabbing at Times 0 and 24. The CytoBrush will be rolled onto a microscope slide to create a cell smear. The smear will be stained using the Wright staining procedure for assessing WBC populations and neutrophils will be counted. The cow will receive her injection (saline or Lutalyse) following completion of the uterine swabbing and CytoBrush procedures at Time 0. Bacterial cultures: Serial dilutions using DPBS as the diluting fluid (0, 1/10 and 1/100) will be made from the original uterine sample and 100 ml will be plated onto each side of a Blood Agar-MacConkey's Agar bacteriological culture biplate. Following culture at 37°C the number of bacterial colonies growing on each agar type will be counted. Colony counts on the blood agar side provide the total number of pathogenic bacteria and counts from the MacConkey's agar side, a selective medium, provide the number of E.coli. Observational and reproductive data: Cows will be evaluated daily for evidence of uterine infections, e.g., vaginal discharge, fever, etc. Herd records will be evaluated in a timely fashion and data pertaining to days open and services per conception will be collected for analysis. Statistical analyses: Differences due to treatment in the total numbers of bacteria, E. coli and neutrophils will be analyzed by repeated measures analysis of variance (ANOVA). If significant effects are observed in the ANOVA, differences between means will be evaluated by Fisher's least significant differences procedures. Observational data, e.g., number of cows observed with uterine infections, will be analyzed for differences using Chi-square procedures. Differences due to treatment in the numbers of days open and services per conception will be evaluated using the pooled t-test. All analyses will be performed using the NCSS statistical software program (Number Cruncher Statistical System; 2000, Jerry Hintze, Kaysville, UT). Efforts used to change knowledge and actionsinclude formal classroom instruction, laboratory instruction,practicums, internships, workshops, extension and outreach. Steps used to measure the success of the project include evaluating differences between saline and Lutalyse treatment intotal numbers of uterine bacteria and neutrophils, incidencesof cows observed with uterine infections and numbers of days open and services per conception.