Progress 06/01/24 to 05/31/25
Outputs
Target Audience:During the reporting period, undergraduate and graduate students were the target audiences focused. These audiences were reached through training activities and sharing the project goals and objectives. In all cases, students were educated about the funding support, purpose of the project, and their roles in contributing to advancing the project. Graduate students were the leaders of individual experiments for the project and worked with undergraduate students staffing the projects. During training and sample collection undergraduate students not involved with the project but working at the university farm where experiments were being conducted were also educated about the research and project goals. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Two graduate students continued training during this reporting period and another graduate student began training. Two graduate students who initiated their studies in the previous reporting period gained additional training related to sample analysis in the current reporting period. Samples collected during the previous and current reporting periods were analyzed in the lab and graduate students gained experience and training in handling data and preparing it for data analysis. Students also received training in initial statistical analysis of data. Training on data analysis and interpretation are underway. A third graduate began work on the project during this reporting period. Initial training in the lab and for working with animals was completed during this reporting period. Project specific training in experimental procedures was initiated and continues. Additional undergraduate students were training in sample collection, animal care procedures, and data collection during this reporting period. How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals?In the next reporting period, we will analyze samples collected for the first experiment of objective 1. These samples are being prepared for sequencing of individual cells. Data analysis will ensue after sequencing data are available. We also plan to begin the second experiment of objective 1. This experiment involves sample collection from cows as well as cell culture work and flow cytometry. We will initially complete the planning stages of the experiment that will involve acquiring materials for the experiment and identifying cows for sample collection. Following planning, we will begin sample collection. With data analysis nearing completion for the first experiment of objective 2, we will finish the data analysis and interpretation and begin drafting a manuscript summarizing results. Drafting a manuscript will require most of the next reporting period and could continue into the following reporting period. We will also continue and complete sample analysis from the second experiment of objective 2. With completion of sample analysis and generation of data, we will be able to initiate data analysis and begin interpreting results.
Impacts
What was accomplished under these goals?
Milk production depends on the cells in the mammary glands of dairy cows. These cells complete the entire program of producing milk. During dairy cow lactation, milk production increases to a peak level but then declines after peak. Previous research has shown that the number of cells in the mammary gland declines after peak production and is the reason that milk production declines. With declining milk production, nutrient use for milk production as a proportion of nutrients consumed also declines. Increasing the persistency of milk production by maintaining greater milk production after peak is a strategy to support conversion of nutrients to milk and increase efficiency. This project focuses on the retention of cells in the mammary glands of cows to increase persistency of lactation. Dairy farmers will benefit from this research. Their profitability is directly tied to milk production. By increasing persistency of lactation, greater milk production per lactation of a cow can be achieved. Environmental benefits will by supported by greater nutrient efficiency for milk production. This supported by increasing the amount of milk produced per unit of nutrients consumed. Additionally, if cows can achieve longer lactations and productive lives, then fewer cows and their replacements should be achievable. In the current reporting period, we began sample collection for the first experiment of objective 1. This experiment involves analyzing the cells that have been shed into milk and are no longer contributing to milk production. These lost cells represent a decrease in future milk production. We have collected cells from milk and tissue from the same mammary glands to compare the cells in milk that were shed with those that are still retained in the mammary glands and productive. We anticipate that, after analysis of these cells in milk and tissue, we will identify characteristics of the cells in milk that resulted in their loss into milk. These samples and the data resulting from the analysis will also provide additional data about the cells of milk and the mammary glands that other researchers will be able to leverage to support their own research. Sample collection was completed in the current reporting period for two experiments supporting objective 2. Sample analysis was initiated for the second experiment of objective 2. This experiment involves manipulating milking frequency to quickly influence milk production. Increasing milking frequency is a management approach employed by dairy farmers to increase milk production. With milk production tied to mammary cell number, this experiment examines if shedding of milk cells into milk is acutely responsive to changing milking frequency. We have collected milk samples and milk cells for analysis and analyses of these samples is ongoing. Sample analysis was completed for the first experiment of objective 2 and data analysis is ongoing. The second experiment of objective 2 investigated the impacts of heat stress on mammary cell shedding into milk. Heat stress in dairy cows reducing milk production acutely and can have long-term effects on lactation production if heat stress occurs in mid-lactation. We completed sample collection from two cohorts of eight dairy cows with sample collection from the second cohort completed in the current reporting period. Sample analysis have also been completed. Data analysis has been completed for some of the measurements resulting from the experiment. Over the course of the nine day experiment, the temperature-humidity index, a measure of heat stress exposure in dairy cows, average 72.4. The cows in the control condition were maintained at a temperature-humidity index of 63.4. Under heat stress conditions, cows increased their breathing rate to 70 breaths per minute compared to 45 for control cows. As expected, rectal temperature also increased to 39.5 degrees C compared to the 38.6 degrees for control cows. All cows decreased food intake by 16% and there were no differences between groups. This is part of the experimental design to control the effects of reduced food intake in the heat stressed cows. Milk yield was reduced similarly in both groups by 19% over the nine day experiment. All of these results indicate that cows experienced heat stress and responded in typical fashion. Our hypothesis for this experiment is that cell shedding into milk will be responsive to reductions in milk yield driven by heat stress. Sample analysis of milk cells in ongoing and data analysis of cell populations will be completed in the next reporting period.
Publications
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Progress 06/01/23 to 05/31/24
Outputs
Target Audience:
Nothing Reported
Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Two graduate students were recruited for the project. Both began their work in August 2023. They completed coursework and experiment planning activities in the second quarter of FY24. Coursework included lab training and data analysis. Experiment planning included facility preparation, animal identificaiton, and supply acquisition. Non-coursework training included participation in journal clubs and seminar attendance. Eight undergraduate students were hired to staff and support FY24Q3 experiments. They received training in animal care and use, responsible research conduct, and general animal management. They were also trained in sample collection and data recording. All received training and information about USDA support, the research hypotheses and objectives, and the general phsyiological pheneonema being studied in the experiments. How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals?Several major activities are planned for the next reporting period. Sample analysis for Experiment B2 will be initiated and completed. Following analysis, data analysis will be completed, and drafting of a manuscript will follow. The second replicate of Experiment B1 will be completed with sample analysis, data analysis, and manuscript preparation to follow. Manuscripts will be submitted in the following reporting period (year 3 of the project). The experiments of objective 1 will be initiated in the next reporting period. Planning forexperiment A2 will be initiated early in the reporting period with sample collection and analysis beginning shortly after. We expect to complete sample collection and analysis of experiment A2. Method development will begin for experiment A1. Refinement of methods will enhance the success of A1. Sample collection will be initiated and completed in the next reporting period but data analysis will not commence until the following experimental period.
Impacts
What was accomplished under these goals?
With acknowledgment of funding, graduate student recruiting was initiated to staff the experiments in this reporting period. Two graduate students were identified and recruited project to begin planning and work on the experiments of objective 2. Following establishment of the graduate students, planning of experiments ensued. In the latter half of the first year, the animal experiments were initiated. Half of experiment B1 was completed. Experiment B1 is a single reversal design and requires two sets of animals. One set was completed in year 1 but the second set will be completed in year 2. Sample collection was completed but analysis will not be initiated until sample collection is completed in year 2. Experiment B2 was initiated and sample collection completed. In year 2, sample analysis will be completed for experiment B2. A third graduate student has been recruited to support experiments of objective 1 starting in the second year of the project. Results and findings will be available after sample and data analysis are completed in the next reporting period.
Publications
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