Progress 05/15/17 to 05/14/23
Outputs
Target Audience:Over the course of this project, we have reached a number of audiences with our findings. Our most recognizable audience are other scientists and professionals reached through our scientific presentation and publications. We published several papers in peer-reviewed journals that are primarily reviewed by scientists domestically and internationally. Our presentations were made at annual conferences attended by scientists and professionals. We also published popular press articles related to project describing the implications of lactation persistency and impacts of management. The audience for these reports were producers in the state of Virginia. Students also presented to stakeholders at meeting for producers held on campus. These are all examples for formal dissemintations of our findings, but we interfaced with many students over the course of the project. Many undergraduate students assisted with experiments over the course of the project and learned about the project, our goals, and the findings, sometimes in real-time, as experiments were completed. We also interfaced with students working at the farm who were not directly working on experiments with us but were supporting farm operations and, therefore, our experiments. Overall, our target audiences were reached through multiple publications, presentations, and informal discussions throughout the project's life. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?The project provided several opportunities for training. In all, three graduate students were supported by the project and received degrees that acknowledged USDA support. One was a MS degree and the other two were PhD degrees. Each of these students gained valuable experience conducting in vivo experiments and conducting lab-based analyses and data analysis that followed. Undergraduate students were also trained as part of the project. These undergraduate were trained to support the animal or lab-based work of the project. Undergraduate research assistants were crucial to completing all the milkings and collecting samples. These students who supported animal work learned about the importance of good recording keeping and responsibility - skills that transcend their research experience. They also learned about the impacts of animal and milking management on dairy cow productivity. Students assisting in the lab supported general lab activities as well as sample preparation. Again, these students learned about research methodology and developed lab skills that were supportive of their further education through graduate school or veterinary medicine. The experience of graduate and undergraduate students through research, in general and through this project specifically, grow their capacity as well as their understanding of agricultural research. How have the results been disseminated to communities of interest?We have been regularly disseminating our results to communities of interest spanning from producer-stakeholders to other scientists and professionals to undegraduate students. Our publications have been published in internationally recognized, peer-reviewed journals. These are broadly read by scientists and professionals in the field. They reach scientists and professionals at all levels from undergraduate students to seasoned professionals. They are mainly of interest to other lactation physiologists and those involved in milking management. Our presentations at scientific conferences have reached similar audiences. In both cases, our findings informed these audiences about evolving understanding of the regulation of milk production and its responsiveness to management through milking frequency. We reached producer-stakeholder audiences through several presentations delivered on campus and popular press articles in a producer-oriented magazine. These reports were more general about milking frequency, lactation persistency, and milking management. We also discussed our experiments and the project as supported by USDA with undergraduate students. These undergraduates were introduced to the topic through discussions or by working on experiements as assistants. All together, we reached diverse audiences that represented the continuum of audiences we hoped to share our findings with. Introducting undergraduate students to research through discussions with graduate students, introducing producers to findings through presentations and publications, and publishing detailed accounts of our experiements for scientists all contributed to sharing our findings with communities of interest. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Objective 1 1) We completed 4 experiments. In the first experiment, we examined the time interval between the milking of the IMF implementation. For this experiment we applied even (4 milkings separated by 6 hours) and uneven (2 milkings separated by 3 hours and two milkings separated by 9 hours) to evaluated the impact of milking interval on milk yield and response in the ensuing lactation. In the second experiment, we evaluated the IMF application duration. We examined three application periods - 10, 20, and 40 days - of IMF to determine the effect on the mammary gland was longer lasting with longer application of IMF in early lactation. In the third experiment, we examined the application of bovine somatotropin to enhance the response to previous early lactation IMF to determine if the ongoing effect of early lactation IMF on the mammary gland could be further stimulated by the application of bovine somatotropin. In the fourth experiment, we reapplied IMF in established lactation following an earlier period of IMF in early lactation. We examined this approach to determine if the persistent effect of IMF that can be established in early lactation can be similarly developed in established lactation thereby maintaining the effect longer into lactation. 2) For all four experiments our main measurement to evaluate responses was milk yield of udder halves. Each udder half in an experiment received a different milking frequency - 4 times daily vs 2 times daily. Milk yield of the udder halves during IMF and throughout lactation was the key measurement completed as it directly answered the research question of the objective related increasing the volume and duration of milk yield in response to treatment. Coupled with measuring milk production were measures of milk components (fat, protein, lactose). 3) Two initial experiments evaluated the application of IMF in early lactation on the effect's persistency. First, the interval or timing of IMF in early lactation was evaluated. More even milking intervals are known to maximize milk yield. We evaluated even and uneven milking intervals for the application of IMF and found that the milk yield response was similar whether cows had even (6 hours apart) or uneven (3 and 9 hours apart) 4X milking intervals. The milk yield increase through lactation was 1.6 kg/d for IMF udder halves. We also evaluated the duration of application of IMF in early lactation hypothesizing that extending the period longer would extend the effect of IMF in early lactation further into lactation. We found no significant difference on overall milk yield through 270 days of lactation between the treatments, but evaluating the milk yield response among the treatments when evaluating by day revealed that the 40 day application period did increase milk yield relative to the 10 and 20 day application period at 180, 210, 240, and 270 days of lactation. In a third experiment, we reapplied IMF in established lactation after cows had received IMF in early lactation. During the reapplication of IMF, milk yield increased significantly in the 4X udder halves. Cows receiving the repeated application of IMF also produced additional milk at 200, 230, and 260 days of lactation, but not at 290 days of lactation. With the objective of increasing milk yield further during lactation, we evaluated the combined effects of early lactation IMF and bovine somatropin. Following application of early lactation IMF and subsequent application of bovine somatotropin in established lactation, we did not observe synergy between the two treatments. The response of both udder halves to somatotropin was similar between the 2X and 4X udder halves. 4X udder halves produced more milk than 2X and somatotropin increased milk production beyond the untreated period, but there was no greater milk yield in 4X udder halves with somatotropin relative to the increase that was expected with somatotropin alone. 4) Our objective was to increase the volume and duration of the milk yield response to early lactation IMF. In evaluating different approaches and practices to enhance the response to early lactation IMF, we found that the interval of milkings was not influential. This imparts flexibility to the application of early lactation IMF at milking giving producers the opportunity to adjust the management of IMF application to fit their farm constraints. Applying the IMF period in early lactation longer does improve the magnitude and duration of the effect further into lactation. Adding a second IMF period in established lactation does improve the duration of the effect and volume later into lactation Objective 2 1) In support of objective 2 we analyzed data from two experiments. In the first, we implemented early lactation IMF and obtained mammary biopsy samples from the cows. These biopsies were obtained after cows had been milked either two times daily or four times daily in different udder halves. Mammary biopsies were obtained from each udder half to evaluate cell signaling differences in the mammary tissue. In an additional experiment, we evaluated the tissue response to early lactation IMF as well as mid-lactation IMF. 2) For the first experiment, we used the tissue from these biopsies for assays to determine the molecular responses of the cells to IMF. These assays provided data on the status or activity of regulatory factors and also on the expression of genes involved in milk synthesis. In the second experiment, we measured the volume of milk holding compartments in the udder halves receiving twice daily or four times daily milking frequency. The two compartments evaluated were the gland cistern where milk is held prior to milking and the alveoli where milk is synthesized and also held until secretion. 3) With the tissue biopsies, we found increases in the activation of a regulatory protein involved in milk protein synthesis known by its abbreviation, STAT5. Both the activation state and the total amount of this protein were increased by 4X milking. Another protein involved in regulating cellular energy use was also upregulated, Akt. These two proteins both work together to stimulate the activity or production of cells for milk synthesis. We measured several other factors but found no change in these. We found that the gland cistern compartment of the mammary gland that supports holding milk released from the alveoli prior to milking was also increased with 4X milking both months after the bout of early lactation IMF and immediately following the bout of IMF in established lactation. The alveolar compartment was not increased. These data support the hypothesis that activity of the cells was increased - milk production by the alveoli caused the additional milk resulting from IMF to accumulate in the cistern and there was no increase in alveolar volume that might result from increased cell numbers. 4) Our data support that early lactation IMF alters the production capacity in the mammary gland through regulation of the cellular machinery in the mammary cells producing milk and that this change in activity alters the structure of the mammary gland to support the increased milk yield. Beyond the direct effects of early lactation IMF, understanding how management practices influence the function and structure of the mammary gland have implications for continued progress in increasing the production and efficiency of dairy cows. As milk yield has progressively increased over decades, the udder of the dairy cow has not multiplied in scale by the same amounts. The efficiency of production has improved and this is likely the result of the same factors observed here - greater synthetic capacity as well as greater milk holding capacity.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2023
Citation:
H. H. Hanling, M. L. McGilliard, and B. A. Corl. 2023. The Enhanced Milk Yield Effect of Early Lactation Increased Milking Frequency and Bovine Somatotropin Is Additive and Not Synergistic. Animals (Basel). 13:2202. https://doi.org/10.3390/ani13132202
- Type:
Journal Articles
Status:
Accepted
Year Published:
2023
Citation:
G. Perez-Hernandez, H. H. Hanling, H. H. Schramm, A. J. Lengi, and B. A. Corl. 2023. Milk production and anatomical udder capacity changes of udder halves subjected to increased milking frequency at two stages of lactation. J. Dairy Sci. (in press)
- Type:
Theses/Dissertations
Status:
Accepted
Year Published:
2022
Citation:
Haylee Hanling, Ph.D. Dissertation, The physiology of enhanced milk yield through increased milking frequency in early lactation. May, 2022.
- Type:
Theses/Dissertations
Status:
Accepted
Year Published:
2023
Citation:
Gabriela Perez-Hernandez, Ph.D. Dissertation, Local regulation of milk synthesis capacity in the mammary gland of lactating dairy cows. August, 2023.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
G. Perez-Hernandez*, H. H. Hanling, and B. A. Corl. 2022. Milk yield, components, and lactation persistency improvement due to increased milking frequency during early and mid-lactation in multiparous cows. J. Dairy Sci. 105(Suppl. 1):301.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
G. Perez-Hernandez*, H. H. Hanling, and B. A. Corl. 2022. Cistern and alveolar capacity of udder halves subjected to increased milking frequency at 2 stages of lactation. J. Dairy Sci. 105(Suppl. 1):107.
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Progress 05/15/21 to 05/14/22
Outputs
Target Audience:As with previous reporting years, our target audience is primarily scientists. At our annual conference, a student delivered two presentations on results from our recent experiment to scientists and other professionals in attendance. We also published a peer-reviewed journal article on our results. We have also reached students, specifically those working on the project. Changes/Problems:We faced a delay in starting our last experiment due to COVID-shifted schedules as described in our previous progress report. We revised our completion date for the project and are on track to complete the project with the revised completion date. What opportunities for training and professional development has the project provided?Two graduate students have continued their studies for their PhD. One nears completion of her dissertation. During the last reporting period, one undergraduate student has been participating in research studies in supporting roles and has learned about the project and that experiment. How have the results been disseminated to communities of interest?We continued presenting results at professional meetings with two conference presentations in 2021. We also published a manuscript with the results of Experiment 2 of Objective 1. What do you plan to do during the next reporting period to accomplish the goals?We will complete sample and data analysis for Objective 2. In addition, we will prepare a manuscript from these results and submit it for publication. We are preparing a manuscript from the results of the fourth experiment of Objective 1 and anticipate submission in the next 60 days.
Impacts
What was accomplished under these goals?
The major source of income for dairy farmers is selling milk. The major expense for most dairy farmers is feed for their cows. Maximizing the efficient conversion of feed to saleable milk is important for profitability. A portion of the feed consumed by a cow is used for maintenance functions and not for actual milk production. Increasing milk production in cows increases the proportion of nutrients utilized for milk production while maintaining the amount of nutrients used for maintenance functions. This increases the efficiency of production due to the increased proportion of nutrients used for milk production. This 'dilution of maintenance' can be achieved using various methods that increase milk production per cow. In this project, we are investigation the use of milking frequency to enhance milk production and increase productive efficiency of the cow and enable farmers to produce more milk from feed. Milking frequency is well known to influence milk production per cow and many farmers have moved from milking cows twice a day to milking three times a day. Labor and facility limitations limit some farmers' ability to increase milking frequency and diminishes their efficiency. Other investigators have found that increasing milking frequency just in the first few weeks of lactation can increase milk production throughout lactation. The impact of this approach, refined through experiments in this project, will enable farmers limited by various constraints to increase their productive efficiency and profitability without facility or labor changes. We completed our fourth experiment for Objective 1, prepared a manuscript from the third experiment, and completed sample collection for Objetive 2. In preparing the manuscript for the third experiment of Objective 1, we revised our statistical analysis after completing a previous progress report. In so doing, we found that bovine somatotropin (bST) did have a significant main effect on milk yield following administration. There was no interaction between the main effects of milking frequency and bST administartion. This indicates that there was no synergy between the two treatments. We had considered several possible outcomes from this experiment including synergy, inhibition, or lack of interaction. Because increased milking frequency acts through local mechanisms and somatotropin acts through systemic mechanisms as well as local, we thought that additional stimulation and support for milk production might result in an additive effect. The lack of interaction and synergy indicates that additional stimulation locally with provided systemic support was not additive. It is also known that there is variability in the responsiveness of cows to increased milking frequency and to bST. We examined the relationship of response among the cows to the two main effect treatments and found that responsiveness to increased milking frequency did not correlate with responsiveness to bST seemingly indicating that separate factors determine how each cow responds to each treatment. We completed sample collection and data analysis for the fourth experiment of Objective 1. Our previous data revealed a declining persistency of the effect of early lactation increased milking frequency in ensuing lactation with udder half differences declining through 300 days of lactation. In this experiment, we sought to reinitiate the effect by repeating the increased milking frequency period in established lactation. All cows were milked with increased milking frequency in early lactation in the right udder half and half of these cows were milked with increased milking frequency right udder half for 20 days starting at 150 days of lactation. Before imposing increased milking frequency in the treated group, there was no difference between udder halves of the control and treated groups. With imposition of increased milking frequency, milk yield and milk protein yield were increased, but milk fat yield was not. Following cessation of increased milking frequency at 170 days of lactation, the treated group maintained increased milk through 290 days of lactation. These results reveal that it is possible to reimpose increased milking frequency for a short period of time and cause a carryover effect. It's possible to increase milking frequency outside of early lactation and changed the mammary gland to produce additional milk after reducing milking frequency again. A manuscript describing these results is in preparation and data will be presented at an upcoming conference. We have completed the animal experimental portion of Objective 2 and collected all samples. Analysis of samples is on-going and data analysis will be completed before the expiration of the project.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
G. Perez-Hernandez, K. Tate, K. D. Hardin, C. Parsons, R. M. Akers, and B. A. Corl. 2021. Effect of increased milking frequency during early lactation on bovine mammary epithelial cell differentiation. J. Dairy Sci. 104(Suppl. 1):257.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
G. Perez-Hernandez, K. Tate, K. D. Hardin, C. Parsons, R. M. Akers, and B. A. Corl. 2021. Yes-associated protein expression of mammary epithelial cells from mammary glands subjected to increased milking frequency. J. Dairy Sci. 104(Suppl. 1):256.
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
H. H. Hanling, M. L. McGilliard, and B. A. Corl. 2021. Uneven milking intervals are adequate to achieve the benefits of increased milking frequency in early lactation. J. Dairy Sci. 104:9355-9361. https://doi.org/10.3168/jds.2020-20100
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Progress 05/15/20 to 05/14/21
Outputs
Target Audience:In this reporting year, our target audience continues to be primarily scientists. We have published one manuscript describing results of an experiment. The coronavirus pandemic limited our efforts to speak directly to others. We have also reached students, specifically those working on the project. Changes/Problems:Coronavirus impacted the timing of the initiation of our current on-going experiment (fourth experiment of Objective 1). It was scheduled to start in the spring of 2020 and was delayed with the university restricted research activitivites. We were not able to start until the fall and this delay will cause us to extend the length of the project. This delay will not impact the experiments or measurements, only the timing of completion. We will complete all experiments, as described, only later than originally planned. What opportunities for training and professional development has the project provided?In the last reporting year, two graduate students have continued their studies for their PhD. Seven undergraduate students have been participating in research studies in supporting roles and have learned about the project and the on-going experiment. How have the results been disseminated to communities of interest?Results have been disseminated through publication of research results. What do you plan to do during the next reporting period to accomplish the goals?We will continue and complete the data collection for the currect experiment (fourth of Objective 1). We hope to complete data analysis as well for this experiment in the next reporting period. We will initiate the experiment for Objective 2 in the next reporting period. We also anticipate submitting another manuscript from this project as well as presenting data at a meeting in the next reporting period.
Impacts
What was accomplished under these goals?
The major source of income for dairy farmers is selling milk. The major expense for most dairy farmers is feed for their cows. Maximizing the efficient conversion of feed to saleable milk is important for profitability. A portion of the feed consumed by a cow is used for maintenance functions and not for actual milk production. Increasing milk production in cows increases the proportion of nutrients utilized for milk production while maintaining the amount of nutrients used for maintenance functions. This increases the efficiency of production due to the increased proportion of nutrients used for milk production. This 'dilution of maintenance' can be achieved using various methods that increase milk production per cow. In this project, we are investigation the use of milking frequency to enhance milk production and increase productive efficiency of the cow and enable farmers to produce more milk from feed. Milking frequency is well known to influence milk production per cow and many farmers have moved from milking cows twice a day to milking three times a day. Labor and facility limitations limit some farmers' ability to increase milking frequency and diminishes their efficiency. Other investigators have found that increasing milking frequency just in the first few weeks of lactation can increase milk production throughout lactation to a similar amount achieved with lactation long increases in milking frequency. The impact of this approach, refined through experiments in this project, will enable farmers limited by various constraints to increase their productive efficiency and profitability without facility or labor changes. We have initiated the fourth experiment of Objective 1. Its initiation was delayed by the coronavirus pandemic, so we have not analyzed any results yet and the experiment is on-going. It will continue well into 2021 and partially into 2022.
Publications
- Type:
Journal Articles
Status:
Accepted
Year Published:
2021
Citation:
H. H. Hanling, M. L. McGilliard, and B. A. Corl. 2021. Uneven milking intervals are adequate to achieve the benefits of increased milking frequency in early lactation. J. Dairy Sci. in press. https://doi.org/10.3168/jds.2020-20100
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Progress 05/15/19 to 05/14/20
Outputs
Target Audience:In the last reporting year, our target audience continued to be primarily scientists. We have presented brief results in two presentations to stakeholders and extension professionals in Virginia who work with dairy farmers. We also presented results as part of a short symposium to a a media reporter. At our annual conference, a student presented results from her recent experiment to scientists and other professionals in attendance. We have also reached students, specifically those working on the project. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?In the last reporting year, a graduate student has continued her studies for her PhD. The third graduate student to work on this project has been recruited and has started her work in support of the project. Two undergraduate students have been participating in research studies. How have the results been disseminated to communities of interest?One graduate student presented findings at the annual meeting of the American Dairy Science Association. Two presentations were made to stakeholders in Virginia including dairy farmers and affiiliated industry professionals. What do you plan to do during the next reporting period to accomplish the goals?In the next reporting year, we will be initiating the fourth and final experiment of Objective 1. In this experiment, 20 cows will undergo increased milking frequency in early lactation. To establish if the effect of increased milking frequency in early lactation can be extended or augmented, ten cows will undergo increased milking frequency in established lactation. This study, as with previous experiments, will require lactation-long sampling and will likely span two reporting years.
Impacts
What was accomplished under these goals?
The major source of income for dairy farmers is selling milk. The major expense for most dairy farmers is feed for their cows. Maximizing the efficient conversion of feed to saleable milk is important for profitability. A portion of the feed consumed by a cow is used for maintenance functions and not for actual milk production. Increasing milk production in cows increases the proportion of nutrients utilized for milk production while maintaining the amount of nutrients used for maintenance functions. This increases the efficiency of production due to the increased proportion of nutrients used for milk production. This 'dilution of maintenance' can be achieved using various methods that increase milk production per cow. In this project, we are investigation the use of milking frequency to enhance milk production and increase productive efficiency of the cow and enable farmers to produce more milk from feed. Milking frequency is well known to influence milk production per cow and many farmers have moved from milking cows twice a day to milking three times a day. Labor and facility limitations limit some farmers' ability to increase milking frequency and diminishes their efficiency. Other investigators have found that increasing milking frequency just in the first few weeks of lactation can increase milk production throughout lactation to a similar amount achieved with lactation long increases in milking frequency. The impact of this approach, refined through experiments in this project, will enable farmers limited by various constraints to increase their productive efficiency and profitability without facility or labor changes. We completed our second and third experiments for Objective 1. Bovine somatotropin is a protein hormone that increases milk production. Increasing milking frequency also increases milk production, and coupling these twomanagement approaches together enables us to evaluate the potential for synergy between the milk yield response induced by milking frequency and the response due to somatotropin. Therefore, we conducted an experiment to infer the metabolic mechanism of increased milking frequency in early lactation by combining it with bST. The objective was to examine the potential for synergistic effects of increased milking frequency in early lactation and application of bovine somatotropin in established lactation. We looked for a change in udder half MY difference of 4X and 2X glands before and after bST injection. We milked 14 cows for 21 days in early lactation unilaterally with 4X right and 2X left udder halves. Cows were sampled using a double bucket milking system with udder half yields collected in separate containers. Right udder halves made 8.60 +/- 1.07 kg/d more milk than left halves on d 20 of 4X milking treatment, which correlates to a 28% increase in milk yield. We administered bST on day 80. Cows were sampled for udder half milk weights as well as fat, protein, milk-solids-not-fat, and lactose every other day from 74-94 DIM. The udder half difference (4X gland milk yield - 2X gland milk yield) was not statistically different before and after bST. There was also a significant increased milk yield carry-over effect due to 4X milking of 2.6 +/- 0.43 kg/d, an 11% increase. There was an overall effect of day for milk, fat, protein, lactose, and SNF yields because the udder half difference in these yields on the final day of 4X treatment were significantly greater than all mid-lactation sampling days. There was no difference in the increased milk, fat, protein, lactose, or SNF yields between mid-lactation sampling days. With these results, we continue to seek methods to maximize the response of cows to the imposition of increased milking frequency in early lactation and to prolong the effects further into lactation. The lack of response to bST was unexpected, but further confirmation of the immediate and prolonged benefits of early lactation increased milking frequency are consistent. Our next experiment seeks to re-establish or augment the effect of early lactation increased milking frequency by repeating the increased milking frequency period in established lactation with the hope of extending the udder half difference even further in lactation and maximizing the response while continuing to minimize the labor commitment needed to achieve this level of increase in milk yield in response to milking frequency.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2019
Citation:
H. Hanling, M. McGilliard, and B. Corl. 2019. Milking interval did not affect the increased milk yield carry-over effect of increased milking frequency in early lactation. J. Dairy Science. 102(Suppl. 1):155.
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Progress 05/15/18 to 05/14/19
Outputs
Target Audience:In this first year of funding, our target audience continues to be primarily scientists. We have presented brief results in three presentations to stakeholders and extension professionals in Virginia that work with dairy farmers. We have also reached students, specifically those working on the project. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?To date, one graduate student has completed training and another is continuing her training. Both had received prior Bachelor's degrees in Animal Science. In total, twenty undergraduate students have assisted with experiments. How have the results been disseminated to communities of interest?One graduate student presented findings from this project at the American Dairy Science Association annual meeting. The audience included other scientists, other students, and industry professionals. Three presentations have been completed to Department of Dairy Science stakeholders who include dairy farmers and industry professionals. Additional members of the audience included extension professionals from Virginia Cooperative Extension. What do you plan to do during the next reporting period to accomplish the goals?In the next reporting period, we will complete analysis of our third experiment and plan the initiation of our fourth experiment. Additionally, we will recruit another graduate student to be trained and assisted in completing the project. Findings from our second experiment will be presented at the 2019 American Dairy Science Association to disseminate our latest results to scientists and industry professionals in attendance.
Impacts
What was accomplished under these goals?
The major source of income for dairy farmers is selling milk. The major expense for most dairy farmers is feed for their cows. Maximizing the efficient conversion of feed to saleable milk is important for profitability. A portion of the feed consumed by a cow is used for maintenance functions and not for actual milk production. Increasing milk production in cows increases the proportion of nutrients utilized for milk production while maintaining the amount of nutrients used for maintenance functions. This increases the efficiency of production due to the increased proportion of nutrients used for milk production. This 'dilution of maintenance' can be achieved using various methods that increase milk production per cow. In this project, we are investigation the use of milking frequency to enhance milk production and increase productive efficiency of the cow and enable farmers to produce more milk from feed. Milking frequency is well known to influence milk production per cow and many farmers have moved from milking cows twice a day to milking three times a day. Labor and facility limitations limit some farmers' ability to increase milking frequency and diminishes their efficiency. Other investigators have found that increasing milking frequency just in the first few weeks of lactation can increase milk production throughout lactation to a similar amount achieved with lactation long increases in milking frequency. The impact of this approach, refined through experiments in this project, will enable farmers limited by various constraints to increase their productive efficiency and profitability without facility or labor changes. We completed one experiment and initiated a second experiment in support of Objective 1. The goal for the first experiment was to determine if milking cows on even milking intervals would enhance the increased milk yield effect of early lactation increased milking frequency. We milked 20 cows unilaterally for 20 days post-calving; the right udder halves were milked 4X and the left were milked 2X. This allowed for each cow to be her own control. Ten cows were milked every 6 hours (the even milking interval group) and 10 were milked on a 9:3:9:3 interval (the uneven milking interval group). The cows were sampled for milk weights and components with a double bucket system every 60 days throughout lactation. We analyzed the difference in milk and milk component yields by subtracting the 2X from the 4X gland values. We did not find any significant difference between the two groups. Udder half difference in milk yield (4X gland yield - 2X gland yield) was only significantly different from zero at the end of the treatment period. We did not see a milk yield carry-over effect. Increased fat yield in 4X glands was significant on all sampling days excluding 120 and 300 DIM, but it was not different between treatment groups or parities. Increased protein yield from 4X glands was significant on all days excluding days 60 and 120. There was no difference between treatments, but there was a tendency effect for treatment by parity because primiparous cows in the even group did not have a significant increase in protein yield. Increased non-fat solids yield was significant on day 20 and 240, and there was a treatment by parity effect. No difference in lactose yield or SCC was detected between treatment, parity, or sampling day. There was an overall parity effect tendency that needs to be evaluated further. Primiparous cows may not respond as well to the increased milking frequency as multiparous cows. There was a significant effect of treatment by parity; the increased milk yield from primiparous cows on uneven milking intervals was greater than those on even intervals. With the second experiment, we aim to examine the potential for synergistic effects of increased milking frequency in early lactation and bovine somatotropin. Bovine somatotropin is a protein hormone that increases milk production. Coupling the two management approaches together enables us to evaluate the potential for synergy between the milk yield response induced by milking frequency and the response due to somatotropin. We milked 14 cows the same way as the even group described above. Cows were sampled in the same fashion as the previous experiment every other day from 74-94 DIM. We administered bST on day 80. Data collection is complete and analysis is on-going. These two experiments support Objective 1 by determining conditions for maximizing the response to increased milking frequency and examining the potential to extend and improve the effects later into lactation. Findings from these experiments will help farmers effectively determine the best approach for application on their farms. No experiments supporting Objective 2 have been initiated yet.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
K. R. Tate, M. L. McGilliard, A. J. Lengi, and B. A. Corl. 2018. Evaluating the duration of increased milking frequency during early lactation for increased yield through lactation. J. Dairy Sci. Vol. 101(Suppl. 2): 169.
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Progress 05/15/17 to 05/14/18
Outputs
Target Audience:In this first year of funding, our target audience has been other scientists and we have also reached students, specifically those working on the project. These communications have been mostly informal, sharing plans for our work with scientists at meetings and then training two graduate students and their associated undergraduate research assistants. In conducting training, we've explained the overall project, the specific experiment they're working on, and milking frequency more generally. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Two graduate students are currently being trained during this project. They both received Bachelor's degrees in Animal Science prior to beginning their Master's degrees on this project. Additionally, 10 undergraduate students have assisted with the experiments supporting objective 1. No additional training or professional development activities have been completed at this early stage of the project. 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?With the completion of one experiment, including the data analysis, we plan to disseminate results to other scientists and share outcomes with producers at a field day. We will be presenting results at the annaul meeting of the American Dairy Science Association. Scientists as well as industry professionals will be in attendance and we will share our findings with them. We anticipate some will carry our findings to the field for application. We will complete our recently initiated experiment examining the effects of milking interval on milk production and persistency of effect through lactation. Further into the second year of the project, we will inititiate and complete and another experiment examining the interaction of early lactation milking frequency and somatotropin, the major milk production regulating factor in dairy cows.
Impacts
What was accomplished under these goals?
The major source of income for dairy farmers is selling milk. The major expense for most dairy farmers is feed for their cows. Maximizing the efficient conversion of feed to saleable milk is important for profitability. A portion of the feed consumed by a cow is used for maintenance functions and not for actual milk production. Increasing milk production in cows increases the proportion of nutrients utilized for milk production while maintaining the amount of nutrients used for maintenance functions. This increases the efficiency of production due to the increased proportion of nutrients used for milk production. This 'dilution of maintenance' can be achieved using various methods that increase milk production per cow. In this project, we are investigation the use of milking frequency to enhance milk production and increase productive efficiency of the cow and enable farmers to produce more milk from feed. Milking frequency is well known to influence milk production per cow and many farmers have moved from milking cows twice a day to milking three times a day. Labor and facility limitations limit some farmers' ability to increase milking frequency and diminishes their efficiency. Other investigators have found that increasing milking frequency just in the first few weeks of lactation can increase milk production throughout lactation to a similar amount achieved with lactation long increases in milking frequency. The impact of this approach, refined through experiments in this project, will enable farmers limited by various constraints to increase their productive efficiency and profitability without facility or labor changes. During this reporting period, we recruited students and staffed the experiments, initiated two experiments, and completed one experiment. Two graduate student have been recruited to the project. Each started experiments supporting objective 1 of the project. The first experiment was started and completed in the first year of funding. This experiment examined the duration of early lactation milking frequnecy. Although several experiments previously reported the effects of early lactation increased milking frequency, none had determined the effects of increasing application time. We used 10, 20, and 40 day application periods and compared milk yield and the yields of milk solids using an udder half milking frequency model. We followed the cows to 270 days in lactation. The 40 day treatment was most effective at increasing the yield of milk and milk solids. Its effect lasted through 270 days in lactation and resulted in about 4 kg/d (8 lbs/d) more milk with increased milking frequency over that period despite returning to twice daily milking after the 40 day treatment period. Milk fat yield increased about 130 g/d and protein yield increase about 111 g/d. Milk fat and protein percentages were unaffected and somatic cell count, a measure of udder health, was unaffected by increased milking frequency in early lactation. Our second experiment is in progress and examines the milking interval spacing for increased milking frequency in early lactation. Data collection is in progress, but no analyses have been completed because less than 10% of the sampling is complete at the time of this submission. These two experiments support objective 1 by determining the best conditions and approach to apply increased milking frequency in early lactation. The conclusions from these experiments will enable farmers to make informed decisions about applying changes in milking frequency on their own farms and the best approaches to achieve thier goals. No experiments supporting objective 2 have been initiated to date.
Publications
- Type:
Theses/Dissertations
Status:
Published
Year Published:
2018
Citation:
Tate, K. R. 2018. Determining the appropriate duration of increased milking frequency during early lactation for increased milk yield and efficient production. in Dairy Science. Masters of Science. Virginia Tech.
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