Abstract
Milk production in dairy cow udders is a complex and dynamic physiological process that has resisted explanatory modelling thus far. The current standard model, Wood’s model, is empirical in nature, represents yield in daily terms, and was published in 1967. Here, we have developed a dynamic and integrated explanatory model that describes milk yield at the scale of the milking session. Our approach allowed us to formally represent and mathematically relate biological features of known relevance while accounting for stochasticity and conditional elements in the form of explicit hypotheses, which could then be tested and validated using real-life data. Using an explanatory mathematical and biological model to explore a physiological process and pinpoint potential problems (i.e., “problem finding”), it is possible to filter out unimportant variables that can be ignored, retaining only those essential to generating the most realistic model possible. Such modelling efforts are multidisciplinary by necessity. It is also helpful downstream because model results can be compared with observed data, via parameter estimation using maximum likelihood and statistical testing using model residuals. The process in its entirety yields a coherent, robust, and thus repeatable, model.
Highlights
A study in 194723 first underscored the need for an explanatory model of milk production physiology to better understand and control udder mastitis[24, 25], a problem that remains a major concern in the dairy industry; this need has yet to be met
Researchers have characterised milk production in cow udders by individually examining different system components, namely the dynamics of the alveolar population over the course of lactation[26,27,28,29], of alveolar milk synthesis between milking sessions[30,31,32,33,34], and of udder emptying during milking[35,36,37]
Scientists focused on the dynamics of alveolar populations and of milk synthesis[38,39,40,41,42]; the links between milk synthesis, udder compartments, and milking interval duration[43,44,45,46,47,48,49,50,51,52]; and the consequences of udder-emptying problems for milk yield[53,54,55,56,57,58,59,60,61,62,63,64,65,66]
Summary
In milk-yield studies, Wood’s model is the standard of reference[1,2,3], in part because of its good fit to observed data, but mostly because no better alternatives exist[4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22]. Other related work led to the creation and exploration of biological simulations of daily yield (e.g., Shorten in 2002). These models were overparameterised and parameter estimation from observed data was not possible. Because the research described above was focused on daily milk yield and did not address udder-emptying dynamics or the precision of session-level measurements, it cannot be used to fully parse the variance associated www.nature.com/scientificreports/. To obtain daily yields (i.e., for a 24-hour period) from such systems, additional calculations[71, 72] must be used, which increases response variability
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
