Know more

About cookies

What is a "cookie"?

A "cookie" is a piece of information, usually small and identified by a name, which may be sent to your browser by a website you are visiting. Your web browser will store it for a period of time, and send it back to the web server each time you log on again.

Different types of cookies are placed on the sites:

  • Cookies strictly necessary for the proper functioning of the site
  • Cookies deposited by third party sites to improve the interactivity of the site, to collect statistics

Learn more about cookies and how they work

The different types of cookies used on this site

Cookies strictly necessary for the site to function

These cookies allow the main services of the site to function optimally. You can technically block them using your browser settings but your experience on the site may be degraded.

Furthermore, you have the possibility of opposing the use of audience measurement tracers strictly necessary for the functioning and current administration of the website in the cookie management window accessible via the link located in the footer of the site.

Technical cookies

Name of the cookie

Purpose

Shelf life

CAS and PHP session cookies

Login credentials, session security

Session

Tarteaucitron

Saving your cookie consent choices

12 months

Audience measurement cookies (AT Internet)

Name of the cookie

Purpose

Shelf life

atid

Trace the visitor's route in order to establish visit statistics.

13 months

atuserid

Store the anonymous ID of the visitor who starts the first time he visits the site

13 months

atidvisitor

Identify the numbers (unique identifiers of a site) seen by the visitor and store the visitor's identifiers.

13 months

About the AT Internet audience measurement tool :

AT Internet's audience measurement tool Analytics is deployed on this site in order to obtain information on visitors' navigation and to improve its use.

The French data protection authority (CNIL) has granted an exemption to AT Internet's Web Analytics cookie. This tool is thus exempt from the collection of the Internet user's consent with regard to the deposit of analytics cookies. However, you can refuse the deposit of these cookies via the cookie management panel.

Good to know:

  • The data collected are not cross-checked with other processing operations
  • The deposited cookie is only used to produce anonymous statistics
  • The cookie does not allow the user's navigation on other sites to be tracked.

Third party cookies to improve the interactivity of the site

This site relies on certain services provided by third parties which allow :

  • to offer interactive content;
  • improve usability and facilitate the sharing of content on social networks;
  • view videos and animated presentations directly on our website;
  • protect form entries from robots;
  • monitor the performance of the site.

These third parties will collect and use your browsing data for their own purposes.

How to accept or reject cookies

When you start browsing an eZpublish site, the appearance of the "cookies" banner allows you to accept or refuse all the cookies we use. This banner will be displayed as long as you have not made a choice, even if you are browsing on another page of the site.

You can change your choices at any time by clicking on the "Cookie Management" link.

You can manage these cookies in your browser. Here are the procedures to follow: Firefox; Chrome; Explorer; Safari; Opera

For more information about the cookies we use, you can contact INRAE's Data Protection Officer by email at cil-dpo@inrae.fr or by post at :

INRAE

24, chemin de Borde Rouge -Auzeville - CS52627 31326 Castanet Tolosan cedex - France

Last update: May 2021

Menu Logo Principal Institut Agro Rennes-Angers

Home page

Relation between milk calcium content and skeletal reserves in dairy cows

Thesis : relation between milk calcium content and skeletal reserves in dairy cows
Can the evolution of milk calcium content during lactation be an indicator of the effect of dairy herd management and feeding on skeletal reserves of dairy cows?

Mineral nutrition of dairy cows

During lactation, cows export a huge amount of calcium in milk and its bones are particularly mobilized. It is necessary to have a better knowledge of bone metabolism during lactation to have a more accurate estimation of needs in calcium and phosphorus of dairy cows. The aim is to:

  • have a better control in calcium intake to avoid a restricted bone reconstitution during lactation
  • reduce recommended phosphorus intake for those animals to limit phosphorus rejects, which may be involved in eutrophization.

The biggest difficulty is that bone cycles are hard to identify on large herds of dairy cows. Actually, it is easy to follow calcium concentration in milk during lactation with Mid-infrared, and it may be an indirect indicator of those cycles. It has recently proved that in lactating mammals that calcium levels regulation may impact on both bone regulation and calcium excretion in milk.

Roto-traite

Calcium and bone cycle during lactation

The working hypothesis of this thesis is that dynamic of milk calcium content during lactation reflects dynamic of bone accretion and resorption in dairy cows and therefore that the monitoring milk calcium content can be a useful tool for characterizing bone accretion and resorption cycles in dairy systems, and for reasoning the mineral nutrition of dairy cows in a dynamic way during lactation. The central questions of this thesis will be to determine:

  • the relationship between the dynamic of milk calcium and that of bone accretion and resorption on the same individual during lactation,
  • the dynamic of bone accretion and resorption can be significantly modulated by the dynamic of mineral supplementation during lactation,
  • the fact of reasoning mineral supply throughout lactation may allow significant reduction in calcium and phosphorus supplementation without penalizing bone reconstruction of cows.

The first task of this thesis will be to monitor jointly dynamic of milk calcium during lactation and those of serum levels of biomarkers of bone accretion and resorption on long term experiment already running on the Inra experimental farms of Le Rheu (Méjusseaume) and Le Pin au Haras (120 cows involved).
A parallel task will be to analyze data already available at UMR Pegase consisting in surveys of feed practices of farms spread over France associated with an annual monitoring the calcium content for individuals . These data will allow defining a range of herd feeding practices, from farms, susceptible to modulate milk calcium content during lactation.
Finally, a specific trial will compare two targeted feeding strategies for their ability to modulate milk calcium content and/or bone accretion and resorption cycles through serum biomarkers. Those measures will be supplemented by measurement of urinary and fecal excretion of calcium and phosphorus, body retention of those elements and the bone composition thanks to biopsy.

Pierre Gaignon is working on this subject of thesis since the 1st november of 2015 for 3 years. He is supervised by Anne Boudon in the team Alimentation and Nutrition.

Contact

Pierre Gaignon : pierre.gaignon[at]rennes.inra.fr (PhD student)
Anne Boudon : anne.boudon[at]rennes.inra.fr (supervisor)
Catherine Hurtaud : catherine.hurtaud[at]rennes.inra.fr (co-supervisor)