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

Substitution rate between grazed pasture and a conserved forage in grazing dairy cows

Thesis : substitution rate between grazed pasture and a conserved forage in grazing dairy cows
The main objective of the thesis is to quantify the influence of grazing conditions and of the level of forage supplementation on pasture intake and milk production in dairy cows.

Study the pasture intake regulation in dairy cow

In the future, the average dairy herd size will continue to increase, while the area available for grazing will probably decrease on a per cow basis. In this context, more dairy herds will be fed during longer periods (several months) on mixed diets comprising grazed pasture and conserved forages. If concentrate supplementation has been studied for a long time, enabling to predict accurately the substitution rate between pasture and concentrate, knowledge on pasture intake regulation when conserved forages are fed is less, making difficult to predict accurately cow performance in such feeding systems. Particularly, it seems difficult to predict the range of pasture/forage substitution rate, as well as to quantify the effects of main sources of variation.

The main hypothesis of the thesis is that grazing conditions, and mainly pasture allowance, along with the level of forage supplementation, are the main determinants of substitution rate. The INRA model, developed at the unit Pegase (GrazeIn) are not able to predict very low substitution rate (close to 0) reported in the literature under very severe grazing conditions.

auge_vache
paturage

An experimental and meta-analysis approach to determine the factors of variation

The thesis in mainly based on an experimental approach to improve partial knowledge available in the literature. Three grazing experiments are planned, with the aim to define the interaction between levels of maize silage supplementation and pasture allowance on the pasture/forage substitution rate. A quantitative meta-analysis of the literature will be done to complete the experimental approach and to determine the main factors of variation of pasture/forage substitution rate in grazing dairy cows.

In the grazing experiments, individual pasture intake will be estimated from the n-alkanes method, clearly identified as the best method for high levels of supplementation. Grazing behaviour will also be recorded to better understand behavioural adaptation of the cows while increasing forage supplementation level.

The thesis of Marcolino F. Miguel is a sandwich PhD carried out partly in Brazil (direction H.M.N. Ribeiro Filho, Santa Catarina State University, Lages), with the completion of two experiments in the University of Lages. The thesis is planned from March 2012 to February 2016, with 12 months spent at UMR Pegase (Syslait team), from november 2013 to october 2014, with a direction by Rémy Delagarde. The third experiment and the meta-analysis are planned during this stay.

Contact

Rémy.Delagarde[at]rennes.inra.fr