Know more

Our use of cookies

Cookies are a set of data stored on a user’s device when the user browses a web site. The data is in a file containing an ID number, the name of the server which deposited it and, in some cases, an expiry date. We use cookies to record information about your visit, language of preference, and other parameters on the site in order to optimise your next visit and make the site even more useful to you.

To improve your experience, we use cookies to store certain browsing information and provide secure navigation, and to collect statistics with a view to improve the site’s features. For a complete list of the cookies we use, download “Ghostery”, a free plug-in for browsers which can detect, and, in some cases, block cookies.

Ghostery is available here for free:

You can also visit the CNIL web site for instructions on how to configure your browser to manage cookie storage on your device.

In the case of third-party advertising cookies, you can also visit the following site:, offered by digital advertising professionals within the European Digital Advertising Alliance (EDAA). From the site, you can deny or accept the cookies used by advertising professionals who are members.

It is also possible to block certain third-party cookies directly via publishers:

Cookie type

Means of blocking

Analytical and performance cookies

Google Analytics

Targeted advertising cookies


The following types of cookies may be used on our websites:

Mandatory cookies

Functional cookies

Social media and advertising cookies

These cookies are needed to ensure the proper functioning of the site and cannot be disabled. They help ensure a secure connection and the basic availability of our website.

These cookies allow us to analyse site use in order to measure and optimise performance. They allow us to store your sign-in information and display the different components of our website in a more coherent way.

These cookies are used by advertising agencies such as Google and by social media sites such as LinkedIn and Facebook. Among other things, they allow pages to be shared on social media, the posting of comments, and the publication (on our site or elsewhere) of ads that reflect your centres of interest.

Our EZPublish content management system (CMS) uses CAS and PHP session cookies and the New Relic cookie for monitoring purposes (IP, response times).

These cookies are deleted at the end of the browsing session (when you log off or close your browser window)

Our EZPublish content management system (CMS) uses the XiTi cookie to measure traffic. Our service provider is AT Internet. This company stores data (IPs, date and time of access, length of the visit and pages viewed) for six months.

Our EZPublish content management system (CMS) does not use this type of cookie.

For more information about the cookies we use, contact INRA’s Data Protection Officer by email at or by post at:

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

Dernière mise à jour : Mai 2018

Menu Logo Principal

Home page

Factors contributing to variation in the proportion of casein in cows’ milk true protein

INRA Prod. Anim., 11(4), 299-310.


1INRA Laboratoire Adaptation des Herbivores aux Milieux, Theix, 63122 Saint-Genès Champanelle

2INRA Station de Recherches sur la Vache Laitière, 35590 Saint-Gilles
3ENITA Marmilhat, 63370 Lempdes

The aim of this study was to identify and rank the various factors, in particular feeding ones, affecting the proportion of caseins in milk true protein. Twenty nine feeding trials involving 821 lactations were used. Lactoprotein genetic variants were known for 551 of these lactations. The main factor affecting the casein/protein ratio was the genetic polymorphism of beta-lactoglobulin : once corrected for other factors, BB type animals exhibited a ratio nearly 3 g/100 g higher than AA animals. kappa-casein variant B also had a positive effect (+1.2 g/100 g in favour of BB animals relative to AA animals). Except in the first week of lactation and in the two last weeks of pregnancy, the casein/protein ratio varied little during lactation. It was significantly reduced when milk cell count exceeded 200 000 cells/ml, even without clinical mastitis. It also decreased slightly with parity. Among the various dietary factors studied (level and type of nitrogen and energy supplies, forage type and preservation method), none had any significant effect on the milk casein/protein ratio, except in drastic dietary situations. That ratio increased very slightly in parallel with the animals’ milk yield and milk protein content. In practice, measuring the milk protein content in animals free of clinical mastitis remains a very precise predictor of casein content, accounting for 93 % of its variation.

Download documents