Status of Non-Sacred Meat in the Midbar

ויקרא פרק ג, ב וְסָמַךְ יָדוֹ עַל-רֹאשׁ קָרְ בָנוֹ וּשְׁ חָטוֹ פֶׁתַח אֹהֶׁל מוֹעֵד
קידושין דף נז/ב ושחט אותו פרט לחולין שלא ישחטו בעזרה

This concept of not offering chulin (non-sacred animals) in the Mishkan should be obvious since the Mishkan is established to offer only sacred animals. However, from the verse in Parshas Re’eh כי תאוה נפשך לאכל בשר וגו' at that time (in the fortieth year) non-sacred meat was allowed to the people in the desert.

Until that time the Jews were only permitted meat of shelamim offered in the Mishkan. And thus, even when the Jews were finally permitted to eat non-holy meat, they can not bring that animal into the Mishkan.