http://revach.net/article.php?id=3943

Section: Hanhagos   Category: Minhagim
Erev Rosh Chodesh Av - Eating Meat Right Before The Nine Days
The Yesod V'Shoresh HaAvodah writes that he sees a scandalous custom that not only do people not fast on Erev Rosh Chodesh Av for Yom Kippur Katan, but they even have a seudah with meat and wine. "Oy Vavoy" to this minhag!   This practice, he says, is Chukos HaGoyim.

On the other hand the Chavas Yair (Mekor Chaim 551) brings that there was a perfectly legitimate minhag in the large Kehilos to announce on Erev Rosh Chodesh Av for everyone to eat meat.  The Taamei HaMinhagim explains that some people like certain milchig dishes even better than meat.  In order to show that we are not eating meat because of aveilus and not for any other reason we specifically eat meat for before the nine days and then stop.  

This minhag is also brought by the Sdei Chemed and the Mishnas Yaakov.  This is similar to the minhag to eat Chometz on Erev Pesach to show that on Pesach we are not eating Chometz for the sole reason of fulfilling Hashem's command.  (See Minhag Yisroel Torah OC 551:7)