The Laws of Eating Milchigs on Shavuos
Rabbi Yochanan Eskenazi
The Rema [494:3] writes that many places have the custom to eat milchig on the first day of Shavuos. There are numerous reasons given for this minhag:
1) On Pesach night we have two cooked foods as a remembrance for the two sacrifices that were brought on Pesach [namely, the korban Pesach and korban Chagiga]. Likewise, on Shavuos we eat milchig food and then fleishig food, which would require two separate breads [one milchig and one fleishig- see Shulchan Aruch YD 89] on one's table, which represents the mizbayach. This provides a remembrance of the two loaves of bread that were brought on Shavuos.
2) The Magen Avraham [494:6] writes that according to the Zohar the seven weeks of sefiras ha'omer correspond to the seven clean days a niddah counts to purify herself. The Gemara [B'choros 6b] teaches that a mother's milk originates from her blood. Therefore, after reaching a level of purity, after sefiras ha'omer, we eat milchig which shows that the impure days have passed. 3) The Mishneh Berurah [494:12] offers an additional explanation. At the time that the Torah was given, upon returning from Har Sinai, they had no food. Practically speaking, milchig food was easier to prepare than fleishig, because after they received the Torah and were taught the various halachos of keeping kosher, in order to eat fleishig they had to make sure they had a kosher knife, clean out the blood and forbidden fats, salt the meat, and cook in new pots.
There emerges a practical difference between the three mentioned reasons. According to the Rema and Mishneh Berurah, one should have milchig specifically during the day meal, since that is when the two breads were brought, and when the people came back from Har Sinai. However, according to the reason of the Zohar, one may fulfill this custom with eating milchig at the night meal since the seven weeks of sefiras ha'omer have passed. Additionally, according to the Mishneh Berurah and Magen Avraham one can have an exclusively milchig meal. However, according to the Rema one is supposed to have a meal that consists of both milchig and fleishig (Koveitz Halachos 11:ftnt. 15).
The common custom is not to have one meal that is partly milchig and partly fleishig (Igros Moshe OC 1:160). Perhaps the reason is because some people are careful never to have milchig and fleishig in the same meal [even in a permissible way- i.e. of eating the milchig first and washing hands and mouth out in between]. Additionally, there is a concern that people may mistakenly eat the fleishig first (Igros Moshe ibid).
Many people have a milchig meal on the 1st night of Shavuos [even though as mentioned according to both the Rema and Mishneh Berurah one should specifically have one on the 1st day]. Perhaps the reason is either because practically it is easier to stay up learning on Shavuos night after having a lighter [dairy] meal (Koveitz Halachos 11:ftnt. 15). It also is more practical to be able drink coffee with milk to assist one to stay up (Rabbi Biberfeld, shlit"a). Another reason is that according to many Poskim there is no mitzvah me'deoraisa on Yom Tov night of "V'samachta b'chagecha" (and you should rejoice on your holidays) [Devarim 16:14] which includes eating meat and drinking wine by the Yom Tov meals (see Rambam Hil' Yom Tov 6:19). Therefore, many specifically eat milchig at night, thus not violating this halacha (Shaar Hatziyon 546:15).