וּמִקְצָת֙ יָמִ֣ים עֲשָׂרָ֔ה נִרְאָ֤ה מַרְאֵיהֶם֙ ט֔וֹב וּבְרִיאֵ֖י בָּשָׂ֑ר מִן־כָּל־הַיְלָדִ֔ים הָאֹ֣כְלִ֔ים אֵ֖ת פַּתְבַּ֥ג הַמֶּֽלֶךְ׃
И в конце десяти дней их лица казались более справедливыми, и они были плотнее во плоти, чем все молодые люди, которые ели царя'с едой.
Ibn Ezra
[Daniel 1:5] U-mi-ketzatam (וּמִקְצָתָם - And at the end of which): [This word literally means "from their end".] Some say [it refers back to the earlier use of the root ק-צ-ה meaning "some", as in] "some of the youths" [were chosen, like] "some of the vessels of the House of God" [were taken, Daniel 1:2]. And [the construction using mi-ketzeh (מִקְצֵה) meaning "from the end/some of"] as in “from the edge/some of his brothers” [Genesis 47:2] is also relevant grammatically. And it [the word u-mi-ketzatam here] means: at the end of the aforementioned years [i.e., the three years]. And behold, similar to it is [the usage in Daniel 1:15]: “And at the end of (u-mi-ketzat - וּמִקְצָת) ten days...”
Rashi
So the steward took away their food and the wine that they should drink, etc.: And it is written about that matter (Daniel 1:15), "When the ten days were over, they looked better and healthier, etc."