אַל יַעֲלֶה עַל הַלֵּב שֶׁבִּימוֹת הַמָּשִׁיחַ יִבָּטֵל דָּבָר מִמִּנְהָגוֹ שֶׁלָּעוֹלָם, אוֹ יִהְיֶה שָׁם חִדּוּשׁ בְּמַעֲשֵׂה בְּרֵאשִׁית; אֶלָּּא עוֹלָם כְּמִנְהָגוֹ הוֹלֵךְ. וְזֶה שֶׁנֶּאֱמַר בִּישַׁעְיָה (יא,ו) "וְגָֿ֚ר זְאֵב֙ עִם־כֶּ֔בֶֿשׂ, וְנָמֵ֖ר עִם־גְּדִֿ֣י יִרְבָּ֑ץ" - מָשָׁל וְחִידָה; עִנְיַן הַדָּבָר: שֶׁיִּהְיוּ יִשְׂרָאֵל יוֹשְׁבִין לָבֶטַח עִם רִשְׁעֵי הָעוֹלָם הַמְּשׁוּלִים בִּזְאֵב וְנָמֵר, שֶׁנֶּאֱמַר: "זְאֵ֚בֿ עֲרָבֿוֹת֙ יְשָׁדְֿדֵ֔ם, נָמֵ֚ר שֹׁקֵד֙ עַל־עָ֣רֵיהֶ֔ם" (ירמיה ה,ו), וְיַחְזְרוּ כֻּלָּם לְדַת הָאֱמֶת, וְלֹא יִגְזְלוּ וְלֹא יַשְׁחִיתוּ אֶלָּא יֹאכְלוּ דָּבָר הַמֻּתָּר בְּנַחַת כְּיִשְׂרָאֵל, שֶׁנֶּאֱמַר: "וְאַרְיֵ֖הֿ כַּבָּקָ֥ר יֹֽאֿכַֿל־תֶּֽבֶֿן" (ישעיה יא,ז; סה,כה)
One should not think that any aspect of Nature will change in the Era of King-Mashiyaħ, or that there will be any new features in the behavior of the physical Universe. The World will continue to function just as it does now. Although Y'sha`yah states that ‘The wolf will live at peace with the lamb and the leopard will lie down with the young goat’ (Y'sha`yah 11:6), these words are just a metaphor, an allegory; that is to say, Yisra´el will live in security among the wicked gentiles who are compared to wolves and leopards... as, for example, in the verse ‘A wolf of the deserts attacks them, a leopard prowls through their cities’ (Yirm'yah 5:6). When those times come, all will return to the true faith and will no longer pillage or destroy; instead, they will eat only that which is permitted, at peace with Yisra´el—as it is written, ‘...lions will eat straw like oxen’ (Y'sha`yah 11:7).
[Mishneh Tοrah, Hilchοt M'lachim §12:1]