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Yosef's Shepard Knowledge - and Lack Thereof
(ב) אֵ֣לֶּה ׀ תֹּלְד֣וֹת יַעֲקֹ֗ב יוֹסֵ֞ף בֶּן־שְׁבַֽע־עֶשְׂרֵ֤ה שָׁנָה֙ הָיָ֨ה רֹעֶ֤ה אֶת־אֶחָיו֙ בַּצֹּ֔אן וְה֣וּא נַ֗עַר אֶת־בְּנֵ֥י בִלְהָ֛ה וְאֶת־בְּנֵ֥י זִלְפָּ֖ה נְשֵׁ֣י אָבִ֑יו וַיָּבֵ֥א יוֹסֵ֛ף אֶת־דִּבָּתָ֥ם רָעָ֖ה אֶל־אֲבִיהֶֽם׃
(2) This, then, is the line of Jacob: At seventeen years of age, Joseph tended the flocks with his brothers, as a helper to the sons of his father’s wives Bilhah and Zilpah. And Joseph brought bad reports of them to their father.

(ב) היה רועה את אחיו בצאן. היה מנהיג ומורה אותם במלאכת מרעה הצאן:

(2) היה רועה את אחיו בצאן, he was giving guidance to them and instructed them in the finer points of being successful shepherds.

(ב) אִלֵין זַרְעֲיַת יַעֲקב יוֹסֵף בַּר שַׁבְסְרִי שְׁנִין הֲוָה בְּמִיפְקֵיהּ מִן בֵּית מֶדְרָשָׁא וְהוּא טְלֵה מִתְרַבֵּי עִם בְּנֵי בִּלְהָה וְעִם בְּנֵי זִלְפָּה נְשַׁיָא דְאָבוֹי וְאַיְיתֵי יוֹסֵף יַת טִיבֵיהוֹן בִּישׁ דְחָמְנוּן דְאָכְלִין בִּשְרָא דְתָּלִישׁ מִן חֵיוָא חַיָיא יַת אוּדְנַיָיא וְיַת דִנְבַּיָיא וְאָתָא וְתַנִי לְוַת אֲבוּהוֹן

(2) These are the generations of Jakob. Joseph was a son of seventeen years. He had come forth from the school, and was a youth brought up with the sons of Bilhah and the sons of Zilpha his fathers wives. And Joseph brought their evil report; for he had seen them eat the flesh that had been torn by wild beasts, the ears and the tails; and he came and told it to his father.

The pirsush Yonasan says there that the brothers were really actually doing a procedure that was helping the animals live longer (ayin sham)
Although as Seforno said, Yosef was fluent in the ways of shepherding, he had failed to learn this new technique from his brothers.