तृट्परीत: परिश्रान्तो बिभत्सुर्यमुनामगात् ॥ १६ ॥
medhyān parvaṇy upāgate
bibhatsur yamunām agāt
A crew of servants carried to King Yudhiṣṭhira the slain animals fit to be offered in sacrifice on some special occasion. Then, feeling thirsty and tired, Arjuna went to the bank of the Yamunā.
As Śrīla Prabhupāda often explained, the kṣatriyas, or warriors, would hunt in the forest for several purposes: to practice their fighting skills, to control the population of ferocious beasts, who were a threat to human beings, and to provide animals for Vedic sacrifices. The killed animals would be given new bodies by the power of the sacrifices. Since priests no longer have that power, the sacrifices would now constitute mere killing and are thus forbidden.
In the Fourth Canto of the Śrīmad-Bhāgavatam we find that the great sage Nārada severely chastised King Prācīnabarhiṣat for abusing this principle of authorized hunting. In fact, the King had become like modern sportsmen, who cruelly kill animals as a so-called hobby.