Final answer:
A stock made from beef or veal bones takes longer to cook than a stock made from fish bones due to the difference in bone density and collagen content.
Step-by-step explanation:
The reason why a stock made from beef or veal bones takes longer to cook than a stock made from fish bones is due to the difference in bone density and collagen content. Beef or veal bones are larger and denser than fish bones, which means they require more time to release their flavors and nutrients into the stock. Additionally, beef and veal bones contain more collagen, a protein that breaks down and creates a rich, gelatinous texture in the stock. This collagen takes longer to break down compared to fish bones, which results in longer cooking times for beef or veal stock.