Answer
The Law of Moses required animal sacrifices to atone for sin in Israel, and there were a lot of sacrifices made: “the same sacrifices repeated endlessly year after year” «For the law having a shadow of good things to come, and not the very image of the things, can never with those sacrifices which they offered year by year continually make the comers thereunto perfect. », (Hebrews 10:1). About one sixth of the laws under the Mosaic system pertained to sacrifices and offerings.
There were five main types of sacrifices in the Old Testament: the burnt offering, the grain offering, the sin offering, the trespass offering, and various types of peace offerings. The God-appointed feasts of Israel required sacrifices, and there were also the daily burnt offerings: a lamb was sacrificed every morning, and another lamb every evening at the tabernacle/temple (Exodus 29:38-42).
There were a large number of animal sacrifices offered every year in Israel. All sin had to be atoned for, including sin committed by a common person «And if any one of the common people sin through ignorance, while he doeth somewhat against any of the commandments of the LORD concerning things which ought not to be done, and be guilty; », (Leviticus 4:27), the priests «If the priest that is anointed do sin according to the sin of the people; then let him bring for his sin, which he hath sinned, a young bullock without blemish unto the LORD for a sin offering. », (Leviticus 4:3), the leaders «When a ruler hath sinned, and done somewhat through ignorance against any of the commandments of the LORD his God concerning things which should not be done, and is guilty; », (Leviticus 4:22), and the nation as a whole «And if the whole congregation of Israel sin through ignorance, and the thing be hid from the eyes of the assembly, and they have done somewhat against any of the commandments of the LORD concerning things which should not be done, and are guilty; », (Leviticus 4:13). In addition to the sacrifices made for sin were offerings for ceremonial cleansing, which involved no moral failing, and voluntary sacrifices made in thanksgiving to God.
Given the sheer number of animals required to fulfill the requirements of the Mosaic Law, we may rightly wonder how the Israelites were able to keep up. The key is that, in the agrarian culture of the day, livestock was always near and usually plentiful. There were few occupations besides farming back then, so most Israelite families owned some livestock. The ones who didn’t knew someone who did. Also, since sacrifices were not only a national religious obligation but also a way to support the tribe of Levi, plans were laid to assure a ready supply.
On certain occasions, huge numbers of animals were sacrificed. For example, at the dedication of King Solomon’s temple, about 960 BC, the celebrants sacrificed 22,000 cattle and 120,000 sheep over a two-week period. There were so many offerings that Solomon had to set up additional altars in the temple courtyard (1 Kings 8:63-65). As large as those numbers seem, they are not at all inconceivable. The previous census by Solomon’s father, David, had put the number of able-bodied fighting men over age 20 at 1.3 million «And Joab gave up the sum of the number of the people unto the king: and there were in Israel eight hundred thousand valiant men that drew the sword; and the men of Judah were five hundred thousand men. », (2 Samuel 24:9), so it would be reasonable to assume a national population in Solomon’s time of over four million. Most of the nation probably would have been present in Jerusalem for at least some of a great historic event such as the dedication of the new temple. The sacrifices made by Solomon were “fellowship offerings” «And Solomon offered a sacrifice of peace offerings, which he offered unto the LORD, two and twenty thousand oxen, and an hundred and twenty thousand sheep. So the king and all the children of Israel dedicated the house of the LORD. », (1 Kings 8:63), which were partly burned on the altars and partly eaten by the people. Even if only half the population attended, 142,000 animals is a reasonable number to feed two million people during two weeks.
We who live in advanced societies with massive food industries and complex transportation systems that do nearly everything for us but put the food into our mouths may find it hard to imagine the huge amounts of livestock recorded in the Bible. But, most likely, the ancients would find it just as hard to believe how much food modern societies throw away every day.