I have read that young lambs were not used for sacrifice - that what was used was one year old Rams with horns. Is this correct? The bible talks about lambs, but is this bad translation?
Both were used, depending on the sacrifice.
When an ox, sheep or goat is born, it must stay with its mother for seven days; from day eight and on, it will be accepted as a burned sacrifice to God.
So the minimum age for any sacrifice is eight days.
The Passover sacrifice -- as well as the standard daily offering -- were less than a year old. But the wrong translation can confuse you on this. Both of them (Passover -- Exodus 12:5; daily offering -- Exodus 29:38) use the Hebrew phrase ben shana, literally, "of a year."
Jewish tradition translates that as within its first year of living, i.e. less than one year old. If someone didn't know any better (especially a native English speaker), they could misread that as "one year old." But that's mistaken. (Just as the year 1865 is in the 19th Century, which confuses a lot of people.)
Note that with Abraham's binding of Isaac, they're talking about finding a lamb to sacrifice, and at the end of the story Abraham finds a mature ram, which was caught by its horns. Maybe that's what you were thinking of?
Rams were also offered as sacrifices; an individual could volunteer to bring one, and the holiday sacrifices consisted of a mix of ram and lamb.
Maimondes' Code (Laws of Processing the Sacrifices 1:15) points out that when a "lamb" is called for, it's less than one year. When a "ram" is specified, it must have lived 31 days into its second year of existence (i.e. it must be at least one year and 31 days old). The animal actually spends one month in a twilight zone during which it's neither a lamb nor a ram.