ORIGINAL: livbucks
Young does often cycle into estrous later resulting in late born fawns with lower survival rates.
Are you calling 1.5 yo doe "young"? I do not believe that 1.5 doe have a problem being timely bred.
Check out the productivity of 2yr. (1.5) and 3 yr. old (2.5) does in Table 2 of this link.
http://www.pgc.state.pa.us/pgc/lib/p...e/21001-05.pdf
It is clear that the 2.5 doe are more productive than the 1.5 doe.