Im gonna tweak my answer a little. I do breed younger males and usually i wIt till they are at least 550 grams. Ive had younger ones go in the past and either got sluggs or very little satisfaction out of the pairings. I never breed girls any smaller then 1500 grams and on the dlip with males once a male gets over 1700 grams hes out of my collection. I have found that the perfect combos is an 800 gram male to up to 2500 gram girls. Now my huge girls over 3000 to 4300 get paired with bigger males.