A lotta folks do that. But it won't make the eggs larger, just stronger shells? First eggs are commonly small, pea sized and progressively get larger as they mature. But I do have one BR that even at 19 months old lays small to barely medium eggs…but she does have some genetic quirks. Final expected size of eggs, I think, are somewhat determined by breed. As time goes by, you'll see largest eggs from larger gals and those that lay nearly every day seem to lay progressively smaller each day, skip a day or so and then larger again.Thanks . I heard also if you grind up egg shells in their food, it offers extra calcium.