Norwegian Jaerhon hens weigh 1.7 kg which equals 3.5 lbs so they are smaller then Leghorns. If you see them together the Jaerhons are obviously smaller than Leghorns. The Jaerhorns' eggs are medium to large which is smaller than Leghorn, but due to their smaller size they are quite feed efficient. They lay almost as many eggs as Leghorns in a smaller package.Sorry I did not answer this question, I would quess the Production blacks would cover most if not all of the Gold color the Norwegions carry. But they would be sex-linked as day olds, so you would not have to raise up the roosters. Just dispatch them or sell them. Sorry again for the delay, I am still figuring the web site out.., buttons and all.
Crossing Production Blacks with Norwegian Jaerhons would make very nice layers but they would not be sex-linked or autosexing. Production Blacks are hybrids and the roos are heterozygous for the sex-linked barred gene. The Production black rooster would be B/b and the Jaerhon hen would be B/-. The resulting offspring would be roos B/B, large white head spot and B/b, small white head spot.The hens would be B/-, small white head spot, and b/-, no head spot. So 50% of the chicks would have small white spots on the head and could not be sexed at hatch. However, with the big combs on the Leghorns and Jaerhons you should be able to sex them by a month or so old. They are also not sex-linked through the gold/silver sex-linked gene as the roo has to be gold and the hen silver for that to work.