If a litter is missing a litter index, it's because either the sow or the boar doesn't have an index. It's always only the latest litter that has a litter index.
By looking at the service list, the same relationship can be observed. By adding columns for 'Index' under 'Animals' and under 'Boar' in the setup - under Danbred.
In the example below, the last sow has received a litter index of 119. (89 sow + boar 149) / 2 = 119)) Whereas the sow above hasn’t, because the boar’s index is missing.
