Is there genetic variation in foetal loss after pregnancy scanning in sheep?

Pregnancy scanning in sheep has become an important management tool for the Australian sheep industry. Industry statistics suggest significant losses from pregnancy scanning to lamb marking, ranging from 10% for singles and 28%for twins (Allworth <i>et al</i>. 2016). This difference is a combination of loss (foetal and lamb) and also errors in the data and/or incomplete recording. This also means that it is not always loss when a ewe has more lambs born than scanned and this could be a combination of scanning error and/or lamb identification error. The expectation is that most foetal loss occurs early in pregnancy. Pregnancy loss after pregnancy diagnosis (typically mid-pregnancy) in healthy sheep is normally low (<5%) and is influenced by litter size (Dixon <i>et al</i>, 2007).