Feed intake and its genetic relationship with growth traits in Merino sheep

The feed cost for maintenance of the ewe flock is a major cost in lamb production systems and a reduction in these feed requirements could have an effect on carrying capacity and both biological and economic efficiency in sheep flocks. However information on the genetic variation of feed intake and its association with other production traits are scarce. This study reports on the variation in relative digestible dry matter intake (rDDMI), defined as the ratio of the digestible dry matter intake of each ewe divided by the group mean and its relationship with growth traits measured in 1279 Merino ewes. DDMI was estimated by faecal marker dilution method. Significant genetic variation was observed in intake with a heritability of 0.33 ± 0.09, suggesting scope for effective genetic selection. Genetic correlation between rDDMI with growth traits were generally low with the highest correlation (0.18 ± 0.09) observed with hogget weight.