Impact of feed use efficiency on mating ewe lambs
New research from University of Western Australia honours student Caris Jones is determining how to increase sheep reproduction while decreasing food costs.
"My work with the Maternal Efficiency flock looks at improving reproduction, feed-use efficiency, lamb survival and growth in Merinos. We aim to improve the conversion of available feed into kilograms of lamb weaned per kilogram of ewe joined."
About Caris Jones
Caris is researching whether improving feed efficiency has a negative impact on the fertility of Merino ewe lambs mated at 7-10 months of age.
She hypothesised that ewe lambs with lower residual feed intake (RFI) - which is the difference between actual and expected feed intake for a given level of maintenance and growth - would be leaner and less fertile than ewes with higher RFI when mated at 7-10 months of age.
Some 224 Merino ewe lambs with known Australian Sheep Breeding Values (ASBVs) were measured for RFI, body composition and reproductive performance.
“Merino ewe lambs that used feed more efficiently were less fertile when mated at 7-10 months of age, however, no differences in body composition were detected via ultrasound measurements,” Caris said.
“The relationship between RFI and fertility is important because it highlights the trade-off between selecting for feed efficiency on the reproductive performance of Merino ewe lambs.”
“Producers who are moving towards breeding ewe lambs may need to consider their breeding objectives carefully to account for the antagonistic relationship between feed efficiency and fertility and its impact on whole flock efficiency.”
Take home messages
Merino ewe lambs that used feed more efficiently were less fertile when mates at 7-10 months of age
No differences in body composition were detected
Producers should consider the relationship between feed efficiency and fertility and its impact on whole flock efficiency