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Subjective measurements of temperament are influenced by sire and diet, and are associated with feed efficiency traits in adult Merino wethers

May, Rebecca (2019) Subjective measurements of temperament are influenced by sire and diet, and are associated with feed efficiency traits in adult Merino wethers. Honours thesis, Murdoch University.

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Abstract

Feed efficiency is a heritable trait and genetic improvements in feed efficiency could be utilised to
reduce feed costs. Differences in feed efficiency have been associated with aspects of temperament in
young growing sheep, the metabolic cost of a stress response could direct energy away from growth or
maintenance of body tissues, however the mechanisms underlying differences in efficiency are poorly
understood in adult sheep. Using wether progeny from 15 different sires we hypothesised that more
docile progeny will be more efficient. Two cohorts of Merino wethers (n = 320) were housed in
individual pens and fed 100% of maintenance for 35 days before being fed either ad libitum or restricted
(60% maintenance) for a further 35 days. During the differential feeding period temperament was
assessed weekly by a subjective measure of avoidance behaviours (chute score and exit score). Feed
efficiency (residual feed intake and residual liveweight change) was determined by measuring daily
feed intake and live weight three times per week. There were sire differences for exit score (range 2.6
to 3.3 out of 5; P<0.05) and for residual liveweight change (range -40g/day to 36g/day; P < 0.05). There
was also a moderate association between temperament and feed efficiency (P < 0.05) however wethers
that had a higher exit score (less docile) gained comparatively more weight than the cohort at the same
liveweight and feed intake. We conclude that differences in temperament may contribute to the
observed variation in feed efficiency, however the response was opposite to what we expected for
reasons unknown.

Item Type: Thesis (Honours)
Murdoch Affiliation: Agricultural Sciences
United Nations SDGs: Goal 12: Responsible Consumption and Production
Supervisor(s): Byrne, Colin, Blumer, Sarah and Thompson, Andrew
URI: http://researchrepository.murdoch.edu.au/id/eprint/54807
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