Sheep Matters_Aug-Sept 17 (redesigned)
Sample copy of new publication aimed at the progressive farmer and professional in the UK sheep industry. For further information and to register your interest go to www.sheepmatters.co.uk
Sample copy of new publication aimed at the progressive farmer and professional in the UK sheep industry. For further information and to register your interest go to www.sheepmatters.co.uk
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Research by SRUC and Signet has<br />
also focused on the heritability of<br />
lamb survival. A lamb survival EBV<br />
could help breeders to improve<br />
the resilience of young animals<br />
by selecting for genes that affect<br />
survivability. This could increase the<br />
productivity of commercial herds<br />
(11).<br />
NEGATIVE EBV SCORE<br />
Fat depth (mm)<br />
CT fat weight (kg)<br />
Want to know more?<br />
A word of caution:<br />
Nature or Nurture?<br />
Different traits have different<br />
levels of heritability across<br />
different breeds. For<br />
example, it is estimated<br />
that footrot resistance in<br />
ewes is heritable at 10-<br />
20% (7). And genes express<br />
themselves differently in<br />
different environments (8).<br />
Many factors, therefore, need<br />
to be taken into account<br />
when developing breeding<br />
objectives. Once breeding<br />
goals are identified it is<br />
possible to decide which<br />
EBVs will best help to achieve<br />
these goals. It is also possible<br />
that significant improvements<br />
in productivity can be made<br />
by changing non-genetic<br />
factors such as nutrition.<br />
<br />
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Worm resistance<br />
<br />
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<br />
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*Health<br />
<br />
EBVs not<br />
<br />
<br />
available for all breeds<br />
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<br />
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Genetic & environmental interaction<br />
Genes interact with a whole range of other<br />
factors. The breeding potential of an<br />
individual animal will only be realised<br />
under good management (e.g. nutrition,<br />
health and welfare monitoring<br />
EBV accuracy<br />
EBVs that are based on limited data are<br />
adjusted down towards the average. As<br />
more data are collected the EBV may<br />
increase. An EBV accuracy value is a good<br />
indicator of the likelihood that a ram’s EBV<br />
will change over time. The higher the<br />
accuracy value (0-99), the more is known.<br />
20<strong>17</strong> AUGUST & SEPTEMBER<br />
13
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