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novel approaches to expression and detection of oestrus in dairy cows

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concentrate on the association between SNP <strong>and</strong> activity. The result<strong>in</strong>g<br />

model was:<br />

Y ijkl = µ + S i + P j + O k + C l + ε ijkl<br />

where Y ijkl is activity at <strong>oestrus</strong>,<br />

the fixed part <strong>of</strong> the model consists <strong>of</strong><br />

µ the overall mean,<br />

S the effect <strong>of</strong> SNP,<br />

P the effect <strong>of</strong> parity,<br />

O the effect <strong>of</strong> oestrous season,<br />

C l the r<strong>and</strong>om effect <strong>of</strong> Cow, <strong>and</strong><br />

ε ijkl the residual error.<br />

3.3 RESULTS<br />

Results are reported for the association between SNPs at 41 loci on 18<br />

genes <strong>and</strong> activity at <strong>oestrus</strong>. None <strong>of</strong> the genes studied (Table 3.1) were<br />

found <strong>to</strong> hold a true significant association with the activity <strong>in</strong>crease at<br />

<strong>oestrus</strong>. 205 <strong>cows</strong> were blood sampled although due <strong>to</strong> the availability <strong>of</strong><br />

genotyp<strong>in</strong>g at each locus <strong>and</strong> activity data at <strong>oestrus</strong> the number <strong>of</strong> <strong>cows</strong><br />

<strong>in</strong> each analysis varied slightly <strong>and</strong> was <strong>of</strong>ten less. This highlights the<br />

seriously limited animal numbers used <strong>in</strong> this study.<br />

Two SNPs on 2 genes were found <strong>to</strong> be significantly associated with activity<br />

at <strong>oestrus</strong> (P

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