Reproductive and some peri-natal variables in a mixed breed beef cattle herd
1994
Ponzoni, R.W. | Gifford, D.R.
SUMMARY: Calving success (CS), days to calving (DC), birth weight (BW) and calving ease (CE) were studied in a mixed breed (Hereford, Jersey × Hereford and Simmental × Hereford) beef cattle herd. DC was not normally distributed and a number of transformations failed in normalising it. Repeatabilities were estimated by analysis of variance. Inclusion (or exclusion) of non calvers and the transformations studied had little effect on the repeatability of DC, which ranged from 0.10 to 0.12. The repeatabilities for CS, BW and CE were 0.08, 0.26 and 0.03, respectively. The residual correlations of CS with DC and functions of DC were high (-0.68 or greater), whereas the correlations among DC and functions of DC were close to one. The correlations of DC with BW and CE varied little with the transformation applied to DC, ranging from 0.26 to 0.28 and 0.10 to 0.12, respectively. The correlation between BW and CE was 0.06. The study points to a number of problems associated with the use of DC as a reproductive variable in beef cattle. It is concluded that although DC is currently a useful field reproductive variable, the search for appropriate female reproductive traits should continue.
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