A new trait, Heifer Livability, will be introduced with the December 1 genetic evaluations.
Genetic progress has been on-going to improve livability in milking herds, with Cow Livability initiated in August 2016. With the new Heifer Livability evaluation on the horizon, the prospects are bright for doing more of the same for calves and yearlings. Genomic evaluation of this trait will increase profitability, and even more importantly will improve animal health and welfare – which will enrich the industry’s image with the public.
Leveraging the National Cooperators Database maintained by CDCB, disposal codes were studied from 3.4 million heifer records of all breeds with birth dates between 2009 and 2016. Differences in breeds and sires confirmed the presence of a genetic component for heifer livability. The mean recorded death loss was 4%, based on deaths between two days of age and when the heifer left the herd, or until the maximum imposed of 18 months. (Stillbirths and deaths in the first two days were excluded as they are accounted for in stillbirth evaluations.)
Genomic predicted transmitting abilities (GPTA) for Heifer Livability in Holsteins ranged from ̶ 1.6% to +1.6% and had a standard deviation (SD) of 0.5%. GPTAs for Jersey ranged from ̶ 0.5% to +0.5% and had a SD of 0.2%. Normally about two-thirds of the observations fall within one SD.
The reliabilities (accuracies) for young animals with genomic tests averaged 46% for Holsteins and 30% for Jerseys. The accuracies for traditional parent average averaged 16% and 12%, respectively, which would be typical for those without genomic tests.
The BV trend for Heifer Livability was +1.4 for HO and +0.7 for JE between birth years 2010 and 2015, corresponding to the other base changes reported recently. Heifer Livability had a favorable genetic trend in recent years, likely because of selection for correlated traits. Correlations of Heifer Livability were 0.44 with productive life, 0.34 to 0.36 with yield traits, and 0.36 with early first calving on proven Holstein bulls. When the Net Merit index is next updated (in 2021), Heifer Livability could get 1% of emphasis.
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Source: CDCB