Location: Animal Genomics and Improvement LaboratoryTitle: Genomic evaluation of dairy heifer livability
Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/6/2021
Publication Date: 8/1/2021
Citation: Neupane, M., Hutchison, J.L., Van Tassell, C.P., Van Raden, P.M. 2021. Genomic evaluation of dairy heifer livability. Journal of Dairy Science. 104(8):8959–8965. https://doi.org/10.3168/jds.2020-19687.
Interpretive Summary: Heifer loss is one of the major issues related to profitability and management in dairy farms. Raising replacement heifers ranks as the second largest cost on dairy farms after the feed and forage cost for cows. Heifer loss also severely affects animal health and welfare. Although US genetic evaluation in dairy cows includes still birth (loss within 48 hours of birth) and cow livability, little information is available on heifer livability. This study addresses the gap in knowledge of heifer survival from 48 hours to start of productive life. The results showed that direct selection of heifer livability trait will help to improve herd performance over time. It will result in decreased cost of replacement heifers along with more productive, and healthier cows. Hence, routine genetic evaluation of heifer livability will be valuable to select cows with increased profitability and improved animal health and welfare.
Technical Abstract: Differences in breeds and sire lines suggest the presence of a genetic component for heifer livability (HLIV). Genomic evaluation for this trait can increase profitability and improve animal health and welfare. Evaluations for HLIV were examined from 3,362,499 calf data records from heifers of all breeds born from 2009-2016. Data were obtained from the national cooperator database maintained by the Council on Dairy Cattle Breeding. The total number of deaths reported was 134,753 (4.01%) that included herds with death loss between 1-25%. Age at death ranged from > 2 days of age until the heifer left the herd with a maximum of 18 months of age was evaluated, but records were not included until three years after the birthdate so that live status of contemporaries could be confirmed by a calving date. Deaths observed until 2 days after birth were included in stillbirth rather than HLIV. The scale used for analysis of HLIV was 0 (died) or 100 (live) and the heritability estimate was 0.4% based on sire model restricted maximum likelihood estimation. Genomic predicted transmitting abilities (GPTA) for Holstein range from -1.6% to +1.6% with a standard deviation of 0.5% and GPTAs for Jersey range from -0.5% to +0.5% with SD of 0.2% compared to means of about 4% overall death loss. Reliabilities of genomic predictions for young animals averaged 46% for Holsteins and 30% for Jerseys while corresponding traditional parent average reliabilities averaged 16% and 12%. Correlations of HLIV 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. The HLIV trait had a favorable genetic trend in recent years, likely because of selection for the correlated traits. The trait HLIV could get 1% of emphasis on net merit index making economic progress worth $50,000 per year. By encouraging more recordings on calf mortality, the reliabilities of evaluations can increase significantly.