Test-day genetic evaluations: a tool to measure herd resilience through monthly milk records
Abstract
This study aimed to explore a herd resilience indicator, LnVar, estimated from monthly testday records. For each Holstein cow in first parity between 2014 and 2018, the expected milk yields were computed at each test-day, using the genetic and environmental effects estimated from a routine test-day genetic evaluation. LnVar was then estimated for each herd-year, as the natural logarithm of the variance within lactation of the deviation between the expected and the observed milk yields. LnVar presented a high variability and was quite repeatable between years. The herd-years with high LnVar were more productive and showed a greater risk of high somatic cell counts, clinical mastitis and short lactations. This study showed that LnVar is a relevant resilience indicator, even with monthly records. The genetic evaluations using test-day records could provide useful information for herd management.
Domains
Animal geneticsOrigin | Files produced by the author(s) |
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