Last December, New Zealand Animal Evaluation Limited (NZAEL) deployed a major upgrade of its evaluation processes, models, and genetic evaluation software. As a result, the evaluations for all traits changed slightly, with significant enhancements for fertility and survival.
The changes brought better accuracy in genetic evaluations, allowing farmers to make better breeding decisions. As with any update to animal evaluation, all new models and processes were rigorously tested and internationally peer-reviewed before final sign-off by the NZAEL Board.
A recent survey on New Zealand’s National Breeding Objective reinforced the importance of fertility to dairy farmers. The new animal evaluation model emphasises fertility more by spreading the breeding values (BVs) wider. This allows greater visibility of where the bulls sit concerning the genetic base.
The enhanced fertility index increased emphasis on key fertility phenotypes, including calving and insemination data recorded on first-calving to fourth-calving cows. There is less reliance on predictor traits.
One change for calving data is the use of Calving Season Day (CSD), in recognition of the better fertility of earlier calved cows within the block. For example, a cow who calved in the first 3 weeks of calving receives a higher fertility score than a cow that calved in week 5. The definition for fertility BV remains as the percentage of cows calved within 42 days from the planned start of calving. There are already plans to investigate and apply further improvements to the fertility BV, including using pregnancy diagnosis information.
Functional survival replaces residual survival. Calculated differently and using actual phenotypic records, Functional Survival is the average probability of survival from one lactation to the next. The trait BV is reported as a percentage. It focuses on reasons why an animal leaves the herd, excluding culling reasons associated with fertility and milk production.
Given the nature of Functional Survival, and the length of time it takes to obtain phenotypic records, (i.e. an animal surviving to fifth lactation), certain predictor traits are used to provide an early indication of functional survival. These traits include the breeding values for body condition score (BCS), legs, udder overall, and milking speed collected during daughter TOP inspections of pedigree and sire-proving herds.
Economic values update
Economic values (EVs) used in the calculation of breeding worth (BW) are a key consideration in all NZAEL updates. Economic weightings were updated in December to reflect the changing economic circumstance on farm and in the global marketplace, and to generate EVs for the new Fertility, Functional Survival and Udder Overall (as of April 2022) BVs.
These enhancements improve the national animal evaluation system for better accuracy in genetic evaluations. This information that allows farmers to make better breeding decisions for their herd.
LIC’s Research & Development team will replicate the changes in their own genomic evaluation system, which incorporates the Single Step Animal Model (SSAM), to align with NZAEL.
Any LIC bulls published by LIC will include genomic information, including for daughter proven bulls. Data published from NZAEL will not include genomic information. Please be aware that bull data will look different depending on which information source you use.
Teat Length BV (TOP)
For several years phenotype data has been collected on the teat length of sire proving daughters. This information, plus a desire to focus more on teat length, resulted in establishing the teat length breeding value.
Udder Overall BV – as of April 2022
The national farmer survey highlighted continued focus on udder traits as important. Especially when you consider the increased production per cow over the last decade and potential future farming practice changes. NZAEL plans to incorporate udder overall into Breeding Worth from April 2022.