Dairy cattle

Integrating pregnancy diagnosis data into New Zealand's national dairy fertility evaluation

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Abstract

Accurate and timely fertility evaluations are critical for dairy breeding programmes, particularly in seasonal systems where reproductive performance strongly influences farm profitability. New Zealand's fertility breeding value has recently transitioned from a calving-date-based trait (Calving Rate at 42 days; CR42) to a conception-based trait (Pregnancy Rate at 42 days; PR42), improving trait definition by separating conception outcomes from gestation length effects. However, this evaluation still relies primarily on calving records to confirm conception, which limits the timeliness of Estimated Breeding Values (EBVs) and delays the availability of accurate selection tools for farmers and breeding companies. Meanwhile, the increasing availability of pregnancy diagnosis (PD) and foetal ageing records in New Zealand presents an opportunity to further enhance the fertility evaluation. Early pregnancy confirmation has the potential to: 1) reduce reliance on delayed calving outcomes, 2) increase the number of usable fertility observations, 3) improve EBV accuracy by reducing phenotype uncertainty, and 4) make fertility EBVs available earlier in the season. Despite widespread industry interest, incorporating PD data into national genetic evaluations presents several methodological challenges that must be addressed before implementation. This paper outlines the design of a national genetic evaluation framework to integrate PD data into the existing conception-based fertility trait. We describe the data processing, phenotype definitions, and implementation considerations required to combine three information sources - mating records, PD outcomes, and calving events - into a unified fertility phenotype. We outline a planned series of steps: 1) quantifying PD data availability and quality, 2) defining trait definition rules for incorporating PD and foetal age, 3) comparing phenotype distributions between PD-informed and calving-derived fertility phenotypes, 4) estimating genetic parameters using the new data structure, and 5) evaluating the impact of PD data through validation. These steps will be implemented within the national genetic evaluation framework used by New Zealand Animal Evaluation (NZAE), alongside collaboration with industry data providers. This work represents one of the first large-scale efforts to operationalise PD records within a national fertility evaluation in a seasonal-calving dairy population. By outlining the methodological pathway and expected benefits, this paper provides a foundation for future integration of early reproductive data into genetic improvement programmes, with the goal of delivering earlier, more accurate fertility EBVs for dairy farmers.

Keywords: 2026

How to Cite:

Fikse, F., Amer, P., Curry, B., Stachowicz, K. & Ooi, E., (2026) “Integrating pregnancy diagnosis data into New Zealand's national dairy fertility evaluation”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2286233. doi: https://doi.org/10.31274/wcgalp.23886

Rights: 1