Reproduction

Genetic analysis of fetal loss in Jersey Cattle

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Abstract

Pregnancy loss is a major contributor to reproductive inefficiency in dairy cattle. While fertilization occurs in approximately 70-75% of inseminations in dairy cows, embryonic and fetal losses reduce calving rates to only 30-35%. Pregnancy losses compromise herd productivity by extending calving intervals, reducing the number of replacement heifers, reducing milk yield, increasing veterinary and labor costs, and increasing the risk of premature culling. Therefore, reducing pregnancy losses and improving pregnancy maintenance is a relevant breeding goal in dairy cattle. The objective of this study was to quantify the genetic variability of pregnancy loss in US Jersey cattle. Our dataset included a total of 1,529,017 lactations with complete reproductive records from 724,525 lactating Jersey cows. Data were collected from 47 U.S. states, from 2000 to 2022. Pregnancy loss was recorded as 1 when either (i) a confirmed abortion was reported, (ii) a confirmed pregnant cow was subsequently recorded as open, or (iii) the interval between two consecutive inseminations was larger than 75 days. A total of 137,387 (9%) of the lactations were identified with at least one event of pregnancy loss. The genetic analysis of pregnancy loss (binary trait) was performed with a Bayesian animal threshold model, fitting lactation (6 levels) and days-in-milk-at-pregnancy (4 levels) as fixed effects, herd-year-season (6,262 levels), service sire (10,694 levels), animal additive genetic (1,170,817 levels) and permanent-environment (724,525 levels) as random effects, with residual variance fixed at one. Additive genetic relationships among animals were modeled through the relationship matrix (A). The lower and upper bound of the 95% credible interval for the heritability estimate of pregnancy loss was 2.6% and 3.8%, with a point estimate of 3.2%. Pearson correlations between the pregnancy loss PTAs (reliability ≥ 0.85) and CDCB PTAs were −0.32 for daughter pregnancy rate, −0.27 for cow conception rate, −0.37 for livability, and −0.56 for productive life (all P < 0.001). The genetic correlation of pregnancy loss between lactations was 0.68 (L1-L2), 0.56 (L1-L3), and 0.70 (L2-L3). In conclusion, pregnancy loss in US Jersey cattle is heritable, indicating that genetic selection can reduce its incidence. Its favorable genetic associations with daughter pregnancy rate, cow conception rate, livability, and productive life, together with moderate-to-high genetic correlations across lactations, support pregnancy loss as a consistent and selectable breeding goal trait.

Keywords: 2026

How to Cite:

Chasco, J., Weigel, K. & Peñagaricano, F., (2026) “Genetic analysis of fetal loss in Jersey Cattle”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2285497. doi: https://doi.org/10.31274/wcgalp.23727

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