Resistance to Retained Placenta (RETP)

RETP measures the resistance to retained placenta

Benefits of Trait

Introduced in April 2018 and April 2020, genetic and genomic evaluations for resistance to retained placenta (RETP) are provided for Holstein and Jersey males and females, respectively. Evaluations are expressed in percentage points of resistance above and below the breed average.

Resistance to Retained Placenta (RETP)

The RETP predicted transmitting ability (PTA) represents the expected resistance of an animal’s offspring to retained placenta in a herd with average management conditions. Larger, positive values are more favorable.

Percentage points

The average resistance rate is equal to 96.4% in U.S. Holsteins. The resistance rate is equivalent to the incidence rate subtracted from 100.

Daughters of a Holstein bull with a MAST PTA of +2.0% are expected to have an average resistance rate to retained placenta of 98% (assuming the breed average resistance is approximately 96%). Daughters of a Holstein bull with a MAST PTA of -2.0% are expected to have an average resistance of 94%. Daughters from the bull with PTA -2.0% are expected to have three times the number of cases of mastitis as daughters from the bull with PTA of +2.0%

BreedMean GL for CowsMean GL for HeifersMean GL for the
current base year (2010)

Holsteins: April 3, 2018
Jerseys: April 7, 2020

RETP is currently available for Holsteins and Jerseys. As more health data become available, evaluations can be provided for additional breeds.

RETP is included in selection indices for Holsteins and Jerseys as part of the Heath $ sub-index.

Estimated heritability is 1.0% for resistance to retained placenta (observed scale).

Young genomic bulls are expected to have reliabilities averaging 42% for resistance to retained placenta, and progeny tested bulls are expected to have genomic reliabilities averaging 47%. As additional data is accumulated, reliabilities will increase.

BreedAverage Reliability for GL of
Young Genotyped Bulls by Breed

The largest significant (P < 0.05) correlation with PTA for resistance to retained placenta was with productive life PTA at 0.17. Additional significant correlations were 0.14 with daughter pregnancy rate PTA, 0.13 with livability PTA, 0.13 with cow conception rate PTA, and 0.12 with heifer conception rate PTA.

CDCB RETP evaluations were developed using producer-recorded data collected through Dairy Herd Information (DHI) affiliates from herds across the U.S. Strict editing was applied to ensure only the most reliable data was included for the development of genetic evaluations. The edited data included a total of 2 million RETP records from 1.1 million cows. These health records are used in conjunction with lactation data available in the national cooperator database, stewarded by CDCB.

The standard deviation (variation) for RETP PTA is 0.8%. Because 1 and 2 standard deviations normally include 68% and 95% of observations, respectively, we assume about 68% of bulls will have a MAST PTA between -0.8% and +0.8% while 95% of the bulls will range from -1.6% to +1.6%.

MAST PTAs range from 2.7 percentage points below to 2.1 percentage points above average in evaluated Holstein bulls born since 1990 with reliabilities of ≥75% (December 2017).

Pre-release analysis indicates the active AI Holstein sires in December 2017 (614 bulls) range from -2.1% to +1.3%, with the average at approximately -0.3 percentage points.

Future Development

In the future, further model improvements and development will be researched and tested. This may include the development of a multi-trait model that incorporates multiple reproductive disorders and/or measures of fertility.

Related Publications
Parker Gaddis, K.L., J.B. Cole, J.S. Clay, and C. Maltecca. 2012. Incidence validation and relationship analysis of producer-recorded health event data from on-farm computer systems in the United States. J. Dairy Sci. 95:5422–5435. doi:10.3168/jds.2012-5572.
Donnelly, M. R., A. R. Hazel, B. J. Heins, & L. B. Hansen, 2018. Health treatment cost of Holsteins in 8 high-performance herds. J. Dairy Sci. (in preparation).
Liang, D., L.M. Arnold, C.J. Stowe, R.J. Harmon, & J.M. Bewley, 2017. Estimating US dairy clinical disease costs with a stochastic simulation model. J. Dairy Sci. 100(2): 1472–1486.

Information last updated March 2018.