# Presentation: 803352

## USDA Genetic Evaluations for Calving Ease

## Calving Ease Evaluations

**Objective:**
**Reduce calving problems during calving (especially first calvings)**
**Procedure:**
**Collect reports on calving difficulty**
**Calculate sire evaluations**

## Frequency of Calving Difficulty

|  |  | Lactation |  |  |
| --- | --- | --- | --- | --- |
| Calving Ease Score |  | 1st | 2nd | 3rd |
| 1 – No Problem |  | 63% | 80% | 81% |
| 2 – Slight Problem |  | 14% | 10% | 9% |
| 3 – Needed Assistance  |  | 14% | 7% | 7% |
| 4 – Considerable Force |  | 5% | 2% | 2% |
| 5 – Extreme Difficulty |  | 3% | 1% | 1% |

## History

**1977**** – NAAB-sponsored evaluations within AI organizations**
**1980**** – NAAB-sponsored evaluations across AI organizations**
**1988**** – Ordered categorical threshold model**
**1990**** – Semi-annual evaluations**
**1999**** – Processing moved from Iowa State University to USDA (November)**
**2002**** – Sire-maternal grandsire (MGS) model**

## Sire – MGS Project

**Improved Data**
**Enhanced detection of duplicate calving reports**
**Use of animal key to deal with identification changes**
**Database maintenance to allow easy update and access**
**Access to pedigree from production evaluations to increase data accuracy and provide missing MGS information**

## Sire – MGS Project

**Improved Model**
**MGS effect added**
**Evaluations of bulls as service sires improved by partially accounting for mates**
**Maternal effect on calving difficulty included in MGS effect**

## Data

**Over ****11 million calving reports**** since 1980**
**Pedigrees matched to production evaluation pedigree database**
**2.5 million pedigree records**** for cows *****without***** unique national identification also included**
**Improved edits yield ****10.5 million**** ****unique calving reports**

## Additional Data Requirements

**Single birth**
**Dam and sire of Holstein or Red & White breed**
**Sire age >18 mo and <15 yr at birth of calf**
**Birth date of Jan. 1, 1980, or later**
**10,195,097 records extracted**

## Threshold model

**Scores assumed to be observations on a continuous underlying scale**
**Thresholds estimated to relate observed scores to underlying scale**

**Procedure allows for differences in amount of change between consecutive scores**

## Model Definition

| MODEL: y = HY + YS + PS + Ys + Ym + s + m + e |  |  |
| --- | --- | --- |
| y | = | CE score |
| HY | = | random herd-year |
| YS | = | fixed year-season |
| PS | = | fixed parity-gender |
| Ys | = | fixed birth year of sire  |
| Ym | = | fixed birth year of MGS  |
| s | = | Sire |
| m | = | MGS |
| e | = | unexplained residual |

## Sire-MGS Model Statistics

|  |  |  | Range |  |
| --- | --- | --- | --- | --- |
| Effect |  | Levels | Minimum | Maximum |
| Herd-year | 204,607 |  | -2.23 | 3.49 |
| Year-season | 44 |  | -0.83 | -0.54 |
| Parity-gender | 6 |  | -1.01 | 0.01 |
| Sire birth year | 15 |  | -0.70 | -0.59 |
| MGS birth year | 29 |  | -0.69 | -0.63 |
| Sire | 120,108 |  | -0.86 | 0.93 |
| MGS | 120,108 |  | -0.38 | 0.44 |

## VC Estimates, Heritabilities, and Correlation of Traits

| (Co)Variance | Sire | 0.022 |
| --- | --- | --- |
|  | MGS | 0.016 |
|  | Sire-MGS | 0.009 |
| Heritability (%) | Direct | 8.6 |
|  | Maternal | 4.8 |
| Correlation | Direct-Maternal | -0.12 |

## Presentation of Evaluations

**Evaluations converted to expected percentage of difficult (scored 4 or 5) births for heifers (****%DBH****)**
**Most frequent %DBH was 8%**
**Genetic Base **
**Daughter CE – MGS born in ****1990**
**Service sire CE  -  sires born in ****1995**** **
**%DBH for MGS relatively constant**
**%DBH for sires increasing**

## Calving Ease Trends

- 1061

- 1025

- 921

- 1486

- 1541

- 1456

- 916

- 1545

- 1477

- 112

## Status of Evaluation System

**Sire-MGS evaluations for CE released in ****August 2002 **
**Web queries to display CE data available to participants**
**Daughter CE may be included in future index calculations**