# Presentation: 503246

## Genetic relationships among fertility traits of Holsteins and Jerseys(abstract 351)

**R.H. MILLER, P.M. V****AN****RADEN, and J.R. WRIGHT**
**Animal Improvement Programs Laboratory**
**Agricultural Research Service, USDA**
**Beltsville, MD 20705-2350**
**J.S. CLAY**
**North Carolina State University, Raleigh, NC 27603‐3435**

**Genetic relationships among fertility traits of Holsteins and Jerseys****(abstract 351)**

## Why evaluate fertility traits?

**Low heritability estimates but large phenotypic variation**
**High economic value**
**Decline in reproductive performance**
**Antagonistic relationship between milk yield and reproductive traits**

## Objectives

**Estimate genetic relationships among fertility traits**
**Determine which reproductive traits have greatest potential use for evaluating daughter fertility of bulls**

## Management factors

**Voluntary waiting period between calving and first breeding**
**Use of bST**
**Designed reproductive programs**

## Data processing factors

**Computer program differences among dairy records processing centers**
**DHI reproduction options**
**Calving interval estimation without subsequent calving date**

## Data

**2.2 million Holstein and 0.2 million Jersey breeding records from 1995 through 2000 that included:**
**Yield (milk, fat, protein) for first 3 test days**
**Identification (service sire, cow, sire, dam)**
**DIM at each service**
**Parity**
**DHI herds with records processed by:**
**AgriTech Analytics**
**AgSource Cooperative Sources**
**Dairy Records Management Systems**
**Pennsylvania DHI Association**

## Data restrictions

**<150 DIM at third test day**
**Daily milk yield between 4.5 and 109 kg**
**Test-day component percentage between 2.0 and 8.0**
**Fat and protein percentages reported for at least 2 of first 3 test days**

## Fertility traits

**Days from calving to first service**
**Days from calving to last reported service ****(days open)**
**Nonreturn to first service within 70 d ****(nonreturn rate)**
**Number of services**

## Fertility restrictions

**Successful breeding if cow not reported in estrus or rebred within 70 d**
**Breedings excluded:**
**Virgin heifers**
**<15 or >365 DIM**
**Cows that left herd <70 d after first service**
**Subsequent breedings within 4 d**
**Non-AI first services**
**Herd:**
**>9 AI matings annually**
**>9 or <90% for annual mean for nonreturn rate**

## Means

| Trait | Holstein | Jersey |
| --- | --- | --- |
| Days to first service | 	90 | 	83 |
| Days open | 	141 | 	125 |
| Nonreturn rate (%) | 	55 | 	57 |
| Number of services | 	2.1 | 	2.0 |

## Analysis

**Fertility traits adjusted for:**
**Parity (fixed; 1, 2, ... 5, 5+)**
**Age deviation within parity (linear regression) **
**2 highest test-day yields (linear regression):**
**Milk**
**Fat**
**Protein**
**Lactation stage at first service ****(nonreturn rate and number of services only)**

## Analysis (continued)

**Heritabilities and genetic correlations estimated with multitrait REML sire model:**
**Observations from 1998 to 2000**
**3447 Holstein bulls with ********40 daughters**
**2602 Jersey bulls**

## Heritability estimates (%)

| Trait | Holstein | Jersey |
| --- | --- | --- |
| Days to first service | 7 | 4 |
| Days open | 4 | 3 |
| Nonreturn rate | 1 | 1 |
| Number of services | 2 | 2 |

## Genetic correlations

| Trait | D1 | DO | NR | NS |
| --- | --- | --- | --- | --- |
| D1 | . . . |   0.85 |  0.24 |  0.15 |
| DO | 0.73 | . . . | –0.21   |  0.61 |
| NR | 0.09 | –0.55 | . . . | –0.88 |
| NS | 0.05 |   0.70 | –0.97 | . . . |

| Legend: |  |
| --- | --- |
| D1 = days to first service | Holstein correlations |
| DO = days open | Jersey correlations |
| NR = nonreturn rate |  |
| NS = number of services |  |

## Phenotypic correlations

| Trait | D1 | DO | NR | NS |
| --- | --- | --- | --- | --- |
| D1 | . . . |  0.41 |  0.00 |  0.00 |
| DO | 0.41 | . . . | –0.32   |  0.76 |
| NR | 0.00 | –0.36 | . . . | –0.57 |
| NS | 0.00 |  0.76 | –0.62 | . . . |

| Legend: |  |
| --- | --- |
| D1 = days to first service | Holstein correlations |
| DO = days open | Jersey correlations |
| NR = nonreturn rate |  |
| NS = number of services |  |

## Days open has higher heritability than nonreturn rate
Days open has moderate to high genetic correlation with days to first service and number of services
Days open appears to be best single measure among fertility traits examined for genetic evaluation of cow fertility

**Days open has moderate to high genetic correlation with days to first service and number of services**
**Days open appears to be best single measure among fertility traits examined for genetic evaluation of cow fertility**

**Conclusions**