# Presentation: 773622

## Correlations Among Measures of Dairy Cattle Fertility and Longevity

## Longevity & Fertility Investigation

**1,062,791 cows born 1992-1994**
**Daughters of 3080 Holstein sires**
**Progeny tested bulls with > 60 daughters**
**Older bulls to provide ties and relationships**
**Compare two measures of longevity**
**Productive Life (max 10 mo / lactation)**
**Lifespan (first calving until death)**
**Develop new fertility evaluation**

## Longevity Parameter Estimates Multi-trait REML Analysis

|  | ProductiveLife | Lifespan |
| --- | --- | --- |
| Heritabilities |  |  |
| New Estimates | 7.6% | 6.7% |
| Official since 1994 | 8.5% |  |
| Genetic correlations |  |  |
| Lifespan with PL | .986 |  |
| Protein | .06 | .15 |
| SCS  | - .31 | - .28 |
| Days Open | - .59 | - .46 |

## Cow Fertility Data Multi-trait REML Analysis

**First lactation records**
**Days Open (DO) = Calving interval – 280d**
**Limits on DO**
**Lower limit of 50d**
**Upper limit of 250d**
**‘****Sold for reproductive problems’ DO = 250d**
**‘****Sold for other reasons’ DO = 150d (mean)**
**Cows sold for dairy not included**

## Fertility Parameter Estimates Multi-trait REML Analysis

| Heritability of DO |  | 3.7% |  |
| --- | --- | --- | --- |
| Correlations with DO |  | Phenotypic | Genetic |
| Milk |  | .11 | .38 |
| Fat |  | .09 | .33 |
| Protein  |  | .10 | .32 |
| SCS |  | .05 | .30 |

## Proposed USDA Fertility Evaluation

**Lactations 1-5 beginning with 1960**
**Days Open data**
**Reported DO confirmed with next calving**
**Exclude most recent 9 months**
**Reported DO if no next calving**
**Exclude most recent 9 months**
**Calving interval – 280 days if no reported DO**
**Exclude most recent 18 months**
**Assigned DO = 250 if sold for infertility**

## Distribution of Days OpenHolstein Calvings 1990 - 2001

**≤**** ****50**

**≥**** ****250**

**Distribution of Days Open****Holstein Calvings 1990 - 2001**

**Cows culled for reproductive reasons**

## Holstein Phenotypic Trend

**5****th**

**4****th**

**3****rd**

**2****nd**

**1****st**

**Lactation**

## Proposed Evaluation Methods

**BLUP Animal Model**
**Same programs used for yield, PL, SCS**
**Adjust for heterogeneous variance**
**Parameter estimates used:**
**Heritability = ****4%**
**Repeatability = ****11%**
**Sire-by-herd interaction = ****1%**

## Evaluation Test Run

**Holstein**** data from May 2002 evaluation**
**36 million**** lactations**
**14 million**** cows**
**Statistics for recent, well-sampled bulls **
**Born 1994 - 1997**
**Milk REL > 80% (mean = 87%)**
**4215 ****Holstein**** bulls**
**314 ****Jersey**** bulls**

## Bull Evaluations

|  | Holstein | Jersey |
| --- | --- | --- |
| Days Open  |  |  |
| PTA range | -11 to +19 | -6 to +12 |
| REL mean  | 59% | 57% |
| PTA correlations |  |  |
| PL | -.46 | -.23 |
| SCS | .13 | -.03 |
| Milk  | .22 | .22 |
| Fat | .18 | .35 |
| Protein | .16 | .17 |

## Days Open Trends

**Phenotypic trend 1960 - 1998 **
**Holstein:****	****+37**** days**
**Jersey:****	****+20**** days **
**Genetic trend 1960 - 1998 **
**Holstein:****	****+17 ****days **
**Jersey:****	****+9**** days **
**Expected correlated response**
**Milk trend ****x**** .38 correlation = ****+17**** days**

## Reporting of Cow Fertility

**Add mean (such as SCS, calving difficulty)?**
**Reverse scale so positive is desirable?**
**Possible names and abbreviations**
**PTA DO****	****Days Open**
**PTA DP****	****Date Pregnant ***or*
**	****	****	****	****Daughter Pregnancy**
**PTA CF****	****Cow Fertility**
**Report preliminary August 2002 rankings?**

## Conclusions

**Date pregnant has low heritability (****~4%****) but high genetic correlation with Productive Life (****>.5****)**
**May 2002 test successful, November 2002 official evaluations possible**
**Indirect selection on PL has reduced decline in fertility, but direct selection could increase lifetime profit.**
**Productive Life preferred over Lifespan**

## Acknowledgments

**Fertility data for the proposed USDA evaluation were prepared by Ashley Sanders**
**Statistical and graphical analysis of results were provided by Mel Tooker**