# Presentation: 667858

## Using  Days  Open  Early  in  Lactation  to  Allow  for  Earlier  DPR  Sire  Proofs

**Melvin Kuhn,  Paul VanRaden,  Jana Edwards**
**Animal Improvement Programs Laboratory**
**Agricultural Research Service, USDA, Beltsville, MD**

## Reason to Project DO Records

| At  90  DIM: |  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Sire1 | 78 | 82 | 88 | 90 | 77 | 68 | 89 | 83 | 79 | . |  |
| Sire2 | 75 | 85 | 90 | . | . | . | . | . | . | . |  |

**Two sires with 10 daughters each:**

| At  250  DIM: |  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Sire1 | 78 | 82 | 88 | 90 | 77 | 68 | 89 | 83 | 79 | 103 |  |
| Sire2 | 75 | 85 | 90 | 204 | 183 | 136 | 172 | 218 | 230 | 240 |  |

## Reason to Project DO Records

| At  90  DIM: |  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Sire1 | 78 | 82 | 88 | 90 | 77 | 68 | 89 | 83 | 79 | . |  |
| Sire2 | 75 | 85 | 90 | . | . | . | . | . | . | . |  |

**Two sires with 10 daughters each:**

| At  250  DIM: |  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Sire1 | 78 | 82 | 88 | 90 | 77 | 68 | 89 | 83 | 79 | 103 |  |
| Sire2 | 75 | 85 | 90 | 204 | 183 | 136 | 172 | 218 | 230 | 240 |  |

|  |  |  |  |  |  |  |  |  |  |  | Avg |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  |  |  |  |  |  |  |  |  |  |  | 82 |
|  |  |  |  |  |  |  |  |  |  |  | 83 |

|  |  |  |  |  |  |  |  |  |  |  | Avg |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  |  |  |  |  |  |  |  |  |  |  | 84 |
|  |  |  |  |  |  |  |  |  |  |  | 103 |

## Prediction Equation

**ŷ  =  Int  +  Lct  +  CE  +  ß1*Age  +  ß2*Age2 **
**      ****+ ß3*Milk  +  ß4*Milk2  + ß5*PrevDO**
**      ****+ ß6*PrevNS  +  ß7*DOx**

**“****DOx” = days open based on most recent breeding**

_**Example:**_
**Cow is 180 DIM and last bred at 110 days,**
******DOx  =  “DO180”  =  110**

## How  Early  in Lactation  Can  Data  Be  Used

| Define: |  |  |
| --- | --- | --- |
| DO70= | last breeding up to 70 days postpartum |  |
| DO90= | last breeding up to 90 days postpartum |  |
| . | . |  |
| . | . |  |
| . | . |  |
| DO250= | last breeding up to 90 days postpartum |  |

**Compare  the  predictions  at  the  various stages  of  lactation**

## Means of Actual and Predicted DO

| Trait | Mean |
| --- | --- |
| Actual | 140.9 |
| DO70 | 140.9 |
| DO90 | 140.5 |
| DO110 | 140.4 |
| DO130 | 140.5 |
| DO150 | 140.6 |
| DO170 | 140.7 |
| DO190 | 140.7 |
| DO210 | 140.7 |
| DO230 | 140.7 |
| DO250 | 140.7 |

## Correlations of Actual DO with Predicted

| DOx | Phenotypic | Genetic |  |
| --- | --- | --- | --- |
| DO70 | .25 | .88 |  |
| DO90 | .34 | .91 |  |
| DO110 | .41 | .93 |  |
| DO130 | .49 | .96 |  |
| DO150 | .57 | .97 |  |
| . | . | . |  |
| . | . | . |  |
| . | . | . |  |
| DO230 | .80 | .993 |  |
| DO250 | .84 | .995 |  |
|  |  |  |  |

## Correlations of Actual DO with Predicted

| DOx | Phenotypic | Genetic | Heritability |
| --- | --- | --- | --- |
| DO70 | .25 | .88 | .071 |
| DO90 | .34 | .91 | .068 |
| DO110 | .41 | .93 | .057 |
| DO130 | .49 | .96 | .050 |
| DO150 | .57 | .97 | .046 |
| . | . | . | . |
| . | . | . | . |
| . | . | . | . |
| DO230 | .80 | .993 | .046 |
| DO250 | .84 | .995 | .046 |
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|  |  | h2 DO  =  .044 |  |

## Which  Records  Get  Projected

**If  pregnancy  confirmed then  “y  =  y” otherwise  y  =  ŷ**

**Probably still impose some upper limit on DOx to avoid extreme observations**

| Breeding date but no next calf | 19% |
| --- | --- |
| Cows sold for repro problems | 5% |

## Summary

**Predictions  for  DO  developed  and  appear  to work  well.**
**As  early  as  90  days  may  be  feasible**
****** ****DPR  proofs  ~  5  months  sooner**
**Projected  records,  could  be  used  for terminal lactations.**
** **