# Presentation: 736683

## Characteristics of genetic evaluations for daughter fertility in relation to other fitness traits

***Abstr. 519***

## DHI-Provo lactation records

| Trait | Mean |  |  | Change |
| --- | --- | --- | --- | --- |
|  | 1990 | 1999 |  |  |
| Calving  1st breeding (d) | 	82 | 	86 |  | 	 5% |
| Calving  conception
(days open) | 	129 | 	154 |  | 	 19% |
| 1st breeding  conception (d) | 	47 | 	68 |  | 	 45% |
| Inseminations/conception | 	2.0 | 	2.3 |  | 	 15% |

## Economic impact

**Lower herd milk yield**
**Increased insemination costs**
**Losses from involuntary culling for fertility**
**International export disadvantage**

## Data donors

**Dairy Records Management Systems ****Raleigh, NC**
**AgSource Cooperative Services ****Verona, WI**
**AgriTech Analytics**
**	****Visalia , CA**
**Pennsylvania DHIA Service Center ****University Park, PA**

## Reproductive traits

**Days to 1st breeding**
**Service period**
**Percentage of nonreturn to 1st service**
**Services per conception**
**Days open**

## Pregnancy rate (PR)

**Percentage of nonpregnant cows that become pregnant during next 21 d **
**Derived from days open:**
**PR = (233 – days open) / 4**

## Selection for fertility?

**Pessimistic**
**R.H. Foote, 1969, JDS**
**R. Nebel, 2003, Holstein International**
**Optimistic**
**Norman *****et al.*****, 2003, ADSA meeting**

## Coefficients of variation (CV)

| Trait | Mean | Pheno-
typic SD | CV (%) |  |
| --- | --- | --- | --- | --- |
|  |  |  | Pheno-
typic | Genetic |
| Protein (kg) | 	314	 | 90 | 13 | 	7 |
| SCS | 	3.1 |  |  |  |
| PL (mo) | 	24 | 13 | 54 | 	16 |
| DPR (%) | 	23 | 15 | 65 | 	13 |

**DPR**** = daughter pregnancy rate, ****PL**** = productive life, ****SCS**** = somatic cell score**

## Genetic progress

**	********G =****	****accuracy ******
**	****	****genetic SD ******
**	****	****selection intensity ******
**	****	****generation interval**
***Dickerson & Hazel, 1944***

## Objectives

**Compare evaluation characteristics**
**DPR**
**Other recent fitness traits**
**Determine appropriate perspective for use of current genetic tools**

## Genetic trend: DPR

## Genetic trend: SCS, PL

## Mean cow reliability (%)

| Trait | Birth year |  |  |
| --- | --- | --- | --- |
|  | 1988 | 1993 | 1998 |
| Protein (kg) | 52 | 51 | 49 |
| SCS | 32 | 35 | 34 |
| PL | 33 | 32 | 31 |
| DPR | 32 | 32 | 30 |

## Heritability (%)

| Trait | Repeat-
ability | Records (no.) |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- |
|  |  | 1 | 2 | 3 | 4 | 5 |
| Protein (kg) | 55 | 	30 | 	39 | 	43 | 	45 | 	47 |
| SCS | 35 | 	10 | 	15 | 	18 | 	20 | 	21 |
| PL |  |  | 	4 | 	7 | 	8 | 	8.5 |
| DPR | 11 | 	4 | 	7 | 	10 | 	12 | 	14 |

## Mean bull reliability (%)

| Trait | Birth year |  |  |
| --- | --- | --- | --- |
|  | 1984-88 | 1989-93 | 1994-98 |
| Protein (kg) | 85 | 86 | 85 |
| SCS | 68 | 73 | 59 |
| PL | 67 | 67 | 61 |
| DPR | 65 | 66 | 57 |
| Service sire CE | 64 | 68 | 73 |
| Daughter CE | 59 | 62 | 59 |
| Feet & Legs | 66 | 70 | 70 |

## Birth year and AI organization

**Effect on PTA variation:**
**No differences among AI organizations for DPR, but an effect found for PL and SCS**

| Trait | Birth year | AI organization |
| --- | --- | --- |
| DPR | 2.6% | .3% |
| PL | 5.8% | .1% |
| SCS | 1.1% | .4% |

## Conclusions

**DPR reliability comparable to reliabilities for other fitness traits**
**DPR should be included in all aspects of genetic programs to reverse decline in reproductive performance**
**Little difference in DPR among AI organizations **
**If fitness traits receive 50% of weight in future net merit indexes, acceptance of lower reliability will become more common**