# Presentation: 684194

## Genetic Evaluations for Mixed Breed Populations

## Goals

**Evaluate crossbred animals without biasing purebred evaluations**
**Accurately estimate breed differences**
**Compute national evaluations and examine changes**
**PTA’s of purebreds and crossbreds**
**Changes in reliability**
**Display results without confusion**

## Methods

**All-breed animal model**
**Purebreds and crossbreds together**
**Unknown parents grouped by breed**
**Variance adjustments by breed**
**Age adjust to 36 months, not mature**
**1988 software, good convergence**
**Within-breed-of-sire model examined but not used**

## Unknown Parent Groups

**Groups formed based on**
**Birth year (flexible) **
**Breed (must have >10,000 cows)**
**Path (dams of cows, sires of cows, parents of bulls)**
**Origin (domestic vs other countries)**
**Paths have >1000 in last 15 years **
**Groups each have >500 animals**

## Data

**Numbers of cows of all breeds**
**22.6 million for milk and fat **
**16.1 million for protein**
**22.5 million for productive life**
**19.9 million for daughter pregnancy rate**
**10.5 million for somatic cell score**
**Type evaluated in separate breed files **
**Calving ease joint HO, BS, and HO x BS**
**Goats in all-breed model since 1988**

## Crossbred Cowswith 1st parity records

| Year | F1    (%) | F1 cows | Back-cross | Het   > 0 | XX cows |
| --- | --- | --- | --- | --- | --- |
| 2005 | 1.3 | 8647 | 2495 | 12621 | 4465 |
| 2004 | 1.2 | 7863 | 1983 | 11191 | 3947 |
| 2003 | .9 | 6248 | 1492 | 9051 | 3111 |
| 2002 | .7 | 4689 | 1467 | 7338 | 2564 |
| 2001 | .5 | 3491 | 1330 | 5878 | 2081 |

## Recent Sires of Crossbred CowsSires born since 1997

|  | Sire
breed | Daughters |  |
| --- | --- | --- | --- |
| Sire Name |  | Pure | Cross |
| Advent | JE | 698 | 73 |
| Golden | JE | 421 | 42 |
| Eagle | BS | 234 | 35 |
| Brendon-P | JE | 207 | 29 |
| Big Time | JE | 522 | 28 |

## Reliability

**Crossbred cows**
**Will have PTAs, most did not before**
**Accurate PTAs from both parents**
**Purebred animals**
**Information from crossbred relatives**
**More contemporaries**

## All- vs Within-Breed EvaluationsCorrelations of PTA Milk

| Breed | 99% REL bulls | Recent bulls | Recent cows |
| --- | --- | --- | --- |
| Holstein | >.999 | .994 | .989 |
| Jersey |   .997 | .988 | .972 |
| Brown Swiss |   .990 | .960 | .942 |
| Guernsey |   .991 | .988 | .969 |
| Ayrshire |   .990 | .963 | .943 |
| Milking Shorthorn |   .997 | .986 | .947 |

## Display of PTAs

**Genetic base**
**Convert all-breed base back to within-breed-of-sire bases**
**Each animal gets just one PTA**
**PTA****brd**** = (PTA****all**** – mean****brd****) SD****brd****/SD****all**** **
**Heterosis and inbreeding**
**Both effects removed in the animal model**
**Heterosis added to crossbred animal PTA**
**Expected Future Inbreeding (EFI) and merit differ with mate breed **

## Genetic Standard Deviation Ratios

| Breed | Yield | DPR | SCS, PL |
| --- | --- | --- | --- |
| Holstein | 1.00 | 1.00 | 1.00 |
| Jersey | .78 | .94 | 1.00 |
| Brown Swiss | .83 | .99 | 1.00 |
| Guernsey | .79 | .97 | 1.00 |
| Ayrshire | .74 | .94 | 1.00 |
| M. Shorthorn | .72 | .91 | 1.00 |

## Schedule

**Interbull test run Sept. 1, 2006**
**Trend validation**
**Convert all-breed PTA back to within-breed bases**
**Scientific publication (JDS)**
**Implementation**
**Expected February 2007**

## Conclusions

**All breed model accounts for:**
**General heterosis**
**Unknown parent groups by breed**
**Heterogeneous variance by breed**
**PTA converted back to within breed bases, crossbreds to breed of sire**
**PTA changes more in breeds with fewer animals**