# Presentation: 465010

## An Example from Dairy Cattle Selection: The Net Merit Index

## The Old Way of Selecting Cattle

## Objectives

**Document USA Net Merit index**
**Compare national selection indexes for dairy cattle**
**Discuss traits that affect profit and direction of selection**
**Outline approach for estimating economic values**

## Selection Theory

**Progress = accuracy ******** intensity ******** genetic SD / generation interval**
**Multiply above by directional loss**
**Accuracy = Corr (EBV, BV)**
**Directional loss = Corr (e******** EBV, a******** EBV)**
**Estimated (e) vs. actual (a) economic values**
**Direction may be the most important factor**

## Direction of Selection

- Trait 1

- Trait 2

- Accuracy contours

- Animals
- selected

## Trait Direction Not Clear

**Concentrated (less) or diluted (more) milk?**
**Large or small cows?**
**Skinny or fat cows?**
**Dairy or beef or dual purpose?**
**Can change direction by replacing a population instead of selecting within**
**Specialized populations can be useful**

## Coefficients of variation (CV)

| Trait | Herit-ability | CV (%) |  |
| --- | --- | --- | --- |
|  |  | Pheno- typic | Genetic |
| Stature  | .42 |   3 |   2 |
| Protein yield | .30 | 13 | 	7 |
| Longevity | .08 | 54 | 	16 |
| Fertility | .04 | 65 | 	13 |

## Measures of accuracyAverages for recently proven Holstein bulls 

| Trait | ACC rBV,EBV | REL r2EBV,BV | BIF ACC 1 - 1-r2  |
| --- | --- | --- | --- |
| Protein yield | .92 | .85 | .61 |
| SCS (mastitis) | .77 | .59 | .36 |
| Productive life | .78 | .61 | .38 |
| Cow fertility | .75 | .56 | .34 |
| Calving Ease | .85 | .72 | .47 |

## Relative Emphasis

**Easily compare selection goals independent of trait units**
**Trait economic value times genetic SD**
**Divide by the sum across all traits**
**Multiply by 100**
**Expresses relative emphasis as percent of total selection**
**Added traits decrease emphasis on others**
**Convenient way to display indexes **

## History of USDA economic indexes(PD$, MFP$, CY$, and NM$)and Holstein Association TPI

|  | Year Introduced and Index Name |  |  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  | 1971 | 1976 | 1977 | 1980 | 1984 | 1987 |  | 1989 | 1992 | 1994 | 1997 | 2000 | 2000 |
| Trait | PD$ | TPI | MFP$ | TPI | CY$ | TPI | TPI |  | TPI | NM$ | TPI | TPI | NM$ |
| Protein |  |  | 27 |  | 53 | 40 | 34 |  | 50 | 43 | 50 | 41 | 36 |
| Fat | 48 |  | 46 |  | 45 | 40 | 34 |  | 17 | 25 | 17 | 16 | 21 |
| Milk | 52 | 60 | 27 | 60 | -2 |  |  |  |  |  6 |  |  |  5 |
| % Fat |  |  |  | 20 |  |  |  |  |  |  |  |  |  |
| Longevity |  |  |  |  |  |  |  |  |  | 20 |  | 13 | 14 |
| SCS |  |  |  |  |  |  |  |  |  |   6 |  |   1 |   9 |
| Udder |  |  |  |  |  |  | 17 |  | 17 |  | 11 |   9 |   7 |
| Feet / legs |  |  |  |  |  |  |  |  |  |  |  5 |   5 |   4 |
| Size |  |  |  |  |  |  |  |  |  |  |  |  |  -4 |
| Final Score |  | 40 |  | 20 |  | 20 | 17 |  | 17 |  | 17 | 14 |  |

## Current National Selection Indexes:Yield and Health Traits

|  | Country (Interbull Code) |  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  | USA |  | DEU | FRA | NZL | NLD | CAN | GBR | AUS | ITA | DNK | SWE |
| % of Interbull Population | 
17.4 |  | 
15.3 | 
12.3 | 
10.6 | 
9.3 | 
4.7 | 
4.7 | 
4.5 | 
4.3 | 
4.1 | 
1.5 |
| Index Name | NM$ | TPI | RZG | ISU | BW | DPS | LPI | PLI | APR | PFT | S – I | TMI |
| Trait |  |  |  |  |  |  |  |  |  |  |  |  |
| Protein | 33 | 32 | 36 | 35 | 34 | 32 | 31 | 57 | 36 | 42 | 21 | 21 |
| Fat | 22 | 18 | 9 | 10 | 13 | 7 | 20 | 11 | 12 | 12 | 10 | 4 |
| Milk |  |  |  |  | -17 | -12 |  | -19 | -20 |  | -3 | -4 |
| % Protein |  |  | 4 | 2 |  |  | 2 |  |  | 3 |  |  |
| % Fat |  |  | 1 | 2 |  |  | 1 |  |  | 2 |  |  |
| Longevity | 11 | 8 | 25 | 13 | 8 | 8 | 7 | 15 | 12 | 8 | 6 | 6 |
| SCS / mastitis | 9 | 5 | 5 | 13 |  | 14 | 3 |  | 7 | 10 | 15 | 12 |
| Fertility | 7 | 5 | 2 | 13 | 10 | 10 | 5 |  |  |  | 9 | 10 |
| Other diseases |  |  |  |  |  |  |  |  |  |  | 2 | 3 |
|  |  |  |  |  |  |  |  |  |  |  |  |  |

## Current National Selection Indexes:Conformation and Management Traits

|  | Country (Interbull Code) |  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  | USA |  | DEU | FRA | NZL | NLD | CAN | GBR | AUS | ITA | DNK | SWE |
| % of Interbull Population  | 17.4 |  | 15.3 | 12.3 | 10.6 | 9.3 | 4.7 | 4.7 | 4.5 | 4.3 | 4.1 | 1.5 |
| Index Name | NM$ | TPI | RZG | ISU | BW | DPS | LPI | PLI | APR | PFT | S – I | TMI |
| Trait |  |  |  |  |  |  |  |  |  |  |  |  |
| Udder traits | 7 | 10 | 6 | 8 |  |  | 16 |  |  | 13 | 9 | 12 |
| Feet / legs | 4 | 5 | 4 | 1 |  | 5 | 11 |  |  | 6 | 5 | 9 |
| Size | -3 |  | 2 | 2 | -18 | -5 | 4 |  | -4 |  | 2 |  |
| Dairy character |  | -2 | 2 |  |  |  |  |  |  |  |  |  |
| Rump |  |  | 1 | 1 |  |  |  |  |  |  |  |  |
| Final score |  | 13 |  |  |  |  |  |  |  | 4 | 2 |  |
| Calving ease | 4 | 2 | 4 |  |  | 7 |  |  |  |  | 6 | 12 |
| Growth / meat |  |  |  |  |  |  |  |  |  |  | 4 | 6 |
| Milking Speed |  |  |  |  |  |  |    <1 |  | 4 |  | 6 |  |
| Temperament |  |  |  |  |  |  |  |  | 5 |  | 2 | 3 |

## Milk Pricing and Feed Cost($ per pound)

| Index | Milk | Fat | Protein |
| --- | --- | --- | --- |
| Fluid Merit | .051 | 1.30 | 1.00 |
| Net Merit | .012 | 1.30 | 2.30 |
| Cheese Merit | -.009 | 1.30 | 3.00 |
| Feed Cost | -.012 | -.35 | -.50 |

## Value of Cow Fertility

**Daughter pregnancy rate (DPR)**
**Pregnancies achieved per 21-day cycle**
**1% higher DPR = 4 fewer days open**
**Fertility expenses per day open**
**Heat detection ($20 / lact ******** .005)****	****	****= ****$.10**
**Semen ($15 / unit + $5 labor) *.025****	****= ****$.50**
**Pregnancy exam ($10 / exam)*.012****	****= ****$.12**
**Lactations too long or short****	****	****= ****$.75**
**Relative value of DPR = ****7%**** of total**

## Value of Calving Ease

**Daughter CE value / difficult birth**
**Veterinary, labor costs****	****	****	****= ****$50**
**Calf death (20% prob)****	****	****	****= ****$25**
**Cow deaths before 1****st**** test (1% prob)****	****= ****$15**
**Service sire CE also includes**
**Yield losses / lactation****	****	****	****= ****$40**
**Fertility and longevity losses****	****	****= ****$30**
**Relative values of each are ****2%**** of total**

## Linear vs Non-linear ProfitCalculation of Net Merit $

**Non-linear profit = (income – expense per lactation) number of lactations + cull value – raising cost**
**Linear profit obtained by taking partial derivatives at trait means**
**Corr (linear, non-linear) = .999**

## Lifetime Net Merit $

**Incomes and expenses estimated from yield traits, SCS, longevity, fertility, conformation, calving ease**
**Example: body size**
**Convert from visual scores to weight**
**Cull price - growth cost + lactations ******** (calves – maintenance) = $-1.28 / kg**
**Less beef = more profit to dairy farmer**

## Goals of Index Calculation

**Give breeders the index they want**
**Breed association or AI committees**
**Emotional approach (TPI)**
**Give scientists the index they want**
**Add incomes, subtract expenses**
**Mathematical approach (NM$)**
**Future prices difficult to prove**

## Top Net Merit BullsMay 2005

| Bull | Cntry |  | Dtrs | NM$ REL |  Net Merit $ | Pro-tein |
| --- | --- | --- | --- | --- | --- | --- |
| O Man  | USA |  | 230 | 93 | 729 | 57 |
| Loe Martin | NLD |  | 166 | 74 | 657 | 79 |
| Lombard | DEU |  | 93 | 70 | 655 | 73 |
| Mascol | DEU |  | 98 | 68 | 645 | 59 |
| Marion | USA |  | 56 | 76 | 613 | 74 |
| S D Jordan | NLD |  | 120 | 76 | 595 | 61 |
| Alton | USA |  | 97 | 82 | 585 | 55 |

## Trait HarmonizationMark, 2003 EAAP meeting

|                 Trait |   Coun-tries | Average corr. | Avg. cor w / USA |
| --- | --- | --- | --- |
| Protein | 27 | .87 | .89 |
| Stature | 21 | .89 | .90 |
| Fore Udder | 21 | .75 | .79 |
| SCS | 20 | .85 | .86 |
| Longevity | 14 | .59 | .74 |
| D. CalvEase | 10 | .83 | .86 |
| M. CalvEase | 10 | .58 | .64 |

## Paul’s Beef Experience

## Interbull Beef Proposal

**Provide international evaluations within ICAR subcommittee**
**Combine raw data files instead of national evaluations**
**Favorable responses received from many countries**
**Charolais, Limousin most likely**

## Conclusions - Dairy

**Many traits in addition to yield contribute to dairy cattle profit**
**Longevity, fertility, health, and type traits get half of emphasis**
**Direction unclear for some traits**
**Indexes began in 1970’s and have improved rapidly in recent years**

## Conclusions - Beef

**An official, published goal:**
**Stimulates economic research**
**Gives breeders direction**
**An overall index helps breeders:**
**Promote their own animals **
**Locate superior breeding stock**
**Compete to improve the breed**