# Presentation: 885489

## A Historical Review of Culling of Dairy Cows from US Dairy Herds

**DR. H. DUANE NORMAN**
**Animal Improvement Programs Laboratory**
**Agricultural Research Service, USDA**
**Beltsville, MD 20705-2350**
**dnorman@aipl.arsusda.gov**** ******** 301-504-8334**

## Optimists vs. pessimists

**Longevity**
**Productive life**
**Survival**
**Stayability**
**Herdlife**
**Life expectancy**

**Culling**
**Disposals**
**Replacement**
**Turnover**

***vs.***

## Selection

**Natural                **** *****vs.  *****Artificial**

***Bos primigenius***
**(extinct, 1672)**

***Bos taurus***
**(Canadian Holstein true type, 1973)**

## Cow population vs. production

## Days open phenotypic trend

**1**

**2**

**3**

**4**

**5**

**Parity**

***Holstein***

## Production (quantity, quality)

**Cows have been selected based on high milk yield**
**Cows should be selected based on profitable production and herdlife of the producer’s choice**

## Culling factors

**Udder health**
**Reproduction**
**Nutrition**
**Veterinarians**
**Conformation**
**Management practices**
**Business economics**

## Longevity measures

**True *****vs.***** functional stayability**
**Voluntary *****vs.***** involuntary culling**

## Longevity definitions

**True longevity is the capability to delay culling**
**Functional longevity is the capability to delay involuntary culling**

## Longevity periods

**Two phases: Productive and Non-Productive phase**
**Nonproductive = Birth to first calving**
**Productive = First calving to disposal**

## Productive life

**Culling dates needed for all animals**
**Genetic evaluation**
**First US national evaluation in 1994**
**First international Holstein bull rankings for longevity in November 2004**
**Correlated traits**

## Economic value of longevity

**Fewer replacement heifers**
**Higher proportion of cows in more profitable lactations**
**Higher yield near maturity**

## Health disorders

**Big impact on voluntary culling**
**Reproductive and udder problems most likely contributors**
**Risk factors (dystocia, displaced abomasum, mastitis)**

## Time of culling

**Immediate**
**Milking prevented**
**Teat injury**
**Downer cow**

**Delayed**
**Milking routine not affected**
**Treated cows**
**Reproductive disorders**

## Factors that impact culling rate

**Management style**
**	****(Hansen *****et al.*****, 1998; Washburn *****et al.*****, 2002; White *****et al.*****, 2002)**

**Herd expansion**
**	****(Faust *****et al.*****, 2001)**

**bST?**

**Culling decision software**
**	****(Lehenbauer and Oltjen, 1998; Groenendaal *****et al.*****, 2004; de Vries, 2004)**

**Replacement costs**
**	****(Norman, 2004, personal communication)**

## Low culling rates

**Expanding herds**** ****(Weigel *****et al.*****, 2003)**
**Type traits**** ****(Caraviello *****et al.*****, 2003, 2004)**
**Bulk milk SCC**** ****(Barkema *****et al.*****, 1998)**
**SCS**** ****(Samore *****et al.*****, 2003)**
**Crossbreeding**** ****(Weigel and Barlass, 2003)**
**Theoretical analysis**** ****(Hill, 1980)**
**Economic evaluation**** ****(Korver and Remkena, 1979)**

## Survival rates (1966–83)

**Nieuwhof *****et al., *****1989**

## Registered vs. grade survival

**Nieuwhof *****et al., *****1989**

## Mean parities through 8

**Nieuwhof *****et al., *****1989**

## Herd composition by parity

**Nieuwhof *****et al., *****1989**

## Conclusions

**Sound information so that producers can minimize cow losses**
**Effective communication so that producers use the information**
**Overall breeding objective that includes but isn’t limited to longevity **