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

Optimists vs. pessimists. LongevityProductive lifeSurvivalStayabilityHerdlifeLife expectancy. CullingDisposalsReplacementTurnover. vs.. Selection. Natural vs. Artificial. Bos primigenius(extinct, 1672). Bos taurus(Canadian Holstein true type, 1973). Cow population vs. production.

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

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    1. 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

    2. Optimists vs. pessimists

    3. Selection Natural vs. Artificial

    4. Cow population vs. production

    5. Days open phenotypic trend

    6. 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

    7. Culling factors

    8. Longevity measures True vs. functional stayability Voluntary vs. involuntary culling

    9. Longevity definitions True longevity is the capability to delay culling Functional longevity is the capability to delay involuntary culling

    10. Longevity periods Two phases: Productive and Non-Productive phase Nonproductive = Birth to first calving Productive = First calving to disposal

    11. 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

    12. Economic value of longevity Fewer replacement heifers Higher proportion of cows in more profitable lactations Higher yield near maturity

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

    14. Time of culling Immediate Milking prevented Teat injury Downer cow

    15. Factors that impact culling rate Management style (Hansen et al., 1998; Washburn et al., 2002; White et al., 2002)

    16. 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)

    17. Survival rates (1966–83)

    18. Registered vs. grade survival

    19. Mean parities through 8

    20. Herd composition by parity

    21. Conclusions

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