Selection of dairy cattle for lifetime profit

1. Selection of dairy cattle for lifetime profit Paul M. VanRaden Animal Improvement Programs Laboratory Agricultural Research Service, USDA, Beltsville, MD paul@aipl.arsusda.gov

2. Objectives • Compare national selection indexes • Document USA Net Merit index • Discuss traits that affect profit and direction of selection • Outline approach for estimating economic values

3. 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

4. Direction of Selection Trait 1 Trait 2

5. Direction of Selection Animals selected Trait 1 Accuracy contours Trait 2

6. Trait Direction Not Clear • Concentrated (less) or diluted (more) milk? • Large or small cows? • Skinny or fat cows? • Dairy or beef or dual purpose? • Direction may be changed more quickly by replacing a population than by selecting within the population

7. 1977 USDA Prediction • “If dual-purpose selection is abandoned in Europe, there may be more advantages to international semen exchange.” • “In the future, particularly if international selection goals become more uniform, research will be needed to determine what can be gained by introducing semen of bulls from other countries into U.S. improvement programs” (R.H. Miller, 1977 JDS)

8. National Index Comparisons • Compare proportion of emphasis (relative value / Σ|relative values|) • Review table published by Holstein International magazine • 1996-2000 monthly in each issue • June 2002, approximately yearly • Examine indexes in further detail

9. Holstein International, June 2002

10. National Selection Indexes:Yield and Health Traits

11. National Selection Indexes:Conformation and Management Traits

12. Questions • Do cow shows and judging contests help or harm education? • What is feed cost for protein, fat? • Net rather than gross income • Does milk volume have negative value only because of quotas? • Milk volume quotas in Europe? • People quotas in Australia, NZ?

13. Prices of Milk and Water

14. Linear vs Non-linear ProfitCalculation 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

15. Lifetime Net Merit $ • Incomes and expenses estimated from yield traits, longevity, SCS, and conformation composites • Example: body size • Convert from composite to weight • Cull price - growth cost + lactations  (calves – maintenance) = $-1.28 / kg • Less beef = more profit to dairy farmer

16. 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

17. Conclusions • Many traits in addition to yield contribute to dairy cattle profit • Longevity, fertility, and health traits have high value • Direction unclear for some traits • Indexes have improved rapidly in recent years

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