2005 Paul VanRaden Animal Improvement Programs Laboratory Agricultural Research Service, USDA, Beltsville, MD An Example from Dairy Cattle Selection: The Net Merit Index

BIF 2005 (2) VanRaden 2005 The Old Way of Selecting Cattle

BIF 2005 (3) VanRaden 2005 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

BIF 2005 (4) VanRaden 2005 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

BIF 2005 (5) VanRaden 2005 Direction of Selection Trait 1 Trait 2 Accuracy contours Animals selected

BIF 2005 (6) VanRaden 2005 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

BIF 2005 (7) VanRaden 2005 Coefficients of variation (CV) Trait Herit- ability CV (%) Pheno- typic Genetic Stature Protein yield Longevity Fertility

BIF 2005 (8) VanRaden 2005 Measures of accuracy Averages for recently proven Holstein bulls Trait ACC r BV,EBV REL r 2 EBV,BV BIF ACC 1 -  1-r 2 Protein yield SCS (mastitis) Productive life Cow fertility Calving Ease

BIF 2005 (9) VanRaden 2005 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

BIF 2005 (10) VanRaden 2005 History of USDA economic indexes (PD$, MFP$, CY$, and NM$) and Holstein Association TPI Year Introduced and Index Name TraitPD$TPIMFP$TPICY$TPI NM$TPI NM$ Protein Fat Milk % Fat20 Longevity SCS Udder Feet / legs Size -4 Final Score

BIF 2005 (11) VanRaden 2005 Current National Selection Indexes: Yield and Health Traits Country (Interbull Code) USADEUFRANZLNLDCANGBRAUSITADNKSWE % of Interbull Population Index NameNM$TPIRZGISUBWDPSLPIPLIAPRPFTS – ITMI Trait Protein Fat Milk % Protein 4223 % Fat 1212 Longevity SCS / mastitis Fertility Other diseases 23

BIF 2005 (12) VanRaden 2005 Current National Selection Indexes: Conformation and Management Traits Country (Interbull Code) USADEUFRANZLNLDCANGBRAUSITADNKSWE % of Interbull Population Index NameNM$TPIRZGISUBWDPSLPIPLIAPRPFTS – ITMI Trait Udder traits Feet / legs Size Dairy character-22 Rump11 Final score1342 Calving ease Growth / meat46 Milking Speed <146 Temperament523

BIF 2005 (13) VanRaden 2005 Milk Pricing and Feed Cost ($ per pound) IndexMilkFatProtein Fluid Merit Net Merit Cheese Merit Feed Cost

BIF 2005 (14) VanRaden 2005 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

BIF 2005 (15) VanRaden 2005 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

BIF 2005 (16) VanRaden 2005 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

BIF 2005 (17) VanRaden 2005 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

BIF 2005 (18) VanRaden 2005 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

BIF 2005 (19) VanRaden 2005 Top Net Merit Bulls May 2005 BullCntryDtrs NM$ REL Net Merit $ Pro- tein O ManUSA Loe MartinNLD LombardDEU MascolDEU MarionUSA S D JordanNLD AltonUSA

BIF 2005 (20) VanRaden 2005 Trait Harmonization Mark, 2003 EAAP meeting Trait Coun- tries Average corr. Avg. cor w / USA Protein Stature Fore Udder SCS Longevity D. CalvEase M. CalvEase

BIF 2005 (21) VanRaden 2005 Paul’s Beef Experience

BIF 2005 (22) VanRaden 2005 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

BIF 2005 (23) VanRaden 2005 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

BIF 2005 (24) VanRaden 2005 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