ALTHOUGH MANY PREDISPOSING FACTORS FOR THE POOR FERTILITY IN HOLSTEIN-FRIESIAN COWS HAVE BEEN IDENTIFIED, THE BIOLOGICAL MECHANISMS UNDERLYING EARLY EMBRYO MORTALITY ARE NOT COMPLETELY UNDERSTOOD. EARLY EMBRYO MORTALITY PREGNANCIES CONTRIBUTE TO SUBFERTILITY AND ANNUAL LOSS OF $1.6 BILLION IN THE DAIRY CATTLE INDUSTRY. PREVIOUSLY WE IDENTIFIED GENES IN TISSUE (ENDOMETRIUM, CORPUS LUTEUM) RESPONSES TO EARLY EMBRYO MORTALITY VIA INGENUITY PATHWAYS ANALYSIS SOFTWARE. WE WILL BE VALIDATING THESE GENES USING MRNA AND PROTEIN ASSAYS AND DETERMINE WHICH GENES CONTRIBUTE TO NORMAL PREGNANCIES COMPARED TO EARLY EMBRYO MORTALITY PREGNANCIES. THE IDENTIFICATION OF MUTATIONS IN CANDIDATE GENES THAT ARE ASSOCIATED WITH FERTILITY TRAITS WILL ALSO BE STUDIED. USE OF CLC GENOMICS WORKBENCH SOFTWARE WILL IDENTIFY THESE MUTATIONS WHICH WILL BE VALIDATED IN A DIFFERENT GROUP OF COWS (N=500) TO THIS STUDY. DAIRIES WILL BE SELECTED BY HAVING HEALTHY COWS AND RECORDS FOR FERTILITY TRAITS IN THEIR DAIRYCOMP SOFTWARE. A GENOTYPE TO PHENOTYPE ASSOCIATION STUDY CAN THEN BE CONDUCTED TO DETERMINE THE DIRECTION (POSITIVE OR NEGATIVE) RELATIONSHIP OF A MUTATION TO FERTILITY WITH HEALTH TRAITS. MUTATIONS THAT ARE POSITIVE AND COULD BE USED AS BLOOD MARKERS TO IMPROVE IN THE SELECTION OF EMBRYO SURVIVAL AND COW HEALTH. LONGER TERM GOALS ARE TIED WITH THE GENOTYPE TO PHENOTYPE STUDY ASSOCIATIONS WITH EARLY EMBRYO MORTALITY PREGNANCIES PROVIDING A BASIS FOR THE USE OF A SINGLE NUCLEOTIDE POLYMORPHISM CHIP. PRODUCERS HAVE THE OPTION TO USE THIS STATE-OF-THE-ART TOOL THAT HAS BLOOD MARKERS THAT ARE POSITIVELY ASSOCIATED WITH EMBRYO SURVIVAL AND COW HEALTH. THIS COULD THEN POTENTIALLY LEAD TO SELECTION OF REPRODUCTIVELY EFFICIENT DAIRY COWS AND MITIGATE THE ANNUAL LOSS OF 1.6 BILLION.