EARLY PREGNANCY LOSS IS A MAJOR HURDLE THAT THE CATTLE INDUSTRY FACES.INDEED, NEARLY HALFOF BEEF COWS WILL BE NONPREGNANT AT DAY 30 FOLLOWING A SINGLE INSEMINATION. SIMILARLY, EARLY PREGNANCY LOSS IN LACTATING DAIRY COWS CAN BE AS GREAT AS 46%. THIS LEADS TO NEGATIVE ECONOMIC EFFECTS THAT STEM FROM AN INCREASED NUMBER OF NONPREGNANT COWS ACCRUING MAINTENANCE COSTS, FEWER TOTAL POUNDS OF CALF AT WEANING, REDUCED LIFETIME MILK PRODUCTION AND INCREASED CULLING IN DAIRY COWS. SUBSTANTIAL EMBRYONIC LOSSES (13-24%) OCCUR DURING BLASTOCYST HATCHING AND EMBRYO ELONGATION, BUT LITTLE PROGRESS HAS BEEN MADE TO ELUCIDATE FACTOR(S) RESPONSIBLE FOR THESE LOSSES. THIS PROPOSAL WORKS TO INVESTIGATE EMBRYONIC LOSSES OCCURRING AT THIS TIME POINT IN DEVELOPMENT.BASED ON PRELIMINARY DATA FROM OUR LAB INVESTIGATING AN EMBRYOKINE CALLED INTERLEUKIN-6 (IL6), THE PROJECT DIRECTOR DEVELOPED ACENTRAL HYPOTHESIS OF THIS PROPOSAL WHICHIS THATIL6 FUNCTIONS AS A KEY FACILITATOR OF EARLY EMBRYONIC DEVELOPMENT IN CATTLE AND THUS, IT IS ESSENTIAL FOR NORMAL DEVELOPMENT IN VIVO. SHEWILL OBJECTIVELY TEST THIS CENTRAL HYPOTHESIS USING CRISPR-CAS9 GENE EDITING AND RNA SEQUENCING TECHNOLOGY IN ADDITION TO OTHER BIOCHEMICAL AND MOLECULAR TECHNIQUES. COLLECTIVELY, THE EXPERIMENTS CONTAINED WITHIN THIS PROPOSAL WILL PROVIDE NOVEL INSIGHTS INTO INNER CELL MASS DEVELOPMENT AND BLASTOCYST ELONGATION IN CATTLE.