Management Factors Affecting Conception Rate Reproductive Outcomes British Friesian vs Holstein Friesian British Friesian 1980 7% Calving rate 55% Holstein Friesian 2005 Late Embryo Mortality Early Embryo Death 28% 10% 7% Early Calving rate Embryo 40% Death 43% 10+% Fertilisation Failure Change in BCS and conception rate • 10-15% decline in conception for each 0.5 unit change in BCS between calving and AI. Effect of Calving to Service Interval on Conception Rate Calving-to-Service Interval (Days) 1-20 21-40 41-60 61-80 >80 CR% 0 30 54 63 72 Concepion Rate (%) Effect of AI timing on Conception Rate 70 60 50 40 30 20 10 0 <6 h 6-12h 12-18h 18-24h >24h Interval from Detected Heat to AI Conception Rate (%) Effect of Calving Difficulty on Conception Rate 60 40 20 0 1 2 3 4 5 6 Calving Difficulty Score Long-term improvement of cow fertility • Use High EBI (Economic Breeding Index sires) Production: Yield fat + Protein • EBI Reproduction: Calving interval Cow survival Summary -1  Calve cows in a moderate BCS  Minimise BCS loss in early lactation.  Have cows gaining in BCS at breeding.  Have heifers well-grown (350-380 kg) at 15 months.  Breed to calve early.  Minimise the risk of calving difficulty . Summary -2  Increase submission rates by paying particular attention to heat detection.  Use tail-paint.  Carry out pre-breeding heat detection.  Ensure that the semen used is of high fertility  Use AI Sires with negative values for calving interval and positive values for survival  Correct AI technique  Inseminate cows at the correct time.