Fertilization and embryonic mortality rates in beef heifers after artificial insemination

Abstract
Reproductive failure is one of the major factors affecting output in beef and dairy herds. A total of 256 beef heifers, in 2 experiments, was used to establish fertilization rate and subsequent embryo survival rates. Fertilization rate following a single artificial insemination was 90%. Pooled estimates of embryo survival showed high survival rates up to day 8 (93%) but markedly reduced (P < 0.001) survival at days 12 (56%), 16 (66%) and 42 (58%). Apparently most embryonic mortality occurs between days 8-16.