Assessment of reproductive wastage in sheep. 2. Interpretation of data concerning embryonic mortality

Abstract

Five theoretical models of embryonic loss based on certain biological concepts concerning the ewe or the embryo are developed. It is shown that these models lead to only three distinguishable distributions of embryonic survivals in single and twin ovulating ewes, emphasizing the difficulties in interpreting such data. Two published sets of data concerning experiments involving embryonic mortality are used to illustrate the use of distribution data in interpreting the results of such experiments. The importance of isolating fertilization failure from embryonic mortality is demonstrated and the difficulties of determining causal relationships are discussed.