Browsing by Author "Cumming, Ian A"

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    A study of ovulation and early prenatal mortality in the New Zealand Romney ewe : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science, Massey University
    (Massey University, 1965) Cumming, Ian A
    The production of a lamb is the end result of a series of events the formation of fertile ova and spermatozoa to the independent existence of the lamb. The main essentials for high rates of reproduction in sheep are a high proportion of multiple ovulations, successful fertilization and gestation,and and a high rate of survival of new born lambs. Fertility is a qualitative term denoting ability to produce young, the quantitative equivalent being fecundity which denotes the number of young produced per individual (Asdell,1946). The expression prenatal mortality is used to cover all loss between ovulation and parturition being the discrepancy between the number of ova and the number of young born alive. The subject of prenatal mortality has been reviewed with reference to farm animals by Laing (1952), Casida (1953,1956), Robinson ( 1957), and Hanly (1961). [From the introduction]