School of Agriculture, Food and Ecosystem Sciences - Theses

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Investigation of infertility in mated sows under intensive conditions

Hennessy, David Peter (1950-) ( 1978)

This thesis details a series of experiments investigating infertility in mated sows. The particular problem of delayed return to oestrus in sows following a normal mating to a fertile boar, was studied. The vaginal biopsy and ultrasonic methods of pregnancy diagnosis were tested for use in diagnosis of pregnancy in herds where a large proportion of sows showed a delayed return to oestrus. These methods were found unsuitable in this instance and so plasma progesterone and oestrogen levels were examined in sows,18 days after mating, in an attempt to identify affected sows. Facilities for hormone analysis were established and workable assays for progesterone, oestrogen and corticoid levels developed. Two laboratory experiments accompanied these field trials. The first was to study the temporal relationships between progesterone, oestrogen, and corticoid levels during the oestrous cycle and early pregnancy in sows. The second was to look at the effects of ACTH administration on plasma progesterone, oestrogen, corticoid, and LH levels and upon oestrus and ovulation. These experiments are described and the results discussed in this thesis. An integrating discussion and summary is included to link each section and to combine the conclusions of this thesis.