Bioscientifica Proceedings

Summary. Ovine and bovine trophoblast protein-1 (oTP-1 and bTP-1) have been strongly implicated as antiluteolytic agents and responsible for maternal recognition of pregnancy in sheep and cattle, respectively. Both are interferons (IFN) belonging to the IFN-α family, but their length (172 residues versus 166 for most IFN-α) places them in an unusual subclass (the IFN-αII). The various isoforms of oTP-1 and bTP-1 produced by trophoblas...

As milk production has increased during the past four decades, conception rates in lactating cows have declined. Although reduced reproductive performance has been associated with high milk yields, measures of postpartum ovarian activity have been more closely related to energy balance. The relationship between daily energy balance and postpartum reproductive activity is confirmed by longer intervals to first ovulation in cows with greater body condition loss. Patterns in dail...

Changes in the nutrition of mature rams and goat bucks lead to profound responses in testicular size and therefore the rate of production of spermatozoa. These effects are largely due to changes in the size of the seminiferous tubules and in the efficiency of spermatogenesis. With the exception of severe undernutrition, the effects on spermatogenic function are not accompanied by similar changes in endocrine function of the testes, as measured by the production of testosterone...

The induction of synchronous ovulatory activity in anovulatory sheep and goats after the introduction of males, the 'male effect', has probably been used to advantage since these species were domesticated and the underlying physiological and behavioural mechanisms have been progressively elucidated over the past 50 years. Less well understood is the analogous effect of oestrous females on males. This review examines the nature and importance of these male–female i...