Bioscientifica Proceedings

Abstract. The efficiency of milk production in pasture-based systems is heavily influenced by calving pattern, necessitating excellent reproductive performance in a short breeding season. Where grazed pasture is the major component of the diet, cows are underfed relative to their intake potential. A number of studies have identified body condition score measurements that are related to likelihood of both submission and conception. In general, fertility variabl...

Summary. Follicular development during early lactation in the sow is characterized by a large population of small-sized follicles and a small population of medium-sized follicles. As lactation progresses there is a gradual shift in number of follicles into medium- or large-sized categories and the percentage of follicles classified as atretic declines. Weaning at birth often leads to aberrant follicular development, apparently because the positive feedbac...

The resumption of ovarian follicular development during lactation and after weaning in sows is a complex process that ultimately determines rebreeding efficiency of sows. Ovarian follicular development before weaning is heterogeneous because multiple patterns of development are observed when individual sows are compared. Sows can have relatively inactive ovaries before weaning with follicles of < 2 mm in diameter. Other sows have nonovulatory follicular waves in which...

A technology that allows for manipulating of oestrus and ovulation, and would then also allow for fixed-time insemination, can be of great benefit for swine farms that operate using sow batch management due, at least in part, to savings in labour and the production of large batches of evenly developed pigs. Thanks to the current knowledge on endocrine regulation of follicle development and ovulation, and the availability of numerous reproductively active substances such ...

The phenomenon of embryonic diapause has been reported to possibly affect ovarian follicular development. The aim of the current study was to identify the impact of the embryonic diapause period on follicle number and oocyte quality in the European roe deer (Capreolus capreolus). In this species, the embryo undergoes five months of developmental delay. We have determined the antral follicle count (AFC), oocyte morphological quality, oocyte meiotic resumption capacity ...

Summary. Ultrasound imaging has shown that cattle exhibit 2 or 3 waves of follicular development during an oestrous cycle. The waves consist of the contemporaneous appearance, about every 7 days, of a group of follicles ≥ 5 mm in diameter. One follicle gradually becomes larger than the rest (i.e. dominant). There are several lines of evidence suggesting that the waves occur regularly under conditions of basal LH and FSH. (1) Cycles with 3 waves of follic...

The development of technologies to grow and mature oocytes from the most abundant primordial follicles holds many attractions for clinical practice, animal production technology and research. However, despite much research attention, it has proved difficult to grow follicles from early stages to maturity in vitro, as relatively little is known about the biology of oogenesis. It is clear that throughout oocyte development in vivo, follicle cell support is fund...

Abstract unavailable© 1987 Journals of Reproduction & Fertility Ltd...

During embryonic diapause, the development of the embryo is paused shortly after conception by metabolic or seasonal factors. When conditions become favorable, the embryo will resume development after reactivation by the maternal reproductive system. Inducing this resting state in in vivo or in vitro manipulated embryos may offer invaluable advantages in the long-term storage of embryos, therefore offering a potential worthwhile and novel alternative in assisted reproduction c...

In experimentally induced diapause model in mice, blastocysts remain dormant for an extended period but resume implantation competency upon estrogen injection. The underlying mechanism by which extended longevity of dormant blastocysts is maintained is unclear. We have previously shown that dormant blastocysts, during experimentally induced diapause, exhibit heightened autophagic activation. Activation of autophagy appears to be a crucial adaptive response for survival in the ...