Bioscientifica Proceedings

Summary. Prolificacy, defined as litter size at birth, is currently considered to be the most important component of sow productivity. However, in spite of a spectacular increase in productivity due to management advances, litter size at birth has remained constant for the past 20 years. This situation seems to question the long-term efficiency of the classical methods of genetic improvement such as within-herd selection and crossbreeding between European...

Abstract unavailable© 1982 The authors...

Summary. Available techniques for the collection and direct transplantation of pig embryos are simple and efficient and could be used for the expansion of new lines, for increasing selection pressure in nucleus herds and for extracting healthy stock from a diseased source. However, the reduced viability of pig embryos during culture in vitro and the inability as yet to preserve them by deep-freezing impose limits to the use of embryo transplantat...

In contrast to nuclear inheritance, cytoplasmic inheritance in mammals is derived mostly, if not exclusively, from the maternal line. Mitochondria, and their DNA molecules (mtDNA), are the genetic units of this method of inheritance. Mammalian mtDNA codes for 13 enzymes used in the mitochondrial energy-generating pathway, oxidative phosphorylation, 22 tRNAs and two rRNAs. Although all transcripts of mtDNA and their translational products remain in the mitochondria, most ...

Pigs begin behavioural preparations for birth about 1-2 days before parturition. Prepartum sows wander to select a suitable site and then construct a maternal nest. The signal that initiates this behavioural cascade probably results from fetal maturation but is unknown. However, endogenous PGF2a appears to be involved early on in an endocrine pathway that projects to the brain and can generate most of the prepartum behavioural components. This period of intense activity ...

Abstract unavailable© 2009 Society for Reproduction and Fertility...

Summary. Evidence is presented for the involvement of a number of specific uterineand conceptus-derived proteins in endometrial differentiation and conceptus or feml development. These secretory proteins include mitogens (insulin-like growth factor-I and -II, epidermal growth factor, uterine lumina] fluid mitogen). binding and transport proteins (uteroferrin, insulin-like growth factor and retinal binding proteins, respectively), protease inhibitors (anti...

Summary. Tests for the detection of pregnancy early after insemination have not yet reached their full potential. Currently, the milk progesterone assay provides the earliest possible test, at an interval of one oestrous cycle after insemination, i.e. 17, 21 and 21 days in sheep, goats and cows respectively. This assay is pregnancy non-specific and rate of detection of pregnant animals is acceptable but less than desirable.Detection of a...

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...

The cervids represent a complex assemblage of taxa characterized by extreme diversity in morphology, physiology, ecology and geographical distribution. Farmed species (for example red deer and fallow deer) are usually the common larger-bodied, gregarious and monotocous species that express marked reproductive seasonality in their temperate environment. Their commercial importance has facilitated considerable research into reproductive physiology and the development of assisted...