Bioscientifica Proceedings

In swine and other livestock, the uterine endometrium exhibits dramatic morphological and secretory changes throughout the oestrous cycle and during pregnancy. Such physiological changes are a reflection of extremely complex interactions between gene products (RNA and protein). The recent development of genomics and proteomics methods, as well as associated bioinformatics tools, has provided the means to begin characterising such interactions. Indeed, the analysis of the...

Embryogenesis is a complex process that is controlled at various levels. As new discoveries are made about molecular mechanisms that control development in other species, it is apparent that these same mechanisms regulate pig embryogenesis as well. Methylation of DNA and modification of histones regulate transcription, and mechanisms such as ubiquitinization, autophagy and microRNAs regulate development post-transcriptionally. Each of these systems of regulation is highl...

The reproductive efficiency of camels under their natural pastoral conditions is low. The reasons for this low reproductive efficiency include the short breeding season, the late age of reaching puberty and the long gestation period of 13 months. The introduction of controlled breeding programmes is important but several problems have to be considered. For example, oestrous behaviour is very vague and difficult to interpret, as it does not often relate to follicular developmen...

Abstract unavailableKeywords: sheep; ovulation rate; nutrition; gonadotrophins; metabolic hormones© 1991 Journals of Reproduction & Fertility Ltd...

Abstract unavailable© 1995 Journals of Reproduction and Fertility Ltd...

Infertility associated with suboptimal nutrition is a major concern among livestock producers. Undernourished prepubertal animals will not enter puberty until they are well fed; similarly, adult, normally cyclic females will stop cycling when faced with extreme undernutrition. Work in our laboratory has focused on how body fat (or adiposity) of an animal can communicate to the brain and regulate reproductive competence. In 1994, the discovery in rodents of the obese (ob</e...

Our current understanding of pre-elongation embryo metabolism and its regulation by factors both intrinsic to the embryo and present in its immediate environment is limited mainly to studies in rodents and of ruminant embryos that have been cultured in vitro. Energy metabolism in such embryos is initially low and dependent on oxidative phosphorylation for the generation of ATP. The embryo exhibits substrate preference for carboxylic acids, such as pyruvate, during thi...

The reproductive efficiency of camels is low under natural pastural conditions and so the use of artifical insemination and embryo transfer are becoming increasingly important to improve their breeding potential. Methods to control their reproductive cycle are therefore essential. This review describes characteristics of the ovarian follicular wave pattern in camels and exogenous hormonal control of ovulation. It also summarizes the difficulties involved with artifical insemin...

The components of heterosexual behaviour in rams are reviewed as a basis for understanding partner preference behaviour. A small percentage of rams will not mate with oestrous females and if given a choice will display courtship behaviour towards another ram in preference to a female. Some of the endocrine profiles of these male-oriented rams differ from those of heterosexual controls. These differences include reduced serum concentrations of testosterone, oestradiol and oestr...

During the past 12 years, ruminants have provided a focus for some significant advances in mammalian reproductive biotechnologies. Lambs were the first offspring generated after nuclear transfer of fetal or adult cells to enucleated oocytes, and many calves of pre-determined gender are today the result of commercialized semen sexing. In 1990, the birth of one calf provided living proof that even 'dead' spermatozoa can be paternal, whereas, more recently, a short-lived ...