Bioscientifica Proceedings

Summary. Studies have consistently demonstrated that 4-cell pig embryos can be cultured to the blastocyst stage in a simple salt solution containing bovine serum albumin (BSA). Pig embryos appear to be detrimentally affected by lower levels of lactate and pyruvate than are mouse embryos, but in general their in-vitro requirements are similar. Results from embryos cultured between the 4-cell and blastocyst stages are consistent enough to allow the use of c...

Summary. Injection of prostaglandin (PG) F-2ct or its analogues has provided a . technique to induce parturition after Day 110 of gestation in the sow. The mean interval from PG injection to parturition ranges from 24 to 28 h, but only 50-60% of the sows farrow during an 8-10 h working day, and as many as 20% of sows may begin parturition before the injection of PG or > 22 h after the injection. The duration of parturition is positively associated with...

Keywords: pigs; nutrition; reproduction; condition; strategy© 1990 Journals of Reproduction & Fertility Ltd...

Conceptus development in mammals depends on an intra-uterine environment filled with histotroph that includes molecules that are secreted by uterine epithelia and/or selectively transported into the uterine lumen. In pigs, total recoverable glucose, fructose, arginine, leucine and glutamine increase in histotroph with advancing days of the peri-implantation period of pregnancy and in allantoic fluid later in gestation. During pregnancy, the uterine luminal epithelium (LE...

Summary. In the ram, the size of the testes is related to the concentrations of FSH, LH and testosterone in the blood. A significant linear relationship is observed between testicular size and the level of FSH until a maximum after which no further increase in testis size is observed. Testicular size is also linearly related to the mean level (25 consecutive hours of sampling) of LH and testosterone in the blood, with apparently no upper limit, and to the freq...

In nuclear transfer reconstructed embryos, the co-ordination of donor nuclear and recipient cytoplasmic cell cycle phases is essential to maintain ploidy and prevent DNA damage. However, the stage of the cell cycle at the time of reconstruction and the method of reconstruction may also have a significant impact on the subsequent development of the embryo and fetus through a number of other mechanisms. This paper reviews some of the information currently available and proposes ...

For a follicle to reach dominance, in mono-ovulatory species such as cattle, requires the integration of a number of processes involving both extra-ovarian signals and intra-follicular paracrine and autocrine regulators. Ovarian transplant studies in both cattle and sheep demonstrated that it takes approximately 4 months for primordial follicles to reach dominance. Gonadotrophins are not a prerequisite for the continued growth of pre-antral follicles, unlike antral folliclcs, ...

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

Summary. In the wild pig mating activity is seasonal. The main breeding period is in late autumn but a second period may occur around April. It is known from other species that seasonal variations in breeding activity are mainly regulated by photoperiod.In the domestic pig seasonal influences on prolificacy still exist: for example, Al boars not only show decreased steroid synthesis, sperm counts and libido in summer compared with t...

Abstract unavailable© 1990 Journals of Reproduction & Fertility Ltd...