Reproductive physiology in the pig with special reference to early weaning

1972 ◽  
Vol 1 ◽  
pp. 5-18 ◽  
Author(s):  
C. Polge
Keyword(s):  
Special Reference ◽  
Post Partum ◽  
Experimental Studies ◽  
Reproductive Physiology ◽  
Early Weaning ◽  
Reproductive Ability ◽  
Profound Influence

The object of this paper is to review some aspects of reproductive physiology in the pig, especially in relation to conditions after farrowing when reproductive ability is normally inhibited by lactation and suckling, and when weaning at different periods after parturition may have a profound influence on the chances of successful conception and pregnancy. In undertaking this review, however, it soon became clear that very few detailed experimental studies had been carried out in sows during the period immediately following parturition. It was considered best, therefore, to compare some of the situations which exist in pigs at other reproductive stages with what little is known about the sow at the post partum stage and during lactation.

scholarly journals REPRODUCTIVE PHYSIOLOGY OF THE POST PARTUM COW

Reproduction ◽  
1969 ◽  
Vol 18 (3) ◽  
pp. 493-500 ◽  
Author(s):  
W. C. WAGNER ◽  
W. HANSEL
Keyword(s):  
Post Partum ◽  
Reproductive Physiology

Oestrous cycle and gestation length in the musky rat-kangaroo, Hypsiprymnodon moschatus (Potoroidae : Marsupialia)

2001 ◽  
Vol 49 (1) ◽  
pp. 37 ◽  
Author(s):  
Shan Lloyd
Keyword(s):  
Epithelial Cells ◽  
Captive Breeding ◽  
Common Ancestor ◽  
Post Partum ◽  
Reproductive Physiology ◽  
Oestrous Cycle ◽  
Gestation Length ◽  
Vaginal Smears ◽  
Breeding Colony ◽  
Male And Female

Wild-caught male and female H. moschatus were maintained in a captive breeding colony. Vaginal smears were taken three times a week until oestrous cycles were detected and gestation lengths approximated. Thereafter, smears were usually taken daily when oestrus was expected. The gestation period (considered to be the number of days from the detection of sperm in the smear until the day young were found in the pouch) was found to last 19 days. Sperm were usually detected in the smear two days before the influx of semi-cornified and cornified epithelial cells, which occurred 17 days before parturition. A pre- or post-partum oestrus was not detected and females did not return to oestrus until at least 6 days after the removal of the last pouch young. H. moschatus has the shortest recorded gestation for any macropod, and gestation occupies approximately 75% of the oestrous cycle. The reproductive physiology of H. moschatus is similar to that of most phalangerids, which may be indicative of a common ancestor.

Population Numbers and Reproductive Health

Endocrinology ◽  
2021 ◽  
Vol 162 (11) ◽  
Author(s):  
Alexander Suvorov
Keyword(s):  
Reproductive Behavior ◽  
Alternative Hypothesis ◽  
Experimental Studies ◽  
Causal Chain ◽  
Reproductive Physiology ◽  
Global Changes ◽  
Population Densities ◽  
Related Factors ◽  
And Behavior ◽  
Population Numbers

Abstract A recent study published in The Lancet predicts a remarkable drop in population numbers following a peak that will be reached by 2064. A unique feature of the upcoming population drop is that it will be almost exclusively caused by decreased reproduction, rather than factors that increase rates of mortality. The reasons for decreased reproduction are also unique, as, unlike previous centuries, limited reproduction today is hardly due to a shortage in resources. In other words, the predicted population drop is almost exclusively due to changes in reproductive behavior and reproductive physiology. Today, global changes in reproductive behavior are mostly explained by social sciences in a framework of demographic transition hypotheses, while changes in reproductive physiology are usually attributed to effects of endocrine-disrupting pollutants. This review outlines a complementary/alternative hypothesis, which connects reproductive trends with population densities. Numerous wildlife and experimental studies of a broad range of animal species have demonstrated that reproductive behavior and reproductive physiology are negatively controlled via endocrine and neural signaling in response to increasing population densities. The causal chain of this control system, although not fully understood, includes suppression of every level of hypothalamic-pituitary-gonadal cascade by hypothalamic-pituitary-adrenal axis, activated in response to increasing stress of social interactions. This paper discusses evidence in support of a hypothesis that current trends in reproductive physiology and behavior may be partly explained by increasing population densities. Better understanding of the causal chain involved in reproduction suppression by population density–related factors may help in developing interventions to treat infertility and other reproductive conditions.

Experimental studies on acute strangulated intestinal obstruction in germfree animals with special reference to the cause of death

1971 ◽  
Vol 6 (1) ◽  
pp. 23-24
Author(s):  
K. Adachi ◽  
M. Miyashita ◽  
A. Shirota ◽  
M. Miki ◽  
K. Ookawa ◽  
...  
Keyword(s):  
Intestinal Obstruction ◽  
Special Reference ◽  
Cause Of Death ◽  
Experimental Studies ◽  
Germfree Animals
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