Fertility rates

In summary, although the available reproductive studies indicate endosulfan has no adverse effects on reproductive performance in animals, adverse effects on male reproductive organs have been seen in young rats and mice. The lack of effects seen in the studies that examined reproductive performance (specifically fertility rate) in treated males and females seems difficult to explain, given the finding of altered spermatogenesis in the more recent studies. 

Lin S, Hwang S, Marshall EG, et al. 1996. Fertility rates among lead workers and professional bus drivers A comparative study. Ann Epidemiol 6 201-208. 

Rabbit Biodynamic versus conventionally grown feed Fertility rate of rabbits remained constant over three generations in rabbits fed biodynamic feed but declined in rabbits fed conventional feed (Staiger, 1986, cited by Vogtmann, 1988)... 

Parental stock Percentage of eggs capable of brooding Fertility rate Hatching rate Number of chicks per hen Feed consumption per chick... 

Growth and fertilization rate normal liver copper >70 mg/kg DW 63% of embryos developed normally (2)... 

Not only is it difficult to detect effects on male fertility because of group-size considerations, effects on male fertility mediated by decreased sperm production are also difficult to detect because of the normally huge excess of sperm included in a rat ejaculate. Sperm production can be decreased by up to 90% without effect on fertility (either pregnancy rate or litter size) in the rat. This is not the case for men, so the sperm excess in the rat represents a serious flaw in the rat model (see Working, 1988). To address this deficiency and improve the sensitivity of the model, it is advisable to determine the effects of the test agent on testes weights, testicular spermatid counts, and histopathology of the testes (preferably plastic sections) in the male fertility study and/or the 14-week toxicity study. In some cases, these parameters may be more predictive of possible effects on male fertility in humans than the fertility rate in rats. 

In mice and male rats, the oral LD50 was approximately 4g/kg symptoms of toxicity were ataxia and hyperactivity followed by inactivity, loss of muscular tone, labored breathing, clonic convulsions, and death within 2-7 days. Daily administration of 132mg/kg body weight in the diet for 13 weeks decreased the fertility of CD rats 14 days at 96mg/kg altered the estrous cycle of females." In female rats 50 mg/kg injected intraperitoneally on the day of proestrus delayed ovulation and resulted in a lower fertility rate, a reduction of live fetuses, an increase in resorptions, and a slower rate of fetal development. Gavage doses in rats of... 

Animal suppliers can be a source of historical control data, although it is usually limited, since they do not typically perform cesarean sections or fetal or pup evaluations, but they may compile some natural delivery data such as litter size and fertility rates in breeding colonies. This type of data can be useful when a laboratory is attempting to gain a basic understanding of the reproductive performance of a species/strain, or gather information about a particular supplier or supplier site with which they are not familiar. 

While fertility rates can vary a great deal, it is common for approximately 50% of pair crosses to produce eggs. Mating rates tend to be significantly higher in groups. 

In the same regard, PPCP introductions through manure and biosolids that are applied to arable land is enhanced by the typically high application rates of these forms of crop fertilizers rates that are usually higher than the crop needs (Kumar et al., 2005). It is recommended that manure and biosolids application rates be based on the nutrient requirements of the intended crop so as to minimize the unintended introduction of these micropollutants into the food chain at levels that can be avoided. 

No effect on sperm motility or on fertilization rate at lower dose some effect on sperm motility at higher dose... 

The hypothesis that environmental endocrine disruptors may contribute to diseases of the male reproductive tract has spurred considerable research on this area, with a particular emphasis on changes that have occurred over time. There are no apparent global changes in sperm counts and fertility, rates of hypospadias and cryptorchidism, and birth sex ratios. Testicular cancer is increasing in most countries, but it is not correlated with other indicators of male reproductive capacity. Moreover, testicular cancer is increasing while DDE and other POPs are decreasing, suggesting that exposure to these compounds is not linked to testicular cancer. 

In a study of the relevance of the serum concentration of human chorionic gonadotrophin in 849 IVF cycles there were no significant relations between hCG concentrations and the proportion of follicles yielding oocytes, the fertilization rate, blastulation rate, or the probabilities of embryo transfer, implantation, or clinical pregnancy (32). This result again stresses the desirability of using moderate doses of hCG, which seems to reduce the risk of ovarian hyperstimulation while maintaining efficacy. 

Geva, E., Bartoov, B., Zabludovsky, N., Lessing, J.B., Lemer-Geva, L., and Amit, A. 1996. The effect of antioxidant treatment on human spermatozoa and fertilization rate in an in vitro fertilization... 

Reducing Total Fertility Rate. Ecological Footprint per capita. 

Reproduce and be genetically maintained through natural mating. Expected fertility rates should be between 70% and 80%. 

The Muscovy is also raised commercially in several areas of the world. Muscovies and common ducks mate naturally although the fertility rate is usually very low. These hybrids are typically sterile and referred to as mule (Muscovy male x common female) or hinny (common male x Muscovy female) ducks. These hybrids are often raised commercially for meat production. In many areas of the world the Kaiya duck is popular, being produced from the cross of Pekin and Tsaiya. It was developed in Taiwan where it is a traditional native breed (Lee, 2006). The Pekin is a meat duck while the Tsaiya, a native duck in Taiwan, is used for egg production. 

Once a strain is frozen as sperm we strongly recommend that 1-2 straws be used to assess the quality of the sperm post-thaw. Although various devices exist to measure sperm motility etc., the only relevant test for sperm function is an actual IVF. Additionally, fertilization rates vary widely among commonly available inbred strains also the introduction of mutations and genetic modifications into a strain can have indirect and unanticipated effects on the quantity and quality of oocytes and sperm produced, as well their performance during IVF (12, 17). 

Typical doses are in the range of 2.5-5 i.u. per mouse. Optimal dose varies by strain, age, and weight of the mouse. Extending the oocyte collection window beyond 14 h post-hCG may reduce fertilization rates and compromise embryo quality due to oocyte aging. 

The use of a low O2 culture environment may not improve fertilization rate, but appears to improve embryo quality (20,21). 

If stud males are not routinely used for mating to superovu-lated females, we find it advantageous to practice mate the stud males to any strain of female on-hand 1-2 weeks prior to the next transgenic NOD experiment. This helps ensure the highest plug and fertility rates when it comes time to mate to superovulated NOD females. 

This test is usually much more sensitive, but considerably more expensive and slower, than the dominant-lethal test,131 and it deals with a clearly defined type of mutation that is transmitted to and scored in viable offspring. Males are exposed to the test substance and mated to untreated females. Male progeny (usually derived only from post-sperroatogonial treatments) are tested for translocations by the fertility test or the cytogenetic test. In the fertility test, males are tested, usually with a sequential procedure, to determine fertility rates.137 Animals suspected of having a translocation (because of decreased fertility) are then subjected to cytologic examination. 

It has been demonstrated that both water stress and varied fertilization rates can result in increased content and greater biochemical diversity of the fraction of glia-dins in wheat (Konopka et al. 2007). 

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