Browsing by Subject "fertility"
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(2020)Hybrid wheat has been the focus of much research for its potential high yield, high protein content and better resistance to biotic and abiotic stresses. Nowadays, only CHA (Chemical Hybridizing Agent) method is used to induce male sterility at a commercial scale. However, this technique is hard to implement on a large production scale and other methods have been investigated for several years. CMS (Cytoplasmic Male Sterility) has been shown to be a promising way to develop hybrid wheat. However, one downside of the technique is the challenging breeding stage step and the associated conversion and restoration process. To fully express the potential gain in yield, the restoration of the cytoplasmic sterility must be complete for the F1 to be fully fertile. In this study, we investigated different methods to assess fertility restoration in nursery and compared the results with the trial notations. The collected data were also used to feed a genomic selection model to predict the behavior of untested hybrids. The results showed a high experimental error of the bagging method originated mostly from human manipulation. The visual scoring showed higher repeatability but was poorly correlated with trial score. A deeper study of the trial scoring revealed an interesting effect coming from the female and an expression of sterility for commercial lines and CHA hybrid checks. Good prediction accuracies were found for genomic selection on both methods, however deeper studies and cross prediction are needed. The multilocation trials remained the best option to score fertility restoration
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(2020)Goals Economics and fertility are widely studied areas, and the link between economics and fertility is well proven. However, less research exists concerning economics as a life course factor to fertility. The first aim of this study is to research whether the 90's depression impacted Finnish children's future fertility. The hypothesis is that if the family's economic situation decreased during the 90's depression, the children would be less willing to have children of their own later in life. The other aim is to clarify whether this effect is different depending on children's age during the depression. Methods Participants in this study were selected among the FinnFamily-register data, consisting of a longitudinal following of 60000 Finish families for four generations. Among the FinnFamily data, 43 432 participants who were born between 1975-1989 were included in this study. Participants and their parents were followed to the end of 2012. Analyses were made using Cox regression. The robust covariance matrix -method was used to allow correlation among members of the same family. Results and conclusions A change in the parents' economic situation during the 90's depression was not connected to a decrease in the child's future fertility. Neither evidence of interaction between parents' income change and child's age was found. However, it was found that the decrease and a major increase in parents' income during the 90's depression was connected to the increase in the probability of having a first child in later life. The connection between income decrease and later fertility remained statistically significant after controlling the education level, sex, age cohort, and number of siblings. The connection between a major income increase and later fertility disappeared when the number of siblings was controlled. The finding was somewhat unexpected, and more research is needed to clarify the reasons behind this effect. Particularly longitudinal research, including measurements of participants' subjective experiences and narratives associating with parents' economic difficulties, is needed in the future.
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(2014)Genetic and phenotypic parameters and relationships for fertility traits, body type traits and production were estimated. The data analyzed included 21,450 Ayrshires. Animals were reared in 2,647 herds, born from 1994 to 2005 and were progeny of 1652 sires. Analyzed fertility traits were days from first service to last insemination and number of inseminations to conception for heifers, and days from calving to first insemination for first parity cows. Production traits were first lactation milk and lifetime milk and body type traits were stature, body depth, chest width, angularity, top line, rump width and rump angle. Variance components and the heritability estimates were calculated by restricted maximum likelihood (REML) method using the DMU software. The heritability estimates of first lactation milk yield and lifetime milk yield were 0.28 and 0.08, re-spectively. The heritabilities for fertility traits in virgin heifers and first lactation cows were low (0.02 – 0.03). Heritability estimates for the type traits varied from 0.10 to 0.43. The largest heritability was found for stature (0.43) and rump width (0.27). The highest positive genetic correlations were angularity with first lactation milk (0.41) and lifetime milk (0.45), and the highest negative genetic correlation was between top line and first lactation milk (-0.33). Chest width and rump angle had a positive genetic correlation to days from calving to first insemination. The significant genetic correlations were heifer fertility with body depth, rump width and rump angle. Estimated correlations between heifer fertility traits and lifetime milk yield were positive and moderate. First parity cow fertility was not related to production traits. Fertility traits and lifetime milk have a low heritability. Progress can be made relatively fast in body traits and first lactation milk by breeding, because of the moderate heritabilities. Selection for some body type traits may cause improvement in production but deterioration in fertility. Declined heifer fertility is associated with high lifetime production. However is not reasonable to put emphasis on poor heifer fertility in selection.
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(2023)Objectives: Life satisfaction has been found to influence whether people have children. More research is needed, however, to clarify the specific role of life satisfaction on fertility intentions and their realization. In addition, no studies so far have examined whether life satisfaction has a moderating role on the realization of fertility intentions. This study examined the associations between life satisfaction and fertility intentions as well as their realization based on the Theory of Planned Behavior. The study contributes to further understanding of people’s fertility decision-making process, which also enables the design of better policies to influence fertility behavior on the societal level. Methods: Two samples from a German longitudinal panel survey (pairfam) were examined: a total sample consisting of men and women aged 18–45 who were in a relationship (n = 1031), and a sample consisting of childless men and women aged 18–35 who were in a relationship (n = 682). Linear regression was used to study the association between life satisfaction and fertility intentions. Logistic regression was used to examine the association between life satisfaction and realized fertility two years later, as well as the moderating role of life satisfaction on the realization of fertility intentions. All models were adjusted for age, gender, education level, employment status, relationship status, parity, and area of residence. Results: Life satisfaction was association with fertility intentions in men, but only in the total sample and not in the childless sample. In addition, life satisfaction was associated with the realization of fertility intentions for the first child for both genders, and among women for all parities. Marginally significant interaction effects were found between life satisfaction and fertility intentions on the likelihood of having a child two years later for women, suggesting that high life satisfaction can increase the likelihood of having a child when fertility intentions are uncertain. Conclusions: Life satisfaction is associated with the intention to have further children in men and with the realization of fertility intentions, especially in women. The results are mainly in line with previous research. They highlight the fact that people’s overall life satisfaction has an important role in fertility behavior and should be considered in policymaking.
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