The present study investigated whether associations between individuals' personality traits and whether they have children have been modified by birth-cohort effects in the 20th-century United States. Participants were from the Midlife Development in the United States study (n = 6,259) and the Wisconsin Longitudinal Study (n = 3,994) and were born between 1914 and 1974. Data on personality trai...

Male reproductive success is determined by the ability of males to gain sexual access to females and by their ability to fertilize ova. Among polygynous mammals, males differ markedly in their reproductive success, and a great deal of effort has been made to understand how selective forces have shaped traits that enhance male competitiveness both before and after copulation (i.e., sperm competi...

The present study investigated whether associations between individuals’ personality traits and whether they have children have been modified by birth-cohort effects in the 20th-century United States. Participants were from the Midlife Development in the United States study (n = 6,259) and the Wisconsin Longitudinal Study (n = 3,994) and were born between 1914 and 1974. Data on personality trai...

The objective of this study was to estimate the heritability of a number of traditional and endocrine fertility traits in addition to d-56 predicted milk yield (MY56), and the genetic and phenotypic correlations between these traits. Various fixed effects such as season, year, herd, lactation number, diet, percentage Holstein (PCH) of the cow, and occurrence of uterine infection (UI), dystocia ...

Genetic selection in primary broiler breeders may modify skeletal structure, possibly impeding semen transfer, and could alter the size and degree of fluctuating asymmetry (FA) of bilateral traits associated with fertility. Hence, we hypothesized specific morphometric traits could predict differential fertility. Sixty primary broiler breeder males from Strains A and B (n = 30/strain) were indiv...

Genetic variation in estrus traits derived from hourly measurements by electronic activity tags was studied in an experimental herd of Holstein (n = 211), Jersey (n = 126), and Red Dane (n = 178) cows. Both virgin heifers (n = 132) and lactating cows in the first 4 parities (n = 895 cow parities) were used, giving a total of 3,284 high-activity episodes indicating estrus. The first estrus after...

The aim of this thesis was to explore conditions for selection and genetic improvement of fertility and longevity in dairy cattle. The background is that single-trait selection for milk production is known to lead to impaired fertility and consequently to shorter lifespan. This in turn results in financial losses and ethical concerns. Since many years, the Swedish dairy farmers have recorded mi...

the study was conducted to determine the effects of turkey (meleagris gallopavo)egg weight on certain egg traits and hatching performance. a total of 178 turkey eggs comprising of three different egg weight groups below 60 g (g i), 61 to 69 g (g ii) and above 70 g (g iii) were used for this study. average egg weight (g), egg length (cm), egg breadth (cm) and egg volume (cm3) values increased wi...