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Factors affecting milk production in the Butana are investigated. Production records of 353 Butana cows with 1,311 calvings during the years 1943-57 from a governmental dairy farm herd on the north of Atbara, Sudan were analysed. Heifers averaged 44 months old at first calving. The average interval between consecutive calving was 416 days. The average milk yield in 253 days was 3,129 lb, with a standard deviation of 1,709 lb. There were highly significant differences between all production traits at different years. No real differences were evident in milk yield records due to month of calving or age of cows in lactation. Repeatability estimates of single record milk yield, calving intervals, lactation periods, and dry periods were: 0.415± 0.037, 0.111±0.039, 0.415 ± 0.043, and 0.221±0.037, respectively. Heritability of a single record milk yield was estimated as 0.278± 0.232 and two records as 0.302±0.286. The total generation length was 25.87 years, and it was estimated that the annual genetic improvement in milk yield amounted to about 0.7% of the herd average. Most of the improvement had been brought about by the selection of the sires used.

There is a growing interest in empirically exploring the biological underpinnings of political attitudes and behavior. Heritability studies are a primary vehicle for conducting such investigations and data sets rich in political phenotypes are becoming broadly accessible. A bottleneck exists, however, in exploiting these opportunities because they involve a statistical re-tooling for political scientists and require a conceptual shift that has substantial implications for the field's traditional theoretical models. Methodologically, most twin studies rely on structural equation models unfamiliar to political scientists. We show this methodological bottleneck is easily navigable; it is the lesser discussed shift in theoretical assumptions poses the larger problem to integrating biological elements into the study of political attitudes and behavior. To address these issues we provide a detailed introduction to a regression-based method for analyzing genetic influence on political attitudes and behaviors that will be methodologically intuitive to political scientists with even minimum quantitative training. In doing so, we provide a platform for bridging important conceptual divides between political science and behavioral genetics. Adapted from the source document.

This paper highlights the role of institutional resources and policies, whose origins lie in political processes, in shaping the genetic etiology of body mass among a national sample of adolescents. Using data from Waves I and II of the National Longitudinal Study of Adolescent Health, we decompose the variance of body mass into environmental and genetic components. We then examine the extent to which the genetic influences on body mass are different across the 134 schools in the study. Taking advantage of school differences in both health-related policies and social norms regarding body size, we examine how institutional resources and policies alter the relative impact of genetic influences on body mass. For the entire sample, we estimate a heritability of .82, with the remaining .18 due to unique environmental factors. However, we also show variation about this estimate and provide evidence suggesting that social norms and institutional policies often mask genetic vulnerabilities to increased weight. Empirically, we demonstrate that more restrictive school policies and policies designed to curb weight gain are also associated with decreases in the proportion of variance in body mass that is due to additive genetic influences.

This paper highlights the role of institutional resources and policies, whose origins lie in political processes, in shaping the genetic etiology of body mass among a national sample of adolescents. Using data from Waves I and II of the National Longitudinal Study of Adolescent Health, we decompose the variance of body mass into environmental and genetic components. We then examine the extent to which the genetic influences on body mass are different across the 134 schools in the study. Taking advantage of school differences in both health-related policies and social norms regarding body size, we examine how institutional resources and policies alter the relative impact of genetic influences on body mass. For the entire sample, we estimate a heritability of .82, with the remaining .18 due to unique environmental factors. However, we also show variation about this estimate and provide evidence suggesting that social norms and institutional policies often mask genetic vulnerabilities to increased weight. Empirically, we demonstrate that more-restrictive school policies and policies designed to curb weight gain are also associated with decreases the proportion of variance in body mass that is due to additive genetic influences.

AbstractAlthough genetic basis of childhood temperament has been well documented in western populations, little is known about whether genes play an important role in childhood temperament in East Asians. The present study examined mother's ratings of Emotionality, Activity, and Sociability (EAS) in 894 pairs of 2- to 9-year-old South Korean twins. The best-fitting model indicated that 34 to 47% of the variances of the EAS were attributable to genetic factors, with the remaining variances being due to the effects of environmental experiences unique to each child. Common family environmental factors were negligible. Genetic variances for Activity and Sociability were primarily nonadditive, whereas those for Emotionality were additive. In spite of well known cultural differences in child rearing practices, social values, and the mean levels of temperament between East Asian and western populations, the pattern of additive vs. nonadditive gene actions and heritability estimates found in the present sample were remarkably similar to those reported in western twin samples. There were no significant age or sex differences in genetic or environmental influences. Overall, these results corroborate cross cultural generality of genetic influences on childhood temperament.

Beckwith and Morris raise concerns about the value of twin studies for understanding the role of genetics in complex human behavior, but virtually all of their concerns have been raised and rebutted before. When it comes to the equal environments assumption (EEA), the best approach is to test for and control possible violations of the EEA on heritability estimates rather than merely rejecting all empirical evidence because of the possibility of EEA violations. In many respects, since the study of the genetic basis of complex human behaviors now includes many methods in addition to twin studies, Beckwith and Morris's critique applies more to the behavioral genetics of a quarter century ago than to today's multifaceted behavioral genetics. Twin studies establish that there is a sizeable genetic component to political orientations, thereby giving cause to look further at the nature of that role by using other methodologies, including molecular genetics. We conclude by pointing out that the normative implications of the relevance of genes to human behavior are not nearly as worrisome as Beckwith and Morris seem to believe.

AbstractThere is a trend among behavioral scientists to view ever more complex attitudes or systems of belief as in some sense genetically determined (or "heritable"). Consistent with this trend is the recent article of Alford, Funk, and Hibbing titled "Are Political Orientations Genetically Transmitted?" in which the authors claim to have demonstrated that when it comes to the transmission of political ideologies, genes count for more than environment. Their article has received an enormous amount of attention among political scientists and in the popular press. I critically evaluate the research technique on the basis of which the authors' support their claims and argue that it suffers from significant methodological flaws. Such flaws notwithstanding, I demonstrate that the authors' data do not clearly support their conclusions. I then question the cogency, from an historical and theoretical perspective, of proposing the existence of "liberal" and "conservative" "phenotypes" and "genotypes." My argument has implications beyond the findings of Alford, Funk, and Hibbing, and applies to all studies that claim to have demonstrated the heritability of complex and politically relevant attitudes.

Final body height is achieved as the result of a combination of genetic and environmental factors. The aim of this article is to review past studies on body height that have followed different scientific traditions. In modern Western societies, about 20% of variation in body height is due to environmental variation. In poorer environments, this proportion is probably larger, with lower heritability of body height as well as larger socioeconomic body height differences. The role of childhood environment is seen in the increase in body height during the 20th century simultaneously with the increase in the standard of living. The most important non-genetic factors affecting growth and adult body height are nutrition and diseases. Short stature is associated with poorer education and lower social position in adulthood. This is mainly due to family background, but other environmental factors in childhood also contribute to this association. Body height is a good indicator of childhood living conditions, not only in developing countries but also in modern Western societies. Future studies combining different scientific traditions in auxology are needed to create a more holistic view of body height.

Hypertension is a complex disease in which environment and heredity interact. It is a polygenic trait that can be studied by investigating its intermediate phenotypes. We have selected the population from the Saguenay-Lac St. Jean region because it is a relative genetic isolate. We have found that the prevalence of hypertension at every age level was greater than in a control Canadian population. A sib pair analysis was used to measure familial correlation and heritability of more than 200 phenotypes among which were renal functions, anthropometric measures and cardiac morphology and reactivity. Very strong familial correlations were estimated for several cardiovascular phenotypes. During a pharmacological infusion of norepinephrine, we observed that systolic blood pressure was increased as expected but that the heritable component of this phenotype increased from null at baseline to close to 70%. Preliminary total genome scans completed on the DNA of the participants have selected several regions linked to these phenotypes. This type of study opens the door to pharmacogenetic studies in which sib pairs are analyzed for their concordant or discordant response to a medication.

The identification of resilient sows can improve reproductive performance in farms exposed to multiple challenges. A common challenge is the porcine reproductive and respiratory syndrome virus (PRRSV). A key issue to deal with disease resilience is to set up a feasible phenotyping strategy. Our aim was to develop a phenotyping criterion to discriminate susceptible from resilient sows in PRRSV-infected farms. A total of 517 Landrace x Large White gilts were classified as resilient (R) or susceptible (S) to PRRSV virus, following vaccination with MLV-PRRSV at 6-7 wk of age, in a PRRSV negative multiplication farm. Female piglets were phenotyped as R if their serum was negative to PRRSV at 7 and 21 d post-vaccination (DPV) or as S if their serum was positive at 7 and/or 21 DPV. Amongst them, 382 gilts were transferred to a PRRSV-positive production farm, where the number of piglets born alive (NBA), stillborn (NSB), mummified (NMU), lost (NLP=NSB+NMU) and total born (NTB = NBA+NLP) were recorded for almost three years. Data were collected during two periods according to the PRRSV farm health status, which were confirmed as either PRRSV-positive stable (endemic) or inestable (epidemic). Analyses were carried out under a Bayesian approach. The heritability for the resilience criterion was estimated using a threshold model. A linear (for NTB and NBA) and a binomial model (for NSB, NMU and NLP) on the resilience criterion by the farm health status were used to assess the difference between R and S sows. The heritability of the resilience criterion was 0.46 (SD 0.06). The probability of a piglet being lost was greater (≥0.97) in S than in R litters, regardless of whether the delivery occurred during a PRRSV outbreak (20.5% vs 17.0%) or not (15.8% vs 13.7%). The lower piglet mortality rate in R sows was due to NSB, in the endemic phase (13.0% vs 15.0% of NTB, with a posterior probability of 98% of S sows showing higher NSB than R sows), and to NMU, in the epidemic phase (4.0% vs 8.4% of NTB, with a posterior probability of >99% of S sows showing higher NMU than R sows). During a PRRSV outbreak, the S sows were twice as likely to give birth to a mummified piglet as compared to R sows. These findings provide evidence that the described phenotyping scheme has a potential use as a PRRSV resilience criterion. ; This research was funded by FEDER project (COMRDI16-1-0035-03). Glòria Abella is a recipient of an industrial PhD award from the Government of Catalonia, Spain (No. 2013 DI 027)

This research, including the Langhill experiment at Crichton Dairy Research Centre and all authors, was funded by the Scottish Government Rural Affairs, Food and the Environment (RAFE) Strategic Research Portfolio 2016-2021. Samples collected pre-2016 were collected as part of a BBSRC project awarded to EW (grant no. BB/K002260/1) and TNM (BB/K002171/1). The authors gratefully acknowledge the high standard of work by all staff at Crichton farm (SRUC, Dumfries, Scotland) in the collection of samples and management of animals, and Ian Archibald (SRUC, Edinburgh, Scotland) for managing the Langhill database and assisting with data extraction. ; Peer reviewed ; Publisher PDF

The use of molecular markers to identify desirable genes in animal production is known as marker-assisted selection. The traditional genetic evaluation model uses the BLUP methodology; when genetic markers are included in the evaluation model, the methodology is known as M-BLUP. In contrast, random regression models (RRM), unlike the models based on production at 305 days, consider factors that change for each animal from one test to another. The objective of this study was to compare variance components, genetic parameters and breeding values for milk production, protein percentage and somatic cell score in Colombian Holstein cattle using BLUP, M-BLUP and RRM. For the estimation of genetic parameters and values, 2003 lactations corresponding to 1417 cows in 55 herds were used, and effects of the order of delivery, herd, and contemporary group were included. The three traits presented greater heritability under the MBLUP model: 0.44 for protein percentage, 0.27 for milk production and 0.28 for somatic cell score. This was because the genetic variance was greater when M-BLUP was used, which allowed a greater accuracy of the breeding value estimation in the three traits. Therefore, the model that includes information on molecular markers is more suitable for genetic evaluation in Colombian Holstein cattle.