Due primarily to a lack of phenotypic data, little research has been undertaken on the genetics of reproductive performance in beef cattle. The objective of this study was to quantify, using data from the Irish national cattle herd, the contribution of additive genetics to phenotypic differences in reproductive performance in beef cattle and to investigate whether routinely available early pred...

The present study was aimed to improve the reproductive performance of Corriedale ewes by nutritional flushing. Forty Corriedale ewes were divided into four treatment groups (TC, T1, T2 and T3) with 10 ewes in each group (n=10). At the beginning of the breeding season extra feeding (flushing regime) was started for approximately 34 days such that two estrus cycles were covered. First group i.e....

Beef cattle production requires reproductive efficiency. However, measures of reproductive traits are not usually collected; consequently, correlated traits that could be used as indicators would be useful. We examined associations between measures of reproductive and productive efficiency that could be used as selection indicators. Data from 194 dams of the genetic groups Angus x Nelore, Carac...

introduction: cloning an individual by transferring somatic nuclei into enucleated recipient oocytes has already been well established. this technology also offers new opportunities to restore threatened species with interspecies somatic cell nuclear transfer (scnt). however, few mammalian species have been studied for their reproductive biology whereas huge differences have been observed betwe...

Body size and development time are two critical phenotypic traits that can be highly adaptive in insects. Recent population genetic analyses and crossing experiments with the mountain pinebeetle (Dendroctonus ponderosaeHopkins) havedescribed substantial levels of neutralmolecular genetic differentiation, genetic differences in phenotypic traits, and reproductive isolation. To determine whether ...

Genetic parameters of longevity in crossbred Mule ewes, and genetic relationships among longevity, growth, body composition, and subjectively assessed traits on Mule lambs and ewes have been estimated using Bayesian linear censored models. Additionally, the genetic associations between longevity and culling reasons were examined. Data comprised 1,797 observations of Mule ewes for longevity, cul...

The objective of this study was to describe the genetic and phenotypic relationship between milk urea nitrogen (MUN) and reproductive traits in Iranian Holstein dairy cows. Test-day MUN data obtained from 57 301 dairy cows on 20 large dairy herds in Iran between January 2005 and June 2009. Genetic parameters for MUN and reproductive traits were estimated with a five-trait model using ASREML pro...

In order to estimate genetic parameters for production traits and reproductive performance, 115 465 records of production traits and 90 942 records of reproductive performance from Iranian Holstein cows that were collected during 1980 to 2004 at Animal Breeding Center of Iran, were used. The estimations were performed using Restricted Maximum Likelihood method (REML) under an animal model by DF...

The genetic basis of fitness traits has been studied widely in animals, yet the contribution of genetic variation to these traits in humans is controversial. In particular, it is difficult to disentangle genetic versus environmental effects on fertility, because of within-family correlations of sociocultural, economic, and other nongenetic factors that influence family sizes. In this study, we ...