the objective of this study was to estimate variance components, genetic and phenotypic trends for somatic cell score. dataset that collected by the animal breeding center of iran was used in this study. data file included 850,729 test day records of somatic cell counts (scc)  on 32,955 cows from lactations one to four, in 472 herds, gathered from years 2002 to 2013 in iran. a test day repeatab...

to estimate heritability and genetic trend for 305-d milk production and lactation persistency, a total of 130,668 monthly test day milk yields belonging to 15,183 first lactation holstein cows in 131 herds and calved from 2000 to 2009 were used. to calculate 305-d milk yield as well as lactation persistency, estimated parameters of wilmink’s exponential function were applied. the parameters of...

A total of 72124 fertility records was used to estimate the genetic and phenotypic trend of fertility traits in Iranian Holstein cow from 1981 to 2007. Fertility traits in this study were: days from calving to first service (DFS), number of insemination per conception (INS), days open (DO), interval between first and last insemination (IFL), calving interval (CI) and success to first inseminati...

this study was carried out to investigate the effect of selection on the reduction of fat-tail size in lori-bakhtiari lambs. the study lasted for five years at the development and breeding center of lori-bakhtiari sheep station. estimation of fat-tail weight, using external fat-tail dimensions was obtained from regression procedure at 6 month age. soft tissue depth at the point 12 cm from the m...

Stochastic switching is an example of phenotypic bet hedging, where an individual can switch between different phenotypic states in a fluctuating environment. Although the evolution of stochastic switching has been studied when the environment varies temporally, there has been little theoretical work on the evolution of phenotypic switching under both spatially and temporally fluctuating select...

A fraction of a genetically homogeneous microbial population may survive exposure to stress such as antibiotic treatment. Unlike resistant mutants, cells regrown from such persistent bacteria remain sensitive to the antibiotic. We investigated the persistence of single cells of Escherichia coli with the use of microfluidic devices. Persistence was linked to preexisting heterogeneity in bacteria...