Estimation of genetic trends is necessary to monitor and evaluate selection programs. The objective of this study was to estimate the genetic trends for milk yield in Iranian Holsteins cows using random regression test day model. Data set was consisted of 743205 test-day records from 1991 to 2008, which were collected by the Animal Breeding Centre of Iran. Breeding, environmental and phenotypic...

Estimated breeding values of test-day (TD) and 305-day milk yield were calculated to compare ranking of animals on the basis of two information sources under an animal model. Two statistical models were used to analyze 780 first lactation (305-day) and monthly milk yield records. The first model was an individual animal model to analyze lactation milk yield with period-season of calving as fixe...

The aim of this study was to model the variances and covariances of body weight in Zandi sheep from 60 to 365 days of age using random regression models (RRM). Legendre polynomials of different orders were used to model the direct and maternal covariances. Mean trends were also modeled through a quadratic regression on orthogonal polynomials of age. Homogeneity and heterogeneity of the residual...

random regression models (rrm) have become common for the analysis of longitudinal data or repeated records on individual over time. the goal of this paper was to explore the use of random regression models with orthogonal / legendre polynomials (rrl) to analyze new repeated measures called clutch size (cs) as a meristic trait for iranian native fowl. legendre polynomial functions of increasing...

Records on 47,360 Yorkshire, 28,762 Landrace, 14,020 Duroc, and 9,983 Hampshire pigs for backfat depth and days to 100 kg made between 1989 and 1992 in herds on the Ontario Swine Improvement Program (OSIP) were used to estimate additive genetic (animal), common environmental (litter), and residual variances and covariances of the two traits. Analysis was by the DFREML program of K. Meyer using ...