Records for Afshari sheep were retrieved from data collected between 2000 and 2005 at the Zanjan University experimental flock, at Zanjan, Iran. (Co)variance components and corresponding genetic parameters for birth weight (BW), weaning weight (WW), 6-month weight (W6), average daily gain from birth to weaning (ADGa), from birth to 6 months (ADGb), from weaning to 6 months (ADGc), Kleiber ratio at weaning (WWKR) and Kleiber ratio at 6 months of age (W6KR) were estimated using univariate and bivariate analyses by the DFREML procedure. The Kleiber ratio, defined as growth rate/metabolic weight, has been suggested to be a useful indicator of growth efficiency and an indirect selection criterion for feed conversion. Estimates of direct heritability (h(2)) were 0.23, 0.27, 0.11, 0.22, 0.07, 0.01, 0.13 and 0.06 for BW, WW, W6, ADGa, ADGb, ADGc, WWKR and W6KR, respectively. Maternal genetic effects represented a relatively large proportion of the total phenotypic variance for BW (m(2) = 0.22), whereas maternal permanent environmental effects were significant for W6 (c(2) = 0.15), ADGb (c(2) = 0.16), ADGc (c(2) = 0.14) and W6KR (c(2) = 0.16). Results of bivariate analyses indicated the variable genetic correlations between traits. The largest positive genetic relationships were between adjacent measurements. The moderate estimates of h(2) for early growth traits indicate that in Afshari sheep faster genetic improvement through selection is possible for these traits. In order to increase the efficiency of feed conversion, use of Kleiber ratio in selection programmes was recommended.

An animal model was used to estimate direct and maternal genetic parameters for birth weight (BW), weaning weight (WW), 9-month weight (W9) and yearling weight (YW) for a population of Zandi sheep. The magnitude of estimates of these parameters was used to evaluate the importance of direct and maternal infl uences on body weight at various stages of Zandi lambs' life. Results confi rmed the potential maternal infl uences to change pattern of body weight's heritability with age. Maternal infl uences were signifi cant for early growth traits. The importance of maternal infl uences diminished with age, although for W9 and YW those effects did not disappear completely. In contrast to variation due to maternal effects, the variance of direct effects increased from birth to a year of age. Estimates of maternal breeding values averaged by year of birth decreased throughout the experiment for both BW and WW. It was concluded that for more precise designing selection programs and, in consequence, increasing effi ciency of selection, inclusion of maternal effects as well as direct-maternal genetic covariance into the model, especially for early growth traits, is necessary.

Abstract. In the present study the growth data of Mehraban sheep were used to estimate direct and maternal additive genetic effects together with direct and maternal permanent environmental effects on body weight from birth to 270 days of age using random regression models. The fixed effects of the model were age of dam, type of birth and contemporary groups. Animal, dam, animal and maternal permanent environmental effects were considered as random effects. The models were fitted to the data using Legendre polynomials for age of lambs. Changes in residual (measurement error) variance with age were modeled by a variance function. Direct heritability estimates for the later ages with the least records tended to be overestimated, particularly heritability beyond 180 days. Maternal heritability estimates increased after birth to a maximum around 120 days of age and decreased thereafter. The results showed that covariance between weights of lambs for a considerable range of ages can be modelled properly using random regression.

In relation to the growing recent interest in the establishment of sperm-mediated gene transfer (SMGT) technology as a convenient and effective method for the simple production of transgenic animals, in this study the possibility of using SMGT to produce transgenic caprine embryos was investigated for the first time. Buck sperm were directly incubated with different concentrations (0-500 ng) of pcDNA/his/Lac-Z plasmid and used for IVF or ICSI. Sperm used for ICSI were categorized into motile or live-immotile group before being injected into oocytes. In a separate experiment, dead sperm prepared by repeated freezing/thawing were used for DNA-incubation before ICSI. Sham injection was carried out by intracytoplasmic injection of approximately the same volume of media containing different doses of DNA using an ICSI needle. Transgene expression and transmission were detected by X-Gal staining and PCR analysis of developed embryos, respectively. A reasonable blastocyst rate was observed in all the groups. Only embryos in the sham group were negative for transgene transmission. Transgene expression was completely dependent on the delivery technique and status of sperm, and was only observed in the live-immotile and dead ICSI groups. The results of this study showed that the technique (IVF vs. ICSI vs. sham injection), sperm status (motile vs. live-immotile vs. dead) and to some extent DNA concentration affect embryo development, transgene transmission and expression.

The aim of the present study was to estimate variance components and genetic parameters among growth traits of Iranian Mehraban sheep using single and two-trait animal models. Analyzed traits included, birth weight (BW), weaning weight (WW), weight at 6 months (W6), weight at 9 months (W9) and yearling weight (YW). (Co)variance components were estimated with REML for an animal model that included fixed effects of year, season, age of dam, sex and type of birth. Random effects included direct and maternal additive genetic effects, maternal permanent environmental effects with a direct-maternal genetic covariance and random residual effects. Direct heritability (h2) was increased from 0.19 at birth to 0.36 at yearling age. Inversely, maternal heritability (m2) estimates were decreased from 0.11 at birth to 0.01 at yearling age. Estimates of maternal permanent environmental variance as a proportion of phenotypic variance (c2) were 0.06 and 0.04 for BW and WW, respectively and they were very negligible for other traits. Direct-maternal genetic correlation (ram) was positive and it increased with age from 0.05 for BW to 0.73 for YW. For the two–trait analyses, the genetic correlations were larger among WW, W6, and W9 (0.59 to 0.82) and were small between BW, W9, and YW (<0.4). Positive genetic correlations between traits show that selection at any age is possible