Association of neuropeptide Y and gonadotrophin-releasing hormone receptor gene SNPs with breeding value for growth and egg production traits in Mazandaran native chickens.

Neuropeptide Y (NPY) and gonadotrophin-releasing hormone receptor (GnRHR) are two candidate genes with a wide variety of physiological functions in growth and especially in reproduction processes. We examined the association of one SNP from each of these genes with growth- and egg production-related traits in Mazandaran native chickens. Two hundred and six individuals were genotyped by PCR-RFLP. Marker-trait association analyses were performed using both breeding value and phenotypic information. The data came from 18 successive generations of selection at a Mazandaran native chicken breeding station in Iran. Data were analyzed with a univariate animal model in an ASREML procedure to estimate breeding values of the birds for these traits. Two alleles were found for both genes, A and a alleles for GnRHR, with frequencies of 0.614 and 0.386, B and b alleles for NPY, with frequencies of 0.780 and 0.221, respectively. The additive genetic effects of the GnRHR gene on egg number and egg mass were significant. Also, body weight at sexual maturity was significantly influenced by the NPY gene. We conclude that GnRHR and NPY genes are associated with egg production and growth traits, respectively.

Animal model estimation of genetic parameters for most important economic traits in Iranian native fowls.

(Co)Variance components and genetic parameters for economic traits in Iranian native fowls were estimated using multivariate animal model analysis with DFREML procedure. The data of four stations of native fowls breeding (Mazandaran: 49536, Esfahan: 23108, West Azarbaijan: 24890 and Fars: 30279) was containing records of cocks and hens collected during period of 1988 to 2006. The recorded traits were Body weight (at 8 weeks or 12 weeks), Age at first egg, egg number at 12 first weeks of production and mean egg weight between 28 to 32 weeks. The most estimated heritabilites, except egg number, were more than 0.20. The highest heritabilites for all traits were related to Fars station, whereas most heritabilites in West Azarbaijan were less than other stations. The heritability for egg number was estimated 0.099+/-0.018 for Esfahan to 0.322+/-0.012 for Fars. The estimated heritabilities of body weight were medium to high and varied from 0.228+/-0.014 for Esfahan to 0.548+/-0.014 for Fars, While, the heritabilities of mean egg weight were high and ranged from 0.223+/-0.021 for West Azarbaijan to 0.638+/-0.013 for Fars. The heritability for age at first egg was estimated 0.270+/-0.021 for Esfahan to 0.520+/-0.014 for Fars. The most estimated genetic correlations, except between Body weight and Egg weight and between age at first egg and egg weight, were negative. The direct genetic correlations between maturity age and egg number were high and negative, ranging from -0.384+/-0.033 to -0.987+/-0.003 for Mazandaran and Fars, respectively.