@article { author = {Ibrahim, A.}, title = {THE PRKAG3 GENE POLYMORPHISMS AND THEIR ASSOCITATIONS WITH GROWTH PERFORMANCE AND BODY INDICES IN BARKI LAMBS}, journal = {Egyptian Journal of Sheep and Goats Sciences}, volume = {10}, number = {3}, pages = {1-14}, year = {2015}, publisher = {Egyptian Association for Sheep and Goats}, issn = {2090-0386}, eissn = {2090-0376}, doi = {10.21608/ejsgs.2015.26637}, abstract = {ABSTRACTIn this study the polymorphisms rof a variable fragment located between exon 4 and exon 6 of the ovine protein kinase adenosine mono-phosphate activated gamma 3 (PRKAG3) gene were detected in 59 males and 62 females of Barki lambs using the polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP) analysis, followed by cloning and sequencing the detected SSCP banding patterns.The associations of PRKAG3 gene polymorphisms with growth traits (birth weight, weaning weight, pre-weaning daily gain, marketing weight and post-weaning daily gain) and body indices (body mass index, skeletal muscle index, body index and relative body index) were tested using general linear models of SAS (2000). The models included animal genotype, gender of lamb and parity of ewe as fixed effects. Age at weaning was included as a covariate in the models assessing the effect of PRKAG3 genotype on pre-weaning daily gain and weaning weight as well as age at marketing was included in the models assessing the effect of PRKAG3 genotype on post-weaning daily gain, marketing weight and body indices.Three genotypes (AA, AB and BB) were identified with frequencies of 0.26, 0.50 and 0.24, respectively. These genotypes were derived from two alleles (A and B) with frequencies of 0.51 and 0.49, respectively. The variation in PRKAG3 gene showed significant associations with marketing weight (P ˂ 0.05), post-weaning daily gain (P ˂ 0.01), skeletal muscle index (P ˂ 0.05) and body mass index (P ˂ 0.01). The presence of B allele was associated with heavier marketing weight (P ˂ 0.05), faster post-weaning daily gain (P ˂ 0.01) and higher body mass index (P ˂ 0.01) and skeletal muscle index (P ˂ 0.05).The presented results give valuable information to select for B allele and against A allele of PRKAG3 gene to improve marketing weight and muscularity of Barki lambs.}, keywords = {}, url = {https://ejsgs.journals.ekb.eg/article_26637.html}, eprint = {https://ejsgs.journals.ekb.eg/article_26637_7b0ec0760d92ffe812ba6e5574247728.pdf} } @article { author = {Ibrahim, A.}, title = {GENETIC AND NON-GENETIC ASPECTS OF EARLY GROWTH TRAITS IN NEW ZEALAND ROMNEY SHEEP}, journal = {Egyptian Journal of Sheep and Goats Sciences}, volume = {10}, number = {3}, pages = {1-12}, year = {2015}, publisher = {Egyptian Association for Sheep and Goats}, issn = {2090-0386}, eissn = {2090-0376}, doi = {10.21608/ejsgs.2015.26638}, abstract = {ABSTRACTThe aim of the present study was to analyze the effect of genetic and non-genetic factors on the early growth traits of New Zealand Romney sheep. Early growth data of 1629 lambs (863 males and 766 females), progenies of 20 rams and 905 ewes, were used to test the factors affecting birth weight (BW), adjusted weight for 90 days (W90) and average daily gain from birth to weaning (ADG) using the general linear model of SAS software (SAS, 2000). The fixed effects were the year of birth, the parity of ewe, the gender of lamb and the type of birth. Bi-interactions between the fixed effects were included in the statistical model. The co-variance components, direct (h2a) and maternal (h2m) heritabilities, and genetic (rG) and phenotypic (rP) correlations among the studied traits were estimated using MTDFREML (Boldman et al., 1995).Year of birth had no effect on all the studied traits. The parity of ewe proved significant effect (P ˂ 0.01) on both W90 and ADG. The gender of lamb and type of birth contributed significantly (p ˂ 0.001) to the variation of the studied traits. The parity of ewe interacted with gender of lamb to significantly (P ˂ 0.01) affect ADG and also interacted with type of birth to significantly affect BW (P ˂ 0.001), W90 (P ˂ 0.001) and ADG (P ˂ 0.05). Significant effects were observed on BW (P ˂ 0.05), W90 (P ˂ 0.001) and ADG (P ˂ 0.01) due to the interaction between gender of lamb and type of birth.The estimates of h2a for BW, WW and ADG were 0.15 ± 0.02, 0.08 ± 0.03 and 0.16 ± 0.05, respectively; however, the corresponding estimates of h2m for these traits were 0.30 ± 0.02, 0.20 ± 0.02 and 0.16 ± 0.05, respectively. The additive genetic variance (σ2a) for BW, WW and ADG were 0.106, 1.419 and 0.0004, respectively, and the corresponding maternal genetic variance (σ2m) for these traits were 0.213, 6.535 and 0.0004, respectively. The estimates of environmental variance (σ2p) were 0.357, 11.289 and 0.0012 for BW, WW and ADG, respectively, which contributed to the higher proportion of total phenotypic variance for all these traits.According to these findings, it is important to consider the role of various environmental factors in New Zealand Romney sheep production, since they affected the early growth performance of lambs. The low to moderate estimates of h2a for early growth traits indicate to the possibility of improving them using traditional or genomic selection. Furthermore, selection for any of the studied traits would be expected to have a large effect on the other growth traits as a result of their moderately positive genetic correlations.}, keywords = {}, url = {https://ejsgs.journals.ekb.eg/article_26638.html}, eprint = {https://ejsgs.journals.ekb.eg/article_26638_0b7b8472e4bb8cfb20ec46f8a8be75d1.pdf} }