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To follow the inheritance potential for heat tolerance after a crossing program in goats, 24 kids from four groups of goat kids (6 kids in each) from Aradi (A) and Damascus (D), their crossbred first-generation F1 (½D½A) and second-generation F2 (¾D¼A), were exposed to acute elevated environmental temperature in controlled climatic chambers. Rectal temperature (RT), respiratory rate (RR), heat tolerance coefficient (HTC), adaptability coefficient (AC), and mRNA expression of heat shock proteins 70 and 90 ((HSP70 and HASP90, respectively), using real-time PCR were estimated. Results showed that Aradi breed goats had the highest level of expression for heat shock proteins 70 and 90, followed by F1, F2, and Damascus (P ≤ 0.01). Crossbreeds and Damascus showed the highest RT, while Aradi breed showed the lowest value (P ≤ 0.01). Aradi and crossbreeds showed the highest RR, while Damascus showed the lowest RR (P ≤ 0.05). Aradi and F1 showed the highest HTC (P ≤ 0.05), while there was no significant difference between pure breeds and crossbreeds in AC. A significant positive phenotypic correlation (0.81) was observed between HSP70 and HSP90. In addition, RR showed moderate positive correlation with both HSP70 and HSP90. It could be concluded that Aradi breed had putative heat tolerance in comparison to its crossbred progeny from the Damascus breed. The crossbreeding may result in some loss of heat tolerance potential, but the crossbreeds still better adapted to high environmental temperature than the Damascus breed. [ABSTRACT FROM AUTHOR]

A genome scan was conducted on the basis of the daughter design to detect quantitative trait loci (QTL) influencing udder morphology traits in Spanish Churra dairy sheep. A total of 739 ewes belonging to 11 half-sib families were genotyped for 182 microsatellite markers covering 3,248.2 cM (Kosambi) of the ovine autosomal genome. Phenotypic traits included scores for 5 linear udder traits: udder depth, udder attachment, teat placement, teat size, and udder shape. Quantitative measurements for the QTL analysis were calculated for each trait from evaluation scores using within-family yield deviations corrected for fixed environmental effects. Joint analysis of all families using Haley-Knott regression identified 5 regions that exceeded the 5% chromosome-wise significance threshold on chromosomes 7, 14, 15, 20, and 26. Based on the across-family results, a within-family analysis was carried out to identify families segregated according to the QTL and to estimate the QTL effect. The allelic substitution effect for individual families ranged from 0.47 to 1.7 phenotypic standard deviation units for udder shape on chromosome 15 and udder depth on chromosome 14, respectively. These QTL regions provide a starting point for further research aimed at the characterization of genetic variability involved in udder traits in Churra sheep. This paper presents the first report of a sheep genome scan for udder-related traits in a dairy sheep outbred population. [ABSTRACT FROM AUTHOR]

Eleven half-sib ovine families, including 1,421 Spanish Churra ewes, were analyzed for 181 microsatellite markers spanning the entire autosomic ovine genome. Using a multimarker regression method, a daughter experimental design was used to identify putative quantitative trait loci (QTL) affecting the somatic cell score (SCS). Chromosome-wise significance thresholds were set empirically by permuting the phenotypic data. Marker order and genetic distances of the autosomic linkage map built for this commercial population were in accordance with the published ovine linkage map. An across-family association analysis revealed a region on chromosome 20 suggestive of evidence for a QTL. Segregation of the QTL into 2 families was inferred from the within-family analysis, and differences in the position of the suggested QTL were found between the 2 half-sib groups. This could be the result of incomplete information associated with the markers for the significant families. The location of the major histocompatibility complex in proximity to the across-family effect suggests this region may harbor a segregating QTL for the SCS in the Churra population. Studies in dairy cattle examining the SCS have reported linkage associations on corresponding bovine orthologous regions, supporting the validity of our findings. [ABSTRACT FROM AUTHOR]

The present study was conducted to evaluate the genetic diversity and relationships of 5 Saudi native chicken populations and a White Leghorn (L) strain as an exotic breed, using 25 microsatellite markers. According to morphological appearance and plumage color and pattern, they were classified into black (BL), black-barred (BR), dark brown (DB), light brown (LB), and gray (G) breeds. Twenty-five microsatellite markers were chosen based on the degree of polymorphism reported in the previous literature. The results revealed that all studied markers exhibited a varied percentage of polymorphism among native chicken populations. However, there were 81 polymorphic loci out of 109 loci. Based on cluster analysis, 3 main clusters of chicken populations were identified. Two clusters comprised native chicken breeds, while the L strain set the third one. Higher similarity was found between either black and gray populations (BL and G) or brown populations (LB and DB). They had a closer relationship to each other. Genetic distance between each couple was 0.11 and 0.12, respectively. The productive results revealed that the black breed had significantly (P < 0.0001) lighter body weight at sexual maturity compared to the other breeds. There was no significant difference between light and dark brown breeds for most productive traits. The genetic diversity we found among Saudi chicken populations may be of interest for improving productive performance and adaptability. [ABSTRACT FROM AUTHOR]