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The aim of this study was to investigate the genetic diversity within and among three breeds of sheep: Corriedale, Merino and Creole. Sheep from the three breeds (Merino n = 110, Corriedale n = 108 and Creole n = 10) were genotyped using the Illumina Ovine SNP50 beadchip ® . Genetic diversity was evaluated by comparing the minor allele frequency (MAF) among breeds. Population structure and genetic differentiation were assessed using STRUCTURE software, principal component analysis (PCA) and fixation index (F ST ). Fixed markers (MAF = 0) that were different among breeds were identified as specific breed markers. Using a subset of 18,181 single nucleotide polymorphisms (SNPs), PCA and STUCTURE analysis were able to explain population stratification within breeds. Merino and Corriedale divergent lines showed high levels of polymorphism (89.4% and 86% of polymorphic SNPs, respectively) and moderate genetic differentiation (F ST = 0.08) between them. In contrast, Creole had only 69% polymorphic SNPs and showed greater genetic differentiation from the other two breeds (F ST = 0.17 for both breeds). Hence, a subset of molecular markers present in the OvineSNP50 is informative enough for breed assignment and population structure analysis of commercial and Creole breeds.

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ABSTRACT:The aim of the paper was to prove the accuracy of various statistical models of variance analysis for estimation of systematic factors that influence milk yield and fat and protein content in dairy goats. Data on daily milk production recorded by methods AT, AC or A4 for the population of Czech White Shorthaired Goats over 1992-2002 was used for calculations. A total of 78 736 test day from 6 234 goats were analysed. Average daily milk production was 3.09 kg with 3.72% of fat and 2.84% of protein. Variability of examined traits was significantly influenced by effects of herd-year or herd-test day, li�er size, parity, season of kidding, stage of lactation and the combined effect parity-year-season of kidding. The variants of model equations in which complex effects of herd-year were replaced by effects of herd-test day showed higher values of reliability for the three traits analysed.Keywords: Czech White Shorthaired Goat; fat; protein; lactation curve; test day 466Original Paper Czech J. Anim. Sci., 49, 2004 (11): 465-473 day Animal Model for BVE in dairy goats. Milerski et al. (1999) found considerable differences in the evaluation of individual animals between the system of evaluation of dairy goats presently used in the Czech Republic and BVE done by BLUP Animal Model. MATERIAL AND METHODSData from the official milk recording of the Czech White Shorthaired breed of goats provided by the Sheep and Goat Breeders Association (SCHOK) was used as the basic material for our calculations. The analysed data were recorded in the period from 1992 to 2002. Daily milk production was recorded by methods AT, AC or A4 (ICAR, 2001). Although the analysed data were recorded in production operations, several fixed effects were included in the model. The most marked effects will be chosen using the ordinary Least Squares Method and the procedure GLM (SAS, 1996).Several checks of performance records were carried out in order to exclude logical inconsistencies and biological improbabilities: (a) Age at first kidding had to be at least 275 days. (b) Difference between lactation number and period (in years) from birth to the 31/12/n (n = production year): 0.5-2 years. (c) Test-day records included for year n had to be between the dates 1st October n-1 and the 31st March n+1. (d) Kidding date had to be between the dates 1st October n-1 and the 30th September n. Other used criteria are shown in Table 1. Poor quality data were excluded from the followings computations. The original performance record database included 87 736 test-day records. The number of data considerably diminished a�er the introduction of the above-mentioned criteria, a total of 78 736 records of daily milk production, 77 536 records of fat percentage and 78 269 records of protein percentage in milk from 6 234 goats were finally analysed.The effects of herd, test day, number and stage of lactation, production year, kidding season and li�er size were tested using the followings five models: e ijklm = random residual RESULTS AND DISCUSSIONMeans and standa...

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Gastrointestinal nematode infections, including Haemonchus contortus, are one of the main causes of economic losses to ovine farmers worldwide. In order to contribute to the control of nematode infections and avoid parasite spreading we generated divergent resistant and susceptible sheep breeds and evaluated the adaptive immunity of these animals developed upon experimental infection against H. contortus. The selection of resistant or susceptible animals from the Corriedale Breed has been based on Expected Progeny Differences for faecal egg counts per gram. Furthermore, animals from the resistant Corriedale line were inseminated with imported semen from Australian Rylington Merino rams. Thus, the objective of this work was to analyze the adaptive immune response in both susceptible and resistant obtained lambs. Our results indicate that there is a potent parasite-specific local and systemic immune response in resistant animals and that although susceptible lambs can produce high levels of IgA antibodies during the infection, their antibody response is delayed which, together with an impaired specific-Th2 response, does not contribute to initial parasite elimination. Our results shed light into the immune mechanisms that mediate resistance to H. contortus and could constitute important assets to sheep farmers, not only as a means to detect resistance, but also to enhance the efficiency of selection in stud flocks.

This study evaluated the phenotypic trends for wool and growth traits of the fine Merino genetic nucleus in Uruguay. Data were collected from one-year-old lambs over a twenty-year period (1999–2018). The overall aim of the selection flock was to reduce fiber diameter with concomitant increases in fleece and live weights. Traits analyzed included fiber diameter (FD), greasy fleece weight (GFW), coefficient of variation of FD (CVfd), staple length (SL), scoured yield (SY), live weight post-shearing (LW), eye muscle area (EMA) and fat thickness (FAT). Data from approximately 5300 one-year-old male and female lambs were analyzed. During the study period, FD decreased by approximately 3 µm, whereas GFW and LW increased by at least 0.5 and 3.0 kg, respectively. There were interactions between the sex of the individual and the year for all wool traits. Except for FAT, all other traits were affected by the dam age. This study indicates that the selection program applied in the fine Merino genetic nucleus over a twenty-year period resulted in reductions in FD and increases in GFW and LW. Therefore, the results indicate it is possible to produce ultrafine wool in semi-extensive grazing systems without compromising other economically relevant traits in one-year-old lambs.

Selection of genetically resistant animals is one alternative to reduce the negative impact of gastrointestinal nematodes (GIN) on sheep production. The aim of this study was to identify genomic regions associated with GIN resistance in Corriedale sheep by single-step genome-wide association studies (ssGWAS) using 170, 507 and 50K single nucleotide polymorphisms (SNPs). Analysis included 19,547 lambs with faecal egg counts (FEC) records, a pedigree file of 40,056 animals and 454, 711 and 383 genotypes from 170, 507 and 50K SNPs, respectively. Genomic estimated breeding values (GEBV) were obtained with single-step genomic BLUP methodology (ssGBLUP), using a univariate animal model, which included contemporary group, type of birth and age of dam as class fixed effects and age at FEC recording as covariate. The SNP effects as wells as p-values were estimated with POSTGSF90 program. Significance level was defined by a chromosome-wise False Discovery Rate of 5%. Significant genomic regions were identified in chromosomes 1, 3, 12 and 19 with the 170 SNP set, in chromosomes 7, 12 and 24 using the 507 SNP chip and only in chromosome 7 with the 50K SNP chip. Candidate genes located in these regions, using Oar_v4.0 as reference genome, were TIMP3, TLR5, LEPR and TLR9 (170 SNPs), SYNDIG1L and MGRN1 (507 SNP chip) and INO80, TLN2, TSHR and EIF2AK4 (50K SNP chip). These results validate genomic regions associated with FEC previously identified in Corriedale and other breeds and report new candidate regions for further investigation.