Abstract. Eight beef cattle breeds, Angus (A), Blonde d' Aquitaine (BA), Charolais (C), Czech Pied (CP), Hereford (H), Limousin (L), Piemontese (P) and Simmental (S), were analysed for the following calf traits: birth weight (BW), 210- and 365-day weight ( 210W, 365W) and average daily gains from birth to 210 days (ADG1), from 210 to 365 days (ADG2) and from birth to 365 days (ADG3). Phenotypic parameters were estimated by linear model procedures including the fixed effects of year of birth (1992–1998), herd, sex (male, female), calf number (single, twin), parity and random sire effects. Literature values of heritability estimates were used to derive genetic standard deviations and genetic range for comparison of genetic variation within and between breeds. The means of Blonde d' Aquitaine were highest for all growth traits except for BW, followed by Charolais and Simmental, then Angus, Czech Pied and Limousin with intermediate values and Piemontese and Hereford with lowest growth except for BW in Piemontese and ADG1 in Hereford. Blonde d' Aquitaine also showed high standard deviations for most growth traits except for BW, whereas for Limousin and Piemontese low standard deviations were estimated and for other breeds no consistent pattern was observed. Coefficients of variation were generally high for Hereford and low for Angus. Hypothetical frequency curves were used for comparison of genetic variation within breeds and between breeds. Comparison of extreme and average breeds showed ranges of genetic levels between 79 and 154 % of the average breed level thus indicating the large overall genetic variation for growth traits in beef cattle. Between-breed selection with immediate impact, but steady erosion by time, as well as within-breed selection with slow but steady increase and renewed variation should both be applied for optimal exploitation of genetic resources in the beef industry.

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The structure of the breed in 2003 was: 39 sires and 350 dams. The breed was closed against immigration in 1992. In 1993 and 2003 coefficients of inbreeding (Fx) were calculated from 5 parental generations for sires and dams in the whole breed and white and black variety. From 1993 to 2003 decreased the Fx (%) in the breed for stallions from 5.65 to 5.57 and for mares from 7.75 to 4.88. The effective population size was in 1993 Ne=114. 00 and 2003 Ne=140.36. The increment of Ne during the 10-year period was 26.36 animals. The average heterozygosity estimated on the frequencies of blood types, biochemical markers and microsatellites was enough large and was connected with a low coefficient of inbreeding. Linear type evolutions of 494 horses of the Old Kladrub breed for 32 traits were used to analyse the effect of variety and stud. The data were used for the estimation of population parameters and heritability coefficients. The specific properties and variation of the Old Kladrub horse in its current state were characterized by the overall mean, standard deviation, coefficient of variation, number of utilized scores and heritabilities. The highest coefficient of variation showed the forelimbs-side view (40.14 %), chest girth (36.25 %) and height at withers (30.97 %). The 8 traits showed heritabilities within the interval of 0.20 to 0.68. These traits are candidates as selection criteria. Significant differences between both varieties were found in 13 from 32 traits. Significant differences were found in 12 of 32 traits between the Kladruby stud and the private studs.

ABSTRACT:The paper deals with the greying process, melanoma, and vitiligo depigmentation occurrence in Old Kladruber horses (OKH). The study includes 376 animals of both sexes at the age of 1-25 years. The evaluation was performed repeatedly during 4 consecutive years. The greying status was measured spectrophotometrically on four body parts using L*a*b* colour system. Melanoma and vitiligo were detected visually and by palpation in all the animals and classified using 5 (3) grade scale. The GLM procedure of SAS package was used to examine the influence of the effects of line, age, sex, stud, and year of evaluation. The GLM analysis confirmed a significant impact of age on greying. Parameter L* showed progressive increase until 10 years of age when all horses reached final grey level. Subsequent analyses suggested the influence of sex, i.e. a notably higher level of greying in mares. The incidence of melanoma was confirmed. Melanoma in OKH most frequently occurs on the bottom of the tail or at the anal and perineal area. Probably only benign forms of melanoma have been detected. The global occurrence of melanoma in OKH (ca. 13%) is substantially lower than in Lipizzan and Camargue horses. Overall incidence of melanoma in horses at the age of 15 and older reached 68%. Genetic parameters were estimated for melanoma grade, grey level, and vitiligo. Greying is strictly influenced by age (h 2 = 0.52 ± 0.07). Prevalence of melanoma progresses with age (h 2 = 0.07 ± 0.04). Vitiligos of both facial and anal parts are influenced by the effects studied (h 2 = 0.20 ± 0.05 and 0.34 ± 0.06 for vitiligo A and vitiligo F, respectively).

An evaluation of the linear description of type in 494 horses of the Old Kladrub breed for 32 traits was used to analyse the effect of variety, stud, sex, year of birth and age at description. A linear model with fixed effects was used. The highest coefficient of variation was calculated for the forelimb side-view (40.14%), chest girth (36.25%) and height at withers (30.97%). 28 out of 32 traits were in the range from 7 to 9 utilized scores. The descriptor used a very high number of scores of the scale. Significant differences between both varieties were found in 13 out of 32 traits. Significant differences were found in 12 out of 32 traits between the Kladruby stud farm and the private studs. There is no reasonable explanation of this fact. A significant variety × stud interaction was recorded in only 7 traits. Significant differences between stallions and mares were recorded in a large number of front and body traits (in 11 out of 18 traits) and in 2 rear traits. Despite of a remarkable number of significant differences between the years of birth (in 18 out of 32 traits) and age at description (in 13 out of 32 traits) both factors are not the important ones for the selection of horses according to the type traits. The description of type traits, performance recording and selection are carried out in the population of four-years-old horses born in the given year. The age at description does not play a role because all horses are now described each year at a standard age of four years. The linear description of type is an important tool for the breeding and conservation of genetic diversity within the breed.

The objective was the estimation of animal × environment interaction for weaning weight (WWT) of the most frequent breeds of beef cattle in the Czech Republic. The environment was represented by 3 areas: Mountain (1), Foothills (2) and Lowland (3). A pairwise analysis was carried out between the areas: 1 vs 2 (n=5 149) and 2 vs 3 (n=4 971) for the estimation of (co)variance components and genetic correlations between the environments. A multiple-trait animal model was used where weaning weights in different areas were considered as different traits. The direct and maternal heritability estimates of WWT were for area (1): 0.12 (direct) and 0.05 (maternal); for (2): 0.26 and 0.11 (direct), 0.10 and 0.11 (maternal) and for (3): 0.26 (direct) 0.03 (maternal). Direct and maternal genetic correlations were between: 1 and 2 0.98 and 0.65 respectively, with standard deviations 0.03 and 0.37 respectively, and between 2 and 3: 0.82 and 0.50 respectively, with standard deviations 0.12 and 0.31 respectivly. The magnitude of the across-areas genetic correlation indicates that the animal by environment interaction was not biologically important and can be ignored in the evaluation of beef cattle in the Czech Republic. Keywords

ABSTRACT:Genotype by environment interactions for weaning weight in beef cattle were tested using several definitions of environments. Four breeds of beef cattle (Hereford, Aberdeen Angus, Beef Simmental, and Charolais) were represented. The environments were defined according to five criteria: altitude, production areas, economic value of the land, less favourable areas, and performance levels of a breed within herds. Ten mixed models were compared including the effects of direct and maternal genetics, herd-year-season, maternal permanent environmental, breed, environment, genotype × environment interaction, sex of calf, and age of dam. The suitability of the models was tested by Akaike's Information Criterion, likelihood ratio test, and magnitude of the residual variance. The most suitable definitions of environment were less favoured areas and herd levels of performance. Estimates of direct heritability ranged from 0.07 to 0.19. Genotype × environment interactions should be included in a genetic evaluation model for interbreed comparisons of beef cattle in the Czech Republic.

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