The composition of sheep milk and its production per lactation are influenced by a large number of factors; however, the most important factors are breed, nutrition, health of the animals, environment and the number and stage of lactation. The effect of the stage of lactation on milk composition in different sheep breeds was studied by Jelínek et al. (1990), Maria and Gabina (1993) ABSTRACT:The evaluation of the effect of the stage of lactation on milk composition, its properties and the quality of rennet curdling was carried out over the period of three successive years using milk samples (n = 162) obtained from a total of 27 ewes of the East Friesian (EF) breed, reared on a small sheep farm in Juřinka in the region of Wallachia. The stage of lactation had a highly significant effect on the contents of all milk components. However, only the contents of total solids (TS), solids non-fat (SNF), fat (F), protein (P) and casein (CN) gradually increased with the advancement of lactation. The stage of lactation also had a highly significant effect both on all the properties of milk and the rennet curdling quality (RCQ). All phenotypic correlations between the particular contents of TS, SNF, F, P, CN and urea nitrogen (UN) were positive and high (P ≤ 0.001). On the other hand, all phenotypic correlations between milk yield and particular contents of TS, SNF, F, P, CN and UN were negative and high (P ≤ 0.001). The majority of phenotypic correlations between rennet clotting time (RCT) and the other particular parameters was insignificant. However, the phenotypic correlations between lactose (L) and RCT and between pH and RCT were positive and high (P ≤ 0.001) whereas the phenotypic correlation between titratable acidity (TA) and RCT was negative and high (P ≤ 0.001). The majority of phenotypic correlations between the rennet curdling quality (RCQ) and the other particular parameters was insignificant. Nevertheless, the phenotypic correlations between pH and RCQ and between RCT and RCQ were positive and high (P ≤ 0.001) whereas the phenotypic correlation between TA and RCQ was negative and high (P ≤ 0.001).

The determination of genetic variability by means of molecular genetic markers FUT1 and ESR2, and the evaluation of their associations with reproduction traits in population of Prestice Black-Pied sows have been implemented. A lower frequency of the allele FUT1A than the frequency of the allele FUT1G in the FUT1 gene was ascertained. In the ESR2 polymorphism, a higher frequency of the allele ESR2A compared with the allele ESR2B was determined. In the second to sixth litters as well as in the first to sixth litters, a significantly lower number of piglets born alive and number of weaned piglets from sows of the FUT1/IFUT1A genotype was found. Moreover, the homozygotes FUT1G /FUT1G significantly exceeded sows of the FUT1A/FUT1A genotype in the total number of born piglets in the first to sixth litters. No significant effect of the ESR2 polymorphism on reproduction was observed.

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The study of molecular genetic variability in genetic resources of farm animals is necessary for optimal conduct of their breeding and for understanding of relations between molecular markers and traits. The determination of variability in the CRC and the MYF4 genes and the evaluation of associations between these genetic markers and the total number born, the number born alive and the number weaned of piglets, weaning weight of piglets and farrowing interval were carried out in population of 102 Přeštice Black-Pied sows. The frequency of the allele CRC n (0.083) was found out to be markedly lower than the frequency of the allele CRC N and there was observed no sow of homozygous recessive genotype in the investigated sample population. In MYF4 locus, the higher frequency of the MYF B allele was detected (0.711). A significant influence of the CRC gene polymorphism on number of piglets alive born in the 1 st and the 1 st -6 th litters was discovered. In the total number of born piglets the significant disparity were ascertained between the

The primary goal of this study was to analyse genetic variation within and among six Dachshund varieties in the Czech Republic using 10 microsatellites from StockMarks Paternity Polymerase Chain Reaction (PCR) Typing kit. A total of 632 Dachshunds were sampled - 99 Standard Smooth-haired, 72 Standard Long-haired, 272 Standard Wire-haired, 42 Miniature Smooth-haired, 73 Miniature Long-haired and 74 Miniature Wire-haired. Average observed heterozygosity and polymorphic information content ranged in particular Dachshund varieties between 0.58-0.70 and 0.57-0.64, respectively. Subsequent analysis of the population structure (F-statistics; Nei's genetic identity) showed that Standard Dachshunds shared allele frequencies most closely with their miniature equivalents, and smooth coat type is closer to Wire-haired coat type than to the Long-haired one. Analysis of molecular variance revealed that 11.81% of the total variance occurred among varieties. The value of combined exclusion probability (0.9955) validated usefulness of this panel of microsatellites for parentage verification in all analysed populations. We carried out 234 parentage verifications with 1.28% cases where parentage did not match.