In marker-assisted selection (MAS) of dairy cattle certain genes are proposed as potential candidates associated with dairy performance traits. Among different candidates, prolactin receptor gene (PRLR) seems to be promising because of its crucial role in transmitting signal from lactogenic hormones to milk protein gene promoters. In this study nine PCR fragments representing most important functional domains of PRLR were screened for polymorphism. Using SSCP method one SNP (A→C) was found in intron 9. The SNP was deposited in GenBank AY484400 and AY339393 at position of 205 nt, for Jersey and Polish Black-and-White cattle, respectively. Allele frequency was estimated in 186 Polish Black-and-White (0.981 and 0.019 for A and C, respectively) and 138 Jersey (0.812 and 0.188 for A and C, respectively) cows. Preliminary analysis showed no significant associations between PRLR genotypes and milk performance traits. However, Jersey cows of CC genotype produced more milk with higher protein content than those of AA and AC genotypes. Because of the low number of cows of CC genotype, it is necessary to investigate more numerous population of cattle in which all genotypes will be efficiently represented.
Investigated were the usefulness and possible objectivization of the results of stallions’ 8-months performance test. No correlation was found between the total results of the test and the number of mares covered by tested stallions, suggesting that the use of stallions does not depend on the result of their 8-month test. Blood samples were analysed after the stamina trial (cross country gallop) and some parametres of free jumping were measured based on video image analyses. Moreover, an analysis of relations was done between performance test trials and investigated parametres. The correlations between evaluations of jumping traits in the performance test ranged from 0.28 to 0.65, while those between the results of jumping skills from the test and measurements based on video image analysis were weak and ranged from -0.2 to 0.3. Blood physiological indicators showed a wide range of values. Lactic acid content was affected by individual riders and breeders and that of total protein by breeders only.
The objective of this study was to investigate the effect of two single nucleotide polymorphisms iIn growth hormone (GH) gene on performance traits in pigs. The animals (n= 320) belonged to four groups of commercial crosses being the progeny of crossbred Polish Landrace × Polish Large White sows and Polish Landrace, Polish Large White, Duroc or Pietrain boars. Genotypes of growth hormone gene (GH) were established with PCR-RFLP technique using MspI and HaeII endonucleases.The GH/MspI and GH/HaeII genotypes were found significantly related to the weight of ham, Wright of ham meat and ham content of carcass. Moreover, nearly significant differences between GH/MIPS genotypes were found for mean fat thickness (from five measurements), fat thickness at lower back (point K2) and over the loin, and for loin eye height. The results presented allow to assume that near the analysed mutation the QTLs for performance traits in pigs are located.