Associations between polymorphism localised in the third exon of the prolactin gene (PRL-RsaI) and milk production traits of Black-and-White and Jersey cattle were analysed. A total of 427 cows were included in the study. PCR-RFLP method was used. The frequencies of genotypes and alleles were as follows: 0.7107 -AA, 0.2851 -AB, 0.0042 -BB; 0.8533 -PRL A and 0.1467 -PRL B for Black-and-White cattle and 0.0919 -AA, 0.4324 -AB, 0.4757 -BB; 0.3081 -PRL A and 0.6919 -PRL B for Jersey cattle. Statistically significant differences between the breeds were observed in the frequencies of genotypes and alleles. Associations between PRL-RsaI polymorphism and milk production traits of Jersey cows and lack of associations with these traits in Black-andWhite cows were observed.

The analysis comprised purebred Charolais bull calves (CH) and crossbred bull calves born from Hereford (CH × HE) and Simmental (CH × SI) cows. Body weights and daily gains were measured in subsequent periods of the experiment and the post-slaughter evaluation was carried out. Carcass lean weight and dressing percentage were evaluated, as well as the lean content of five prime cuts. Total weight of the five prime cuts was measured and its share in the half-carcass weight was determined. The rib-eye area was also measured. The CH × SI crossbreds reached significantly higher body weights at weaning, 210-day body weights and weights at finishing, as well as significantly higher daily gains in all the periods (<I>P</I> < 0.05, <I>P</I> < 0.01) and were characterized by the heaviest carcasses and most cuts, particularly the round. The crossbreds had the highest total weight of five prime cuts and total lean weight, highest weight of the round and lean weight in the round. Other relationships were found analyzing the share of each cut in the carcass. The share of tenderloin and rump in the carcass of CH × SI was significantly lower compared to the purebred bulls (<I>P</I> < 0.01) and CH × HE (<I>P</I> < 0.05). They also had a significantly lower share of the shoulder, shank and shin, as compared to the other groups, as well as a significantly higher (<I>P</I> < 0.05) share of the neck, as compared to the purebred bulls. The purebred bulls also achieved good results and had the highest share of the prime cuts and the largest mean rib-eye area.

Abstract. The aim of the study was to compare the frequencies of protein polymorphisms in milk produced by cows with various proportion of HF genes within their genotypes, managed in two farms. Frequency analyses of beta-lactoglobulin (BLG) and three casein fractions (CSN1S1, CSN2, and CSN3) in individual genetic groups of animals were carried out in milk of 342 cows. Also, milk content of casein and whey proteins was assayed. The highest level of casein was found in farm B, in all the genotypic groups of cows, while the proportion of whey proteins in milk was highest in farm A, in the genotypic group of cows with 25% to 50% of HF genes. As far as the remaining groups of cows are concerned, the level of whey proteins was equal in both studied farms. A genetic differentiation of polymorphisms in milk protein was found in the analysed farms. Frequency of kappa-casein B (CSN3 B) genetic variants, which are desired in processing, was higher in farm A.

The general aim of the present work was to compare dairy performance and some reproductive parameters of Holstein-Friesian (HF) cows imported from Sweden as an in-calf heifers, and their age mates in Poland. The animals were kept freely on the deep litter on the farm owned by Agro-company “Witkowo” and feeding was based on TMR (total mixed ration) system during whole year. All ration’s ingredients (bulky feed, concentrate, miscellaneous additives) were mixed and fed as all-mash. The feed ration depended from the physiological condition of a cow and it was composed of corn and grass ensilage, mash concentrate, crushed corn meal, brewer’s grains and beet pulp.Cows imported from Sweden as in-calf heifers obtained higher milk, fat and protein yield in both lactations comparing to home cows. Significant statistical differences were observed for kg of milk, kg of protein, for FCM (P<0.01) and for kg of fat (P<0.05) in 2nd lactation. Fat and protein content in milk was in average higher for home cows (P<0.01). Big differences (P<0.01) were observed in SBT (proportion of protein to fat content) and RTB (difference between concentration of fat and protein) at imported cows in 2nd lactation. As far as reproduction parameters (gestation interval, calving interval, insemination index) are concerned was cows from Sweden better too. Heifers from Sweden calved earlier. The usage of high genetic potential of imported cows is possible only with providing them optimum living conditions suitable to their needs.

Przytulski T., B. Bartoszewicz, H. Kamieniecki, A. Kaw~cki, A. Klemke, L. Niemyska, W. Belec: Genetic Resistance to Leukaemia in Black-and-White Cattle. Acta vet. Brno, 50, 1981: 61-66. Data obtained from 1312 Black-and-White cows of 75 bulls from different farms shows that bulls transmitted different levels of resistance or susceptibility to leukaemia to their daughters. It can be used in practice for early elimination of bulls which are genetically predisposed to leukaemia. The h 2 of leukaemia resistance was 0.13. Relationship between blood groups, transferrins, postalbumins, amylase, xCn, cc.,-Cn, {J-Cn (caseins) and {J-Lg phenotypes and leukaemia was also analyzed. In cows secreting xCn AA types there is a significantly lower incidence of leukaemia than in cows producing xCn BB or AB types. The frequency of Y2D'G'1' allele in cows with leukaemia was very high. The differences for the other phenotypes were not significant. Resistance, leukaemia, cattle, polymorphism.Leukaemia is a major animal disease. A significant percentage of domestic and wildlife animal