The investigations were carried out on the material of 570 ejaculates taken by manual metod from 30 boars used for insemination: Large White, Landrace, hampshire, duroc and pietrain. Young boars at the age of approximately 7-8 months, not used in reproductive per-formance, were chosen. One ejaculate taken from each boar in each successive month was ex-amined in sperm morphology. After collecting semen slides were immediately prepared. In each slide the morphology of 500 spermatozoa, including spermatozoa with proper proportions and showing major and minor abnormalities was evaluated. It was found that the percentage of nor-mal spermatozoa morphology shapes differently with boars of each breeds in particular months of the year. The semen taken from spring and winter had more spermatozoa with proper proportions than in the summer and early autumn period. The boars of wbp and hampshire breeds are less susceptible on influence of the seasonal factors, which appears profitable sperm mor-phological of every period of the year near insignificant amplitude of changes in next months of year. The semen quality of boars: Landrace, duroc and pietrain show the larger sensibility on operation of the seasonal factors.

The experiment was performed in 2003 and 2004, on a herd of 140 dairy cows. The aim of the study was to determine the effect of TMR and PMR feeding as well as of the pro-portion of HF genes on cow productivity. Slight differences were found between cows fed a TMR and PMR with regard to the yields of milk, milk fat, milk protein and ECM (energy-cor-rected milk) per day of lactation. This indicates that the higher productivity of cows fed a PMR resulted only from the fact that lactation periods were by over a month longer in this group. It follows that the feeding systems tested in the study had no impact on production results. Re-gardless of the feeding system applied, statistically significantly higher yields of milk, milk fat, milk protein and ECM as well as yields determined per day of lactation were attained in the group of crossbred cows with morę than 75% of HF genes. In the group of purebred Black-and-White cows better production results were achieved in the TMR system.

Research was conducted on Peking duck eggs from the reserve flock 44. Egg quality evaluation was carried out in the 28th, 36th and 44th week of ducks life, in other words in the 5th, 13th and 21 sh reproduction week. At each date 30 eggs were evaluated, 90 eggs intotal, al-ways 24 hours from laying. With the ducks age the following values have increased: egg weight (from 77.8 to 86.8 g), egg length (from 63.5 to 64.8 mm), egg width (from 46.4 to 48.9 mm) and the shell surface (from 86.3 to 92.8 cm²). The egg shape became slightly rounder and its shell colour dark-ened. Egg albumen content has decreased from 60.4 to 57.1%, while yolk content has increased - from 29.7 to 33.1%. Both the quality of thick albumen, determined by Haugh units, and the quality of yolk, described by its diameter, have deteriorated.

The aim of research was to state the daily milk yield of Polish Holsztyn-Friesian for cows before and after estrus for more precise determination of the effective insemination time. The daily milk yield of 125 cows in estrus cycle was analyzed in herd with efficiency of about 7000 kg of milk in 305-day lactation. The milkiness level and occurrence dates of 474 estrus cases were taken from documentation of that herd from January 2004 to December 2005. The milk yield was analyzed 3 days before estrus, on estrus day and 3 days after estrus. On estrus day it was observed that the milkiness decreased significantly of about 2.9 kg (11.9%) with relation to 3-day periods before and after estrus. The breed and genotype of cows, the next lactation and its stage and the daily yield levels had statistically significant influence on the milk yield decrease on estrus day. Differences in milkiness decrease on estrus day between old cows (IV lactation and higher) and younger (I, II, III lactation) and between cows with the lowest milk yield level (< 20 kg) and the highest (> 30 kg) turned out to be statistically significant. The cows milkiness reduction on estrus day (about 11.9%) can be the valuable information mak-ing it possible to determine estrus occurrence date.

The coefficients of phenotypic correlation based on the milking features dates of 488 990 cows examined between 1975 and 1992 were estimated. The estimation was made in use with AM. The attention was paid especially on the effect of the level of a productive herd. There was observed a great impact of the level of the production on the precision of an estimation. The results of the phenotypic correlation had a very strong flexibility of the estimations obtained.

Cows from the active population of the Pomerania and Kujawy regions, calved in 1998-2002, were investigated. Statistical analyses were performed using information on milk yield, fat, protein and lactose content, and somatic cell count in the milk obtained from 846 343 test-day milkings. Correlations between LNSCC and milk traits were calculated within lactation number, stage of lactation, daily yield, season of the year, and herd size. Somatic cell count was found to have a highly significant effect on milk traits. This effect was negative for daily yield and lactose content, and positive for fat and protein content. Factors that have the strongest dif-ferentiating effect on the relationship between LNSCC and daily milk yield were the age of cows and lactation period. A stronger relationship was found between LNSCC and milk yield in older cows (>4 lactations) and in cows in the final period of lactation (>10 months). Season of the year had a weak differentiating effect on the relationship between LNSCC and daily yield and had a stronger effect on the relationships between LNSCC and fat and protein content. For LNSCC and fat content, the highest correlations were obtained in the autumn and winter months. For LNSCC and protein content, the correlations were highest in the spring and summer period.