ANALYSIS OF PRODUCTION PROGRESS IN SELECTED DAIRY HERDS IN TERMS OF ASSESSMENT OF UTILITY VALUE. PART 1. ANALYSIS OF THE PROGRESS OF PRODUCTION IN MILK YIELD, INCLUDING MILK YIELD, PROTEIN PERCENTAGE AND FAT PERCENTAGE AND THEIR MUTUAL RELATIONSHIP

The purpose of the study was to analyze the production progress in selected dairy cattle herds included in the performance evaluation. The study analyzed production traits such as milk yield, percentage fat, percentage protein, somatic cell count, urea content in milk and the following sources of variation: year of study, month of year and herd, in addition, the fat-protein ratio and energy corrected milk (ECM) and fat corrected milk (FCM) indices were calculated over 21 years in the herds included in the analysis. In addition, the study took into account the most important aspects of dairy farming and breeding, which can include: behavior, nutrition, welfare, milking systems, and the functional types of cattle and the breeds belonging to them.Analysis of variance for production traits showed that all sources of variation (year of study, month of year, herd) had a statistically high effect on the traits evaluated (milk yield, percent fat, percent protein, somatic cell count, urea content fat-protein ratio, and FCM and ECM indices). An analysis of variance was also conducted for interactions: month × herd, year × month and year × herd.Least-squares means and standard deviation were calculated for the analyzed traits in successive study years and months of the year by herd. Detailed results of the analyzed traits by study year and herd and month and herd are presented in line graphs. Summarizing the results of the analyses, it can be said that all the analyzed herds showed significant production progress in basic traits such as milk yield, fat and protein percentages. It should be noted that the number of somatic cells was characterized by significant fluctuations, which may indicate a significant influence of the environment on this parameter. However, it should be emphasized that during most of the study period, the number of somatic cells was definitely within the specified norms.Improvement of milk yield in herds was achieved as a result of changes in cow breeding technology. The introduction of a change in the herds’ feeding system from traditional to total mixed ration (TMR) feeding resulted in an improvement in both milk yield and milk quality composition. The production results obtained in these herds are of great application importance. Therefore, it is recommended to implement modern technological systems in the form of the TMR feeding system in dairy cattle herds.Dairy performance in the selected cow herds has increased over the analyzed period of 21 years. This testifies to properly conducted breeding work, thanks to which there was an increase in production in these herds.