The aim of this study was to determine the factors affecting mastitis cases and to estimate the correlations of somatic cell count (SCC) with milk yield in Holstein cows. The study was conducted in two private dairy farms in Hódmezõvásárhely, South-Hungary. A total of 882 Holstein cows were tested by SCC, fat and protein contents of milk monthly intervals. To test milk SCC and components, two groups were designed, and to examine effect of parity on first mastitis day (FMD) and total mastitis cases (TMC), four groups were divided. It was noted that higher SCC caused to higher TMC. While cows had higher protein content exposed to higher FMD and TMC, cows had lower daily milk yield (DMY) had higher values by mastitis case parameters. In parity evaluation, only primiparous cows had statistically lower TMC. The cows with lower SCC were found in advance in change of milk yield (CMY) up to 6.858±0.947 kg. A negative correlation coefficient was estimated between SCC and DMY. Finally, monitoring SCC of milk is offered to prevent milk production losses and new mastitis occurrences in the herds.

Main aim of cattle breeding is to keep cattles with high productivity in production as long as possible. Thus length of productive lifetime can be increased. Culling is a complex decision. During that age, phases of lactation cycle, milk production, reproduction attributes and health stage all have to be taken into account. Optimal timing is important at culling as too early or too late culling results in economic loss.  Culling decision is influenced by economic factors as well such as quantity and price of milk, price of culled cow, purchase price and raising cost of heifer. Many heifer have to be settled into production so all heifer which is suitable for reproduction has to be kept for breeding. As a result of this, all heifer that is healthy in context of reproduction biology has to be taken into breeding. Investigations of this study were made on a Hungarian dairy cattle farm. There is untied system on the farm. Cattles are grouped based on production level and stage of lactation. Daily milking number is three. Culling reasons were analysed in the first three lactations. Based on investigated data, 1175 cow were culled during five years which means 235 cows annually. There were differences between culling reasons. Udder health problems were the main reasons of culling. These presented 30% of the total cullings with 348 individuals. Several individuals were culled without fertilisation in the given lactation. The reason of this could be that the cow did not get pregnant again or other diseases and injuries occurred during lactation period. Most diseases occurred in the first 25 days of second lactation.