This study examined the impact of heat stress during specific periods before and after insemination to identify the most critical time affecting insemination success in dairy cows. A total of 47,199 insemination records from 6751 Holstein-Friesian cows (2002–2024) were analysed using generalised linear mixed models (GLMMs) with a binomial distribution. The periods assessed were the day of insemination, 21–6 days before (P1), 5–2 days before (P2), 1 day before to 1 day after (P3), 2–7 days after (P4), and 8–30 days after insemination (P5). Mild heat stress significantly reduced insemination success on the day of insemination, with a critical THI threshold of 60. Among all periods, P1 was the most sensitive to heat stress, with even mild stress negatively affecting outcomes. Severe heat stress (THI ≥ 72) also impacted P3 and P5, whereas P2 and P4 showed no significant effect. Heritability estimates increased with heat stress intensity, suggesting genetic variability in resilience. These findings highlight the importance of managing heat stress from three weeks before to one month after insemination and support the potential for genetic selection to improve reproductive performance under heat stress conditions.

One of the most important decisions in dairy cattle production today is the correct choice of culling time for cows. In the culling decision process, the farmer has to take into account a number of factors, the complexity of which makes the decision-making task difficult. A crucial factor is the evolution of reproductive indicators. The aim of the research was to develop a microsimulation method that can be used to easily investigate the impact on profitability of increasing pregnancy rates and when the culling decision is made. In the microsimulation, the stock was examined without changing any other conditions. A microsimulation method has been developed to determine with high accuracy the effect of the pregnancy rate and the increase in culling days on the economic indicators of individual dairy farms. By microsimulation, the effect of changing these two parameters on the expected milk production of cows, the most important economic indicator for cattle farms, was investigated. The other parameters of economic importance were simulated using a cattle farm database. The purpose of microsimulation is to assist in producing certain managerial decisions in order to achieve better profitability and economic efficiency. In summary, the results showed that increasing the pregnancy rate can successfully reduce the length of the calving interval, but the improved pregnancy rate did not show a significant increase in milk production. In order to obtain results that can be used by farms, the authors intend to further develop the model in the future, adapting it to farms and taking into account their specificities.

Recently, a new type of cow’s milk has been commercialized in the markets, called A2 milk. It is derived from a specific allelic composition on chromosome 6. The only difference between A1 and A2 milk results from the polymorphism at the 67 amino acid chain. In this position, A2 milk has a proline amino acid, while A1 milk has a histidine amino acid. Proteins are one of the most important components of milk, especially casein, and have received significant attention as they are the source of bioactive opioid peptides called beta-casomorphin-7. Peptides are released through enzymatic digestion of casein and whey proteins. More precisely, this bioactive peptide is produced by sequential gastrointestinal digestion of bovine A1 variants proteins, while this phenomenon is not present in variant A2. Studies have reported that A1 milk can be harmful to health not only for adults but also for infants and that β-casein A2 becomes a safer choice following the relationship between disease risk and consumption of the beta-casomorphin-7 peptide. Indeed, epidemiological studies suggest that the released beta-casomorphin-7 peptide is a risk factor for the development of diseases in humans, but this has not yet been validated by other studies. In contrast, A2 milk has been suggested as an appropriate substitute for A1 milk since populations consuming milk containing high levels of the A2 beta-casein variant have lower rates of diseases, such as diabetes, coronary heart disease, autism, and schizophrenia.

Dairy cow longevity is a key driver of farm profitability, animal welfare, and environmental sustainability. Despite genetic progress in milk production, the average herd life has declined in many high-yielding dairy systems, raising concerns about early culling. This study analyzed data from 2057 Holstein–Friesian cows in Hungary to characterize the distribution and timing of culling events and to identify major risk factors affecting productive lifespan. We studied age, parity, milk yield, and culling reason using descriptive statistics, Kruskal–Wallis tests, multinomial logistic regression, and Kaplan–Meier survival analysis. Udder health problems were found to be the most frequent cause of culling (22.8%), followed by metabolic disorders (18.2%), locomotive problems (17.3%), and reproductive disorders (17.1%). Economic reasons such as low milk production contributed to a smaller proportion of culling. Most cows were culled after the second or third lactation, with survival probability dropping sharply within the first 1500–2000 days of life. Cows reaching four or more lactations represented a small but economically and genetically valuable subset of the herd. Our results indicated that in Hungary culling decisions are largely determined by health problems, which represent a greater limitation to the productive potential of dairy cows than economic factors. This research recommends that breeding programs prioritize genetic selection for robustness and that herd management adopts preventive health and reproductive strategies to prolong cow longevity, ultimately enhancing the efficiency and sustainability of dairy production systems. Additionally, prevention of animal wastage to foster animal welfare could be suggested as an additional advantage.

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.