Abstract Due to climate changes and the gradual warming of the earth, the possibility of heat stress in dairy cows and its complications on production and reproduction has increased. Reducing heat stress is an important challenge for livestock farmers, especially in Isfahan. Therefore, thermal stress management to improve reproductive performance in the cattle industry as the foundation of the herd economy, due to the great importance of the herd, the unfavorable performance of reproductive pus will reduce the profitability of the herd. Applying a criterion to check thermal stress and eva‎luate solutions to reduce stress may be in livestock management and nutritional strategies. Therefore, this study was conducted with the aim of investigating the use of performance indicators from summer to winter to quantify and compare them in Isfahan. The traits studied in this study include; Milk produced in 150 days, milk corrected for energy, milk corrected for pleasure, production rate of pleasure and breeding, somatic cell score, calving interval to the first insemination, conception rate in the first insemination, conception rate in summer and winter. In this study, 17000 records collected in the 1 st to 4 th periods of 1392 to 1400 were used to determine the process of operation, production and reproduction at the level of 31 Holstein cattle herds. Statistical analysis was done using GLM MIXUREG and MEANS (9.4) SAS software. Mean and standard error of production and reproduction traits in flowers including milk produced in 150 days, milk corrected for increase and energy, percentage of increase and milk, amount of body cells respectively 36.5±4, 35.9±4.7, 34.1 ± 4.5 weight per day, 3.4± 0.2, 3.1 ± 0.1, 4.25± 0.77 were estimated. The capture rate in summer and winter was reported as 44.3±0.31,51.9±0.35, and the interval from calving to the first inoculation was reported as 75.1±0.2 0.68±0.2.According to the resulting winter, production and reproductive performance was better than summer. The best production performance was related to the second and third births, and the reproductive performance (first rate) increased with the increase in births. Dairy cattle performance was affected by summer heat stress in all climate zones, but some zones were more affected than others. When comparing the ratio of summer to winter for each trait, the difference between the observation areas and farms that have a suitable cooling system is less than 30 meters between the springs and the crown of 13 meters with the east-west direction, which is well equipped. A suitable provider. It shows that the summer yield is different in the climate zone identified by the summer to winter season and shows a useful index for monitoring the degree of heat stress based on yield. In recent years, the production process is improving in these flowers due to management reasons, nutrition and ventilation. In general, the reproductive performance in Holstein dairy herds is the same as the dairy production in this period. This research was done with the aim of providing a comprehensive and clear view of climate change on the dairy cattle industry and also providing suggestions for better management of this issue. Keywords: Summer-Winter Ratio index_ Productive Performance_ Reproductive Performance_ Dairy Cow

غلامرضا قرباني خراجي , فرزاد هاشمزاده

ابوالفضل مهناني

عباس رجائي راد , حسين رضوي زادگان جهرمي