Nine hundreds of lactating Holstein cows in three locations (300 cows at each location) were used to evaluate the effect of nutrition and temperature humidity index (THI) conditions on dairy cattle performance (milk production and composition, digestibility, rumination, rumen pH). Three rations (chemically varied in physical effective NDF (peNDF), neutral detergent fiber (NDF), starch, dietary cation anion difference (DCAD), forage to concentrate ratio (F:C), crude protein (CP), either extract (EE), acid detergent fiber (ADF) and non fiber carbohydrates (NFC) were used at the three locations (R1 in L1, R2 in L2 and R3 in L3). Reviewing the nutritional and THI conditions of dairy farming systems in three countries in the Middle East and provides an up-to-date description of farming systems in these countries. Due to the common dairy farming problems in the region, the study focuses on three countries: Sudan (L1), Lebanon (L2) and Kuwait (L3) for an in-depth evaluation of the nutritional and THI conditions of dairy farming systems. The results indicated that increasing the intake of peNDF increase rumination and ruminal pH, but did not affect intake of DM or NDF. So, the models of those predict rumen pH should include both peNDF and fermentable organic matter (OM) intake. Dietary particle size expressed as peNDF, was a reliable indicator of rumination activity. The digestibility of dry matter (DM), CP, EE and NDF increased as concentrations of CP and NFC increased in the ration. While, the digestibility of OM, NFC and ADF was decreased. Milk production and composition negatively affected by increasing of THI. As the THI increased from 63 to 76; the animal performance decreased either in dry matter intake (DMI) and milk production and composition.