Nutrition is a key factor in the dairy cattle performance. The large variation in dairy cattle production is dependent on the nutrition. As a consequence, the objectives of this book were to evaluate the effects of nutritional, and some environmental conditions (expressed as Temperature-Humidity index THI) on productive performance in Holstein cattle in some Arab countries (Sudan - Lebanon and Kuwait). on feed intake, digestion coefficient of nutrients, rumen pH, rumination, milk production and composition and some reproduction parameters. We propose mechanisms that can be impact either in milk production or quality and/or reproduction. Our performance results indicate that the interaction between nutrition and environment is very important effective factor on feed intake and digestibility. As well as on animal production (milk yield, energy corrected milk, fat corrected milk, milk yield 305-day, energy corrected milk 305-day, fat corrected milk 305-day, peak of milk and milk constituents) and reproduction (days open, conception rate, pregnancy rate and calving interval) performance.