In the nutrition of dairy cows, the balance of protein, energy, vitamins, and minerals is highly important. If this balance is not achieved, dairy cows may experience body weight loss or excessive fattening. In dairy cow rations, insufficient energy can lead to reduced milk yield, excessive body weight loss, decreased resistance to diseases, silent or absent estrus, and fertility problems. When there is an energy deficiency in the ration, the unconscious use of high-protein feeding programs disrupts the protein–energy balance in favor of protein. As a result, an energy deficit occurs, causing cows to lose body condition. The most beneficial practice in dairy cow nutrition is to provide lactating cows with a mixture of the concentrate and roughage they will consume throughout the day. Barns for dairy cows should be kept clean and well-ventilated. Cows should always have access to high-quality, clean, and fresh water. Providing water only at certain times reduces feed intake and causes losses in both milk yield and reproductive performance.