New guide values for nutrient excretions of suckling cows

The current Swiss guide values for nutrient excretions and forage consumption of suckling cows which are used for the compulsory nutrient balance are from 2001. In the meantime suckling cow production has changed and strongly gained in importance. In the framework of the ongoing revision of the Fertilizer Guidelines these guide values are therefore adapted to current practice. The principle used for calculating excretions is input in feed minus retention in milk, calf (until birth) and growth. The calculation were based on a new model to estimate feed consumption, official feed content values and results of surveys. Excretions and consumption were calculated for three weight/breed categories: heavy animals (>700 kg live weight), medium heavy animals (600 – 700 kg; main category) and light animals (500 – 600 kg). The new guide values for Nitrogen (N), Potassium (K) and Magnesium (Mg) excretions as well as forage consumption are somewhat higher than the old values, e.g. for the medium heavy category they are 85 kg N per year, (12 kg P), 117 kg K, 27 kg Mg, and 4500 kg forage dry matter. However, this will not have a big influence on the nutrient balance because the changes are very similar for excretions and consumption.