Rations in this trial were formulated on a crude protein basis. Lactating diets for dairy cows can be designed according to production. Most dairy farmers group their lactating cows according to production as well as reproductive status. Therefore, a nutritionist can design feeding programs according to production to yield not only cost-effective rations, but also environmentally friendly rations. For my clients the protein level used are according to the CPM model.
Forage analysis is important for designing dairy nutrition programs.
Wet chemistry ought to be used for all mineral analysis, as the NIR is not accurate in predicting minerals in feedstuffs. For silage analysis, I use wet chemistry analysis and test for the nutrients and components as described by William Chalupa, Nutritional Quality of Feedstuffs, 1998. Avoid mineral interactions and formulate for moderate levels of selenium, copper, zinc, potassium, and salt levels in dairy diets. When water contains high levels of sulfur, he recommends adding zinc, copper, and manganese from non-sulfur sources such as chelated zinc, copper and manganese. Chelated sources of trace minerals, having high bioavailabilty, can economically be fed to meet the requirements of the lactating and dry cow reducing the excretions of minerals such as copper.