In the studies 120 head of mature cows were divided into 3 feeding groups. According to Trotter, the results showed that neither cow performance nor nursing calf performance was adversely affected as adequate energy and protein levels were provided by the substitution of corn and soybean meal for hay. Knowing the quality of the hay is of particular importance when the hay is being limit fed. Trotter also noted that providing adequate bunk space for both hay and concentrate was important. Although the nutrient needs of the cows were met, they were hungry and tended to test the fences.
Energy needs increase as temperature decreases .
It varies based on hair coat and body condition. Below their LCT, cows will lose weight unless additional energy supplementation is provided . The following is an example which helps to drive home the importance of energy supplementation. A 1200 lb. cow in moderate body condition and a dry hair coat is about 8 weeks from calving. The 60 days just prior to calving is a critical period in cow nutrition.