Replacement of Yellow Corn Grains by Chocolate By-Products in Lactating Cows Rations: Effects on Nutrients’ Digestibility, Milk Yield and Composition, Some Blood Parameters and Economic Efficiency

The present experiment aimed to evaluate the partial replacement of yellow corn grains with chocolate by-products in the ration of lactating cows on feed utilization, blood profile, and lactation performance. For this goal, thirty multiparous Holstein cows (600±35 kg BW, 3±1 parity, 180±25 days in milk, and previous milk production of 20±2 kg/d), were randomly divided into 2 groups. Following a cross-over design for 60 days, the concentrated feed mixtures (CFM; 11 kg/head/d) were formulated from YCG, wheat bran, soybean meal, linseed meal, CBP (in Chocolate group) and some feed additives. Corn silage (17 kg/head/d) and alfalfa hay (3 kg/head/d) were used as roughages in the TMR formulation with a roughage: concentrate ration 43.7:56.3. During the first experimental period (Control), animals received the same pattern of the CFM in the adaptation period without any replacement, meanwhile, 20% of YCG was substituted by CBP in the CFM for the second period (Chocolate). Replacing 20% of YCG by CBP in the CFM of dairy cows ration increased milk production (actual 2.53% and fat corrected milk by 6.95%) and fat content (by +8%) in milk as well as feed efficiency in CBP group compared to control. Higher nutrient digestibility was observed in chocolate treatments compared to YCG group. The replacement increased the concentrations of plasma albumin, HDL, LDL and total cholesterol in comparison with the control. Replacement of YCG by CBP in dairy cow ration improve milk yield, composition, digestibility and economic efficiency and this trail can be recommended in dairy cow farms as a novel nutrition strategy. Therefore, additional experiments with treatments known to reduce blood triglyceride and cholesterol levels are recommended.