Effects of Partial Replacement of Soybean Meal with Corn Gluten Meal, Fish Meal, or Their Combination on Dairy Calves’ Performance and Insulin Concentration

The partial replacement of soybean meal (SBM) with different protein sources (corn gluten meal; CGM, and fish meal; FM) was evaluated on the performance, blood metabolites, microbial protein synthesis, and insulin concentration in Holstein dairy calves. Forty-four Holstein female calves with average body weight (BW) 42 ± 0.81 kg and 3-d age were allocated in a completely randomized design with four treatments: 1) control diet with soybean meal as a sole protein source (SBM); 2) partial replacement (5%) of SBM with corn gluten meal (CGM); 3) partial replacement (5%) of SBM with fish meal (FM) and 4) replacement of SBM with a combination (2.5% each) of CGM and FM meal (CGM-FM). The study lasted 11 weeks with the weaning date on d-66, though the study lasted until d-80. The statistical analysis was considered as three separate periods including pre-weaning (3-66 d), post-weaning (66-80 d), and the entire period (3-80 d). The results revealed that the starter intake and average daily gain were not affected among experimental treatments (P>0.05). Replacing SBM with a combination of fish meal and corn gluten meal (CGM-FM) caused improved feed efficiency (P 0.05). The greatest insulin concentration was found to be for CGM-FM among experimental treatments (P<0.05). In conclusion, the results showed that the partial replacement of SBM with the combination of CGM and FM in dairy calves’ starter diet improved the growth performance and contributed to a higher insulin concentration.