Diets for dairy heifers were assessed with corn silage and soybean or cotton seed based concentrate. Four experimental diets consisting of the combination of two concentrate levels, 1 or 2 kg, and two protein sources, soybean meal or cotton seed meal. The effect of the interaction was observed for intake of dry matter (DM), neutral detergent fiber (NDF) in % live weight and total digestible nutrient intake (TDN). The quantity of concentrate influenced the intakes of crude protein (CP), NDF, ether extract (EE), non-fibrous carbohydrates (NFC), organic matter (OM) and CP per kg TDN. There was no significant effect of the treatments for DM, NDF, OM and NDT digestibility but the protein source influenced the CP, EE and NFC digestibility. There was an effect of concentrate quantity for weight gain (WG), and there was effect of the concentrate quantity × protein source interaction for weight gain per cm of height gain of the cernelha. The diet consisting of 1 kg cotton seed based concentrate was insufficient to reach 800 g/day weight gain and diets consisting of 2 kg concentrate resulted in greater weight gain. However, the diet consisting of 2 kg soybean meal based concentrate was more efficient because it gave greater linear growth to the heifers with an 820g mean gain per day. Body weight prediction equations based on the thorax perimeter are more accurate in prediction compared to the other linear measurements.
intake; energy; dairy heifers; protein
