Performance of Holstein Calves, Heifers and First-Lactating Cows Fed Starter Diets with Different Protein Levels and Types of Soybean Meal

Holstein calves were fed pelleted starter diets with crude protein (CP) concentrations of 18%, 22% and 24% per dry matter (DM) containing soybean meal (SBM) (SBM18, SBM20 and SBM24), respectively, for 10 weeks from 14 days of age. Another diet with a CP concentration of 18% per DM was tested using commercial xylose-soybean meal (XSB; Yasminomax) instead of SBM. Each diet was fed to 24 calves and the feed consumption, nutrient intake, body weight (BW) gain, skeletal growth and selected blood metabolites were determined. Weaned animals were kept under observation for economic characteristics such as post-weaning (days 84 to 196) weight gain, withers height, weight at first heat, number of services per pregnancy and milk yield during first lactation. The average daily starter consumption was highest in calves fed SBM20. The average BW gain and total DM intake were highest in calves fed SBM20. Feed efficiency was highest in calves fed SBM24, but protein efficiency was highest in calves fed SBM20. A decreased blood glucose and increased blood insulin concentrations were observed in calves fed SBM18. Blood urea N and blood glucose were highest in calves fed SBM24. The service rate, age at first parturition and milk yield varied according to diet (P<0.001).