PSIV-7 Evaluating Relationships Among Empty Body, Protein, and Fat Gain and Retained Energy for Pre- and Postweaning Calves

Abstract

Abstract Discrepancies in the predictability of the nutritional equation used to predict empty body gain in preweaning and postweaning calves could be due to differences in proportion of protein and fat in the gain. The objective of this study was to understand the differences in the relationships of empty body weight gain (EBG) with protein (EBP) and fat (EBF) gain, and retained energy (RE) in preweaning and postweaning calves. A literature search was performed to create a dataset comprised of EBG and composition of gain in calves. The relationships of EBG with EBP, EBF, and RE was compared in preweaning and postweaning calves using R statistical software. Pearson correlation coefficients of EBG with EBP, EBF, and RE were 0.971, 0.839, and 0.934 and 0.805, 0.807, and 0.889 for preweaning and postweaning calves, respectively. A nonlinear regression model was used to evaluate the relationship between EBG and RE including the effects of age (defined as 0 for preweaning and 1 for postweaning calves) and type (defined as 0 for dairy and 1 for beef calves), [EBG = (a + b * age + c * type) * RE^ (d + e * age + f * type)]. The power coefficients were not different (P > 0.05) between preweaning and postweaning calves (0.379 and 0.446 ± 0.041, respectively), but the exponents were different (P ≤ 0.05; 0.921 and 0.558 ± 0.079, respectively). In conclusion, the relationship between empty body weight gain and composition of gain differs between preweaning and postweaning calves, suggesting that a more robust equation or group of equations should be used in nutrition models.