A new equation to predict dry matter intake by Nellore beef cattle in commercial feedlots in Brazil

Abstract

This study aimed to create an equation to predict the dry matter intake (DMI) of Nellore cattle using intake data from Azevedo et al. (2016) and intake data from animals raised in commercial feedlots in Brazil. This equation will then be compared with other equations already published. A correlation analysis between performance variables and DMI was performed. The metabolic body weight (MBW), average daily gain (ADG) and average daily gain squared (ADG2) variables were included in the model to generate the prediction equation using SAS software. The new prediction equation was validated according to accuracy and precision in two feedlots. After validation, the new equation was compared to Equation 2.1 published by Azevedo et al. (2016) and other equations published by McMeniman et al. (2010), Anele et al. (2014) and Silva et al. (2021) in two other commercial feedlots using the software Model Evaluation System v. 3.2.3. The proposed equation for commercial feedlots was DMI = -2.1948 + 0.08338 * MBW + 3.9328 * ADG - 0.9030 * ADG2. Neither the equations proposed by Anele et al. (2014) and Silva et al. (2021) nor Equations 3 and 4 published by McMeniman et al. (2010) proved to be adequate in predicting intake in commercial feedlots. The Azevedo et al. (2016) Equation 2.1 and the new equation generated in the commercial herd in tropical conditions accurately predicted the actual intake of validation herds 1 and 2. Equation 5 proposed by McMeniman et al. (2010) was accurate and precise to predict the actual intake only in feedlot 2. However, the new equation presented better accuracy and precision indicators. This new equation is more adequate in predicting the intake of Nellore beef cattle in commercial feedlots. The new equation can make feedlot beef cattle feeding systems in Brazil more accurate in tropical conditions and, therefore, more suitable.