Prediction of the growth performance of feedlot cattle using phenotypic and anthropometric measures

Abstract

The price of purchasing and feeding feedlot cattle are expenses which contribute the most to the overall costs of a feedlot. Therefore, if the feedlot owner can purchase a specific breed type, or cattle with a specific weight or size, knowing that these cattle are likely to outperform the rest of the cattle, it may be possible to improve profits by maximising average daily gain (ADG) and reduce days in feed (DIF). Although, it is understood that other factors such as maturity type, frame size, nutrition, management and environment influence ADG and DIF. The purpose of this study was to assess the possibility of predicting the future growth performance of cattle entering the feedlot using phenotypic and anthropometric measurements. This study merely tried to determine if the ADG and DIF could be predicted based on initial measurements. Measurements such as initial body weight, initial hip height, initial shoulder height, initial body length and various ratios were used. The results of this study show that the use of these selected phenotypic and anthropometric measurements are useful predictors of the future feedlot performance of cattle. Cattle with higher initial weights (271.01 ± 40.288kg, P = 0.000), i.e. cattle which were heavier at placement, had higher ADG (1.45 ± 0.491kg, P = 0.000) compared to smaller cattle with lower initial weights. This is within limits because if the initial weight becomes too high the ADG decreases again. Larger and heavier cattle at placement also spent a shorter period (156.88 ± 32.287 days, P = 0.000) in the feedlot. This particular feedlot classifies cattle into either ideal (≥200kg) or sub-ideal (<200kg), while the initial weight in this study was taken on day one of cattle being in the feedlot, excluding the backgrounding period. Cattle classified as being of the ideal weight were fed for a shorter period compared to those categorised as sub-ideal, but the final weights and carcass weights did not differ. Although this feedlot suspected that the sheath length may influence the various variables, the lack of any significant effect indicates that there is no point in the feedlot taking this measurement. At best the tendency for cattle with a small sheath to have a numerically better initial weight, ADG, final weight and carcass weight may be explored in future research. The initial body length measurement had the strongest positive correlation with ADG (r = 0.329, R2 = 11.7%, P = 0.000), while the initial weight had the strongest negative correlation with DIF (r = - 0.668, R2 = 46.3%, P = 0.000). Therefore, the ADG and DIF can be predicted using certain of the anthropometric and phenotypic measurements.