Validation of a mechanistic dynamic pre-weaned lamb growth and body composition simulation model

Lamb growth and body composition simulation models can provide valuable insights into the assessment of feeding regimens and rearing systems, allowing optimisation of farm profitability without the need for in-vivo trials. The objective of the present study was to evaluate the performance of a published mechanistic dynamic model on the growth and body composition of preweaned lambs using independently published data sets. Data generated from eight treatments, representing three artificial lamb rearing experiments (n = 77 lambs) were used. Initial body composition data were obtained from four lambs at approximately two days of age, with the remaining lambs being provided with defined nutritional treatments until the trial end-point. The body composition of lambs at slaughter was determined in six treatments across two experiments. Feed intake and live weight (LW) of lambs were recorded in all treatments. The LW, average daily gain (ADG) and ash deposition rates of lambs were accurately simulated by the model (paired t-test, P > 0.05). The overall empty body weight (EBW), gutfill, protein and fat deposition rates were overestimated, and water deposition rate was underestimated by the model (paired t-test, P < 0.05). Collectively, these results suggest that the model can be used at the farm level with acceptable accuracy to determine lamb growth. Further improvements in the model are required for protein, fat and water deposition rates, gutfill and EBW to make it more applicable for wider usage