Estimating the daily weight gain of beef stocker cattle grazing bermudagrass as affected by initial age and body condition

Objective: Our objective was to develop an age x BCS factor (ABCf) that could be used to estimate the ADG of stockers grazing bermudagrass (Cynodon dactylon [L.] Pers.) pasture as influenced by their age and BCS at the onset of stocking, hereafter referred to as the initial age and BCS.Materials and Methods: Data on the ADG of stock-ers grazing bermudagrass in the southern United States were obtained from multiple sources, including literature, for various scenarios of initial age x BCS. Then, an ABCf for each age x BCS scenario was calculated by dividing its ADG by the ADG of calves 7 to 10 mo old with BCS of 5, a standard age x BCS scenario. Finally, an ABCf equa-tion was derived by regressing the ABCf values against the BCS values under each age group.Results and Discussion: We derived the following ABCf equation to estimate the ADG of a stocker grazing bermudagrass pasture as ADG ' = ADG x ABCf, where and BCS on ADG of stockers grazing bermudagrass pas-ture. Current ADG indices or estimates do not account for the interacting effects of initial age and BCS. By incorpo-rating the ABCf into an ADG prediction system, the scien-tific community and stakeholders can more accurately as-sess the effects of these attributes on animal performance and develop appropriate purchase pricing and supplemen-tation strategies before and during stocking.