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 × BCS factor (ABC_f) 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 × BCS. Then, an ABC_f for each age × 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 × BCS scenario. Finally, an ABC_f equa- tion was derived by regressing the ABC_f values against the BCS values under each age group.

Results and Discussion

We derived the following ABC_f equation to estimate the ADG of a stocker grazing bermudagrass pasture as ADG′ = ADG × ABC_f, 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 ABC_f 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.