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Range cattle grazing in semi-arid regions are commonly limited by lack of nutrients from low-quality forage. Due to this, managers are faced with the challenge of monitoring diet quality in order to address nutrient limitations. Near-infrared spectroscopy (NIRS) of fecal samples is a method used to determine diet quality in grazing animals. When combined with a nutritional balance analyzer such as the NUTBAL system, fecal NIRS can be used to monitor nutritional status and predict animal performance. In addition, previous research has shown that forage intake and forage quality are positively correlated. Our research aimed to test the ability of NUTBAL to predict animal performance as represented by body condition score (BCS) in cattle (n=82 Animal Units) grazing on the Santa Rita Experimental Range (SRER) in southern Arizona. Previous work conducted on other Arizona rangelands led to the hypothesis that fecal NIRS coupled with NUTBAL can be used to monitor diet quality and project BCS in a Southern Arizona commercial grazing operation. Data collection occurred between June 2016 and June 2017. Standing biomass and botanical composition were measured prior to each grazing period and relative utilization was measured following each grazing period. During the midpoint of the grazing period in each pasture, 30 body condition scores and a fecal composite of 15 samples was collected. Fecal derived diet quality varied between minimum values of 4.00 % CP and 58.40 % DOM in March 2017, to a maximum of 10.75% CP and 61.25% in early August 2016. This study confirmed the ability of fecal NIRS paired with NUTBAL to project future animal performance within 0.5 a BCS more than 80% of the time in cattle grazing on the SRER. With this information, cattle managers in Southern Arizona can better address animal performance needs and nutrient deficiencies.