Grazing as an alternative for utilization of saline-sodic soils in the San Joaquin Valley: Selenium accretion and performance of beef heifers

Abstract

Two experiments were conducted to evaluate Se accumulation and health of non-pregnant, non-breeding beef cattle grazing on forages with a high Se content due to irrigation with saline drainage water. Heifers grazed experimental pastures of “Jose” tall wheatgrass (TWG; Thinopyrum ponticum var. “Jose”) and creeping wildrye (CWR; Leymus triticoides var. “Rio”) for190days in Experiment 1 (2007) and for 165days in Experiment 2 (2008). In experiment 1, mean Se concentrations were similar in TWG and CWR herbage (4.0 versus 3.7±0.26mg/kg dry weight; p=0.34) as was crude protein (113 versus 114±7.9g/kg dry weight; p=0.94). Concentrations of Se in blood increased by 300% during the grazing period, and were similar for heifers grazing the TWG or CWR pastures (0.94 versus 0.87±0.03mg/kg; p=0.89). Heifers grazing on TWG gained more body weight than did heifers grazing on CWR (0.59 versus 0.27±0.07kg/days; p<0.01). In experiment 2, concentration of Se (4.0 versus 2.8mg/kg±0.19mg/kg dry weight; p<0.01) and crude protein (79 versus 90±5.6g/kg dry weight; p<0.01) differed, for TWG and CWR, respectively. Within 20days, Se concentrations in blood had increased by 300% and by nearly 200% in heifers grazing on TWG or CWR. All data cited are least square means±standard error of the mean. Data from our two grazing seasons are consistent in demonstrating the safety of grazing beef cattle for a period of up to 6months on TWG and CWR forages having high levels of Se due to irrigation with saline drainage water. This suggests that forage production using saline drainage water is a viable alternative for saline soils with limited potential for producing high value, salt-sensitive, crops.