Forage Quality of Prostrate Kochia Compared with Three Browse Species1

Abstract

AbstractProstrate kochia [Kochia prostrata (L.) Schrad.], a shrub native to Asia, has received considerable attention because of its adaptation as a browse plant on western ranges. Prostrate kochia is a member of the Chenopodiaceae, the same family to which halogeton [Halogeton glomeratus (Bieb.) C. A. Mey.] and greasewood [Sarcobatus vermiculatus (Hook.) Torr.] belong. Both of these accumulate oxalates and can be toxic, depending on environmental conditions.This report presents data comparing crude protein, crude fiber, beta carotene, tannins, and oxalates of 13 prostrate kochia introductions to winterfat [Ceratoides lanata( Pursh.) J. T. Howell], an Iranian saltbush (Atriplex verrucifera Bieb.), and fourwing saltbush [Atriplex canescens (Pursh.) Nutt.], a favored browse plant native to the western range, during the browse utilization season of August to March.Two‐month‐old seedlings were transplanted to the field at Central Ferry, Wash. in early April. The soil was a Snake River bar alluvial classified as “Spofford” silt loam “fine‐silty, mixed, mesic typic Natrixerolls” with a pH of 6.7. Harvests were made at the end of the second and third growing seasons.Crude protein exhibited a regular downward trend from 14.7% to 8.9% in prostrate kochia, while fourwing saltbush varied from 13.60%, to 11.40%, and winterfat from 16.8% to 10.1%. Crude fiber increased from 19% to 42% in prostrate kochia. There was little change in fourwing saltbush and winterfat (14.6% to 17.8% and 30% to 33%, respectively). The highest tannin value was 7.0 mg/g in prostrate kochia, well below the critical level of 25 mg/g reported by E. D. Donnelly and W. B. Anthony in 1969. Oxalates averaged 1.20% in prostrate kochia, 1.75% in fourwing saltbush and 1.55% in winterfat. Using the 45 g critical level for sheep reported by H. L. Morton and coworkers in 1959, it would require daily consumption in excess of 2.25 kg of 2% oxalate forage before oxalates would be toxic. In August the carotene levels were comparable, but fourwing saltbush and winterfat were clearly superior during the winter months. Carotene levels dropped from 42 mg/100 g to 6.9 mg/100 g in January in prostrate kochia, but increased to 11 mg/100 g in March due to early bud development. The average of fourwing saltbush was 50 mg/100 g in August and 13 mg/100 g in March. Winterfat contained 50.5 mg/100 g in August, dropped to 19.6 mg/100 g in January, and climbed to 30.4 mg/100 g in March.