Cattle grazing and biosolids in West Texas

Lime stabilized biosolids applications on rangelands were evaluated by cattle grazing in 2000 and 2001 on six, 16-ha pastures. Three pastures were treated with 20 dry ton per ha and 3 untreated pastures were used as a control. Average daily gain of steers grazed on test pastures for 120 days were evaluated through two grazing seasons. Forage samples were collected to determine forage availability and forage quality. At the end of each performance trial, animal tissues were collected from liver, muscle, kidney, and heart to evaluate trace elements. An additional four, 8-ha pastures were used to document animal behavior. Each of these four pastures was divided in half. Biosolids was applied in one half of the pasture at 20 dry ton/ha; the other half was untreated. Animal behavior was evaluated in 4-day consecutive periods, during 12 hours of direct observations at the beginning and end of each grazing season of the performance trial.

Average daily gain was similar (P>0.05) between treated and untreated areas with 0.249 and 0.238 kg per animal and with 0.140 and 0.139 kg per ha in year 2000, as well as 0.435 and 0.377 kg per animal and 0.154 and 0.118 kg per ha in year 2001. Tissue samples from steers grazing on treated pastures were similar in trace elements (P>0.05) compared with those collected on untreated pastures. The steers spent 5 hours and 40 minutes per day grazing in 2000 with 57% of grazing time spent in the biosolids-treated area. In 2001, steers spent 6 hours and 53 minutes grazing with 56% of grazing time spent in the biosolids area. In conclusion, biosolids affect animal performance when conditions are favorable especially rainfall and temperature. However, steer grazing behavior showed preferences for grazing activities on the biosolids areas. Biosolids applications positively affect forage quality, especially crude protein.