Comparison of dry season urea supplements containing salt, sulfur or molasses for steers grazing native pasture in the dry tropics of northern Queensland

Abstract

The effects of feeding dry season supplements of salt and urea (NaU), salt, urea and sulfur (NaUS) and molasses and urea (MU) on the liveweight of steers grazing native pasture in northern Queensland were studied over four years. Liveweight during the feeding period was improved (P < 0.05) by each supplement in three years out of four, with a mean level of response of 49 g/d. The supplements gave similar results in two years while in one year NaU and MU were better than NaUS (P < 0.05) and in another NaUS was better than NaU (P < 0.05). Compensatory growth by unsupplemented animals after the feeding period eroded liveweight responses to supplements in most cases. Blood sulfate level was not affected by treatment, nor was it related to liveweight in either the feeding or post-feeding periods. Mean levels for unsupplemented animals were 15.8 and 21.2 ¦g/ml for the feeding and post-feeding periods, respectively. Salivary Na:K ratios exceeded 18:1 throughout the year for unsupplemented and NaUS groups, indicating sodium sufficiency.