Stimulation of wool growth by Desmanthus spp. as a supplement to a diet of Mitchell grass hay

Abstract

Desmanthus spp. have been released for the more favoured environments of southern Queensland and offer the possibility of fulfilling the role of Stylosanthes in the semi-arid clay soil Mitchell grass bioregion of western Queensland. An experiment was carried out to evaluate the potential of Desmanthus spp. to enhance live weight gains and wool production of sheep grazing Mitchell grass. Thirty-six Merino wethers in individual metabolism cages were fed a basal diet of 600 g/hd/d of Mitchell grass plus mineral, alone or supplemented with 200 g hay of one of 4 Desmanthus spp.accessions, or Stylosanthes hamata cv. Verano. The basal diet supplied 7.96 g/d N and the supplemented diets 8.73-12.43 g/d N, and N retention was 5.16 g/d on the basal diet and 4.82-7.29 g/d on the supplemented diets. All sheep lost weight during the study, with greater losses (P<0.05) on the Control diet. Wool growth varied from 0.53 mg/cm2/d for the Control to 0.7] mg/cm2/d for the diet containing D. virgatus CPI 78382. Verano stylo and the Desmanthus accessions had similar beneficial effects on wool growth. These results associated with the agronomic adaptation of Desmanthus genotypes to the Mitchell grass bioregion suggest that these legumes have potential to improve wool growth in that area.