A comparison of potatoes with grain sorghum in feedlot diets for production of prime lambs

Abstract

A feedlot experiment was conducted to compare diets using either potatoes or grain sorghum, each fed with or without a protein meal supplement, for production feeding of Border Leicester x Merino lambs. Diets also included chaffed pasture hay, urea and a mineral-vitamin mix. The protein supplement consisted of a mixture of soybean, cottonseed and fishmeal, and was added to provide an extra 10% crude protein in the basal diet. The experiment ran for 11 weeks, which included an introductory period of 3 weeks and an experimental period of 8 weeks. Liveweight gains (g head-1 day-1) and feed conversion ratios (g dry feed eaten/g liveweight change) for the diets based on potatoes only, potatoes plus protein, grain only and grain plus protein during the experimental period were 11 5 and 9.1:1,178 and 7.0 : 1,96 and 7.6 : 1 and 184 and 5.6 : 1, respectively. Liveweight gains were similar for potato and grain diets, but potato diets at both levels of protein were utilized less efficiently than grain sorghum (P < 0.05). Protein supplements increased liveweight gain (P < 0.05) and improved feed conversion ratios for both energy sources (P < 0.01). It is concluded that potatoes are a feasible alternative to grain for use in feedlot diets for lambs where normal marketing of potatoes is not considered practical.