Some problems of introducing feedlot rations to lambs.

Abstract

Animal Production in Australia SOME PROBLEMS OF INTRODUCING FEEDLOT RATIONS TO LAMBS D.G. HALL* and J.G. MULHOLLAND** Lotfeeding of lambs in Australia has become a more common practice recently. Frequently, rations are based on oats and hay with a protein supplement such as meatmeal. Problems have occurred getting pasture fed lambs started on concentrate feeds. Reports of lotfeeding often ignore the introductory period in biological and economic assessments. This paper describes some of the problems encountered during the early phase of feeding when rations based on oats, hay or wheaten straw, and meatmeal or lupins (Lupinus angustifolius) were fed to lambs. Three diets, each with three replications were formulated to contain an estimated 14% crude protein: Diet 1 - 56% oats, 14% meatmeal, 30% pasture hay; Diet 2 - 37% oats, 33% lupins, 30% pasture hay; Diet 3 - 39% oats, 41% lupins, 20% wheaten straw. Crude protein contents of the components were oats 7.9%, meatmeal 47.1%, lupins 24.7%, hay 9.6% and wheaten straw 4.1%. Limestone and salt were given at 1.5%o of the ration but added only to the concentrate portion. The hay and straw were hammermilled through a 25 mm screen. Feeding took place over 91 days with feed being provided daily and residues removed weekly. Fifty four wether and 54 ewe second cross lambs,(26.2+1.8 kg) were weaned in mid-October and placed on pasture. After 10 days, they were drenched, vaccinated, weighed and allocated to nine pens. Pens had concrete floors and a shade area. The sheep were fed 750 g/h/ d of medium quality lucerne for the first week. This was gradually replaced by each ration during the next week, the roughage and concentrate being fed as separate portions and supplied to requirements. The lambs gained 2.5 kg /h on week in the feedlot, lambs lost an ed 66, 50 and 22 days after feeding accustomed to the diets after about TABLE 1 the pasture after weaning, but in the first average 2.6 kg/h . These losses were recoverof each diet started. When lambs had become 35 days, growth rates were more acceptable. Iiveweight gain and intake of lambs on three feedlot diets Means with different subscripts were significantly different (PcO.05) The low intakes and low overall liveweight gains highlight the importance of the introductory period. Intakes were low possibly because: the roughage was only of low to medium quality; the high levels of supplements added to the concentrate portion of the diet resulted in a dusty diet, particularly Diet 1 with meatmeal; and the temperature during the first 35 days was often over 30�C, which can also reduce intake (Ames and Brink 1977). We conclude that the introductory phase should form part of any assessment of lamb growth in a feedlot and that there is a need to improve rations and management when introducing grass fed lambs to concentrate feeds. AMES, D.R., and BRINK, D.R. (1977). J. Anim. Sci. 44:136. * N.S.W. Department of Agriculture, *Cowra, N.S.W. 2794; **WaggaWagga,N.S.W. 2650. 650