Lamb growth on N fertilized pangola grass and legume based pastures in south east Queensland.

Abstract

Animal Production in Australia LAMB GROWTH ON N-FERTILIZED PANGOLA GRASS AND LEGUME BASED PASTURES IN SOUTH EAST QUEENSLAND PAMELA BOULTON� and B.W. NORTON* Initial studies of fat lamb production from tropical legume-grass pastures in south eastern Queensland recorded poor lamb growth and legume persistence under grazing (Fleming 1974). Since then lamb growth studies on N-fertilized Pangola grass have identified correct control measures for intestinal parasites, the occurrence of cobalt deficiency (Norton and Hales 1976) and other management techniques which have improved lamb growth from these pastures. This experiment reinvestigates the potential value of tropical legumes for lamb production in summer and autumn in this subtropical environment. Two groups of 36 lambs ([Border Leicester x Merino] x Dorset Horn) were weaned at 14 weeks onto Pangola grass in November (Mean Liveweight, 24.2 kg) and February (Mean Liveweight 23.1 kg). After 2 weeks, 12 lambs from the first (summer) group were allocated to each of the following pastures, Pangola grass (Digitaria decwnbens) fertilized with 115 kg N/ha (30 lamb/ha), Lotononis bainesii (24 lamb/ha), and StyZosanthes gzhnensb cv. Schofield (24 lamb/ha), and 6 lambs on each pasture given a cobaltbullet and grinder. This experiment lasted 12 weeks (31/11/76 to 23/2/77) after which the second (autumn) group of weaners were allocated to these paddocks and treated with cobalt bullets as was the first group. This experiment lasted 8 weeks. No irrigation was applied during either trial. TABLE 1 The effects of pasture type, season of grazing and cobalt supplementation on liveweight change (g/d) of lambs Treatment effects (cobalt supplementation, season and pasture type) are shown in Table 1. Lambs grew significantly (PcO.05) better on Lotononis than on Stylo, both these pastures being better than Pangola grass, There was no significant effect of either cobalt supplementation or season on lamb growth from the legume pastures. There was a significant response in lamb growth on Pangola grass to cobalt supplementation in both seasons, with cobalt supplemented lambs growing significantly (P < 0.05) better in autumn than summer. These studies demonstrate that given appropriate management, good lamb growth can be obtained on tropical pastures. Further studies are being conducted to determine optimum management strategies for year round lamb production in this environment. FLEMING, R.J. (1974). M.Agr.Sc. Thesis, University of Queensland. NORTON, B.W, and HALES, J.W. (1976). Proc. Aust. Soc. Anim. Prod. 11: 393. $94 Victoria Street, St. George, Qld 4393. *Department of Agriculture, University of Queensland, St. Lucia, Qld 4067. 641