Lamb Stocking Rate and Supplementation Effects on Mixed Triticale and Ryegrass Swards Characteristics

An experiment was carried out from 9 June to 22 October 1997, using a Lolium multiflorum L. (ryegrass) and Triticosecale Wittmack (triticale) mixed sward grazed by lambs in a rotational grazing system, to determine the effect of stocking rate (SR; 20, 30 and 40 lambs/ha) and supplementation (S; with or without) on herbage production, composition and nutritive value. SR affected significantly before and after grazing herbage mass and sward height, being higher the values of these variables at the lower SR (3232, 2611 and 2345 kg DM ha-1, P \u3c 0.05; 2557, 1761 and 1612 kg DM ha-1, P \u3c 0.01; 17, 11 and 9 cm, P \u3c 0.01 respectively). Increments in SR had an effect on post grazing sward composition, increasing the proportion of ryegrass (32, 36 and 47 %, P\u3c 0.05) and decreasing triticale contribution (68, 64 and 55 %, P\u3c 0.05) for 20, 30 and 40 lambs/ha. The effect of SR on sward nutritive value was not very clear. Before grazing, S affected significantly herbage mass, being higher the values at the supplemented treatments (2787 vs. 2672 kg DM ha-1, P \u3c 0.10). This experiment showed the high potential of forage production and nutritive value of ryegrass and triticale swards for lamb production in the sandy soil region of Uruguay, and the dominant effect of SR, compared to S, on most of the sward variables considered