Abstract:
Animal Production in Australia Vol. 15 DEGRADATION CHARACTERISTICS OF GRASS AND LEGUME PASTURES IN GRAZING LAMBS by K.A. ARCHER* and T.J. KEMPTON** The low productivity of lambs weaned onto grass as opposed to legume based pastures is partly related to differences in digestion characteristics of the species (Beever et al. 1978). Differences between species have been shown in the proportion of organic matter digested in the rumen, the efficiency of microbial protein synthesis, and the outflow of total protein from the rumen. This study was undertaken to estimate differences in the degradation characteristics of clover and grass species as predicted using the nylon bag technique as suggested by Kempton (1980). Four lambs (liveweight 30 kg) were prepared with oesophageal and rumen fistulae and allocated to either a grass based or legume based pasture. The lambs grazed those pastures for four weeks, after which 300g feed extrusa samples were collected from the oesophageal fistulae. Five nylon bags (10 x 20cm, 60~ pore size) each containing 50g fresh material \were placed in the rumen of the respective donor animals. Bags were withdrawn at 4, 8, 24, 32 and 50 hours, washed under tap water and dried at 75'C. DM disappearance characteristics were calculated as described by Kemp-ton (1980). Results are given in Table 1. TABLE 1 Mean values for characteristics of DM disappearance of grass and legume samples when incubated in nylon bags in the rumen of grazing lambs. Each value is the mean of four observations * Dept. of Agriculture, R-M-13. 944, Tamworth, N.S.W. 2340. ** Dept. of Biochemistry and Nutrition, University of New England, Armidale, N.S.W., 2351. 652