Nutritive value of Medicago truncatula (cv. Jemalong) as pasture for sheep. 2 Voluntary intake and animal production

Author: T.S. Brand, S.W.P. Cloete, T.T. de Villiers, F. Franck and J. Coetzee
Year: 1991
Issue: 3
Volume: 21
Page: 137 - 143

The experiment was conducted to (i) determine the excretion pattern of an indigestible marker for sheep, (ii) compare three different techniques used to determine intake, (iii) determine the crude protein (CP) and digestible organic matter (DOM) intake of wethers and reproducing ewes grazing medic pasture, and (iv) evaluate their production. The percentage of chromium excreted during the determination of the excretion pattern varied between 82,5 and 108,2 when expressed as percentages of representative grab samples taken throughout the day. The diurnal variation in the percentage of chromium excreted (y) was described by the equation, y = 310,9 – 30,44x + 1,03x2 (R2 = 0,67; n = 40), where x. represents the time of sampling. Intake of DOM estimated by the total collection of faeces was significantly (P 0,01 0,01) lower than values obtained by the total collection of chromium and llh00 chromium grab samples, possibly due to losses of faeces from the bags, No significant difference occurred between the latter two techniques, which resulted in DOM intake results that were highly correlated (r = 0,80). Significant (P 0,01) differences in DOM (variation between 370 and 716 g/d) and CP intake (variation between 55 and 227 g/d) by Merino wethers were observed between months, and a seasonal pattern was observed. The same trend was found with the reproducing South African Mutton Merino (SAMM) ewes; DOM intake varying between 445 and 1008 g/d, while CP intakes varied between 48 and 333 g/d. The live mass of the wethers (variation between 48 and 84 kg) and ewes (variation between 64 and 85 kg) differed significantly (P 0,01) between months, generally following a seasonal trend corresponding to DOM and CP intakes. Wool production of the Merino wethers (6,5 sheep/ha) was 60,5 (1981) and 39,7 (1982) kg greasy wool/ha for two year periods. SAMM ewes (5,2 ewes/ha) produced 23,4 kg greasy wool/ha (1981) while meat production was 62,4 (1981) and 90,4 (1982) kg/ha. Lambs were weaned (ca. 100 days) at 31,8 (1981) and 33,8 (1982) kg, with average daily gains of 263 and 294 g/d in the respective years.


Keywords: chromium oxide, excretion patern, intake, legume, Medicago spp., medics, sheep
Read article