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

Abstract

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) lower than values obtained by the total collection of chromium and 11h00 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 woolf 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.

Die eksperiment is uitgevoer om (i) die uitskeidingspatroon van 'n onverteerbare merker vir skape te bepaal, (ii) drie verskillende tegnieke van'innamebepaling te vergelyk, (iii) ruprote'ien(RP)- en verteerbare oganiese materiaal(VOM)- inname van Merinohamels asook van reproduserende Suid-Afrikaanse Vleismerino(SAVM)-ooie op medicweiding te bepaal, en (iv) hul gepaardgaande produksie te evalueer. Die persentasie chroom in die grypmonsters soos in die uitskeidingskurwe .bepaal, het tussen 82,5 en 108,2 gevarieer. Die persentasie chroom in die grypmonsters (y) is beskryf deur die vergelyking, y = 310,9 - 30,44x + 1,03x² (R² = 0,67; n = 40), waar x die tyd van monsterneming verteenwoordig. Die VOM-inname is betekenisvol (P≤0.01) laer deur die totale miskolleksietegniek beraam, moontlik as gevolg van verliese uit die missakke, Geen verskille het voorgekom tussen VOM-inname soos met die 11h00-chroomgrypmonsters en totale chroomkolleksie bepaal nie, met 'n hoogsbetekenisvol korrelasie tussen VOM-inname beraam volgens die metodes (r = 0,80). Betekenisvolle (P ≤ 0,01) verskille in YOM (variasie tussen 370 en 716 g/d)- en RP (variasie tussen 55 en 227 g/d)-inname by Merinohamels is tussen maande waargeneem, en inname het 'n tipiese seisoenale patroon gevolg. Dieselfde tendens het .by die SAVM-ooie voorgekom (VOM-inname het tussen 445 en 1008 g/d gevarieer terwyl RP-inname tussen 48 en 333 g/d gevarieer het). Liggaamsmassa van die hamels (48 tot 84 kg) en ooie (64 tot 85 kg) het betekenisvol (P≤0,01) tussen maande gevarieer, en dieselfde seisoenale tendens as inname gevolg. Rouwolproduksie van die hamels (veebelading van 6,5 skape/ha) was 60,5 (1981) en 39,7 (1982) kg/ha onderskeidelik vir twee jare, terwyl die ooie (5,2 ooie/ha) 23,4 kg rouwol/ha (1981) geproduseer het. Lamsvleisproduksie deur ooie het 62,4 (1981) en 90,4 (1982) kg/ha bedra. Die 100-dae-speenmassas van die lammers was 31,8 (1981) en 33,8 (1982) kg, terwyl die ooreenstemmende gemiddelde daaglikse toenames van die lammers 263 en 294 g /d vir die onderskele jare was.

Kewords: Medicago spp, legume, medics, excretion pattern, chromium oxide, intake, sheep