Utilization of Lolium multiflorum by sheep 1. Influence of dry matter content and correlated factors on voluntary intake

Abstract

The intake by young sheep of Lolium multiflorum cv. Midmar (ryegrass) with dry matter (DM) contents of between 10.2% and 20.5% was studied. Intake was measured on pasture, while at the same time herbage was cut and fed either fresh or dry indoors. Additional variables were sward height at pasture and chop length indoors. Quality parameters did not change much between DM contents studied. Intake of wet herbage remained fairly constant irrespective of DM content, suggesting that moisture levels exert a controlling influence on intake. Organic matter (OM) intake increased dramatically with DM content, from 47.4 to 87.4 g kg⁻¹ W^0.75 day⁻¹. Sward height did not influence OM intake significantly, but chop length of cut herbage did. At low DM content the long chop length depressed intake, possibly because of increased chewing and rumination times, while no effect was observed at higher DM contents. It was concluded that if the intake of Midmar ryegrass is to be maximized the DM content of pasture should be at least 18–20%.

Die inname van Lolium multiflorum cv. Midmar (raaigras) deur jong skape is tussen droëmateriaalinhoude (DM) van 10.2% en 20.5% bestudeer. Inname is op weiding gemeet, terwyl materiaal terselftertyd gesny is en óf nat óf droog binnenshuis gevoer is. Bykomende veranderlikes op weiding was weihoogte en binnenshuis snylengte. Kwaliteitsparameters het nie veel verskil tussen die DM‐inhoudsgrense wat bestudeer is nie. Die inname van nat materiaal het, onge‐ag DM‐inhoud, bykans konstant gebly, wat daarop dui dat hoë vogpeile inname gedeeltelik beheer. Organiese materiaalinname (OM) het dramaties gestyg met DM‐inhoud, van 47.4 tot 87.4 g kg⁻¹ W^0.75 dag⁻¹. Weihoogte het nie OM‐inname betekenisvol beïnvloed nie, maar wel lengte van gesnyde materiaal. By lae DM‐inhoud het ‘n lang snylengte inname onderdruk, waarskynlik as gevolg van ‘n toename in kou‐ en herkoutyd, terwyl geen effek by hoër DM‐inhoude waargeneem is nie. Die gevolgtrekking is gemaak dat maksimum inname van Midmar‐raaigras verkry sal word by ‘n DM‐inhoud van tenminste 18–20%.

Additional index words:

• Chop length
• digestibility
• fresh herbage
• pasture
• sward height