Utilization of Lolium multiflorum by sheep 2. The effect of drying the herbage on soluble nitrogen content and partial digestion

Abstract

The amount of soluble N and the effective degradation of fresh and dry herbage of Lolium multiflorum cv. Midmar (ryegrass) was determined by the nylon bag technique. In another experiment the digestion and disappearance of organic matter (OM) and nitrogen (N) were measured on fresh and dry ryegrass herbage fed to sheep either ad lib or at ad lib‐20%. The amount of soluble N was reduced by drying at 60°C but the effective degradation remained unaltered. The disappearance of OM and N components in the digestive tract was not significantly influenced by treatment but the effect of level of intake was significant. There was, however, no significant treatment × feeding level interaction. The soluble N content of ryegrass did not affect non‐ammonia N absorption in the small intestine significantly. It was concluded that amino acid absorption from the small intestine will not be limiting at dry matter contents of Midmar ryegrass of 18–20%.

Die hoeveelheid en effektiewe degradasie van N van nat en droë weidingsmateriaal van Lolium multiflorum cv. Midmar (raaigras) is deur middel van die nylonsaktegniek bepaal. In ‘n verdere eksperiment is die vertering en verdwyning van organiese materiaal (OM) en stikstof (N) op nat en gedroogde raaigras met skape by ad lib en ad lib‐20% bepaal. Droging by 60°C het die hoeveelheid oplosbare N in die voer verlaag maar nie die effektiewe degradasie daarvan nie. Die verdwyning van OM en N in die spysverteringskanaal is nie deur behandeling beïnvloed nie maar die invloed van voedingspeil was betekenisvol. Daar was egter geen betekenisvolle behandeling × voedingspeil interaksie nie. Die oplosbare N‐inhoud in raaigras het nie die nie‐ammoniak N absorpsie in die dunderm betekenisvol beïnvloed nie. Die gevolgtrekking is gemaak dat aminosuurabsorpsie vanuit die dunderm nie beperkend sal wees by Midmar‐raaigras met ‘n droëmateriaalinhoud van 18–20% nie.

Additional index words:

• Digestibility
• intake
• non‐ammonia nitrogen
• nylon bag