Voluntary intake of several planted pastures by sheep and an assessment of NDF and IVDOM as possible predictors of intake

Abstract

The aim was to study the quality and quantity of pasture selected by sheep on various planted pastures. A further aim was to assess NDF and IVDOM as easy measurable parameters for use in equations to predict intake. Pasture samples were collected using oesophageal‐fistulated sheep and from knowledge of the in vitro digestibility of these samples and the total faeces voided as measured with faeces bags, intake was calculated. Pastures observed included ryegrass, cocksfoot, C. dactylon, Smuts finger, triticale, E. curvula, Eragrostislucerne combination, lucerne and sainfoin. Nitrogen content of oesophageal samples varied between 2,3 and 5,1%, NDF between 33 and 65% and IVDOM between 50 and 80%. Intake of grass DOM varied from 24,4 to 43,3 g/kg W^0,75/day for lambs and from 29,0 to 37,4 g/kg W^0,75/day for mature wethers. DOM intake on the two legumes was generally poor and varied between 13,7 and 22,9 g/kg W^0,75/day. Although some of the variation in voluntary intake is accounted for by the variation in NDF and IVDOM, these two parameters are of limited value as general predictors, but may be used in selection indices.

Die doel van die studie was oin die kwaliteit en kwantiteit van die weiding wat deur skape geselekteer is op verskeie aangeplante weidings te bestudeer. ‘n Tweede doel was om NBV en IVVOM as maklik meetbare parameters vir gebruik in innamevoorspellingsvergelykings te evalueer. Weidingsmonsters is deur slukdermgefistuleerde skape bekom. Deur gebruik te maak van die in vitro verteerbaarheid van hierdie monsters en die totale misuitskeiding, soos gemeet in missakke, is vrywillige inname beraam. Data is bekom van die volgende weidings: raaigras, kropaargras, C. dactylon, Smutsvinger, korog, E. curvula, Eragrostislusernkombinasie, lusern en sainfoin. Die N‐inhoud van slukdermmonsters het gewissel van 2,3 tot 5,1%, die NBV van 33 tot 65% en die IVVOM van 50 tot 80%. Die inname van gras‐VOM het gewissel van 24,4 tot 43,3 g/kg W^0,75/dag vir lammers en 29,0 tot 37,4 g/kg W^0,75/dag in die geval van volwasse hamels. Die VOM inname op die twee peulplante was meesal teleurstellend en het gewissel tussen 13,7 en 22,9 g/kg W^0,75/dag. Alhoewel ‘n deel van die variasie in vrywillige inname verklaar word deur die variasie in NBV en IVVOM, is hierdie twee parameters van beperkte waarde as algemene voorspellers. Hulle kan wel gebruik word in seleksie‐indekse.

Additional index words:

• In vitro digestibility of organic matter (IVDOM)
• neutral detergent fibre (NDF)
• oesophageal samples
• pasture selection